From 0221e4d6c8a577e2355696de260d101ce28a9570 Mon Sep 17 00:00:00 2001 From: Brian Paul Date: Wed, 28 Feb 2001 18:41:50 +0000 Subject: [PATCH] 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 --- progs/demos/shadowtex.c | 143 ++++++++++++++++++++++++++++++++++++++++++------ 1 file changed, 126 insertions(+), 17 deletions(-) diff --git a/progs/demos/shadowtex.c b/progs/demos/shadowtex.c index 0daf77d..112ee0d 100644 --- a/progs/demos/shadowtex.c +++ b/progs/demos/shadowtex.c @@ -1,4 +1,4 @@ -/* $Id: shadowtex.c,v 1.3 2001/02/26 18:26:32 brianp Exp $ */ +/* $Id: shadowtex.c,v 1.4 2001/02/28 18:41:50 brianp Exp $ */ /* * Shadow demo using the GL_SGIX_depth_texture, GL_SGIX_shadow and @@ -28,6 +28,7 @@ */ +#include #include #include #include @@ -54,15 +55,19 @@ static GLfloat SpotAngle = 40.0 * DEG_TO_RAD; static GLfloat ShadowNear = 4.0, ShadowFar = 24.0; static GLint ShadowTexWidth = 256, ShadowTexHeight = 256; -static GLboolean ShowDepth = GL_FALSE; static GLboolean LinearFilter = GL_FALSE; -static GLfloat ShadowImage[256*256]; - static GLfloat Bias = -0.06; static GLboolean Anim = GL_TRUE; +static GLuint DisplayMode; +#define SHOW_NORMAL 0 +#define SHOW_DEPTH_IMAGE 1 +#define SHOW_DEPTH_MAPPING 2 +#define SHOW_DISTANCE 3 + + static void DrawScene(void) @@ -111,8 +116,8 @@ DrawScene(void) * source's point of view. */ static void -ShadowMatrix(const GLfloat lightPos[4], const GLfloat spotDir[3], - GLfloat spotAngle, GLfloat shadowNear, GLfloat shadowFar) +MakeShadowMatrix(const GLfloat lightPos[4], const GLfloat spotDir[3], + GLfloat spotAngle, GLfloat shadowNear, GLfloat shadowFar) { GLfloat d; @@ -132,7 +137,7 @@ ShadowMatrix(const GLfloat lightPos[4], const GLfloat spotDir[3], static void -EnableTexgen(void) +EnableIdentityTexgen(void) { /* texgen so that texcoord = vertex coord */ static GLfloat sPlane[4] = { 1, 0, 0, 0 }; @@ -156,6 +161,46 @@ EnableTexgen(void) } +/* + * Setup 1-D texgen so that the distance from the light source, between + * the near and far planes maps to s=0 and s=1. When we draw the scene, + * the grayness will indicate the fragment's distance from the light + * source. + */ +static void +EnableDistanceTexgen(const GLfloat lightPos[4], const GLfloat lightDir[3], + GLfloat lightNear, GLfloat lightFar) +{ + GLfloat m, d; + GLfloat sPlane[4]; + GLfloat nearPoint[3]; + + m = sqrt(lightDir[0] * lightDir[0] + + lightDir[1] * lightDir[1] + + lightDir[2] * lightDir[2]); + + d = lightFar - lightNear; + + /* nearPoint = point on light direction vector which intersects the + * near plane of the light frustum. + */ + nearPoint[0] = LightPos[0] + lightDir[0] / m * lightNear; + nearPoint[1] = LightPos[1] + lightDir[1] / m * lightNear; + nearPoint[2] = LightPos[2] + lightDir[2] / m * lightNear; + + sPlane[0] = lightDir[0] / d / m; + sPlane[1] = lightDir[1] / d / m; + sPlane[2] = lightDir[2] / d / m; + sPlane[3] = -(sPlane[0] * nearPoint[0] + + sPlane[1] * nearPoint[1] + + sPlane[2] * nearPoint[2]); + + glTexGenfv(GL_S, GL_EYE_PLANE, sPlane); + glTexGeni(GL_S, GL_TEXTURE_GEN_MODE, GL_EYE_LINEAR); + glEnable(GL_TEXTURE_GEN_S); +} + + static void DisableTexgen(void) { @@ -170,6 +215,7 @@ static void ComputeLightPos(GLfloat dist, GLfloat latitude, GLfloat longitude, GLfloat pos[4], GLfloat dir[3]) { + pos[0] = dist * sin(longitude * DEG_TO_RAD); pos[1] = dist * sin(latitude * DEG_TO_RAD); pos[2] = dist * cos(latitude * DEG_TO_RAD) * cos(longitude * DEG_TO_RAD); @@ -209,15 +255,31 @@ Display(void) /* * Step 2: copy depth buffer into texture map */ - glCopyTexImage2D(GL_TEXTURE_2D, 0, GL_DEPTH_COMPONENT, - 0, 0, ShadowTexWidth, ShadowTexHeight, 0); + if (DisplayMode == SHOW_DEPTH_MAPPING) { + /* load depth image as gray-scale luminance texture */ + GLfloat *depth = malloc(ShadowTexWidth * ShadowTexHeight + * sizeof(GLfloat)); + if (depth) { + glReadPixels(0, 0, ShadowTexWidth, ShadowTexHeight, + GL_DEPTH_COMPONENT, GL_FLOAT, depth); + glTexImage2D(GL_TEXTURE_2D, 0, GL_LUMINANCE, + ShadowTexWidth, ShadowTexHeight, 