357 lines
10 KiB
C
357 lines
10 KiB
C
/*
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* Use GL_ARB_fragment_program and GL_ARB_vertex_program to implement
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* simple per-pixel lighting.
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*
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* Brian Paul
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* 17 April 2003
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*/
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#include <assert.h>
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#include <string.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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#include <GL/glut.h>
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static GLfloat Diffuse[4] = { 0.5, 0.5, 1.0, 1.0 };
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static GLfloat Specular[4] = { 0.8, 0.8, 0.8, 1.0 };
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static GLfloat LightPos[4] = { 0.0, 10.0, 20.0, 1.0 };
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static GLfloat Delta = 1.0;
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static GLuint FragProg;
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static GLuint VertProg;
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static GLboolean Anim = GL_TRUE;
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static GLboolean Wire = GL_FALSE;
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static GLboolean PixelLight = GL_TRUE;
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static GLfloat Xrot = 0, Yrot = 0;
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static PFNGLPROGRAMLOCALPARAMETER4FVARBPROC glProgramLocalParameter4fvARB_func;
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static PFNGLPROGRAMLOCALPARAMETER4DARBPROC glProgramLocalParameter4dARB_func;
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static PFNGLGETPROGRAMLOCALPARAMETERDVARBPROC glGetProgramLocalParameterdvARB_func;
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static PFNGLGENPROGRAMSARBPROC glGenProgramsARB_func;
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static PFNGLPROGRAMSTRINGARBPROC glProgramStringARB_func;
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static PFNGLBINDPROGRAMARBPROC glBindProgramARB_func;
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static PFNGLISPROGRAMARBPROC glIsProgramARB_func;
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/* These must match the indexes used in the fragment program */
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#define DIFFUSE 1
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#define SPECULAR 2
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#define LIGHTPOS 3
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static void Redisplay( void )
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{
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glClear( GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT );
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if (PixelLight) {
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glProgramLocalParameter4fvARB_func(GL_FRAGMENT_PROGRAM_ARB,
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LIGHTPOS, LightPos);
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glEnable(GL_FRAGMENT_PROGRAM_ARB);
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glEnable(GL_VERTEX_PROGRAM_ARB);
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glDisable(GL_LIGHTING);
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}
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else {
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glLightfv(GL_LIGHT0, GL_POSITION, LightPos);
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glDisable(GL_FRAGMENT_PROGRAM_ARB);
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glDisable(GL_VERTEX_PROGRAM_ARB);
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glEnable(GL_LIGHTING);
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}
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glPushMatrix();
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glRotatef(Xrot, 1, 0, 0);
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glRotatef(Yrot, 0, 1, 0);
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glutSolidSphere(2.0, 10, 5);
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glPopMatrix();
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glutSwapBuffers();
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}
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static void Idle(void)
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{
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LightPos[0] += Delta;
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if (LightPos[0] > 25.0)
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Delta = -1.0;
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else if (LightPos[0] <- 25.0)
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Delta = 1.0;
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glutPostRedisplay();
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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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glFrustum( -1.0, 1.0, -1.0, 1.0, 5.0, 25.0 );
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glMatrixMode( GL_MODELVIEW );
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glLoadIdentity();
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glTranslatef( 0.0, 0.0, -15.0 );
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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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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 'x':
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LightPos[0] -= 1.0;
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break;
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case 'X':
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LightPos[0] += 1.0;
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break;
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case 'w':
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Wire = !Wire;
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if (Wire)
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glPolygonMode(GL_FRONT_AND_BACK, GL_LINE);
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else
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glPolygonMode(GL_FRONT_AND_BACK, GL_FILL);
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break;
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case 'p':
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PixelLight = !PixelLight;
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if (PixelLight) {
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printf("Per-pixel lighting\n");
