diff --git a/docs/contents.html b/docs/contents.html index efd75191935..6fc7c584ab2 100644 --- a/docs/contents.html +++ b/docs/contents.html @@ -78,7 +78,6 @@
  • Help Wanted
  • Development Notes
  • Source Documentation -
  • Mesa Subset Driver
  • GL Dispatch diff --git a/docs/subset-A.html b/docs/subset-A.html deleted file mode 100644 index 6dcd843749b..00000000000 --- a/docs/subset-A.html +++ /dev/null @@ -1,3572 +0,0 @@ - - - - - Mini GLX Specification - - - -

    Mesa Subset Specification

    -

    Tungsten Graphics, Inc.

    -

    February 26, 2003

    -

    Copyright © 2002-2003 by Tungsten Graphics, Inc., -Cedar Park, Texas. All Rights Reserved.
    -
    -Permission is granted to make and distribute verbatim copies of this -document provided the copyright notice and this permission notice are -preserved on all copies.
    -

    -

    OpenGL is a trademark of Silicon -Graphics, Inc..

    -

    1. Introduction

    -This document describes a subset of the Mesa implemented by Tungsten -Graphics, Inc. for embedded devices.  Prior to reading this -document the reader should be familiar with the OpenGL 1.2.1 -specification dated April 1, 1999 (available from http://www.opengl.org/developers/documentation/specs.html.) - Experience with OpenGL programming is highly advisable.
    -
    -Tungsten Graphics, Inc. is working with industry standards -organizations +in an attempt to standardize this Mesa subset and any -other possible subsets +as a result of this work.
    -
    -Appendix A contains a list of issues of which some may not be resolved.
    -
    -To summarize, the following major features of Mesa are omitted from the -subset:
    - -

    Further reductions are made at a lower level of detail.
    -

    -

    Mesa function names are printed in bold -face.  Function parameters are printed in italics.
    -

    -

    The Tungsten Graphics, Inc. Mesa subset library is hereafter -referred to as the subset.
    -
    -

    -

    2. Primitive Specification

    -

    2.1 glBegin, glEnd and glVertex Commands

    -The basic rendering primitives are points, lines and triangles. - Quadrilaterals and polygons are composed of triangles. - Primitives are drawn with the glBegin -and glEnd commands and a subset -of the glVertex commands:
    -
    -
    void glBegin(GLenummode)
    -void glEnd(void)
    -
    -void glVertex2f(GLfloat x, GLfloat y)
    -void glVertex2fv(const GLfloat -*v)
    -void glVertex3f(GLfloat x, GLfloat y, GLfloat z)
    -void glVertex3fv(const GLfloat -*v)
    -
    -
    -The mode parameter to glBegin may be one of the following
    -
    -
    GL_POINTS - a series of individual -points
    -GL_LINES - a series of disjoint line segments
    -GL_LINE_STRIP - series of connected line segments
    -GL_LINE_LOOP - a closed loop of line segments
    -GL_TRIANGLES - a series of individual triangles
    -GL_TRIANGLE_STRIP - a connected strip of triangles
    -GL_TRIANGLE_FAN - a sequence of triangles all sharing a common vertex
    -GL_QUADS - a sequence of individual quadrilaterals
    -GL_QUAD_STRIP - a connected strip of quadrilaterals
    -GL_POLYGON - a closed, convex polygon
    -
    -
    -
    -The glVertex commands take two -or three floating point coordinates, or a pointer to an array of two or -three floating point coordinates.  Vertices are actually 4-element -homogeneous coordinates.  The fourth component, unspecified by the -subset's glVertex commands, is -one.
    -
    - -

    2.2 Other Per-vertex Commands
    -

    -The glColor and glTexCoord commands may be used to -specify colors and texture coordinates for each vertex:
    -
    -
    void glColor3f(GLfloatred, GLfloat green, GLfloat blue)
    -void glColor3fv(const GLfloat *rgb)
    -void glColor4f(GLfloat red, GLfloat green, GLfloat blue, GLfloat alpha)
    -void glColor4fv(const GLfloat *rgba)
    -void glTexCoord2f(GLfloat s, GLfloat t)
    -void glTexCoord2fv(const -GLfloat *c)
    -
    -
    -The glColor commands specify -the color and optionally, the alpha value, for subsequent vertices. - For the glColor3 commands, -alpha is set to one.
    -
    -The glTexCoord2 commands -specify the texture coordinate for subsequent vertices.  Texture -coordinates are actually four-component coordinates: (s, t, r, q). - The glTexCoord2 commands -set s and t explicitly.  The r and q components are zero and one, -respectively.
    -
    -Only glVertex, glColor and glTexCoord commands are allowed -between glBegin and glEnd.  Calling any other -command between glBegin and glEnd will result in the error -GL_INVALID_OPERATION.
    -
    -

    2.3 Unsupported Commands

    -None of the following commands related to primitive specification are -supported by the subset:
    -
    -
    Per-Vertex commands:
    -
    -
    -
    glVertex2d, -glVertex2i, glVertex2s, glVertex3d, glVertex3i, glVertex3s, glVertex4d, -glVertex4i, glVertex4s, glVertex2dv, glVertex2iv, glVertex2sv, -glVertex3dv, glVertex3iv, glVertex3sv, glVertex4dv, glVertex4iv, -glVertex4sv,
    -glNormal3b, glNormal3d, glNormal3f, glNormal3i, glNormal3s,     glNormal3bv, glNormal3dv, glNormal3fv, -glNormal3iv, glNormal3sv,
    -glIndexd, glIndexf, glIndexi, glIndexs, glIndexub, glIndexdv, -glIndexfv, glIndexiv, glIndexsv, glIndexubv,
    -glColor3b, glColor3d, glColor3i, glColor3s, glColor3ub, glColor3ui, -glColor3us,     glColor3bv, -glColor3dv, glColor3iv, glColor3sv, glColor3ubv, glColor3uiv, -glColor3usv, lColor4b, -glColor4d, glColor4i, glColor4s, glColor4ub, glColor4ui, glColor4us, glColor4bv, glColor4dv, glColor4iv, -glColor4sv, glColor4ubv, glColor4uiv, glColor4usv,
    -    glTexCoord1d, glTexCoord1f, -glTexCoord1i, glTexCoord1s, glTexCoord2d, glTexCoord2i, glTexCoord2s, -glTexCoord3d, glTexCoord3f, glTexCoord3i, glTexCoord3s, glTexCoord4d, -glTexCoord4f, glTexCoord4i, glTexCoord4s, glTexCoord1dv, glTexCoord1fv, -glTexCoord1iv, glTexCoord1sv, glTexCoord2dv, glTexCoord2iv, -glTexCoord2sv, glTexCoord3dv, glTexCoord3fv, glTexCoord3iv, -glTexCoord3sv, glTexCoord4dv, glTexCoord4fv, glTexCoord4iv, -glTexCoord4sv,
    -glEdgeFlag, glEdgeFlagv
    -
    -
    -Vertex array commands:
    -
    glVertexPointer, -glColorPointer, glIndexPointer, glTexCoordPointer, glEdgeFlagPointer, -glNormalPointer, glInterleavedArrays, glArrayElement, glDrawArrays, -glDrawElements, glDrawRangeElements, glEnableClientState, -glDisableClientState
    -
    -
    -

    -Rectangle commands:
    -
    glRects, -glRecti, glRectf, glRectd, glRectsv, glRectiv, glRectfv, glRectdv,
    -
    -
    -
    -
    Lighting commands:
    -
    -
    glMaterialf, -glMateriali, glMaterialfv, glMaterialiv
    -
    -
    -
    Evaluator commands:
    -
    glEvalCoord1d, -glEvalCoord1f, glEvalCoord1dv, glEvalCoord1fv, glEvalCoord2d, glEvalCoord2f, -glEvalCoord2dv, glEvalCoord2fv,
    -    glEvalPoint1, glEvalPoint2
    -
    -
    -
    -

    3. Coordinate Transformation

    -

    3.1 Vertex Transformation

    -Vertex coordinates are transformed by the current modelview and -projection matrices then mapped to window coordinates as specified by -the viewport.  The following coordinate transformation commands are -supported by the subset
    -
    -
    glMatrixMode(GLenum mode)
    -glLoadIdentity(void)
    -glPushMatrix(void)
    -glPopMatrix(void)
    -glLoadMatrixf(const GLfloat *m)
    -glMultMatrixf(const GLfloat *m)
    -glRotatef(GLfloat angle, GLfloat x, GLfloat y, GLfloat z)
    -glTranslatef(GLfloat x, GLfloat y, GLfloat z)
    -glScalef(GLfloat x, GLfloat y, GLfloat z)
    -glFrustum(GLdouble left, GLdouble right, GLdouble bottom, GLdouble top, GLdouble near, GLdouble far)
    -glOrtho(GLdouble left, GLdouble right, GLdouble bottom, GLdouble top, GLdouble near, GLdouble far)
    -glViewport(GLint x, GLint y, GLsize width, GLsizei height)
    -
    -
    -The glMatrixMode command -specifies the current matrix. - The mode parameter may be GL_MODELVIEW or GL_PROJECTION to specify -the modelview matrix or projection matrix.  Subsequent matrix -commands will effect the current matrix.  Also associated with the -modelview and projection matrices are a modelview matrix stack and -projection matrix stack.
    -
    -The glLoadIdentity command -replaces the current matrix with the identity matrix.  The matrix -elements are specified in column-major order.
    -
    -The glPushMatrix command pushes -a copy of the current matrix onto either the modelview matrix stack or -the projection matrix stack.  The glPopMatrix -command replaces the current matrix with a copy of the top matrix off -the modelview matrix stack or projection matrix stack, the pops the -stack.  Matrix stacks are useful for traversing and rendering -hierarchical models.
    -
    -The glMultMatrixf command -post-multiplies the current matrix by the specified matrix.  The -matrix elements are specified in column-major order.
    -
    -The glRotatef command -post-multiplies the current matrix by a rotation matrix defined by the -angle and rotation axis defined by x, y and z.
    -
    -The glTranslatef command -post-multiplies the current matrix by a translation matrix defined by -the x, y and z translation parameters.
    -
    -The glScalef command -post-multiplies the current matrix by a scaling matrix defined by the x, y and z scale factors.
    -
    -The glFrustum command -post-multiplies the current matrix by a perspective projection matrix. - The near and far values specify the position of -the hither and yon Z-axis clipping planes.  The left, right, bottom and top parameters are the X and Y -extents at the near clipping plane.  glFrustum is normally used to modify -the projection matrix.
    -
    -The glOrtho command -post-multiplies the current matrix by an orthographic projection matrix. - The near and far values specify the position of -the hither and yon Z-axis clipping planes.  The left, right, bottom and top parameters specify the X and -Y-axis clipping planes.  glOrtho -is normally used to modify the projection matrix.
    -
    -The glViewport command -specifies the mapping of coordinates from normalized device coordinates -to window coordinates.  The x -and y parameters specify the -viewport's lower-left corner in the window and the width and height parameters specify the size -of the viewport.  glViewport -does not effect the current matrix.
    -
    -A coordinate transformed to window coordinates is hereafter known as (xw, -yw, zw).
    -
    -

