--- /dev/null
+/*
+ * Use GL_ARB_fragment_program and GL_ARB_vertex_program to implement
+ * simple per-pixel lighting.
+ *
+ * Brian Paul
+ * 17 April 2003
+ */
+
+#include <assert.h>
+#include <string.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <math.h>
+#include <GL/glut.h>
+
+
+static GLfloat Diffuse[4] = { 0.5, 0.5, 1.0, 1.0 };
+static GLfloat Specular[4] = { 0.8, 0.8, 0.8, 1.0 };
+static GLfloat LightPos[4] = { 0.0, 10.0, 20.0, 1.0 };
+static GLfloat Delta = 1.0;
+
+static GLuint FragProg;
+static GLuint VertProg;
+static GLboolean Anim = GL_TRUE;
+static GLboolean Wire = GL_FALSE;
+static GLboolean PixelLight = GL_TRUE;
+
+static GLfloat Xrot = 0, Yrot = 0;
+
+static PFNGLPROGRAMLOCALPARAMETER4FVARBPROC glProgramLocalParameter4fvARB_func;
+static PFNGLGENPROGRAMSARBPROC glGenProgramsARB_func;
+static PFNGLPROGRAMSTRINGARBPROC glProgramStringARB_func;
+static PFNGLBINDPROGRAMARBPROC glBindProgramARB_func;
+static PFNGLISPROGRAMARBPROC glIsProgramARB_func;
+
+/* These must match the indexes used in the fragment program */
+#define DIFFUSE 1
+#define SPECULAR 2
+#define LIGHTPOS 3
+
+
+
+static void Redisplay( void )
+{
+ glClear( GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT );
+
+ if (PixelLight) {
+ glProgramLocalParameter4fvARB(GL_FRAGMENT_PROGRAM_ARB,
+ LIGHTPOS, LightPos);
+ glEnable(GL_FRAGMENT_PROGRAM_ARB);
+ glEnable(GL_VERTEX_PROGRAM_ARB);
+ glDisable(GL_LIGHTING);
+ }
+ else {
+ glLightfv(GL_LIGHT0, GL_POSITION, LightPos);
+ glDisable(GL_FRAGMENT_PROGRAM_ARB);
+ glDisable(GL_VERTEX_PROGRAM_ARB);
+ glEnable(GL_LIGHTING);
+ }
+
+ glPushMatrix();
+ glRotatef(Xrot, 1, 0, 0);
+ glRotatef(Yrot, 0, 1, 0);
+ glutSolidSphere(2.0, 10, 5);
+ glPopMatrix();
+
+ glutSwapBuffers();
+}
+
+
+static void Idle(void)
+{
+ LightPos[0] += Delta;
+ if (LightPos[0] > 25.0)
+ Delta = -1.0;
+ else if (LightPos[0] <- 25.0)
+ Delta = 1.0;
+ glutPostRedisplay();
+}
+
+
+static void Reshape( int width, int height )
+{
+ glViewport( 0, 0, width, height );
+ glMatrixMode( GL_PROJECTION );
+ glLoadIdentity();
+ glFrustum( -1.0, 1.0, -1.0, 1.0, 5.0, 25.0 );
+ glMatrixMode( GL_MODELVIEW );
+ glLoadIdentity();
+ glTranslatef( 0.0, 0.0, -15.0 );
+}
+
+
+static void Key( unsigned char key, int x, int y )
+{
+ (void) x;
+ (void) y;
+ switch (key) {
+ case ' ':
+ Anim = !Anim;
+ if (Anim)
+ glutIdleFunc(Idle);
+ else
+ glutIdleFunc(NULL);
+ break;
+ case 'x':
+ LightPos[0] -= 1.0;
+ break;
+ case 'X':
+ LightPos[0] += 1.0;
+ break;
+ case 'w':
+ Wire = !Wire;
+ if (Wire)
+ glPolygonMode(GL_FRONT_AND_BACK, GL_LINE);
+ else
+ glPolygonMode(GL_FRONT_AND_BACK, GL_FILL);
+ break;
+ case 'p':
+ PixelLight = !PixelLight;
+ if (PixelLight) {
+ printf("Per-pixel lighting\n");
+ }
+ else {
+ printf("Conventional lighting\n");
+ }
+ break;
+ case 27:
+ exit(0);
+ break;
+ }
+ glutPostRedisplay();