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}
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else {
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printf("Conventional lighting\n");
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}
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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 SpecialKey( int 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 GLUT_KEY_UP:
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Xrot -= step;
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break;
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case GLUT_KEY_DOWN:
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Xrot += step;
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break;
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case GLUT_KEY_LEFT:
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Yrot -= step;
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break;
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case GLUT_KEY_RIGHT:
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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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/* A helper for finding errors in program strings */
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static int FindLine( const char *program, int position )
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{
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int i, line = 1;
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for (i = 0; i < position; i++) {
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if (program[i] == '\n')
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line++;
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}
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return line;
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}
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static void Init( void )
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{
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GLint errorPos;
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/* Yes, this could be expressed more efficiently */
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static const char *fragProgramText =
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"!!ARBfp1.0\n"
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"PARAM Diffuse = program.local[1]; \n"
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"PARAM Specular = program.local[2]; \n"
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"PARAM LightPos = program.local[3]; \n"
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"TEMP lightDir, normal, len; \n"
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"TEMP dotProd, specAtten; \n"
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"TEMP diffuseColor, specularColor; \n"
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"# Compute normalized light direction \n"
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"DP3 len.x, LightPos, LightPos; \n"
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"RSQ len.y, len.x; \n"
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"MUL lightDir, LightPos, len.y; \n"
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"# Compute normalized normal \n"
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"DP3 len.x, fragment.texcoord[0], fragment.texcoord[0]; \n"
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"RSQ len.y, len.x; \n"
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"MUL normal, fragment.texcoord[0], len.y; \n"
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"# Compute dot product of light direction and normal vector\n"
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"DP3 dotProd, lightDir, normal;"
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"MUL diffuseColor, Diffuse, dotProd; # diffuse attenuation\n"
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"POW specAtten.x, dotProd.x, {20.0}.x; # specular exponent\n"
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"MUL specularColor, Specular, specAtten.x; # specular attenuation\n"
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"ADD result.color, diffuseColor, specularColor; # add colors\n"
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"END \n"
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;
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static const char *vertProgramText =
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"!!ARBvp1.0\n"
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"ATTRIB pos = vertex.position; \n"
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"ATTRIB norm = vertex.normal; \n"
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"PARAM modelviewProj[4] = { state.matrix.mvp }; \n"
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"PARAM invModelview[4] = { state.matrix.modelview.invtrans }; \n"
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"# typical modelview/projection transform \n"
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"DP4 result.position.x, pos, modelviewProj[0]; \n"
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"DP4 result.position.y, pos, modelviewProj[1]; \n"
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"DP4 result.position.z, pos, modelviewProj[2]; \n"
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"DP4 result.position.w, pos, modelviewProj[3]; \n"
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"# transform normal by inv transpose of modelview, put in tex0 \n"
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"DP3 result.texcoord[0].x, norm, invModelview[0]; \n"
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"DP3 result.texcoord[0].y, norm, invModelview[1]; \n"
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"DP3 result.texcoord[0].z, norm, invModelview[2]; \n"
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"DP3 result.texcoord[0].w, norm, invModelview[3]; \n"
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"END\n";
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;
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if (!glutExtensionSupported("GL_ARB_vertex_program")) {
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printf("Sorry, this demo requires GL_ARB_vertex_program\n");
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exit(1);
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}
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if (!glutExtensionSupported("GL_ARB_fragment_program")) {
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printf("Sorry, this demo requires GL_ARB_fragment_program\n");
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exit(1);
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}
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/*
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* Get extension function pointers.
