src/fp/tri-depthwrite.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
   8
   9 static void Init(void)
  10 {
  11    static const char *modulate2D =
  12       "!!ARBfp1.0\n"
  13       "MUL result.depth.z, fragment.color.z, {.1}.x; \n"
  14       "MOV result.color.xy, fragment.color; \n"
  15       "END"
  16       ;
  17    GLuint modulateProg;
  18
  19    if (!glutExtensionSupported("GL_ARB_fragment_program")) {
  20       printf("Error: GL_ARB_fragment_program not supported!\n");
  21       exit(1);
  22    }
  23    printf("GL_RENDERER = %s\n", (char *) glGetString(GL_RENDERER));
  24
  25    /* Setup the fragment program */
  26    glGenProgramsARB(1, &modulateProg);
  27    glBindProgramARB(GL_FRAGMENT_PROGRAM_ARB, modulateProg);
  28    glProgramStringARB(GL_FRAGMENT_PROGRAM_ARB, GL_PROGRAM_FORMAT_ASCII_ARB,
  29                         strlen(modulate2D), (const GLubyte *)modulate2D);
  30
  31    printf("glGetError = 0x%x\n", (int) glGetError());
  32    printf("glError(GL_PROGRAM_ERROR_STRING_ARB) = %s\n",
  33           (char *) glGetString(GL_PROGRAM_ERROR_STRING_ARB));
  34
  35    glEnable(GL_FRAGMENT_PROGRAM_ARB);
  36
  37    glClearColor(.3, .3, .3, 0);
  38 }
  39
  40 static void Reshape(int width, int height)
  41 {
  42
  43     glViewport(0, 0, (GLint)width, (GLint)height);
  44
  45     glMatrixMode(GL_PROJECTION);
  46     glLoadIdentity();
  47     glOrtho(-1.0, 1.0, -1.0, 1.0, -0.5, 1000.0);
  48     glMatrixMode(GL_MODELVIEW);
  49 }
  50
  51 static void Key(unsigned char key, int x, int y)
  52 {
  53
  54     switch (key) {
  55       case 27:
  56         exit(1);
  57       default:
  58         return;
  59     }
  60
  61     glutPostRedisplay();
  62 }
  63
  64 static void Draw(void)
  65 {
  66     glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT);
  67         glEnable(GL_DEPTH_TEST);
  68
  69
  70     glBegin(GL_TRIANGLES);
  71     glColor4f(.8,0,.5,0);
  72         glVertex3f( 0.9, -0.9, -30.0);
  73         glVertex3f( 0.9,  0.9, -30.0);
  74         glVertex3f(-0.9,  0.0, -30.0);
  75
  76     glColor4f(0,.8,.7,0);
  77         glVertex3f(-0.9, -0.9, -40.0);
  78     glColor4f(0,.8,.7,0);
  79         glVertex3f(-0.9,  0.9, -40.0);
  80     glColor4f(0,.8,.3,0);
  81         glVertex3f( 0.9,  0.0, -40.0);
  82     glEnd();
  83
  84     glFlush();
  85 }
  86
  87
  88 int main(int argc, char **argv)
  89 {
  90     glutInit(&argc, argv);
  91
  92     glutInitWindowPosition(0, 0); glutInitWindowSize( 300, 300);
  93
  94     glutInitDisplayMode(GLUT_DEPTH | GLUT_RGB | GLUT_SINGLE);
  95
  96     if (glutCreateWindow("Depth Test") == GL_FALSE) {
  97         exit(1);
  98     }
  99
 100     Init();
 101
 102     glutReshapeFunc(Reshape);
 103     glutKeyboardFunc(Key);
 104     glutDisplayFunc(Draw);
 105     glutMainLoop();
 106         return 0;
 107 }