0, + GL_LUMINANCE, GL_FLOAT, depth); + free(depth); + } + } + else { + /* The normal shadow case */ + glCopyTexImage2D(GL_TEXTURE_2D, 0, GL_DEPTH_COMPONENT, + 0, 0, ShadowTexWidth, ShadowTexHeight, 0); + } /* * Step 3: render scene from point of view of the camera */ glViewport(0, 0, WindowWidth, WindowHeight); - if (ShowDepth) { - ShowDepthBuffer(WindowWidth, WindowHeight, 1, 0); + if (DisplayMode == SHOW_DEPTH_IMAGE) { + ShowDepthBuffer(WindowWidth, WindowHeight, 0, 1); } else { glMatrixMode(GL_PROJECTION); @@ -231,7 +293,6 @@ Display(void) glRotatef(Zrot, 0, 0, 1); glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); glLightfv(GL_LIGHT0, GL_POSITION, LightPos); - glEnable(GL_TEXTURE_2D); if (LinearFilter) { glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR); @@ -240,10 +301,32 @@ Display(void) glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST); } - ShadowMatrix(LightPos, SpotDir, SpotAngle, ShadowNear, ShadowFar); - EnableTexgen(); + if (DisplayMode == SHOW_DEPTH_MAPPING) { + glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_COMPARE_SGIX, GL_FALSE); + glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_REPLACE); + glEnable(GL_TEXTURE_2D); + MakeShadowMatrix(LightPos, SpotDir, SpotAngle, ShadowNear, ShadowFar); + EnableIdentityTexgen(); + } + else if (DisplayMode == SHOW_DISTANCE) { + glMatrixMode(GL_TEXTURE); + glLoadIdentity(); + glMatrixMode(GL_MODELVIEW); + EnableDistanceTexgen(LightPos, SpotDir, ShadowNear+Bias, ShadowFar); + glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_REPLACE); + glEnable(GL_TEXTURE_1D); + } + else { + assert(DisplayMode == SHOW_NORMAL); + glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_COMPARE_SGIX, GL_TRUE); + glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE); + glEnable(GL_TEXTURE_2D); + MakeShadowMatrix(LightPos, SpotDir, SpotAngle, ShadowNear, ShadowFar); + EnableIdentityTexgen(); + } DrawScene(); DisableTexgen(); + glDisable(GL_TEXTURE_1D); glDisable(GL_TEXTURE_2D); } @@ -301,12 +384,22 @@ Key(unsigned char key, int x, int y) printf("Bias %g\n", Bias); break; case 'd': - ShowDepth = !ShowDepth; + DisplayMode = SHOW_DISTANCE; break; case 'f': LinearFilter = !LinearFilter; printf("%s filtering\n", LinearFilter ? "Bilinear" : "Nearest"); break; + case 'i': + DisplayMode = SHOW_DEPTH_IMAGE; + break; + case 'm': + DisplayMode = SHOW_DEPTH_MAPPING; + break; + case 'n': + case ' ': + DisplayMode = SHOW_NORMAL; + break; case 'z': Zrot -= step; break; @@ -367,10 +460,13 @@ Init(void) exit(1); } + glTexParameteri(GL_TEXTURE_1D, GL_TEXTURE_WRAP_S, GL_CLAMP); + glTexParameteri(GL_TEXTURE_1D, GL_TEXTURE_MIN_FILTER, GL_LINEAR); + glTexParameteri(GL_TEXTURE_1D, GL_TEXTURE_MAG_FILTER, GL_LINEAR); + glTexParameteri(GL_TEXTURE_1D, GL_TEXTURE_WRAP_T, GL_CLAMP); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP); #ifdef GL_SGIX_shadow - glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_COMPARE_SGIX, GL_TRUE); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_COMPARE_OPERATOR_SGIX, GL_TEXTURE_LEQUAL_R_SGIX); #endif @@ -379,6 +475,16 @@ Init(void) glTexParameterf(GL_TEXTURE_2D, GL_SHADOW_AMBIENT_SGIX, 0.3); #endif + /* setup 1-D grayscale texture image for SHOW_DISTANCE mode */ + { + GLuint i; + GLubyte image[256]; + for (i = 0; i < 256; i++) + image[i] = i; + glTexImage1D(GL_TEXTURE_1D, 0, GL_LUMINANCE, + 256, 0, GL_LUMINANCE, GL_UNSIGNED_BYTE, image); + } + glEnable(GL_DEPTH_TEST); glEnable(GL_LIGHTING); glEnable(GL_LIGHT0); @@ -390,7 +496,10 @@ PrintHelp(void) { printf("Keys:\n"); printf(" a = toggle animation\n"); - printf(" d = toggle display of depth texture\n"); + printf(" i = show depth texture image\n"); + printf(" m = show depth texture mapping\n"); + printf(" d = show fragment distance from light source\n"); + printf(" n = show normal, shadowed image\n"); printf(" f = toggle nearest/bilinear texture filtering\n"); printf(" b/B = decrease/increase shadow map Z bias\n"); printf(" cursor keys = rotate scene\n"); -- 2.7.4