    3.2 Clipping

    -View-volume clipping automatically discards or trims primitives which -lie completely or partially outside of the view volume specified by glFrustum and glOrtho.  Note that the glViewport command does not define a -clipping region.
    -
    -Clipping occurs in clip coordinate -space - the coordinates produced after applying the projection -matrix.
    -
    -

    3.3 Current Raster Position

    -The current raster position specifies the location for drawing images -with glBitmap.  The current -raster position is set with the commands:
    -
    -
    void glRasterPos2f(GLfloatx, GLfloat y)
    -void glRasterPos2fv(const -GLfloat *v)
    -void glRasterPos2i(GLint x, GLint y)
    -void glRasterPos2iv(const -GLint *v)
    -
    -
    -glRasterPos specifies a -4-component coordinate (x, y, 0, 1).  The coordinate is processed -like a vertex; it is transformed by the modelview matrix, the projection -matrix and mapped to the viewport.  The resulting window coordinate -is stored as the current raster position.  The coordinate is -clipped-tested against the frustum like a vertex.  If the -coordinate is clipped, then the current raster position becomes invalid -and subsequent glBitmap commands -have no effect.
    -
    -glRasterPos also updates the -current raster color and current raster texture coordinates.  The -current raster color is updated (copied) from the current color (as -specified by glColor). - The current raster texture coordinate is updated (copied) from the -current texture coordinate (as specified by glTexCoord).
    -
    -

    3.4 Unsupported Commands

    -The following commands related to vertex transformation are not -supported by the subset:
    -
    -
    User-defined clip plane commands:
    -
    glClipPlane
    -
    -
    -
    -
    Lighting and material commands:
    -
    glLightModeli, -glLightModelf, glLightModeliv, -glLightModelfv, glLightf, -glLighti, glLightfv, glLightiv, glColorMaterial
    -
    -
    -
    Automatic texture coordinate generation -commands:
    -
    -
    -
    glTexGend, -glTexGenf, glTexGeni, glTexGendv, -glTexGenfv, glTexGeniv,
    -
    -
    -Double-valued commands:
    -
    glLoadMatrixd, -glMultMatrixd, glRotated, glTranslated, glScaled
    -
    -
    -Depth Range command:
    -
    glDepthRange -(the near value is always 0.0 and the far value is always 1.0)
    -
    -
    -Extra RasterPos commands:
    -
    glRasterPos2d, -glRasterPos2s, glRasterPos3d, glRasterPos3f, glRasterPos3i, -glRasterPos3s, glRasterPos4d, glRasterPos4f, glRasterPos4i, -glRasterPos4s, glRasterPos2dv, glRasterPos2sv, glRasterPos3dv, -glRasterPos3fv, glRasterPos3iv, glRasterPos3sv, glRasterPos4dv, -glRasterPos4fv, glRasterPos4iv, glRasterPos4sv
    -
    -
    -
    -
    -

    4. Rasterization

    -This section describes the commands and options for drawing points, -lines, triangles and bitmaps.  Rasterization -is the term for the process which produces fragments from the geometric -description of a primitive (a point, line, polygon or bitmap).  For -example, given the two coordinates for the end-points of a line segment, -rasterization determines which pixels in the frame buffer are modified -to draw the line.  A -fragment is a tuple which consists of a window coordinate, colors and -texture coordinates.  The fragments produced by rasterization are -subsequently processed by the per-fragment operations described later.
    -
    -

    4.1 Point Rasterization

    -Points are rendered with the command sequence glBegin(GL_POINTS), glVertex, ... glEnd.  The window coordinate (xw, -yw, zw) is truncated to rasterize the point. - The truncated coordinate with its associated color and texture -coordinate is sent as a single fragment to the per-fragment processing -stages.
    -
    -The glPointSize command is not -supported; only 1-pixel points are supported.
    -
    -Point smoothing (antialiasing) is also not supported.
    -
    -

    4.2 Line Rasterization

    -Lines are rendered with the command sequence glBegin(mode), glVertex, glVertex, ... glEnd where mode is one of GL_LINES, -GL_LINE_STRIP or GL_LINE_LOOP.  Lines are rasterized as described -in the OpenGL specification.  Note that OpenGL specifies the half-open convention for drawing -lines: the last fragment in a line segment is omitted so that endpoint -pixels shared by two line segments will only be drawn once instead of -twice.
    -
    -

    4.2.1 Line Width

    -The width of lines can be controlled by
    -
    -
    void glLineWidth(GLfloatwidth)
    -
    -
    -where width is the line width -in pixels.  The width defaults to 1.0.  Attempting to set the -width to a value less than or equal to zero will raise the error -GL_INVALID_VALUE.
    -
    -

    4.2.2 Line Stipple
    -

    -Lines may be stippled (i.e. dashed) with the command
    -
    -
    glLineStipple(GLintfactor, GLushort pattern)
    -
    -
    -pattern describes an on/off -pattern for the fragments produced by rasterization and factor specifies how many subsequent -fragments are kept or culled for each pattern bit.  Line stippling -can be enabled or disabled by the commands glEnable(GL_LINE_STIPPLE) and glDisable(GL_LINE_STIPPLE).
    -
    -

    4.2.3 Line Antialiasing

    -Lines may be antialiased.  For antialiased lines, each fragment -produced by rasterization is assigned a coverage value which describes how -much of the fragment's area is considered to be inside the line.  Later, the -alpha value of each fragment is multiplied by the coverage value. - By blending the fragments into the frame buffer, the edges of -lines appear smoothed.
    -
    -Line antialiasing can be enabled or disabled with the commands glEnable(GL_LINE_SMOOTH) and glDisable(GL_LINE_SMOOTH).
    -
    -

    4.3 Polygon Rasterization

    -Polygons, quadrilaterals and triangles share the same polygon -rasterization options.
    -
    -Triangles are rendered by the command sequence glBegin(mode),glVertex, glVertex, ... glEnd where mode may be one of GL_TRIANGLES, -GL_TRIANGLE_STRIP or GL_TRIANGLE_FAN. - For GL_TRIANGLES mode, the number of vertices should be a multiple -of three - extra vertices will be ignored.  For GL_TRIANGLE_STRIP -and GL_TRIANGLE_FAN, at least three vertices should be specified. - If less than three are specified, nothing is drawn.  
    -
    -Quadrilaterals are rendered by -the command sequence glBegin(mode),glVertex, glVertex, ... glEnd where mode may be one of GL_QUADS or -GL_QUAD_STRIP.   For -GL_QUADS, the number of vertices should be a multiple of four - extra -vertices will be ignored.  For GL_QUAD_STRIP, the number of -vertices should be even and at least four.  Extra vertices (one) -will be ignored.
    -
    -Convex polygons are rendered -by the command sequence glBegin(GL_POLYGON),glVertex, glVertex, ... glEnd. - If less than three vertices are specified, nothing is drawn.
    -
    -

    4.3.1 Polygon Orientation

    -The winding order of vertices -(clockwise or counter-clockwise) is significant.  It is used to -determine the front-facing or back-facing orientation of polygons. - By default, a front-facing polygon's vertices are in -counter-clockwise order (in window coordinates).  Figures 2.4 and -2.5 of the OpenGL 1.2.1 specification illustrate the winding order for -front-facing triangles and quadrilaterals, respectively.
    -
    -The command
    -
    -
    void glFrontFace(GLenum mode)
    -
    -
    -specifies whether clockwise or counter-clockwise winding indicates a -front-facing polygon.  If mode -is GL_CW then polygons with clockwise winding are front-facing.  If mode is GL_CCW then polygons with -counter-clockwise winding are front-facing.  The default value is -GL_CCW.  If mode is not -GL_CCW or GL_CW then the error GL_INVALID_ENUM will be raised.
    -
    -

    4.3.2 Polygon Culling

    -Polygons may be culled (discarded) depending on whether they are -front-facing or back-facing.  The command
    -
    -
    void -glCullFace(GLenum mode)
    -
    -
    -specifies whether front-facing, back-facing or all polygons should be -culled.  If mode is -GL_FRONT then front-facing polygons will be culled.  If mode is GL_BACK then back-facing -polygons will be culled. Otherwise, if mode -is GL_FRONT_AND_BACK then all polygons will be culled.  Any other -value for mode will raise the -error GL_INVALID_ENUM.
    -
    -Polygon culling is enabled and disabled with the commands glEnable(GL_CULL_FACE) and glDisable(GL_CULL_FACE), -respectively.
    -
    -

    4.3.3 Polygon Antialiasing

    -Polygons may be antialiased in order to smooth their edges. - Polygon antialiasing is enabled and disabled with the commands glEnable(GL_POLYGON_SMOOTH) and glDisable(GL_POLYGON_SMOOTH).
    -
    -When polygon antialiasing is enabled each fragment produced by polygon, -triangle and quadrilateral rasterization will be given a coverage value which indicates how -much of the fragment is covered by the polygon.  Fragments -completely inside the polygon have coverage 1.0.  Fragments -completely outside the polygon have zero coverage (in theory). - Fragments which intersect the polygon's edge have a coverage value -in the range (0, 1).
    -
    -The fragment's alpha value is multiplied by the coverage value. - By enabling the appropriate blending mode, polygon edges will -appear smoothed.
    -
    -

    4.4 Shading

    -The command
    -
    -
    void glShadeModel(GLenummode)
    -
    -
    -determines whether colors are interpolated between vertices during -rasterization.  If mode is -GL_FLAT then vertex colors are not interpolated.  The color used -for drawing lines, triangles and quadrilaterals is that of the last -vertex used to specify each primitive.  For polygons, the color of -the first vertex specifies the color for the entire polygon.  If mode is GL_SMOOTH then vertex colors -are linearly interpolated to produce the fragment colors.
    -
    -