+}
+
+static void SpecialKey( int key, int x, int y )
+{
+ const GLfloat step = 3.0;
+ (void) x;
+ (void) y;
+ switch (key) {
+ case GLUT_KEY_UP:
+ Xrot -= step;
+ break;
+ case GLUT_KEY_DOWN:
+ Xrot += step;
+ break;
+ case GLUT_KEY_LEFT:
+ Yrot -= step;
+ break;
+ case GLUT_KEY_RIGHT:
+ Yrot += step;
+ break;
+ }
+ glutPostRedisplay();
+}
+
+
+/* A helper for finding errors in program strings */
+static int FindLine( const char *program, int position )
+{
+ int i, line = 1;
+ for (i = 0; i < position; i++) {
+ if (program[i] == '\n')
+ line++;
+ }
+ return line;
+}
+
+
+static void Init( void )
+{
+ GLint errorPos;
+
+ /* Yes, this could be expressed more efficiently */
+ static const char *fragProgramText =
+ "!!ARBfp1.0\n"
+ "PARAM Diffuse = program.local[1]; \n"
+ "PARAM Specular = program.local[2]; \n"
+ "PARAM LightPos = program.local[3]; \n"
+ "TEMP lightDir, normal, len; \n"
+ "TEMP dotProd, specAtten; \n"
+ "TEMP diffuseColor, specularColor; \n"
+
+ "# Compute normalized light direction \n"
+ "DP3 len.x, LightPos, LightPos; \n"
+ "RSQ len.y, len.x; \n"
+ "MUL lightDir, LightPos, len.y; \n"
+
+ "# Compute normalized normal \n"
+ "DP3 len.x, fragment.texcoord[0], fragment.texcoord[0]; \n"
+ "RSQ len.y, len.x; \n"
+ "MUL normal, fragment.texcoord[0], len.y; \n"
+
+ "# Compute dot product of light direction and normal vector\n"
+ "DP3 dotProd, lightDir, normal;"
+
+ "MUL diffuseColor, Diffuse, dotProd; # diffuse attenuation\n"
+
+ "POW specAtten.x, dotProd.x, {20.0}.x; # specular exponent\n"
+
+ "MUL specularColor, Specular, specAtten.x; # specular attenuation\n"
+
+ "ADD result.color, diffuseColor, specularColor; # add colors\n"
+ "END \n"
+ ;
+
+ static const char *vertProgramText =
+ "!!ARBvp1.0\n"
+ "ATTRIB pos = vertex.position; \n"
+ "ATTRIB norm = vertex.normal; \n"
+ "PARAM modelviewProj[4] = { state.matrix.mvp }; \n"
+ "PARAM invModelview[4] = { state.matrix.modelview.invtrans }; \n"
+
+ "# typical modelview/projection transform \n"
+ "DP4 result.position.x, pos, modelviewProj[0]; \n"
+ "DP4 result.position.y, pos, modelviewProj[1]; \n"
+ "DP4 result.position.z, pos, modelviewProj[2]; \n"
+ "DP4 result.position.w, pos, modelviewProj[3]; \n"
+
+ "# transform normal by inv transpose of modelview, put in tex0 \n"
+ "DP4 result.texcoord[0].x, norm, invModelview[0]; \n"
+ "DP4 result.texcoord[0].y, norm, invModelview[1]; \n"
+ "DP4 result.texcoord[0].z, norm, invModelview[2]; \n"
+ "DP4 result.texcoord[0].w, norm, invModelview[3]; \n"
+
+ "END\n";
+ ;
+
+ if (!glutExtensionSupported("GL_ARB_vertex_program")) {
+ printf("Sorry, this demo requires GL_ARB_vertex_program\n");
+ exit(1);
+ }
+ if (!glutExtensionSupported("GL_ARB_fragment_program")) {
+ printf("Sorry, this demo requires GL_ARB_fragment_program\n");
+ exit(1);
+ }
+
+ /*
+ * Get extension function pointers.
