Now there's four possible display modes:
1. normal, shadowed rendering 2. display depth texture image 3. display depth texture mapped onto scene 4. render grayscale scene where gray level = distance from light source
This commit is contained in:
Brian Paul
parent
feb555af03
commit
0221e4d6c8
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@ -1,4 +1,4 @@
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/* $Id: shadowtex.c,v 1.3 2001/02/26 18:26:32 brianp Exp $ */
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/* $Id: shadowtex.c,v 1.4 2001/02/28 18:41:50 brianp Exp $ */
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/*
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* Shadow demo using the GL_SGIX_depth_texture, GL_SGIX_shadow and
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@ -28,6 +28,7 @@
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*/
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#include <assert.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <math.h>
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@ -54,15 +55,19 @@ static GLfloat SpotAngle = 40.0 * DEG_TO_RAD;
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static GLfloat ShadowNear = 4.0, ShadowFar = 24.0;
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static GLint ShadowTexWidth = 256, ShadowTexHeight = 256;
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static GLboolean ShowDepth = GL_FALSE;
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static GLboolean LinearFilter = GL_FALSE;
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static GLfloat ShadowImage[256*256];
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static GLfloat Bias = -0.06;
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static GLboolean Anim = GL_TRUE;
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static GLuint DisplayMode;
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#define SHOW_NORMAL 0
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#define SHOW_DEPTH_IMAGE 1
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#define SHOW_DEPTH_MAPPING 2
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#define SHOW_DISTANCE 3
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static void
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DrawScene(void)
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@ -111,8 +116,8 @@ DrawScene(void)
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* source's point of view.
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*/
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static void
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ShadowMatrix(const GLfloat lightPos[4], const GLfloat spotDir[3],
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GLfloat spotAngle, GLfloat shadowNear, GLfloat shadowFar)
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MakeShadowMatrix(const GLfloat lightPos[4], const GLfloat spotDir[3],
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GLfloat spotAngle, GLfloat shadowNear, GLfloat shadowFar)
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{
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GLfloat d;
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@ -132,7 +137,7 @@ ShadowMatrix(const GLfloat lightPos[4], const GLfloat spotDir[3],
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static void
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EnableTexgen(void)
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EnableIdentityTexgen(void)
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{
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/* texgen so that texcoord = vertex coord */
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static GLfloat sPlane[4] = { 1, 0, 0, 0 };
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@ -156,6 +161,46 @@ EnableTexgen(void)
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}
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/*
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* Setup 1-D texgen so that the distance from the light source, between
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* the near and far planes maps to s=0 and s=1. When we draw the scene,
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* the grayness will indicate the fragment's distance from the light
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* source.
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*/
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static void
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EnableDistanceTexgen(const GLfloat lightPos[4], const GLfloat lightDir[3],
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GLfloat lightNear, GLfloat lightFar)
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{
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GLfloat m, d;
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GLfloat sPlane[4];
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GLfloat nearPoint[3];
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m = sqrt(lightDir[0] * lightDir[0] +
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lightDir[1] * lightDir[1] +
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lightDir[2] * lightDir[2]);
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d = lightFar - lightNear;
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/* nearPoint = point on light direction vector which intersects the
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* near plane of the light frustum.
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*/
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nearPoint[0] = LightPos[0] + lightDir[0] / m * lightNear;
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nearPoint[1] = LightPos[1] + lightDir[1] / m * lightNear;
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nearPoint[2] = LightPos[2] + lightDir[2] / m * lightNear;
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sPlane[0] = lightDir[0] / d / m;
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sPlane[1] = lightDir[1] / d / m;
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sPlane[2] = lightDir[2] / d / m;
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sPlane[3] = -(sPlane[0] * nearPoint[0]
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+ sPlane[1] * nearPoint[1]
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+ sPlane[2] * nearPoint[2]);
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glTexGenfv(GL_S, GL_EYE_PLANE, sPlane);
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glTexGeni(GL_S, GL_TEXTURE_GEN_MODE, GL_EYE_LINEAR);
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glEnable(GL_TEXTURE_GEN_S);
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}
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static void
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DisableTexgen(void)
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{
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@ -170,6 +215,7 @@ static void
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ComputeLightPos(GLfloat dist, GLfloat latitude, GLfloat longitude,
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GLfloat pos[4], GLfloat dir[3])
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{
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pos[0] = dist * sin(longitude * DEG_TO_RAD);
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pos[1] = dist * sin(latitude * DEG_TO_RAD);
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pos[2] = dist * cos(latitude * DEG_TO_RAD) * cos(longitude * DEG_TO_RAD);
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@ -209,15 +255,31 @@ Display(void)
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/*
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* Step 2: copy depth buffer into texture map
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*/
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glCopyTexImage2D(GL_TEXTURE_2D, 0, GL_DEPTH_COMPONENT,
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0, 0, ShadowTexWidth, ShadowTexHeight, 0);
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if (DisplayMode == SHOW_DEPTH_MAPPING) {
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/* load depth image as gray-scale luminance texture */
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GLfloat *depth = malloc(ShadowTexWidth * ShadowTexHeight
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* sizeof(GLfloat));
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if (depth) {
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glReadPixels(0, 0, ShadowTexWidth, ShadowTexHeight,
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GL_DEPTH_COMPONENT, GL_FLOAT, depth);
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glTexImage2D(GL_TEXTURE_2D, 0, GL_LUMINANCE,
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ShadowTexWidth, ShadowTexHeight, 0,
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GL_LUMINANCE, GL_FLOAT, depth);
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free(depth);
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}
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}
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else {
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/* The normal shadow case */
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glCopyTexImage2D(GL_TEXTURE_2D, 0, GL_DEPTH_COMPONENT,
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0, 0, ShadowTexWidth, ShadowTexHeight, 0);
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}
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/*
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* Step 3: render scene from point of view of the camera