    4.5 Bitmap Rasterization

    -A bitmap is a monochromatic, binary image in which each image element -(or pixel) is represented by one bit.  Fragments are only generated -for the bits (pixels) which are set.  Bitmaps are commonly used to -draw text (glyphs) and markers.
    -
    -A bitmap is drawn with the command
    -
    -
    void glBitmap(GLsizeiwidth, GLsizei height, GLfloat xOrig, GLfloat yOrig, GLfloat xMove, GLfloat yMove, const  GLubyte *image)
    -
    -
    -width and height specify the image size in -pixels.  xOrig and yOrig specify the bitmap origin. - xMove and yMove are added to the current -raster position after the bitmap is rasterized.  image is a pointer to the bitmap -data.
    -
    -If the current raster position is not valid, glBitmap has no effect.
    -
    -

    4.5.1 Bitmap Unpacking

    -The first step in bitmap rendering is unpacking. - Unpacking is the process of extracting image data from -client memory subject to byte swapping, non-default row strides, etc. - The unpacking parameters are specified with the command
    -
    -
    void -glPixelStorei(GLenum pname, GLint value)
    -
    -
    -The following unpacking parameters may be set:
    -
    - - - - - - - - - - - - - - - - - - -
    Parameter (pname)
    -     		Value (value)
    -     		Default
    -
    GL_UNPACK_ROW_LENGTH
    -     		Width of the image in memory, in -pixels.
    -     		0
    -
    GL_UNPACK_LSB_FIRST
    -     		GL_FALSE indicates that the most -significant bit is unpacked first from each byte.  GL_TRUE -indicates that the least significant bit is unpacked first from each -byte.
    -     		GL_FALSE
    -
    -
    -
    -The GL_UNPACK_ROW_LENGTH specifies the stride (in pixels) for advancing -from one row of the image to the next.  If it's zero, the width parameter to glBitmap specifies the width of the -image in memory.
    -
    -GL_UNPACK_LSB_FIRST determines whether the least significant or most -significant bit in each byte is unpacked first.  Unpacking occurs -in left to right order (in image space).
    -
    -The value of bit (i, j) of the image (where i is the image row and j is -the image column) is found as follows:
    -
    -
    rowLength = (GL_UNPACK_ROW_LENGTH != 0) -? GL_UNPACK_ROW_LENGTH : width;
    -
    -byte = image[((rowLength + 7) -/ 8) * i + j / 8];
    -
    -if (GL_UNPACK_LSB_FIRST != 0)
    -    bitMask = 1 << (j % 8);
    -else
    -    bitMask = 128 >> (j % 8);
    -
    -if (byte & bitMask)
    -    bit = 1;
    -else
    -    bit = 0;
    -
    -
    - -

    4.5.2 Rasterization

    -If the current raster position is (xrp, yrp, zrp, -wrp), then the bitmap is rasterized according to the -following algorithm:
    -
    -for (j = 0; j < height; -j++) {
    -    for (i = 0; i < width; -i++) {
    -        if (bit(i,j)) {
    -            fragment.x = -floor(xrp - xOrig) -+ i;
    -            fragment.y = -floor(yrp - yOrig) -+ j;
    -            fragment.color -= GL_CURRENT_RASTER_COLOR;
    -            -fragment.texture = GL_CURRENT_RASTER_TEXTURE_COORDS;
    -            -ProcessFragment(fragment)
    -         }
    -    }
    -}
    -
    -After the bitmap has been rendered the current raster position is -updated as follows:
    -
    -
    xrp = xrp + xMove
    -yrp = yrp + yMove
    -
    -
    -

    4.5.3 Per-fragment Operations

    -XXX supported?  See issue in appendix A.
    -
    -

    4.6 Unsupported Commands

    -The following commands related to rasterization are not supported by -the subset.
    -
    -
    Point commands:
    -
    glPointSize
    -
    -
    -Polygon commands:
    -
    glPolygonStipple
    -glPolygonOffset
    -glPolygonMode
    -
    -
    -
    -
    Pixel storage commands:
    -
    -
    glPixelStoref
    -
    -
    -
    -

    5. Texture Mapping
    -

    -There are four elements to texture mapping: texture coordinate -specification, texture image specification, texture sampling and texture -application.
    -
    -Texture mapping is enabled and disabled with the commands glEnable(GL_TEXTURE_2D) and glDisable(GL_TEXTURE_2D).
    -
    -

    5.1 Texture Image Specification

    -A texture image is specified with the command:
    -
    -
    void glTexImage2D(GLenum target, GLint level, GLint internalFormat, GLsizei width, GLsizei height, GLint border, GLenum format, GLenum type, const GLvoid *pixels )
    -
    -
    -target must be GL_TEXTURE_2D. - level indicates the -mipmap level for mipmap textures.  internalFormat -is a hint to indicate the preferred internal storage format for the -texture.  width and height indicate the image size in -pixels (or texels).  border must -be zero.  format and type describe the pixel format and -data type for the incoming image.  pixels -points to the incoming texture image.  These parameters are -described in more detail below.
    -
    -

    5.1.1 Texture Image Size and Mipmaps

    -

    -Texture images must have dimensions (width and height) that are powers -of two. For example: 256 x 256, 32 x 1024, 1 x 8, etc.  That is, it -must be the case that width = -2n and height = 2m -for some positive integers n and m.
    -
    -Mipmapping is a method of antialiasing or filtering textures to improve -their appearance.  A mipmap is a set of images consisting of a base -image and a set of filtered, reduced-resolution images.  If the -base image (level=0) is of -width 2n and height 2m then the level 1 image must -be of width 2n-1 and height 2m-1.  Each mipmap -level is half the width and height of the previous level, or at least -one.  The last mipmap level has a width and height of one.
    -
    -The following is an example of a mipmap's image levels:
    -
    - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    mipmap level
    -     		width
    -     		height
    -
    0
    -     		256
    -     		64
    -
    1
    -     		128
    -     		32
    -
    2
    -     		64
    -     		16
    -
    3
    -     		32
    -     		8
    -
    4
    -     		16
    -     		4
    -
    5
    -     		8
    -     		2
    -
    6
    -     		4
    -     		1
    -
    7
    -     		2
    -     		1
    -
    8
    -     		1
    -     		1
    -
    -
    -If the width or height parameters are not powers of -two, the error GL_INVALID_VALUE is raised.  If the image levels in -a mipmap do not satisfy the restrictions listed above the texture is -considered to be inconsistent -and the system will behave as if the texturing is disabled.
    -
    -

    5.1.2 Texture Image Formats and Unpacking

    -The glTexImage2D command's format and type parameters describe the format -of the incoming texture image.  Accepted values for format are GL_INTENSITY, GL_RGB and -GL_RGBA.  The type -parameter must be GL_UNSIGNED_BYTE.  Pixel component values are -thus in the range 0 through 255.
    -
    -If format is GL_INTENSITY then -the image has one byte per pixel which specifies the pixel's red, green, -blue and alpha values.
    -
    -If format is GL_RGB then the -image has three bytes per pixel which specify the pixel's red, green and -blue values (in that order).  The alpha value defaults to 255.
    -
    -If format is GL_RGBA then the -image has four bytes per pixel which specify the pixel's red, green, -blue and alpha values (in that order).
    -
    -The command
    -
    -
    void -glPixelStorei(GLenum pname, -GLint value)
    -
    -
    -controls the unpacking of texture image data from client memory.  pname may be GL_UNPACK_ROW_LENGTH to -indicate the stride, in pixels, between subsequent rows of the image in -client memory.  If GL_UNPACK_ROW_LENGTH is zero (the default) then -the width parameter to glTexImage2D determines the stride.
    -
    -

    5.1.3 Internal Texture Format

    -glTexImage2D converts the incoming -texture image to one of the supported internal texture formats.
    -
    -The internalFormat parameter -indicates the desired internal format for the texture and may be either -GL_INTENSITY8, GL_RGB5 or GL_RGBA8.
    -
    -If internalFormat is -GL_INTENSITY8 then the texture has one byte per texel (texture element) -which indicates the texel's intensity (or brightness).  The -intensity is obtained from the incoming image's red channel.
    -
    -If internalFormat is GL_RGB5 -then the texture is stored with two bytes per texel:  5 bits per -red value, 5 bits per green value and 5 bits per blue value.
    -
    -If internalFormat is -GL_RGBA8 then the texture is stored with four bytes per texel:  8 -bits for each of the red, green,  blue and alpha values.
    -
    -The internal format is also significant to texture application (see -section 5.4).
    -
    -

    5.2 Texture Coordinates

    -Texture coordinates control the mapping from local polygon space to -texture image space.  Texture coordinates are set for each vertex -with the glTexCoord commands. - During line and polygon rasterization the vertex's texture -coordinates are interpolated across the primitive to produce a texture -coordinate for each fragment.  The fragment texture coordinates are -used to sample the current texture image.
    -
    -Texture coordinates are normally in the range [0, 1].  Values -outside that range are processed according to the texture wrap mode.  The -texture wrap mode is set with the command
    -
    -
    void glTexParameteri(GLenum target, GLenum pname, GLint value)
    -
    -
    -target must be GL_TEXTURE_2D. - If pname is -GL_TEXTURE_WRAP_S or GL_TEXTURE_WRAP_T then value must be either -GL_CLAMP_TO_EDGE or GL_REPEAT.
    -
    -For GL_CLAMP_TO_EDGE, texture coordinates are effectively clamped to -the interval [0, 1].
    -
    -For GL_REPEAT, the integer part of texture coordinates is ignored; only -the fractional part of the texture coordinates is used.  This -allows texture images to repeated or tiled across an object.
    -
    -

    5.3 Texture Sampling

    -Texture sampling is the process of using texture coordinates to extract -a color from the texture image.  Multiple, weighted samples may be -taken from the texture and combined during the filtering step.
    -
    -During texture coordinate interpolation a level of detail value (lambda) is -computed for each fragment.  For a mipmapped texture, lambda -determines which level (or levels) of the mipmap will be sampled to -obtain the texture color.
    -
    -If lambda indicates that multiple texels map to a single screen pixel, -then the texture minification -filter will be used.  Otherwise, if lambda indicates that a single -texel maps to multiple screen pixels, then the texture magnification filter will be used.
    -
    -

