progs/fp/tri-abs.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
  10 static void Init( void )
  11 {
  12    static const char *modulate2D =
  13       "!!ARBfp1.0\n"
  14       "TEMP R0;\n"
  15       "SUB R0, {0.5}.x, fragment.color; \n"
  16       "ABS result.color, R0; \n"
  17       "END"
  18       ;
  19    GLuint modulateProg;
  20
  21    if (!glutExtensionSupported("GL_ARB_fragment_program")) {
  22       printf("Error: GL_ARB_fragment_program not supported!\n");
  23       exit(1);
  24    }
  25    printf("GL_RENDERER = %s\n", (char *) glGetString(GL_RENDERER));
  26
  27    /* Setup the fragment program */
  28    glGenProgramsARB(1, &modulateProg);
  29    glBindProgramARB(GL_FRAGMENT_PROGRAM_ARB, modulateProg);
  30    glProgramStringARB(GL_FRAGMENT_PROGRAM_ARB, GL_PROGRAM_FORMAT_ASCII_ARB,
  31                         strlen(modulate2D), (const GLubyte *)modulate2D);
  32
  33    printf("glGetError = 0x%x\n", (int) glGetError());
  34    printf("glError(GL_PROGRAM_ERROR_STRING_ARB) = %s\n",
  35           (char *) glGetString(GL_PROGRAM_ERROR_STRING_ARB));
  36
  37    glEnable(GL_FRAGMENT_PROGRAM_ARB);
  38
  39    glClearColor(.3, .3, .3, 0);
  40 }
  41
  42 static void Reshape(int width, int height)
  43 {
  44
  45     glViewport(0, 0, (GLint)width, (GLint)height);
  46
  47     glMatrixMode(GL_PROJECTION);
  48     glLoadIdentity();
  49     glOrtho(-1.0, 1.0, -1.0, 1.0, -0.5, 1000.0);
  50     glMatrixMode(GL_MODELVIEW);
  51 }
  52
  53 static void Key(unsigned char key, int x, int y)
  54 {
  55
  56     switch (key) {
  57       case 27:
  58         exit(1);
  59       default:
  60         return;
  61     }
  62
  63     glutPostRedisplay();
  64 }
  65
  66 static void Draw(void)
  67 {
  68    glClear(GL_COLOR_BUFFER_BIT);
  69
  70    glBegin(GL_TRIANGLES);
  71    glColor3f(0,0,1);
  72    glVertex3f( 0.9, -0.9, -30.0);
  73    glColor3f(1,0,0);
  74    glVertex3f( 0.9,  0.9, -30.0);
  75    glColor3f(0,1,0);
  76    glVertex3f(-0.9,  0.0, -30.0);
  77    glEnd();
  78
  79    glFlush();
  80
  81 }
  82
  83
  84
  85 int main(int argc, char **argv)
  86 {
  87     GLenum type;
  88
  89     glutInit(&argc, argv);
  90     glutInitWindowPosition(0, 0); glutInitWindowSize( 250, 250);
  91
  92     type = GLUT_RGB;
  93     type |= GLUT_SINGLE;
  94     glutInitDisplayMode(type);
  95
  96     if (glutCreateWindow("First Tri") == 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 }