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-rw-r--r--progs/demos/shadowtex.c143
1 files changed, 126 insertions, 17 deletions
diff --git a/progs/demos/shadowtex.c b/progs/demos/shadowtex.c
index 0daf77defc8..112ee0dad08 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 <assert.h>
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
@@ -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");
generated by cgit v1.2.3 (git 2.39.1) at 2024-12-24 01:09:07 +0000