    5.3.1 Texture Minification

    -The texture minification filter is set with the glTexParameteri command by setting target to GL_TEXTURE_2D, setting pname to GL_TEXTURE_MIN_FILTER and -setting value to GL_NEAREST, -GL_LINEAR, GL_NEAREST_MIPMAP_NEAREST,  -GL_NEAREST_MIPMAP_LINEAR,   GL_LINEAR_MIPMAP_NEAREST or -GL_LINEAR_MIPMAP_LINEAR.
    -
    -GL_NEAREST samples the texel nearest the texture coordinate in the -level 0 texture image.
    -
    -GL_LINEAR samples the four texels around the texture coordinate in the -level 0 texture image.  The four texels are linearly weighted to -compute the final texel value.
    -
    -GL_NEAREST_MIPMAP_NEAREST samples the texel nearest the texture -coordinate in the level N texture image.  N is the level of detail -and is computed by the partial derivatives of the texture coordinates -with respect to the window coordinates.
    -
    -GL_NEAREST_MIPMAP_LINEAR samples two texels nearest the texture -coordinates in the level N and N+1 texture images.  The two texels -are linearly weighted to compute the final texel value.  N is the -level of detail and is computed by the partial derivatives of the -texture coordinates with respect to the window coordinates.
    -
    -GL_LINEAR_MIPMAP_NEAREST samples four texels around the texture -coordinate in the level N texture image.  The four texels are -linearly weighted to compute the final texel value.  N is the level -of detail and is computed by the partial derivatives of the texture -coordinates with respect to the window coordinates.
    -
    -GL_LINEAR_MIPMAP_LINEAR samples four texels around the texture -coordinate in the level N texture image and four texels around the -texture coordinate in the level N+1 texture image.  The eight -texels are linearly weighted to compute the final texel value.  N -is the level of detail and is computed by the partial derivatives of the -texture coordinates with respect to the window coordinates.
    -
    -Filter modes other than GL_LINEAR and GL_NEAREST requires that the -texture have a complete set of mipmaps.  If the mipmap is -incomplete, it is as if texturing is disabled.
    - 
    -

    5.3.2 Texture Magnification

    -The texture magnification filter is set with the glTexParameteri command -by setting target to -GL_TEXTURE_2D, setting pname to -GL_TEXTURE_MAG_FILTER and setting value -to GL_NEAREST or GL_LINEAR.
    -
    -GL_NEAREST samples the texel nearest the texture coordinate in the -level 0 texture image.
    -
    -GL_LINEAR samples the four texels around the texture coordinate in the -level 0 texture image.  The four texels are linearly weighted to -compute the final texel value.
    -
    -

    5.4 Texture Application

    -The sampled texture value is combined with the incoming fragment color -to produce a new fragment color.  The fragment and texture colors -are combined according to the texture environment mode and the current -texture's base internal format.  The texture environment mode is -set with the command
    -
    -
    void -glTexEnvi(GLenum target, -GLenum pname, GLint value)
    -
    -
    -target must be GL_TEXTURE_ENV. - If pname is -GL_TEXTURE_ENV_MODE then value -must be one of GL_REPLACE, GL_MODULATE, GL_DECAL, or GL_BLEND.
    -
    -There is also a texture environment -color that can factor into texture application.  The texture -environment color can be set with the command
    -
    -
    void -glTexEnvfv(GLenum target, -GLenum pname, const GLfloat *value)
    -
    -
    -target must be GL_TEXTURE_ENV. - If pname is -GL_TEXTURE_ENV_COLOR then value must -point to an array of four values which specify the red, green, blue, -and alpha values of the texture environment color.  The values are -clamped to the range [0, 1].  The default color is (0, 0, 0, 0).
    -
    -The following table describes the arithmetic used for each combination -of environment mode and base internal format.  (Rf, Gf, Bf, Af) is -the incoming fragment color.  (Rt, Gt, Bt, At) is the sampled -texture color.  Lt is the sampled texture luminance.  'It' is the sampled texture -intensity.  (Rc, Gc, Bc, Ac) is the texture environment color. - (Rv, Gv, Bv, Av) is the resulting value.
    -
    -
    - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    Base Internal Format
    -     		GL_REPLACE
    -     		GL_MODULATE
    -     		GL_DECAL
    -     		GL_BLEND
    -
    GL_INTENSITY
    -     		Rv = It
    -Gv = It
    -Bv = It
    -Bf = It
    -     		Rv = Rf * It
    -Gv = Gf * It
    -Bv = Bf * It
    -Av = Af * It    		undefined
    -     		Rv = Rf*(1-It) + Rc*It
    -Gv = Gf*(1-It) + Gc*It
    -Bv = Bf*(1-It) + Bc*It
    -Av = Af*(1-It) + Ac*It
    GL_RGB
    -     		Rv = Rt
    -Gv = Gt
    -Bv = Bt
    -Av = Af
    -     		Rv = Rf * Rt
    -Gv = Gf * Gt
    -Bv = Bf * Bt
    -Av = Af
    -     		Rv = Rt
    -Gv = Gt
    -Bv = Bt
    -Av = Af    		Rv = Rf*(1-Rt) + Rc*Rt
    -Gv = Gf*(1-Gt) + Gc*Gt
    -Bv = Bf*(1-Bt) + Bc*Bt
    -Av = Af
    GL_RGBA
    -     		Rv = Rt
    -Gv = Gt
    -Bv = Bt
    -Av = At
    -     		Rv = Rf * Rt
    -Gv = Gf * Gt
    -Bv = Bf * Bt
    -Av = Af * At    		Rv = Rf*(1-At) + Rt*At
    -Gv = Gf*(1-At) + Gt*At
    -Bv = Bf*(1-At) + Bt*At
    -Av = Af
    -     		Rv = Rf*(1-Rt) + Rc*Rt
    -Gv = Gf*(1-Gt) + Gc*Gt
    -Bv = Bf*(1-Bt) + Bc*Bt
    -Av = Af*At
    -
    -
    -
    -

    5.5 Texture Objects

    -Texture objects encapsulate a set of texture images (mipmap) and -related state into a named object.  This facilitates use of -multiple textures in an application.  Texture objects are named -with GLuints (unsigned integers).  There is a default texture -object with the name/identifier zero which can never be deleted.
    -
    -

    5.5.1 Creating Texture Objects

    -A texture object is created by binding a new GLuint identifier to the -GL_TEXTURE_2D target with the command:
    -
    -
    void glBindTexture(GLenum target, GLuint textureID)
    -
    -
    -target must be GL_TEXTURE_2D. - textureID may be any -unsigned integer.  If textureID -does not name an existing texture object, a new texture object with that -ID will be created, initialized to the default state.  Whether the -ID is new or existed previously, that named texture object is bound as -the current texture object. - Subsequent glTexParameter andglTexImage2D calls will effect the -current texture object.
    -
    -

    5.5.2 Deleting Texture Objects

    -One or more texture objects may be deleted with the command:
    -
    -
    void glDeleteTextures(GLsizein, const GLuint *textureIDs)
    -
    -
    -textureIDs is an array of n texture IDs.  The named -texture objects will be deleted.  If the current texture object is -deleted the default texture object (number 0) will be bound as the -current texture object.
    -
    -

    5.5.3 Allocating Texture Object Identifiers

    -A list of new, unused texture IDs can be obtained by calling the command
    -
    -
    void glGenTextures(GLsizei n, GLuint *textureIDs)
    -
    -
    -An array of n unused texture -IDs will be returned in the textureIDs -array.
    -
    -
    -

    6. Per-fragment Operations

    -The fragments produced by rasterization are subjected to a number of -operations which either modify the fragment or test the fragment -(discarding the fragment if the test fails.)  This chapter -describes the per-fragment operations.  They are presented in the -order in which they're performed.  If a fragment fails a test it is -discarded and not subjected to subsequent tests or modifications.
    -
    -

    6.1 Scissor Test

    -The scissor test limits rendering to a 2-D rectangular region of the -framebuffer.  The command
    -
    -
    void glScissor(GLintx, GLint y, GLsizei width, GLsizei height)
    -
    -
    -defines a clipping region with the lower-left corner at (x, y) and the given width and height.  The scissor test is -enabled and disabled with the command glEnable(GL_SCISSOR_TEST) -and glDisable(GL_SCISSOR_TEST).
    -
    -If the incoming fragment's position is (xf, yf) -then the fragment will pass the test if x <= xf < x + width and y <= yf < y + height.  Otherwise, the -fragment is discarded.
    -
    -If width or height is less than zero the error -GL_INVALID_VALUE is raised.  The default scissor rectangle bounds -are (0, 0, w, h) where w is the initial window width and h is the -initial window height.  The scissor test is disabled by default.
    -
    -

    6.2 Alpha Test

    -The alpha test compares the fragment's alpha value against a reference -value and discards the fragment if the comparison fails.  The test -is specified by the command
    -
    -
    void glAlphaFunc(GLenummode, GLclampf reference)
    -
    -
    -mode specifies an inequality -and reference specifies a value -to compare against.  The following table lists all possible -modes and the -corresponding test:
    -
    - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    Comparison mode
    -     		The test passes if
    -
    GL_LESS
    -     		alpha < reference
    -
    GL_LEQUAL
    -     		alpha <= reference
    GL_GREATER
    -     		alpha > reference
    GL_GEQUAL
    -     		alpha >= reference
    GL_EQUAL
    -     		alpha == reference
    GL_NOTEQUAL
    -     		alpha != reference
    GL_NEVER
    -     		never pass
    -
    GL_ALWAYS
    -     		always passes
    -
    -
    -The reference parameter is -clamped to the range [0, 1].
    -
    -The alpha test is enabled and disabled with the commands glEnable(GL_ALPHA_TEST) and glDisable(GL_ALPHA_TEST).
    -
    -The default mode is GL_ALWAYS and the default reference value is 0.
    -
    -