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*/
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glProgramLocalParameter4fvARB_func = (PFNGLPROGRAMLOCALPARAMETER4FVARBPROC) glutGetProcAddress("glProgramLocalParameter4fvARB");
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assert(glProgramLocalParameter4fvARB_func);
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glProgramLocalParameter4dARB_func = (PFNGLPROGRAMLOCALPARAMETER4DARBPROC) glutGetProcAddress("glProgramLocalParameter4dARB");
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assert(glProgramLocalParameter4dARB_func);
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glGetProgramLocalParameterdvARB_func = (PFNGLGETPROGRAMLOCALPARAMETERDVARBPROC) glutGetProcAddress("glGetProgramLocalParameterdvARB");
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assert(glGetProgramLocalParameterdvARB_func);
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glGenProgramsARB_func = (PFNGLGENPROGRAMSARBPROC) glutGetProcAddress("glGenProgramsARB");
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assert(glGenProgramsARB_func);
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glProgramStringARB_func = (PFNGLPROGRAMSTRINGARBPROC) glutGetProcAddress("glProgramStringARB");
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assert(glProgramStringARB_func);
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glBindProgramARB_func = (PFNGLBINDPROGRAMARBPROC) glutGetProcAddress("glBindProgramARB");
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assert(glBindProgramARB_func);
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glIsProgramARB_func = (PFNGLISPROGRAMARBPROC) glutGetProcAddress("glIsProgramARB");
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assert(glIsProgramARB_func);
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/*
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* Fragment program
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*/
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glGenProgramsARB_func(1, &FragProg);
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assert(FragProg > 0);
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glBindProgramARB_func(GL_FRAGMENT_PROGRAM_ARB, FragProg);
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glProgramStringARB_func(GL_FRAGMENT_PROGRAM_ARB,
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GL_PROGRAM_FORMAT_ASCII_ARB,
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strlen(fragProgramText),
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(const GLubyte *) fragProgramText);
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glGetIntegerv(GL_PROGRAM_ERROR_POSITION_ARB, &errorPos);
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if (glGetError() != GL_NO_ERROR || errorPos != -1) {
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int l = FindLine(fragProgramText, errorPos);
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printf("Fragment Program Error (pos=%d line=%d): %s\n", errorPos, l,
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(char *) glGetString(GL_PROGRAM_ERROR_STRING_ARB));
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exit(0);
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}
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assert(glIsProgramARB_func(FragProg));
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glProgramLocalParameter4fvARB_func(GL_FRAGMENT_PROGRAM_ARB, DIFFUSE, Diffuse);
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glProgramLocalParameter4fvARB_func(GL_FRAGMENT_PROGRAM_ARB, SPECULAR, Specular);
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/*
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* Do some sanity tests
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*/
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{
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GLdouble v[4];
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glProgramLocalParameter4dARB_func(GL_FRAGMENT_PROGRAM_ARB, 8,
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10.0, 20.0, 30.0, 40.0);
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glGetProgramLocalParameterdvARB_func(GL_FRAGMENT_PROGRAM_ARB, 8, v);
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assert(v[0] == 10.0);
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assert(v[1] == 20.0);
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assert(v[2] == 30.0);
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assert(v[3] == 40.0);
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glGetProgramLocalParameterdvARB_func(GL_FRAGMENT_PROGRAM_ARB, DIFFUSE, v);
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assert(v[0] == Diffuse[0]);
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assert(v[1] == Diffuse[1]);
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assert(v[2] == Diffuse[2]);
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assert(v[3] == Diffuse[3]);
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}
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/*
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* Vertex program
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*/
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glGenProgramsARB_func(1, &VertProg);
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assert(VertProg > 0);
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glBindProgramARB_func(GL_VERTEX_PROGRAM_ARB, VertProg);
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glProgramStringARB_func(GL_VERTEX_PROGRAM_ARB,
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GL_PROGRAM_FORMAT_ASCII_ARB,
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strlen(vertProgramText),
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(const GLubyte *) vertProgramText);
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glGetIntegerv(GL_PROGRAM_ERROR_POSITION_ARB, &errorPos);
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if (glGetError() != GL_NO_ERROR || errorPos != -1) {
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int l = FindLine(fragProgramText, errorPos);
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printf("Vertex Program Error (pos=%d line=%d): %s\n", errorPos, l,
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(char *) glGetString(GL_PROGRAM_ERROR_STRING_ARB));
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exit(0);
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}
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assert(glIsProgramARB_func(VertProg));
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/*
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* Misc init
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*/
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glClearColor(0.3, 0.3, 0.3, 0.0);
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glEnable(GL_DEPTH_TEST);
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glEnable(GL_LIGHT0);
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glEnable(GL_LIGHTING);
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glMaterialfv(GL_FRONT_AND_BACK, GL_DIFFUSE, Diffuse);
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glMaterialfv(GL_FRONT_AND_BACK, GL_SPECULAR, Specular);
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glMaterialf(GL_FRONT_AND_BACK, GL_SHININESS, 20.0);
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printf("GL_RENDERER = %s\n", (char *) glGetString(GL_RENDERER));
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printf("Press p to toggle between per-pixel and per-vertex lighting\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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glutInitWindowPosition( 0, 0 );
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glutInitWindowSize( 200, 200 );
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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( Redisplay );
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if (Anim)
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glutIdleFunc(Idle);
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Init();
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glutMainLoop();
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return 0;
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}
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