src/fp/tri-depth.c

   1
   2 #include <stdio.h>
   3 #include <string.h>
   4 #include <stdlib.h>
   5 #define GL_GLEXT_PROTOTYPES
   6 #include <GL/glut.h>
   7 #include "GL/gl.h"
   8
   9
  10
  11 static void Init( void )
  12 {
  13    /* scale of 10.0 gives me a visible result on nv hardware.
  14     */
  15    static const char *modulate2D =
  16       "!!ARBfp1.0\n"
  17       "MUL result.color, fragment.position.z, {10.0}.x; \n"
  18       "END"
  19       ;
  20    GLuint modulateProg;
  21
  22    if (!glutExtensionSupported("GL_ARB_fragment_program")) {
  23       printf("Error: GL_ARB_fragment_program not supported!\n");
  24       exit(1);
  25    }
  26    printf("GL_RENDERER = %s\n", (char *) glGetString(GL_RENDERER));
  27
  28    /* Setup the fragment program */
  29    glGenProgramsARB(1, &modulateProg);
  30    glBindProgramARB(GL_FRAGMENT_PROGRAM_ARB, modulateProg);
  31    glProgramStringARB(GL_FRAGMENT_PROGRAM_ARB, GL_PROGRAM_FORMAT_ASCII_ARB,
  32                         strlen(modulate2D), (const GLubyte *)modulate2D);
  33
  34    printf("glGetError = 0x%x\n", (int) glGetError());
  35    printf("glError(GL_PROGRAM_ERROR_STRING_ARB) = %s\n",
  36           (char *) glGetString(GL_PROGRAM_ERROR_STRING_ARB));
  37
  38    glEnable(GL_FRAGMENT_PROGRAM_ARB);
  39
  40    glClearColor(.3, .3, .3, 0);
  41 }
  42
  43 static void Reshape(int width, int height)
  44 {
  45
  46     glViewport(0, 0, (GLint)width, (GLint)height);
  47
  48     glMatrixMode(GL_PROJECTION);
  49     glLoadIdentity();
  50     glOrtho(-1.0, 1.0, -1.0, 1.0, -0.5, 1000.0);
  51     glMatrixMode(GL_MODELVIEW);
  52 }
  53
  54 static void Key(unsigned char key, int x, int y)
  55 {
  56
  57     switch (key) {
  58       case 27:
  59         exit(1);
  60       default:
  61         return;
  62     }
  63
  64     glutPostRedisplay();
  65 }
  66
  67 static void Draw(void)
  68 {
  69    glClear(GL_COLOR_BUFFER_BIT);
  70
  71    glBegin(GL_TRIANGLES);
  72    glColor3f(0,0,1);
  73    glVertex3f( 0.9, -0.9, -40.0);
  74    glColor3f(1,0,0);
  75    glVertex3f( 0.9,  0.9, -40.0);
  76    glColor3f(0,1,0);
  77    glVertex3f(-0.9,  0.0, -25.0);
  78    glEnd();
  79
  80    glFlush();
  81
  82
  83 }
  84
  85
  86 int main(int argc, char **argv)
  87 {
  88     GLenum type;
  89
  90     glutInit(&argc, argv);
  91
  92
  93
  94     glutInitWindowPosition(0, 0); glutInitWindowSize( 250, 250);
  95
  96     type = GLUT_RGB;
  97     type |= GLUT_SINGLE;
  98     glutInitDisplayMode(type);
  99
 100     if (glutCreateWindow("First Tri") == GL_FALSE) {
 101         exit(1);
 102     }
 103
 104     Init();
 105
 106     glutReshapeFunc(Reshape);
 107     glutKeyboardFunc(Key);
 108     glutDisplayFunc(Draw);
 109     glutMainLoop();
 110         return 0;
 111 }