    6.3 Stencil Test

    -The stencil buffer stores an N-bit integer value for each pixel in the -frame buffer.  The stencil test compares the stencil buffer value -at the fragment's position to a reference value and possibly discards -the fragment based on the outcome.  Furthermore, the stencil buffer -value may be updated or modified depending on the outcome.  If -there is no stencil buffer the stencil test is bypassed.
    -
    -Stenciling is controlled by the commands
    -
    -
    void glStencilFunc(GLenumfunc, GLint ref, GLuint mask)
    -void glStencilOp(GLenum stencilFail, GLenum depthTestFail, GLenum depthTestPass)
    -
    -
    -The glStencilFunc command controls the -stencil test while glStencilOp -command controls the how the stencil buffer is updated/modified after -the test.
    -
    -ref is clamped to the range [0, -2N-1] where N is the number of bits per stencil value in the -stencil buffer.
    -
    -The following table lists all possible values for the func parameter and when the stencil -test will pass.  Both the stencil buffer value and the stencil -reference value are bit-wise ANDed with the mask parameter before the test.
    -
    - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    Stencil func value
    -     		Stencil test passes if
    -
    GL_LESS
    -     		(ref&mask) < (stencil buffer value -& mask)
    -
    GL_LEQUAL
    -     		(ref -& mask) <= (stencil -buffer value & mask)
    GL_GREATER
    -     		(ref -& mask) > (stencil -buffer value & mask)
    GL_GEQUAL
    -     		(ref -& mask) >= (stencil -buffer value & mask)
    GL_EQUAL
    -     		(ref -& mask) == (stencil -buffer value & mask)
    GL_NOTEQUAL
    -     		(ref -& mask) != (stencil -buffer value & mask)
    GL_NEVER
    -     		never passes
    -
    GL_ALWAYS
    -     		always passes
    -
    -
    -
    -If the stencil test passes, the fragment is passed to the next -per-fragment operation.  Otherwise, if the stencil test fails, the -value in the stencil buffer is updated according to the value of the stencilFail parameter to glStencilOp.
    -
    - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    stencilFail -value
    -     		New stencil buffer value
    -
    GL_KEEP
    -     		originalValue
    -
    GL_ZERO
    -     		0
    -
    GL_INVERT
    -     		BitWiseInvert(originalValue) -i.e. ~originalValue
    -
    GL_REPLACE
    -     		ref
    -
    GL_INCR
    -     		originalValue + 1, clamped to -[0, 2N-1]
    GL_DECR
    -     		originalValue - 1, clamped to -[0, 2N-1]
    -
    -
    -The depthTestFail and depthTestPass parameters to glStencilOp are ignored.  Values -for func and stencilFail other than those listed -in the table will cause the error GL_INVALID_ENUM to be raised.
    -
    -The stencil test is enabled and disabled with the commands glEnable(GL_STENCIL_TEST) and glDisable(GL_STENCIL_TEST).
    -
    -The default stencil function is GL_ALWAYS.  The default stencil -reference value is 0.  The default stencil mask is ~0.  The -default stencil fail operation is GL_KEEP.
    -
    -Values written into the stencil buffer are masked with the command
    -
    -
    void glStencilMask(GLuintmask)
    -
    -
    -Only the bits which are set in mask -will be modified in the stencil buffer when written to.  If each -stencil buffer value has N bits, only the least significant N bits of mask are relevant.  The default -stencil mask is ~0.
    -
    -

    6.4 Blending and Logicop

    -Blending or a logic operation combines the incoming fragment color with -the destination frame buffer color according to a blending equation or -bit-wise Boolean logical operation.
    -
    -Blending is enabled and disabled with the commands glEnable(GL_BLEND) and glDisable(GL_BLEND).
    -
    -The logic operation is enabled and disabled with the commands glEnable(GL_LOGIC_OP) and glDisable(GL_LOGIC_OP).
    -
    -If both blending and the logic operation are enabled, the logic -operation has higher priority; blending is bypassed.
    -
    -

    6.4.1 Logic Op

    -The command
    -
    -
    void glLogicop(GLenummode)
    -
    -
    -Specifies the Boolean logic operation for combining the incoming -fragment color with the destination frame buffer color.  Both the -incoming fragment color and destination frame buffer colors are -interpreted as four-tuples of unsigned integer color components in the -range [0, 2N-1] where N is the number of bits per color -channel.  N may not be the same for all color channels.
    -
    -The following table lists all values for mode and the boolean arithmetic used -to combine the incoming fragment color value (src) with the destination framebuffer -color value (dst).  Standard ANSI C operators used.
    -
    - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    LogicOp mode
    -     		Resulting channel value
    -
    GL_CLEAR
    -     		0
    -
    GL_SET
    -     		~0
    -
    GL_COPY
    -     		src
    -
    GL_COPY_INVERTED
    -     		~s
    -
    GL_NOOP
    -     		dst
    -
    GL_INVERT
    -     		~dst
    -
    GL_AND
    -     		src & dst
    -
    GL_NAND
    -     		~(src & dst)
    -
    GL_AND_REVERSE
    -     		src & ~dst
    -
    GL_AND_INVERTED
    -     		~src & dst
    -
    GL_OR
    -     		src | dst
    -
    GL_NOR
    -     		~(src | dst)
    -
    GL_OR_REVERSE
    -     		src | ~dst
    -
    GL_OR_INVERTED
    -     		~src | dst
    -
    GL_XOR
    -     		src ^ dst
    -
    GL_EQUIV
    -     		~(src ^ dst)
    -
    -
    -The fragment's color is replaced by the result of the logic operation.
    -
    -Specifying any value for mode -other than those listed in the above table will cause the error -GL_INVALID_ENUM to be raised.
    -
    -The default value for mode is -GL_COPY.  The logic operation is disabled by default.
    -
    -

    6.4.2 Blending

    -The command
    -
    -
    void glBlendFunc(GLenumsrcTerm, GLenum dstTerm)
    -
    -
    -specifies the terms of the blending equation.  If Cf = (Rf, Gf, -Bf, Af) is the incoming fragment color and Cb = (Rb, Gb, Bb, Ab) is the -frame buffer color, then the resulting color Cv = (Rv, Gv, Bv, Av) is -computed by:
    -
    -
    Cv = Cf * srcTerm + Cb * dstTerm
    -
    -
    -All possible values for srcTerm -and the corresponding arithmetic term are listed in the following table:
    -
    - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    srcTerm
    -     		srcTermArithmetic
    -
    GL_ZERO
    -     		(0, 0, 0, 0)
    -
    GL_ONE
    -     		(1, 1, 1, 1)
    -
    GL_DST_COLOR
    -     		(Rb, Gb, Bb, Ab)
    -
    GL_ONE_MINUS_DST_COLOR
    -     		(1-Rb, 1-Gb, 1-Bb, 1-Ab)
    -
    GL_SRC_ALPHA
    -     		(Af, Af, Af, AF)
    -
    GL_ONE_MINUS_SRC_ALPHA
    -     		(1-Af, 1-Af, 1-Af, 1-Af)
    -
    GL_DST_ALPHA
    -     		(Ab, Ab, Ab, Ab)
    -
    GL_ONE_MINUS_DST_ALPHA
    -     		(1-Ab, 1-Ab, 1-Ab, 1-Ab)
    -
    GL_SRC_ALPHA_SATURATE
    -     		(m, m, m, 1) where m = MIN(Af, -1-Ab)
    -
    -
    -All possible values for srcTerm -and the corresponding arithmetic term are listed in the following table:
    -
    - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    dstTerm
    -     		dstTermArithmetic
    -
    GL_ZERO
    -     		(0, 0, 0, 0)
    -
    GL_ONE
    -     		(1, 1, 1, 1)
    -
    GL_SRC_COLOR
    -     		(Rf, Gf, Bf, Af)
    -
    GL_ONE_MINUS_SRC_COLOR
    -     		(1-Rf, 1-Gf, 1-Bf, 1-Af)
    -
    GL_SRC_ALPHA
    -     		(Af, Af, Af, AF)
    -
    GL_ONE_MINUS_SRC_ALPHA
    -     		(1-Af, 1-Af, 1-Af, 1-Af)
    -
    GL_DST_ALPHA
    -     		(Ab, Ab, Ab, Ab)
    -
    GL_ONE_MINUS_DST_ALPHA
    -     		(1-Ab, 1-Ab, 1-Ab, 1-Ab)
    -
    -
    -The fragment's color is replaced by the result of the blending equation.
    -
    -Values for srcTerm and dstTerm other than those listed in -the table will cause the error GL_INVALID_ENUM to be raised.
    -
    -The default value for srcTerm -is GL_ONE.  The default value for dstTerm -is GL_ZERO.  Blending is disabled by default.
    -
    -

    6.5 Color Mask

    -The final fragment color is written into the current color buffer at -the end of the per-fragment operations.  Normally, all color -channels in the frame buffer are replaced with the final fragment color. - However, the command
    -
    -
    void glColorMask(GLbooleanredMask, GLboolean greenMask, GLboolean blueMask, GLboolean alphaMask)
    -
    -
    -allows selective writing to individual color channels.  If redMask is GL_TRUE then writing to -the red color channel is enabled, otherwise it's disabled. - Similarly, the green, blue and alpha channels can also be masked.
    -
    -Initially all four mask values are GL_TRUE.
    -
    -Color masking is not enabled/disabled with the glEnable/glDisable commands.
    -
    -

    7. Frame Buffer Operations

    -The frame buffer is considered to be a two-dimensional array of pixels. - The frame buffer is also organized into layers or logical buffers. - There may be a front color buffer, back color buffer and stencil -buffer.  A double-buffered frame buffer has both a front color -buffer and back color buffer.  A single-buffered framebuffer only -has a front color buffer.  Each pixel in a color buffer has a red, -green and blue value and an optional alpha value.
    -
    -

    7.1 Clearing Buffers

    -Buffers are cleared (set to uniform values) with the command
    -
    -
    void glClear(GLbitfieldbuffers)
    -
    -
    -buffers is a bitmask for which -the value may be the bitwise-OR of the values GL_COLOR_BUFFER_BIT and -GL_STENCIL_BUFFER_BIT.  If the GL_COLOR_BUFFER_BIT bit is -specified, the current color buffer will be cleared.  If the -GL_STENCIL_BUFFER_BIT bit is specified, the stencil buffer will be -cleared.
    -
    -The current color buffer is specified with the command
    -
    -
    void glDrawBuffer(GLenum buffer)
    -
    -
    -buffer may be either GL_FRONT, -GL_BACK or GL_NONE.  GL_FRONT indicates that the front color buffer -will be modified by glClear and -any drawing command.  GL_BACK indicates that the back color buffer -will be modified by glClear and -any drawing command.  GL_NONE indicates that neither color buffer -will be modified by glClear or -any drawing command.  GL_BACK is only valid for double-buffered -frame buffers.
    -
    -The current scissor rectangle, set by the glScissor command, effects glClear, limiting -the clear to the scissor rectangle, if it's enabled.  Furthermore, only the color channels enabled by glColorMask will be effected by glClear(GL_COLOR_BUFFER_BIT). - Likewise, only the stencil bits enabled by glStencilMask will be effected by glClear(GL_STENCIL_BUFFER_BIT).
    -
    -The current clear color is set with the command
    -
    -
    void glClearColor(GLclampfred, GLclampf green, GLclampf blue, GLclampf alpha)
    -
    -
    -Subsequent calls to glClear -will use the color (red, green, blue, -alpha) to clear the front or back color buffers.
    -
    -The current stencil clear value is set with the command
    -
    -
    void glClearStencil(GLintclearValue)
    -
    -
    -If the stencil buffer is N bits deep, the least significant N bits of clearValue will be used to clear the -stencil buffer.
    -
    -
    -

