progs/trivial/vbo-drawelements.c

   1 /* Basic VBO */
   2
   3 #include <assert.h>
   4 #include <string.h>
   5 #include <stdio.h>
   6 #include <stdlib.h>
   7 #include <math.h>
   8 #include <GL/glew.h>
   9 #include <GL/glut.h>
  10
  11 struct {
  12    GLfloat pos[3];
  13    GLubyte color[4];
  14 } verts[] =
  15 {
  16    { {  0.9, -0.9, 0.0 },
  17      { 0x00, 0x00, 0xff, 0x00 }
  18    },
  19
  20    { {  0.9,  0.9, 0.0 },
  21      { 0x00, 0xff, 0x00, 0x00 }
  22    },
  23
  24    { { -0.9,  0.9, 0.0 },
  25      { 0xff, 0x00, 0x00, 0x00 }
  26    },
  27
  28    { { -0.9, -0.9, 0.0 },
  29      { 0xff, 0xff, 0xff, 0x00 }
  30    },
  31 };
  32
  33 GLuint indices[] = { 0, 1, 2, 3 };
  34
  35 GLuint arrayObj, elementObj;
  36
  37 static void Init( void )
  38 {
  39    GLint errno;
  40    GLuint prognum;
  41
  42    static const char *prog1 =
  43       "!!ARBvp1.0\n"
  44       "MOV  result.color, vertex.color;\n"
  45       "MOV  result.position, vertex.position;\n"
  46       "END\n";
  47
  48    glGenProgramsARB(1, &prognum);
  49    glBindProgramARB(GL_VERTEX_PROGRAM_ARB, prognum);
  50    glProgramStringARB(GL_VERTEX_PROGRAM_ARB, GL_PROGRAM_FORMAT_ASCII_ARB,
  51                       strlen(prog1), (const GLubyte *) prog1);
  52
  53    assert(glIsProgramARB(prognum));
  54    errno = glGetError();
  55    printf("glGetError = %d\n", errno);
  56    if (errno != GL_NO_ERROR)
  57    {
  58       GLint errorpos;
  59
  60       glGetIntegerv(GL_PROGRAM_ERROR_POSITION_ARB, &errorpos);
  61       printf("errorpos: %d\n", errorpos);
  62       printf("%s\n", (char *)glGetString(GL_PROGRAM_ERROR_STRING_ARB));
  63    }
  64
  65
  66    glEnableClientState( GL_VERTEX_ARRAY );
  67    glEnableClientState( GL_COLOR_ARRAY );
  68
  69    glGenBuffersARB(1, &arrayObj);
  70    glGenBuffersARB(1, &elementObj);
  71
  72    glBindBufferARB(GL_ARRAY_BUFFER_ARB, arrayObj);
  73    glBindBufferARB(GL_ELEMENT_ARRAY_BUFFER_ARB, elementObj);
  74
  75    glBufferDataARB(GL_ARRAY_BUFFER_ARB, sizeof(verts), verts, GL_STATIC_DRAW_ARB);
  76    glBufferDataARB(GL_ELEMENT_ARRAY_BUFFER_ARB, sizeof(indices), indices, GL_STATIC_DRAW_ARB);
  77
  78    glVertexPointer( 3, GL_FLOAT, sizeof(verts[0]), 0 );
  79    glColorPointer( 4, GL_UNSIGNED_BYTE, sizeof(verts[0]), (void *)(3*sizeof(float)) );
  80
  81 }
  82
  83
  84
  85 static void Display( void )
  86 {
  87    glClearColor(0.3, 0.3, 0.3, 1);
  88    glClear( GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT );
  89
  90    glEnable(GL_VERTEX_PROGRAM_ARB);
  91    glDrawElements( GL_TRIANGLES, 3, GL_UNSIGNED_INT, NULL );
  92
  93    glFlush();
  94 }
  95
  96
  97 static void Reshape( int width, int height )
  98 {
  99    glViewport( 0, 0, width, height );
 100    glMatrixMode( GL_PROJECTION );
 101    glLoadIdentity();
 102    glOrtho(-1.0, 1.0, -1.0, 1.0, -0.5, 1000.0);
 103    glMatrixMode( GL_MODELVIEW );
 104    glLoadIdentity();
 105    /*glTranslatef( 0.0, 0.0, -15.0 );*/
 106 }
 107
 108
 109 static void Key( unsigned char key, int x, int y )
 110 {
 111    (void) x;
 112    (void) y;
 113    switch (key) {
 114       case 27:
 115          exit(0);
 116          break;
 117    }
 118    glutPostRedisplay();
 119 }
 120
 121
 122
 123
 124 int main( int argc, char *argv[] )
 125 {
 126    glutInit( &argc, argv );
 127    glutInitWindowPosition( 0, 0 );
 128    glutInitWindowSize( 250, 250 );
 129    glutInitDisplayMode( GLUT_RGB | GLUT_SINGLE | GLUT_DEPTH );
 130    glutCreateWindow(argv[0]);
 131    glewInit();
 132    glutReshapeFunc( Reshape );
 133    glutKeyboardFunc( Key );
 134    glutDisplayFunc( Display );
 135    Init();
 136    glutMainLoop();
 137    return 0;
 138 }