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demo of GL_SGIX_shadow
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Brian Paul
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393
progs/demos/shadowtex.c
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393
progs/demos/shadowtex.c
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/* $Id: shadowtex.c,v 1.1 2001/02/20 16:43:50 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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* GL_SGIX_shadow_ambient extensions.
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*
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* Brian Paul
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* 19 Feb 2001
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*
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* Copyright (C) 1999-2001 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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#include <stdio.h>
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#include <stdlib.h>
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#include <math.h>
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#include <GL/glut.h>
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#include "../util/showbuffer.c"
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#define DEG_TO_RAD (3.14159 / 180.0)
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static GLint WindowWidth = 450, WindowHeight = 300;
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static GLfloat Xrot = 15, Yrot = 0, Zrot = 0;
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static GLfloat Red[4] = {1, 0, 0, 1};
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static GLfloat Green[4] = {0, 1, 0, 1};
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static GLfloat Blue[4] = {0, 0, 1, 1};
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static GLfloat Yellow[4] = {1, 1, 0, 1};
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static GLfloat LightDist = 10;
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static GLfloat LightLatitude = 45.0;
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static GLfloat LightLongitude = 45.0;
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static GLfloat LightPos[4];
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static GLfloat SpotDir[3];
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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 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 void
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DrawScene(void)
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{
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GLfloat k = 6;
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/* sphere */
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glPushMatrix();
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glTranslatef(1.6, 2.2, 2.7);
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glMaterialfv(GL_FRONT_AND_BACK, GL_AMBIENT_AND_DIFFUSE, Green);
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glColor4fv(Green);
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glutSolidSphere(1.5, 15, 15);
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glPopMatrix();
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/* dodecahedron */
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glPushMatrix();
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glTranslatef(-2.0, 1.2, 2.1);
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glMaterialfv(GL_FRONT_AND_BACK, GL_AMBIENT_AND_DIFFUSE, Red);
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glColor4fv(Red);
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glutSolidDodecahedron();
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glPopMatrix();
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/* icosahedron */
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glPushMatrix();
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glTranslatef(-0.6, 1.3, -0.5);
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glScalef(1.5, 1.5, 1.5);
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glMaterialfv(GL_FRONT_AND_BACK, GL_AMBIENT_AND_DIFFUSE, Yellow);
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glColor4fv(Red);
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glutSolidIcosahedron();
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glPopMatrix();
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/* a plane */
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glPushMatrix();
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glTranslatef(0, -1.1, 0);
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glMaterialfv(GL_FRONT_AND_BACK, GL_AMBIENT_AND_DIFFUSE, Blue);
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glColor4fv(Blue);
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glNormal3f(0, 1, 0);
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glBegin(GL_POLYGON);
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glVertex3f(-k, 0, -k);
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glVertex3f( k, 0, -k);
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glVertex3f( k, 0, k);
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glVertex3f(-k, 0, k);
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glEnd();
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glPopMatrix();
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}
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/*
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* Load the GL_TEXTURE matrix with the projection from the light
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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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{
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GLfloat d;
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glMatrixMode(GL_TEXTURE);
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glLoadIdentity();
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glTranslatef(0.5, 0.5, 0.5 + Bias);
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glScalef(0.5, 0.5, 0.5);
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d = shadowNear * tan(spotAngle);
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glFrustum(-d, d, -d, d, shadowNear, shadowFar);
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gluLookAt(lightPos[0], lightPos[1], lightPos[2],
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lightPos[0] + spotDir[0],
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lightPos[1] + spotDir[1],
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lightPos[2] + spotDir[2],
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0, 1, 0);
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glMatrixMode(GL_MODELVIEW);
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}
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static void
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EnableTexgen(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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static GLfloat tPlane[4] = { 0, 1, 0, 0 };
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static GLfloat rPlane[4] = { 0, 0, 1, 0 };
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static GLfloat qPlane[4] = { 0, 0, 0, 1 };
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glTexGenfv(GL_S, GL_EYE_PLANE, sPlane);
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glTexGenfv(GL_T, GL_EYE_PLANE, tPlane);
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glTexGenfv(GL_R, GL_EYE_PLANE, rPlane);
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glTexGenfv(GL_Q, GL_EYE_PLANE, qPlane);
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glTexGeni(GL_S, GL_TEXTURE_GEN_MODE, GL_EYE_LINEAR);
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glTexGeni(GL_T, GL_TEXTURE_GEN_MODE, GL_EYE_LINEAR);
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glTexGeni(GL_R, GL_TEXTURE_GEN_MODE, GL_EYE_LINEAR);
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glTexGeni(GL_Q, GL_TEXTURE_GEN_MODE, GL_EYE_LINEAR);
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glEnable(GL_TEXTURE_GEN_S);
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glEnable(GL_TEXTURE_GEN_T);
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glEnable(GL_TEXTURE_GEN_R);
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glEnable(GL_TEXTURE_GEN_Q);
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}
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static void
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DisableTexgen(void)
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{
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glDisable(GL_TEXTURE_GEN_S);
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glDisable(GL_TEXTURE_GEN_T);
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glDisable(GL_TEXTURE_GEN_R);
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glDisable(GL_TEXTURE_GEN_Q);
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}
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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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pos[3] = 1;
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dir[0] = -pos[0];
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dir[1] = -pos[1];
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dir[2] = -pos[2];
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}
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static void
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Display(void)
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{
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GLfloat ar = (GLfloat) WindowWidth / (GLfloat) WindowHeight;
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GLfloat d;
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ComputeLightPos(LightDist, LightLatitude, LightLongitude,
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LightPos, SpotDir);
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/*
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* Step 1: render scene from point of view of the light source
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*/
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/* compute frustum to enclose spot light cone */
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d = ShadowNear * tan(SpotAngle);
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glMatrixMode(GL_PROJECTION);
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glLoadIdentity();
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glFrustum(-d, d, -d, d, ShadowNear, ShadowFar);
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glMatrixMode(GL_MODELVIEW);
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glLoadIdentity();