    8. Other Features

    -

    8.1 Frame Buffer Readback

    -A rectangular region of pixels can be read from the frame buffer and -placed in client memory with the command
    -
    -
    void glReadPixels(GLintx, GLint y, GLsizei width, GLsizei height, GLenum format, GLenum type, GLvoid *data)
    -
    -
    -x and y specify the coordinate of the -lower-left corner of the region to read and width and height specify the size of the -rectangular region to read.  format -specifies the format of image data and must be either GL_RGB or -GL_RGBA.  type specify the -data type of the image data and must be either GL_UNSIGNED_BYTE or -GL_FLOAT.  Other values for format -or type will cause the error -GL_INVALID_ENUM to be raised.
    -
    -The framebuffer may contain 3-component colors (red, green, blue) or -4-component colors (red, green, blue, alpha).  If an alpha channel -is not present, alpha values default to 1.0.
    -
    -The frame buffer color components (red, green, blue, alpha) are either -converted to 8-bit unsigned integers in the range[0, 255] if type is GL_UNSIGNED_BYTE or -converted to floating point values in the range [0, 1] if type is GL_FLOAT.  The (red, -green, blue, alpha) tuples are then stored as GL_RGB triplets (by -dropping the alpha component) or GL_RGBA quadruples in client memory.
    -
    -Image data is packed into -client memory according to the pixel packing parameters which are set by -the command
    -
    -
    void glPixelStorei(GLenum pname, GLint value)
    -
    -
    -pname must be -GL_PACK_ROW_LENGTH.  value -indicates the stride (in pixels) between subsequent rows in the -destination image.  If GL_PACK_ROW_LENGTH is zero (the default) -then the width parameter to glReadPixels indicates the row stride.
    -
    -Pixel readback takes place as follows:
    -
    -
    if (GL_PACK_ROW_LENGTH == 0)
    -    rowLength = width;
    -else
    -    rowLength = GL_PACK_ROW_LENGTH
    -
    -if (format == GL_RGB) {
    -    for (i = 0; i < height; -i++) {
    -        for (j = 0; j < width; j++) {
    -            k = (i * -rowLength + j) * 3;
    -            data[k+0] = FrameBuffer(x + j, y + i).red;
    -            data[k+1] = FrameBuffer(x + j, y + i).green;
    -            data[k+2] = FrameBuffer(x + j, y + i).blue;
    -        }
    -    }
    -}
    -else {
    -    for (i = 0; i < height; -i++) {
    -        for (j = 0; j < width; j++) {
    -            k = (i * -rowLength + j) * 4;
    -            data[k+0] = FrameBuffer(x + j, y + i).red;
    -            data[k+1] = FrameBuffer(x + j, y + i).green;
    -            data[k+2] = FrameBuffer(x + j, y + i).blue;
    -            data[k+3] = FrameBuffer(x + j, y + i).alpha;
    -        }
    -    }
    -}
    -
    -
    -The function FrameBuffer(c, r) -returns the pixel in the frame buffer at column c of row r.  data is considered to be either a -GLubyte pointer or a GLfloat pointer, depending on the type parameter.  Similarly, the -FrameBuffer function returns either GLubyte values in the range [0, 255] -or GLfloat values in the range [0,1], depending on the type parameter.
    -
    -Pixels may be read from either the front or back color buffer. - The command
    -
    -
    void glReadBuffer(GLenumbuffer)
    -
    -
    -specifies the source for reading images with glReadPixels.  If buffer is GL_FRONT then front color -buffer is the source.  If buffer -is GL_BACK then the back color buffer is the source.  It is illegal -to specify GL_BACK when the color buffer is not double buffered. - Any invalid value for buffer -will raise the error GL_INVALID_ENUM.
    -
    -The default read source is GL_BACK if the frame buffer is double -buffered.  Otherwise, the default read source is GL_FRONT.
    -
    -

    8.2 Selection Mode

    -Selection mode is typically used to implement picking: determining which -primitive(s) are present at particular window positions.  The -command
    -
    -
    GLint glRenderMode(GLenummode)
    -
    -
    -is used to enable selection mode.  If mode is GL_SELECTION the graphics -library is put into selection mode.  If mode is GL_RENDER the graphic -library is put into normal rendering mode.  Any other value for mode will raise the error -GL_INVALID_ENUM.
    -
    -When in selection mode rendering commands will not effect the -framebuffer.  Instead, a record of the primitives that would have -been drawn is placed in the selection buffer.  The selection buffer -is specified with the command
    -
    -
    void glSelectionBuffer(GLsizein, GLuint *buffer)
    -
    -
    -buffer     is an array of n -unsigned integers.  No more than n -values will be placed in the buffer.
    -
    -The name stack is a stack -(LIFO) of unsigned integer names.  The following commands -manipulate the name stack:
    -
    -
    void glInitNames(void)
    -void glPushName(GLuint name)
    -void glPopName(void)
    -void glLoadName(GLuint name)
    -
    -
    -glInitNames resets the name -stack to an empty state.  glPushName pushes the given name value onto the stack.  glPopName pops the top name from the -stack.  glLoadName replaces the top value on -the stack with the specified name. - Stack underflow and overflow conditions cause the errors -GL_STACK_OVERFLOW and GL_STACK_UNDERFLOW to be raised.
    -
    -While in selection mode, primitives (points, lines, polygons) are -transformed and clip-tested normally.  Primitives which aren't -discarded by clipping cause the hit data to be updated.  The hit -data consists of three pieces of information: a hit flag, a minimum Z -value and a maximum Z value.  First, the hit flag is set. - Then, for each of the primitive's vertices, the vertex Z value is -compared to the minimum and maximum Z values.  The minimum Z value -is updated if the vertex's Z value is less than the minimum Z value. - The maximum Z value is updated if the vertex's Z value is greater -than the maximum Z value.
    -
    -When any of glInitNames, glPushName, glPopName, glLoadName or glRenderMode are called and the hit -flag is set, a hit record is -written to the selection buffer.
    -
    -A hit record consists of a sequence of unsigned integers.  The -first value is the size of the name stack.  The second value is the -minimum Z value multiplied by 232-1.  The third value is -the maximum Z value multiplied by 232-1.  The remaining -values are the values in the name stack, in bottom to top order. - The hit flag is cleared after a hit record is written to the -selection buffer.  Hit records are places sequentially into the -selection buffer until it is full or selection mode is terminated.
    -
    -Selection mode is terminated by calling glRenderMode(GL_RENDER).   The -return value of glRenderMode -will be -1 if the selection buffer overflowed.  Otherwise, the -return value will indicate the number of values written into the -selection buffer.
    -
    -

    8.3 Synchronization

    -The command
    -
    -
    void glFlush(void)
    -
    -
    -makes the graphics library to flush all pending graphics commands. - The command
    -

    -void glFinish(void)
    -
    -
    -makes the graphics library flush the command queue and wait until those -commands are completed.  glFlush -will not return until all previous graphics commands have been fully -completed.
    -
    -These commands are typically used to force completion of rendering to -the front color buffer.  Otherwise, rendering to the front color -buffer may not appear.  The swapbuffers -command (part of the window system binding library) does an implicit -flush before swapping the front and back color buffers.  The glReadPixels command also does an -implicit flush before reading pixel data from the frame buffer.
    -
    -

    9. State Queries

    -The current value of nearly all library state variables can be queried. - This chapter describes the commands used for querying the value of -state variables.
    -
    -