+ */
+ glProgramLocalParameter4fvARB_func = (PFNGLPROGRAMLOCALPARAMETER4FVARBPROC) glutGetProcAddress("glProgramLocalParameter4fvARB");
+ assert(glProgramLocalParameter4fvARB_func);
+
+ glGenProgramsARB_func = (PFNGLGENPROGRAMSARBPROC) glutGetProcAddress("glGenProgramsARB");
+ assert(glGenProgramsARB_func);
+
+ glProgramStringARB_func = (PFNGLPROGRAMSTRINGARBPROC) glutGetProcAddress("glProgramStringARB");
+ assert(glProgramStringARB_func);
+
+ glBindProgramARB_func = (PFNGLBINDPROGRAMARBPROC) glutGetProcAddress("glBindProgramARB");
+ assert(glBindProgramARB_func);
+
+ glIsProgramARB_func = (PFNGLISPROGRAMARBPROC) glutGetProcAddress("glIsProgramARB");
+ assert(glIsProgramARB_func);
+
+ /*
+ * Fragment program
+ */
+ glGenProgramsARB_func(1, &FragProg);
+ assert(FragProg > 0);
+ glBindProgramARB_func(GL_FRAGMENT_PROGRAM_ARB, FragProg);
+ glProgramStringARB_func(GL_FRAGMENT_PROGRAM_ARB,
+ GL_PROGRAM_FORMAT_ASCII_ARB,
+ strlen(fragProgramText),
+ (const GLubyte *) fragProgramText);
+ glGetIntegerv(GL_PROGRAM_ERROR_POSITION_ARB, &errorPos);
+ if (glGetError() != GL_NO_ERROR || errorPos != -1) {
+ int l = FindLine(fragProgramText, errorPos);
+ printf("Fragment Program Error (pos=%d line=%d): %s\n", errorPos, l,
+ (char *) glGetString(GL_PROGRAM_ERROR_STRING_ARB));
+ exit(0);
+ }
+ assert(glIsProgramARB_func(FragProg));
+
+ glProgramLocalParameter4fvARB(GL_FRAGMENT_PROGRAM_ARB, DIFFUSE, Diffuse);
+ glProgramLocalParameter4fvARB(GL_FRAGMENT_PROGRAM_ARB, SPECULAR, Specular);
+
+ /*
+ * Do some sanity tests
+ */
+ {
+ GLdouble v[4];
+ glProgramLocalParameter4dARB(GL_FRAGMENT_PROGRAM_ARB, 8,
+ 10.0, 20.0, 30.0, 40.0);
+ glGetProgramLocalParameterdvARB(GL_FRAGMENT_PROGRAM_ARB, 8, v);
+ assert(v[0] == 10.0);
+ assert(v[1] == 20.0);
+ assert(v[2] == 30.0);
+ assert(v[3] == 40.0);
+ glGetProgramLocalParameterdvARB(GL_FRAGMENT_PROGRAM_ARB, DIFFUSE, v);
+ assert(v[0] == Diffuse[0]);
+ assert(v[1] == Diffuse[1]);
+ assert(v[2] == Diffuse[2]);
+ assert(v[3] == Diffuse[3]);
+ }
+
+ /*
+ * Vertex program
+ */
+ glGenProgramsARB_func(1, &VertProg);
+ assert(VertProg > 0);
+ glBindProgramARB_func(GL_VERTEX_PROGRAM_ARB, VertProg);
+ glProgramStringARB_func(GL_VERTEX_PROGRAM_ARB,
+ GL_PROGRAM_FORMAT_ASCII_ARB,
+ strlen(vertProgramText),
+ (const GLubyte *) vertProgramText);
+ glGetIntegerv(GL_PROGRAM_ERROR_POSITION_ARB, &errorPos);
+ if (glGetError() != GL_NO_ERROR || errorPos != -1) {
+ int l = FindLine(fragProgramText, errorPos);
+ printf("Vertex Program Error (pos=%d line=%d): %s\n", errorPos, l,
+ (char *) glGetString(GL_PROGRAM_ERROR_STRING_ARB));
+ exit(0);
+ }
+ assert(glIsProgramARB_func(VertProg));
+
+ /*
+ * Misc init
+ */
+ glClearColor(0.3, 0.3, 0.3, 0.0);
+ glEnable(GL_DEPTH_TEST);
+ glEnable(GL_LIGHT0);
+ glEnable(GL_LIGHTING);
+ glMaterialfv(GL_FRONT_AND_BACK, GL_DIFFUSE, Diffuse);
+ glMaterialfv(GL_FRONT_AND_BACK, GL_SPECULAR, Specular);
+ glMaterialf(GL_FRONT_AND_BACK, GL_SHININESS, 20.0);
+
+ printf("GL_RENDERER = %s\n", (char *) glGetString(GL_RENDERER));
+ printf("Press p to toggle between per-pixel and per-vertex lighting\n");
+}
+
+
+int main( int argc, char *argv[] )
+{
+ glutInit( &argc, argv );
+ glutInitWindowPosition( 0, 0 );
+ glutInitWindowSize( 200, 200 );
+ glutInitDisplayMode( GLUT_RGB | GLUT_DOUBLE | GLUT_DEPTH );
+ glutCreateWindow(argv[0]);
+ glutReshapeFunc( Reshape );
+ glutKeyboardFunc( Key );
+ glutSpecialFunc( SpecialKey );
+ glutDisplayFunc( Redisplay );
+ if (Anim)
+ glutIdleFunc(Idle);
+ Init();
+ glutMainLoop();
+ return 0;
+}
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