211 lines
5.6 KiB
C
211 lines
5.6 KiB
C
/*
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* GL_SGIS_pixel_texture demo
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*
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* Brian Paul
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* 6 Apr 2000
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*
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* Copyright (C) 2000 Brian Paul All Rights Reserved.
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*
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* Permission is hereby granted, free of charge, to any person obtaining a
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* copy of this software and associated documentation files (the "Software"),
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* to deal in the Software without restriction, including without limitation
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* the rights to use, copy, modify, merge, publish, distribute, sublicense,
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* and/or sell copies of the Software, and to permit persons to whom the
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* Software is furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included
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* in all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
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* OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
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* BRIAN PAUL BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
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* AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
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* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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*/
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/*
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* How this works:
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* 1. We load the image into a 2D texture.
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* 2. We generate a sequence of RGB images in which the R component
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* is really the S texture coordinate and the G component is really
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* the T texture coordinate.
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* By warping the mapping from R to S and G to T we can get non-linear
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* distortions.
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* 3. Draw the warped image (a 2-D warping function) with pixel texgen
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* enabled.
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* 4. Loop over the warped images to animate.
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*
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* The pixel texgen extension can also be used to do color-space
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* conversions. For example, we could convert YCR to RGB with a
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* 3D texture map which takes YCR as the S,T,R texture coordinate and
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* returns RGB texel values.
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*
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* You can use this extension in (at least) two ways:
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* 1. glDrawPixels w/ color space conversion/warping
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* 2. glDrawPixels to spatially warp another image in texture memory
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*
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* We're basically using glDrawPixels to draw a texture coordinate image.
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*/
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#include <math.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <GL/glut.h>
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#include <GL/glext.h>
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#include "readtex.c" /* I know, this is a hack. */
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#define TEXTURE_FILE "../images/girl.rgb"
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static int ImgWidth = 300, ImgHeight = 300;
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#define FRAMES 20
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static GLubyte *ImgData[FRAMES];
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static GLint Frame = 0;
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static GLboolean TextureFlag = GL_TRUE;
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static void Display( void )
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{
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glClear( GL_COLOR_BUFFER_BIT );
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if (TextureFlag) {
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glEnable(GL_PIXEL_TEXTURE_SGIS);
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glEnable(GL_TEXTURE_2D);
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}
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else {
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glDisable(GL_PIXEL_TEXTURE_SGIS);
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glDisable(GL_TEXTURE_2D);
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}
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glColor3f(1, 1, 1);
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glRasterPos2f(10, 10);
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glDrawPixels(ImgWidth, ImgHeight, GL_RGB, GL_UNSIGNED_BYTE, ImgData[Frame]);
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glutSwapBuffers();
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}
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static void Reshape( int width, int height )
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{
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glViewport( 0, 0, width, height );
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glMatrixMode( GL_PROJECTION );
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glLoadIdentity();
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glOrtho(0, width, 0, height, -1, 1);
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glMatrixMode( GL_MODELVIEW );
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glLoadIdentity();
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}
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static void Key( unsigned char key, int x, int y )
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{
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(void) x;
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(void) y;
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switch (key) {
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case ' ':
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TextureFlag = !TextureFlag;
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break;
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case 27:
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exit(0);
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break;
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}
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glutPostRedisplay();
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}
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static void Idle(void)
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{
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Frame++;
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if (Frame >= FRAMES)
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Frame = 0;
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glutPostRedisplay();
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}
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static GLubyte warp(GLfloat s, int frame)
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{
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static const GLfloat pi = 3.14159265;
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static int halfFrame = FRAMES / 2;
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GLfloat y, weight, v;
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if (frame >= halfFrame)
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frame = halfFrame - (frame - halfFrame);
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y = sin(s * pi);
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weight = (float) frame / (FRAMES-1);
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v = y * (0.8 * weight + 0.2);
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return (GLint) (v * 255.0F);
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}
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static void InitImage(void)
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{
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int i, j, frame;
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for (frame = 0; frame < FRAMES; frame++) {
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ImgData[frame] = (GLubyte *) malloc(ImgWidth * ImgHeight * 3);
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for (i = 0; i < ImgHeight; i++) {
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for (j = 0; j < ImgWidth; j++) {
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GLubyte *pixel = ImgData[frame] + (i * ImgWidth + j) * 3;
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pixel[0] = warp((float) j / (ImgWidth - 0), frame);
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pixel[1] = warp((float) i / (ImgHeight - 0), frame);
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pixel[2] = 0.0;
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}
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}
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}
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}
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static void Init( int argc, char *argv[] )
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{
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const char *exten = (const char *) glGetString(GL_EXTENSIONS);
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if (!strstr(exten, "GL_SGIS_pixel_texture")) {
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printf("Sorry, GL_SGIS_pixel_texture not supported by this renderer.\n");
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exit(1);
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}
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/* linear filtering looks nicer, but it's slower, since it's in software */
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#if 1
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glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
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glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
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#else
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glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
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glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
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#endif
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glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_REPLACE);
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glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
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if (!LoadRGBMipmaps(TEXTURE_FILE, GL_RGB)) {
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printf("Error: couldn't load texture image\n");
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exit(1);
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}
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glClearColor(0.3, 0.3, 0.4, 1.0);
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InitImage();
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printf("Hit SPACE to toggle pixel texgen\n");
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}
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int main( int argc, char *argv[] )
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{
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glutInit( &argc, argv );
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glutInitWindowSize( 330, 330 );
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glutInitWindowPosition( 0, 0 );
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glutInitDisplayMode( GLUT_RGB | GLUT_DOUBLE );
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glutCreateWindow(argv[0] );
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Init( argc, argv );
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glutKeyboardFunc( Key );
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glutReshapeFunc( Reshape );
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glutDisplayFunc( Display );
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glutIdleFunc( Idle );
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glutMainLoop();
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return 0;
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}
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