    9.1 General State Queries

    -The command
    -
    -
    void glGetFloatv(GLenumpname, GLfloat *values)
    -
    -
    -returns the value(s) of the state variable specified by pname.  The following table -lists all accepted values for pname -and a description of the value(s).  Specifying any other value for pname causes the error -GL_INVALID_ENUM to be raised.
    -
    - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    Variable (pname)
    -     		Number of values
    -     		Value(s) Description
    -
    GL_ALPHA_BITS
    -     		1
    -     		Number of bits per alpha value -in the frame buffer.
    -
    GL_ALPHA_TEST
    -     		1
    -     		Zero if the alpha test is -disabled.
    -One if the alpha test is enabled.
    -
    GL_ALPHA_TEST_FUNC
    -     		1
    -     		The alpha test function.
    -
    GL_BLEND
    -     		1
    -     		Zero if blending is disabled.
    -One if blending is enabled.
    -
    GL_BLEND_DST
    -     		1
    -     		Blend destination function/term.
    -
    GL_BLEND_SRC
    -     		1
    -     		Blend source function/term.
    -
    GL_BLUE_BITS
    -     		1
    -     		Number of bits per blue value in -the frame buffer.
    -
    GL_COLOR_CLEAR_VALUE
    -     		4
    -     		Clear color (red, green, blue, -alpha).
    -
    GL_COLOR_WRITE_MASK
    -     		4
    -     		Color buffer writemask (red, -green, blue, alpha).
    -Zero if writing is disabled.
    -One if writing is enabled.
    -
    GL_CULL_FACE
    -     		1
    -     		Zero if polygon culling is -disabled.
    -One if polygon culling is enabled.
    -
    GL_CULL_FACE_MODE
    -     		1
    -     		Polygon cull mode: GL_FRONT, -GL_BACK or GL_FRONT_AND_BACK.
    -
    GL_CURRENT_COLOR
    -     		4
    -     		Current color (red, green, blue, -alpha).
    -
    GL_CURRENT_RASTER_COLOR
    -     		4
    -     		Current raster position color -(red, green, blue, alpha).
    -
    GL_CURRENT_RASTER_TEXTURE_COORDS
    -     		4
    -     		Current raster position texture -coordinates (s, t, r, q).
    -
    GL_CURRENT_RASTER_POSITION
    -     		4
    -     		Current raster position (x, y, -z, w).
    -
    GL_CURRENT_POSITION_VALID
    -     		1
    -     		Zero if current raster position -is invalid.
    -One if current raster position is valid.
    -
    GL_CURRENT_TEXTURE_COORDS
    -     		4
    -     		Current texture coordinates (s, -t, r, q)
    -
    GL_DOUBLEBUFFER
    -     		1
    -     		Zero if color buffer is -single-buffered.
    -One if color buffer is double-buffered.
    -
    GL_DRAW_BUFFER
    -     		1
    -     		Current color draw buffer: -GL_FRONT or GL_BACK.
    -
    GL_FRONT_FACE1
    -     		Polygon front-face winding: -GL_CW or GL_CCW.
    -
    GL_GREEN_BITS
    -     		1
    -     		Number of bits per green value -in the frame buffer.
    -
    GL_LINE_SMOOTH
    -     		1
    -     		Zero if line smoothing is -disabled.
    -One if line smoothing is enabled.
    -
    GL_LINE_STIPPLE
    -     		1
    -     		Zero if line stippling is -disabled.
    -One if line stippling is enabled.
    -
    GL_LINE_STIPPLE_PATTERN
    -     		1
    -     		Line stipple pattern.
    -
    GL_LINE_STIPPLE_REPEAT
    -     		1
    -     		Line stipple repeat factor.
    -
    GL_LINE_WIDTH
    -     		1
    -     		Line width in pixels.
    -
    GL_LINE_WIDTH_GRANULARITY
    -     		1
    -     		Aliased line width granularity.
    -
    GL_LINE_WIDTH_RANGE
    -     		2
    -     		Minimum and maximum aliased line -widths.
    -
    GL_ALIASED_LINE_WIDTH_RANGE
    -     		2
    -     		Minimum and maximum antialiased -line widths.
    GL_COLOR_LOGIC_OP
    -     		1
    -     		Zero if logicop is disabled.
    -One if logicop is enabled.
    -
    GL_LOGIC_OP_MODE
    -     		1
    -     		Logicop function.
    -
    GL_MATRIX_MODE
    -     		1
    -     		Matrix mode: GL_MODELVIEW or -GL_PROJECTION.
    -
    GL_MAX_MODELVIEW_STACK_DEPTH
    -     		1
    -     		Maximum size of the modelview -matrix stack.
    -
    GL_MAX_NAME_STACK_DEPTH
    -     		1
    -     		Maximum size of the selection -name stack.
    -
    GL_MAX_PROJECTION_STACK_DEPTH
    -     		1
    -     		Maximum size of the projection -matrix stack.
    -
    GL_MAX_TEXTURE_SIZE
    -     		1
    -     		Maximum 2D texture image width -and height.
    -
    GL_MAX_VIEWPORT_DIMS
    -     		2Maximum viewport width and -height in pixels.
    -
    GL_MODELVIEW_MATRIX
    -     		16
    -     		Current/top modelview matrix -values.
    -
    GL_MODELVIEW_MATRIX_STACK_DEPTH
    -     		1
    -     		Current size of the modelview -matrix stack.
    -
    GL_NAME_STACK_DEPTH
    -     		1
    -     		Current size of the selection -name stack.
    -
    GL_PACK_ROW_LENGTH
    -     		1
    -     		Pixel packing row length.
    -
    GL_POLYGON_SMOOTH
    -     		1
    -     		Zero if polygon smoothing is -disabled.
    -One if polygon smoothing is enabled.
    -
    GL_PROJECTION_MATRIX
    -     		16
    -     		Current/top projection matrix -values.
    -
    GL_PROJECTION_STACK_DEPTH
    -     		1
    -     		Current size of projection -matrix stack.
    -
    GL_READ_BUFFER
    -     		1
    -     		Current read buffer: GL_FRONT or -GL_BACK.
    -
    GL_RED_BITS
    -     		1
    -     		Number of bits per red value in -the frame buffer.
    -
    GL_RENDER_MODE
    -     		1
    -     		Current rendering mode: -GL_RENDER or GL_SELECTION.
    -
    GL_RGBA_MODE
    -     		1
    -     		Always one.
    -
    GL_SCISSOR_BOX
    -     		4
    -     		Scissor box (x, y, width, -height).
    -
    GL_SCISSOR_TEST
    -     		1
    -     		Zero if scissor test is disabled.
    -One if scissor test is enabled.
    -
    GL_SELECTION_BUFFER_SIZE
    -     		1
    -     		Size of selection buffer.
    -
    GL_SHADE_MODEL
    -     		1
    -     		Shade model: GL_FLAT or -GL_SMOOTH.
    -
    GL_STENCIL_BITS
    -     		1
    -     		Number of bits per stencil value -in the frame buffer.
    -
    GL_STENCIL_CLEAR_VALUE
    -     		1
    -     		Stencil buffer clear value.
    -
    GL_STENCIL_FAIL
    -     		1
    -     		Stencil fail operation.
    -
    GL_STENCIL_FUNC
    -     		1
    -     		Stencil function.
    -
    GL_STENCIL_REF
    -     		1
    -     		Stencil reference value.
    -
    GL_STENCIL_TEST
    -     		1
    -     		Zero if stencil test is disabled.
    -One if stencil test is enabled.
    -
    GL_STENCIL_VALUE_MASK
    -     		1
    -     		Stencil mask value.
    -
    GL_STENCIL_WRITE_MASK
    -     		1
    -     		Stencil buffer write mask.
    -
    GL_TEXTURE_2D
    -     		1
    -     		Zero if 2D texture mapping is -disabled.
    -One if 2D texture mapping is enabled.
    -
    GL_TEXTURE_BINDING_2D1
    -     		Name of currently bound 2D -texture object.
    -
    GL_TEXTURE_ENV_COLOR
    -     		4
    -     		Texture environment color (red, -green, blue, alpha).
    -
    GL_TEXTURE_ENV_MODE
    -     		1
    -     		Texture environment mode.
    -
    GL_UNPACK_ROW_LENGTH
    -     		1
    -     		Pixel unpacking row length.
    -
    GL_UNPACK_LSB_FIRST
    -     		1
    -     		Zero if most significant bit is -unpacked first for bitmaps.
    -One if least significant bit is unpacked first for bitmaps.
    -
    GL_VIEWPORT
    -     		4
    -     		Current viewport (x, y, width, -height).
    -
    -
    -
    -

    9.2 String Queries

    -The command
    -
    -
    const GLubyte *glGetString(GLenum name)
    -
    -
    -is used to query string-valued values.  The legal values for name are described in the following -table:
    -
    - - - - - - - - - - - - - - - - - - - - - - - -
    name
    -     		Return value
    -
    GL_VERSION
    -     		The library version, such as -"1.2".
    -
    GL_RENDERER
    -     		The renderer, such as "Mesa DRI -Radeon".
    -
    GL_VENDOR
    -     		The vendor of this -implementation, such as "Tungsten Graphics, Inc."
    -
    GL_EXTENSIONS
    -     		A white-space separated list of -the supported extensions.
    -
    -

    9.3 Error Queries

    -The command
    -
    -
    GLenum glGetError(void)
    -
    -
    -returns the current error code.  The current error code will be -set by a GL command when an error condition has been detected.  If -the current error code is already set, subsequent errors will not be -recorded.  The error code is reset/cleared to GL_NO_ERROR when glGetError returns.  The -following error codes are possible:
    -
    - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    Error code
    -     		Meaning
    -
    GL_NO_ERROR
    -     		No error has been recorded.
    -
    GL_INVALID_ENUM
    -     		An enum parameter had an invalid -value.
    -
    GL_INVALID_VALUE
    -     		A numeric parameter had an -invalid value.
    -
    GL_INVALID_OPERATION
    -     		A function was called when not -legal to do so.
    -
    GL_STACK_OVERFLOW
    -     		The current transformation -matrix stack is full.
    -
    GL_STACK_UNDERFLOW
    -     		The current transformation -matrix stack is empty.
    -
    GL_OUT_OF_MEMORY
    -     		The system ran out of dynamic -memory.
    -
    -
    -
    -

    10. Unsupported Features

    -This section lists other features and functions which are not supported -and not previously discussed.
    -
    -

    10.1 Feedback Mode

    -Feedback mode and the following related functions are not supported.
    -
    -
    glFeedbackBuffer
    -glPassThrough
    -
    -
    -

    10.2 1D and 3D Textures
    -

    -Only 2D texture images are supported.  The following functions -used to specify 1D and 3D texture images are not supported:
    -
    -
    glTexImage1D
    -glTexImage3D
    -glTexSubImage1D
    - glTexSubImage3D
    -glCopyTexImage1D
    - glCopyTexSubImage1D
    - glCopyTexSubImage3D
    -
    -
    -

    10.3 Alternate Texture Image Commands
    -

    -Texture images may only be specified with glTexImage2D.  The following -alternate texture image commands are not supported:
    -
    -
    glTexSubImage2D
    -glCopyTexImage2D
    -glCopyTexSubImage2D
    -
    -
    -

    10.4 Proxy Textures

    -Proxy textures are not supported and the GL_PROXY_TEXTURE_2D token is -not supported by any function.
    -
    -
    -

    10.5 Other Texture Commands

    -The following commands related to texture mapping are not supported by -the subset:
    -
    -
    glPrioritizeTextures
    -glAreTexturesResident
    -glIsTexture
    -glTexEnviv
    -glTexEnvf
    -glTexParameterf
    -glTexParameteriv
    -glTexParameterfv
    -
    -
    -
    -

    10.6 Copy and Draw Pixels
    -

    -The following commands are not supported:
    -
    -
    glDrawPixels
    -glCopyPixels
    -glPixelZoom
    -
    -
    -

    10.7 Color Index Mode
    -

    -Color index mode and the following related commands are not supported:
    -
    - -
    glIndexub
    -    glIndexi
    -glIndexs
    -glIndexf
    -glIndexd
    -    glIndexubv
    -    glIndexiv
    -glIndexsv
    -glIndexfv
    -glIndexdv
    -glIndexMask
    -    glClearIndex
    -glIndexPointer
    -
    -
    -

    10.8 Pixel Transfer Operations

    -The pixel transfer operations (scale, bias, look-up table, etc) are not -supported and the following commands are omitted:
    -
    -
    glPixelTransferf
    -glPixelTransferi
    -glPixelMapfv
    -glPixelMapuiv
    -glPixelMapusv
    -glGetPixelMapfv
    -glGetPixelMapuiv
    -glGetPixelMapusv
    -
    -
    -

    10.9 Hints

    -Hints and the following related command is not supported:
    -
    -
    glHint
    -
    -
    -