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gluLookAt(LightPos[0], LightPos[1], LightPos[2], /* from */
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0, 0, 0, /* target */
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0, 1, 0); /* up */
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glViewport(0, 0, ShadowTexWidth, ShadowTexHeight);
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glClear(GL_DEPTH_BUFFER_BIT);
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DrawScene();
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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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/*
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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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glMatrixMode(GL_PROJECTION);
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glLoadIdentity();
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glFrustum(-ar, ar, -1.0, 1.0, 4.0, 50.0);
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glMatrixMode(GL_MODELVIEW);
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glLoadIdentity();
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glTranslatef(0.0, 0.0, -22.0);
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glRotatef(Xrot, 1, 0, 0);
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glRotatef(Yrot, 0, 1, 0);
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glRotatef(Zrot, 0, 0, 1);
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if (ShowDepth) {
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ShowDepthBuffer(WindowWidth, WindowHeight, 1, 0);
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}
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else {
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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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ShadowMatrix(LightPos, SpotDir, SpotAngle, ShadowNear, ShadowFar);
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EnableTexgen();
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DrawScene();
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DisableTexgen();
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glDisable(GL_TEXTURE_2D);
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}
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glutSwapBuffers();
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}
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static void
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Reshape(int width, int height)
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{
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WindowWidth = width;
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WindowHeight = height;
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}
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static void
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Idle(void)
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{
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Yrot += 5.0;
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/*LightLongitude -= 5.0;*/
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glutPostRedisplay();
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}
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static void
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Key(unsigned char key, int x, int y)
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{
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const GLfloat step = 3.0;
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(void) x;
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(void) y;
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switch (key) {
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case 'a':
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Anim = !Anim;
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if (Anim)
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glutIdleFunc(Idle);
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else
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glutIdleFunc(NULL);
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break;
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case 'b':
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Bias -= 0.01;
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break;
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case 'B':
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Bias += 0.01;
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break;
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case 'd':
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ShowDepth = !ShowDepth;
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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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case 'Z':
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Zrot += step;
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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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printf("Bias %g\n", Bias);
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}
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static void
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SpecialKey(int key, int x, int y)
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{
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const GLfloat step = 3.0;
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const int mod = glutGetModifiers();
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(void) x;
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(void) y;
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switch (key) {
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case GLUT_KEY_UP:
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if (mod)
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LightLatitude += step;
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else
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Xrot += step;
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break;
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case GLUT_KEY_DOWN:
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if (mod)
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LightLatitude -= step;
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else
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Xrot -= step;
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break;
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case GLUT_KEY_LEFT:
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if (mod)
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LightLongitude += step;
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else
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Yrot += step;
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break;
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case GLUT_KEY_RIGHT:
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if (mod)
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LightLongitude -= step;
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else
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Yrot -= step;
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break;
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}
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glutPostRedisplay();
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}
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static void
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Init(void)
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{
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if (!glutExtensionSupported("GL_SGIX_depth_texture") ||
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!glutExtensionSupported("GL_SGIX_shadow")) {
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printf("Sorry, this demo requires the GL_SGIX_depth_texture and GL_SGIX_shadow extensions\n");
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exit(1);
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}
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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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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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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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if (glutExtensionSupported("GL_SGIX_shadow_ambient"))
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glTexParameterf(GL_TEXTURE_2D, GL_SHADOW_AMBIENT_SGIX, 0.3);
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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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}
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static void
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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(" b/B = decrease/increase shadow map Z bias\n");
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printf(" cursor keys = rotate scene\n");
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printf(" <shift> + cursor keys = rotate light source\n");
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}
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int
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main(int argc, char *argv[])
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{
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glutInit(&argc, argv);
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glutInitWindowPosition(0, 0);
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glutInitWindowSize(WindowWidth, WindowHeight);
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glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE | GLUT_DEPTH);
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glutCreateWindow(argv[0]);
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glutReshapeFunc(Reshape);
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glutKeyboardFunc(Key);
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glutSpecialFunc(SpecialKey);
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glutDisplayFunc(Display);
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if (Anim)
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glutIdleFunc(Idle);
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Init();
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PrintHelp();
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glutMainLoop();
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return 0;
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}
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