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*/
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glViewport(0, 0, WindowWidth, WindowHeight);
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if (ShowDepth) {
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ShowDepthBuffer(WindowWidth, WindowHeight, 1, 0);
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if (DisplayMode == SHOW_DEPTH_IMAGE) {
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ShowDepthBuffer(WindowWidth, WindowHeight, 0, 1);
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}
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else {
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glMatrixMode(GL_PROJECTION);
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@ -231,7 +293,6 @@ Display(void)
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glRotatef(Zrot, 0, 0, 1);
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glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
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glLightfv(GL_LIGHT0, GL_POSITION, LightPos);
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glEnable(GL_TEXTURE_2D);
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if (LinearFilter) {
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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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@ -240,10 +301,32 @@ Display(void)
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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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}
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ShadowMatrix(LightPos, SpotDir, SpotAngle, ShadowNear, ShadowFar);
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EnableTexgen();
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if (DisplayMode == SHOW_DEPTH_MAPPING) {
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glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_COMPARE_SGIX, GL_FALSE);
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glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_REPLACE);
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glEnable(GL_TEXTURE_2D);
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MakeShadowMatrix(LightPos, SpotDir, SpotAngle, ShadowNear, ShadowFar);
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EnableIdentityTexgen();
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}
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else if (DisplayMode == SHOW_DISTANCE) {
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glMatrixMode(GL_TEXTURE);
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glLoadIdentity();
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glMatrixMode(GL_MODELVIEW);
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EnableDistanceTexgen(LightPos, SpotDir, ShadowNear+Bias, ShadowFar);
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glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_REPLACE);
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glEnable(GL_TEXTURE_1D);
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}
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else {
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assert(DisplayMode == SHOW_NORMAL);
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glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_COMPARE_SGIX, GL_TRUE);
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glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);
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glEnable(GL_TEXTURE_2D);
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MakeShadowMatrix(LightPos, SpotDir, SpotAngle, ShadowNear, ShadowFar);
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EnableIdentityTexgen();
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}
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DrawScene();
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DisableTexgen();
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glDisable(GL_TEXTURE_1D);
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glDisable(GL_TEXTURE_2D);
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}
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@ -301,12 +384,22 @@ Key(unsigned char key, int x, int y)
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printf("Bias %g\n", Bias);
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break;
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case 'd':
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ShowDepth = !ShowDepth;
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DisplayMode = SHOW_DISTANCE;
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break;
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case 'f':
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LinearFilter = !LinearFilter;
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printf("%s filtering\n", LinearFilter ? "Bilinear" : "Nearest");
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break;
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case 'i':
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DisplayMode = SHOW_DEPTH_IMAGE;
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break;
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case 'm':
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DisplayMode = SHOW_DEPTH_MAPPING;
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break;
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case 'n':
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case ' ':
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DisplayMode = SHOW_NORMAL;
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break;
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case 'z':
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Zrot -= step;
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break;
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@ -367,10 +460,13 @@ Init(void)
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exit(1);
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}
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glTexParameteri(GL_TEXTURE_1D, GL_TEXTURE_WRAP_S, GL_CLAMP);
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glTexParameteri(GL_TEXTURE_1D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
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glTexParameteri(GL_TEXTURE_1D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
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glTexParameteri(GL_TEXTURE_1D, GL_TEXTURE_WRAP_T, GL_CLAMP);
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glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP);
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glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP);
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#ifdef GL_SGIX_shadow
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glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_COMPARE_SGIX, GL_TRUE);
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glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_COMPARE_OPERATOR_SGIX,
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GL_TEXTURE_LEQUAL_R_SGIX);
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#endif
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@ -379,6 +475,16 @@ Init(void)
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glTexParameterf(GL_TEXTURE_2D, GL_SHADOW_AMBIENT_SGIX, 0.3);
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#endif
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/* setup 1-D grayscale texture image for SHOW_DISTANCE mode */
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{
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GLuint i;
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GLubyte image[256];
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for (i = 0; i < 256; i++)
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image[i] = i;
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glTexImage1D(GL_TEXTURE_1D, 0, GL_LUMINANCE,
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256, 0, GL_LUMINANCE, GL_UNSIGNED_BYTE, image);
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}
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glEnable(GL_DEPTH_TEST);
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glEnable(GL_LIGHTING);
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glEnable(GL_LIGHT0);
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@ -390,7 +496,10 @@ PrintHelp(void)
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{
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printf("Keys:\n");
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printf(" a = toggle animation\n");
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printf(" d = toggle display of depth texture\n");
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printf(" i = show depth texture image\n");
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printf(" m = show depth texture mapping\n");
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printf(" d = show fragment distance from light source\n");
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printf(" n = show normal, shadowed image\n");
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printf(" f = toggle nearest/bilinear texture filtering\n");
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printf(" b/B = decrease/increase shadow map Z bias\n");
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printf(" cursor keys = rotate scene\n");
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