    10.10 State Query Commands
    -

    -The following state query commands are not supported:
    -
    -
    glGetBooleanv
    -glGetIntegerv
    -glGetDoublev
    -glGetPointerv
    -glGetTexEnvi
    -glGetTexEnvf
    -glGetTexParameteriv
    -glGetTexParameterfv
    -glGetTexLevelParameteriv
    -glGetTexLevelParameterfv
    -glGetTexImage
    -glGetClipPlane
    -
    -
    -

    10.11 Attribute Stacks

    -State attribute stacks and the following related commands are not -supported:
    -
    -
    glPushAttrib
    -glPopAtttrib
    -
    -
    -

    10.12 Double-Valued Functions

    -All functions which take double-precision floating point values, but -for which there is an equivalent single-precision valued function, are -omitted.  This includes, but is not limited to:
    -
    -
    glVertex2d
    -glVertex2dv
    -glVertex3d
    - glVertex3dv
    -glVertex4d
    - glVertex4dv
    -glColor3d
    -glColor3dv
    -glColor4d
    - glColor4dv
    -glTexCoord1d
    -glTexCoord1dv
    -glTexCoord2d
    - glTexCoord2dv
    -glTexCoord3d
    - glTexCoord3dv
    -glTexCoord4d
    - glTexCoord4dv
    -glRasterPos2d
    - glRasterPos2dv
    -glRasterPos3d
    - glRasterPos3dv
    -glRasterPos4d
    - glRasterPos4dv
    -glLoadMatrixd
    -glMultMatrixd
    -glScaled
    -glRotated
    -glTranslated
    -glRectd
    -glRectdv
    -
    -
    -

    10.13 Evaluators

    -Evaluators and the following related commands are not supported:
    -
    -
    glMap1f
    -glMap2d
    -glMap2f
    -glGetMapdv
    -glGetMapfv
    -glGetMapiv
    -glEvalCoord1d
    -glEvalCoord1f
    -glEvalCoord1dv
    -glEvalCoord1fv
    -glEvalCoord2d
    -glEvalCoord2f
    -glEvalCoord2dv
    -glEvalCoord2fv
    -glMapGrid1d
    -glMapGrid1f
    -glMapGrid2d
    -glMapGrid2f
    -glEvalPoint1
    -glEvalPoint2
    -glEvalMesh1
    -glEvalMesh2
    -
    -
    -

    10.14 Display Lists

    -Display lists and the following related commands are not supported:
    -
    -
    glIsList
    -glDeleteLists
    -glGenLists
    -glNewList
    -glEndList
    -glCallList
    -glCallLists
    -glListBase
    -
    -
    -

    10.15 Accumulation Buffer

    -The accumulation buffer and the following related commands are not -supported:
    -
    -
    glAccum
    -glClearAccum
    -
    -
    -

    10.16 Fog

    -Fog and the following related commands are not supported:
    -
    -
    glFogi
    -glFogf
    -glFogiv
    -glFogfv
    -
    -
    -

    10.17 Depth Test

    -Depth testing and the following related commands are not supported:
    -
    -
    glDepthFunc
    -glDepthMask
    -glDepthRange
    -glClearDepth
    -
    -
    -

    10.18 Imaging Subset

    -The OpenGL imaging subset (which implements features such as -convolution, histogram, min/max recording, color matrix and color -tables) is not supported.
    -
    -
    -

    Appendix A: Issues

    -This appendix lists documentation and subset issues with their current -status.  For items which are still open, the documentation (above) -follows the recommended solution.
    -
    -

    A.1 Vertex Arrays

    -Should vertex arrays be supported?  Is there a performance -advantage?
    -
    -RESOLUTION: No, there isn't enough of a performance advantage to -justify them.
    -
    -

    A.2 Polygon Antialiasing and Edge Flags

    -Should edge flags be supported for antialiasing?
    -
    -Edge flags don't effect antialiasing, at least not normally.  A -number of approaches to antialiasing have been summarized in email.
    -
    -RECOMMENDATION: don't support edge flags.  They don't effect -polygon antialiasing.
    -
    -RESOLUTION: closed, as of 26 Feb 2003.
    -
    -

    A.3 glRasterPos vs. glWindowPos

    -Should glRasterPos and/or glWindowPos commands be supported?
    -
    -RESOLUTION: Closed: implement glRasterPos commands, but not glWindowPos -commands.
    -
    -

    A.4 GL_IBM_rasterpos_clip extension

    -Should the GL_IBM_rasterpos_clip extension be implemented?
    -
    -RESOLUTION:  No.  It's not required.
    -
    -

    A.5 Image Formats and Types

    -Which image formats and types should be supported for glTexImage2D and glReadPixels?
    -
    -OpenGL specifies a large -variety of image formats and data types.  Only a few are commonly -used.
    -
    -RECOMMENDATION:  we propose a subset:
    -
    -For glTexImage2D only allow type=GL_UNSIGNED_BYTE and format=GL_RGBA, GL_RGB, -GL_INTENSITY.   Only allow internalFormat -to be GL_RGBA, GL_RGB or GL_INTENSITY as well.  Basically, only -support image formats/types that are directly supported by the Radeon -hardware.  This will allow glTexImage2D -to basically just use memcpy to -copy texture images.
    -
    -For glReadPixels, only allow type = GL_UNSIGNED_BYTE or GL_FLOAT. - Only allow format = -GL_RGB or GL_RGBA.  This is just enough to support the OpenGL -conformance tests.
    -
    -RESOLUTION: open
    -
    -

    A.6 Texture Environment Modes

    -Which texture environment modes should be supported?  OpenGL 1.2 -has GL_REPLACE, GL_MODULATE, GL_DECAL and GL_BLEND.  GL_DECAL isn't -defined for all base internal texture formats.  GL_ADD is another -useful mode.  Perhaps drop GL_DECAL mode and add GL_ADD mode.
    -
    -RECOMMENDATION: implement the standard modes GL_REPLACE, GL_MODULATE, -GL_DECAL and GL_BLEND.
    -
    -RESOLUTION: open
    -
    -

    A.7 Truncated Mipmaps and LOD Control

    -Should we support the GL_TEXTURE_BASE_LEVEL, GL_TEXTURE_MAX_LEVEL, -GL_TEXTURE_MIN_LOD and GL_TEXTURE_MAX_LOD texture parameters?
    -
    -RECOMMENDATION:  We propose omitting these features at this time, -in the interest of simplifying the driver.
    -
    -RESOLUTION: open
    -
    -

    A.8 Texture Priorities and Residency

    -Should the subset support texture priorities via glPrioritizeTextures and the glAreTexturesResident command?
    -
    -RECOMMENDATION:  Few applications use these features and -functions.  We propose omitting them to simplify the driver.
    -
    -RESOLUTION: open
    -
    -

    A.9 Pixel Pack/Unpack Alignment Control

    -Should we support the GL_PACK_ALIGNMENT and GL_UNPACK_ALIGNMENT options?
    -
    -These are used to align pixel data addresses to 1, 2 and 4-byte -multiples for glBitmap, glTexImage2D -and glReadPixels.  These -aren't strictly needed since the user can provide a 1, 2 or 4-byte -aligned address and appropriate GL_PACK_ROW_LENGTH or -GL_UNPACK_ROW_LENGTH values instead.
    -
    -RECOMMENDATION:  We recommend omitting them to simplify the driver.
    -
    -RESOLUTION: open
    -
    -

    A.10 Pixel Pack/Unpack Skip Rows/Pixels Control

    -Should we support the GL_UNPACK_SKIP_PIXELS, GL_UNPACK_SKIP_ROWS, -GL_PACK_SKIP_PIXELS and GL_PACK_SKIP_ROWS options for pixel -unpacking/packing?
    -
    -These options aren't really needed since the user can adjust the start -address and GL_PACK/UNPACK_ROW_LENGTH parameters to achieve the same -effect.
    -
    -RECOMMENDATION:  omit these parameters.
    -
    -RESOLUTION: open
    -
    -

    A.11 Texture State Queries

    -Should we support the command glGetTexEnvi/fv, -glGetTexParameteri/fv and glGetTexLevelParameteri/fv?
    -
    -RECOMMENDATION:  No. They're seldom needed and their -implementation is several hundred lines of code in length.
    -
    -RESOLUTION:  open
    -
    -

    A.12 glGetIntegerv, glGetBooleanv and glGetDoublev

    -Should we support the commands glGetIntegerv, -glGetBooleanv and glGetDoublev -in addition to glGetFloatv?
    -
    -RECOMMENDATION:  Omit the boolean, integer and double-valued -functions. All state values which can be queried by these commands can -be expressed as floating point values and queried with glGetFloatv.  The -implementation of the other three commands involves many lines of code.
    -
    -RESOLUTION:  open
    -
    -

    A.13 glBitmap and Per-Fragment Operations

    -Should bitmaps rendered with glBitmap -be subjected to the per-fragment operations?
    -
    -If bitmaps are implemented with points it will be easy to implement the -per-fragment operations.  Otherwise, it could be difficult.
    -
    -RECOMMENDATION:  Implement glBitmap by drawing points/pixels with -the hardware.  This will make supporting the per-fragments -trivially easy.  Also, it makes portrait-mode display relatively -easy.
    -
    -RESOLUTION:  open
    -
    -

    A.14 Reduced gl.h Header File

    -Should we produce a reduced gl.h header file which only defines the -tokens and functions which are implemented by the subset?
    -
    -RECOMMENDATION: yes.  It would be a useful reference to -programmers to quickly determine which functions and tokens are -supported.
    -
    -RESOLUTION: open
    -
    -

    A.15 glPolygonMode

    -Is glPolygonMode needed?
    -
    -RECOMMENDATION: No.  Omit it.
    -
    -RESOLUTION: closed, as of 26 Feb 2003
    -
    -
    -

    - - diff --git a/docs/subset.html b/docs/subset.html deleted file mode 100644 index 0ceb136668f..00000000000 --- a/docs/subset.html +++ /dev/null @@ -1,25 +0,0 @@ - - - - - Mesa Subset Driver - - - - -

    Mesa Subset Driver

    - -

    -In 2002/2003 Tungsten Graphics was contracted to develop a subset Mesa/Radeon -driver for an embedded environment. The result is a reduced-size DRI driver -for the ATI R200 chip, for use with -fbdev/DRI environment. -

    - -

    -The specification for this subset can be found -here. -

    - - -