progs/tests/mapvbo.c

   1 /*
   2  * Test glMapBuffer() call immediately after glDrawArrays().
   3  * See details below.
   4  *
   5  * NOTE: Do not use freeglut with this test!  It calls the Display()
   6  * callback twice right away instead of just once.
   7  *
   8  * Brian Paul
   9  * 27 Feb 2009
  10  */
  11
  12
  13 #include <stdio.h>
  14 #include <stdlib.h>
  15 #include <GL/glew.h>
  16 #include <GL/glut.h>
  17
  18 static GLuint BufferID;
  19
  20
  21 static GLuint Win;
  22
  23
  24
  25
  26 /*
  27  * Create VBO (position and color) and load with data.
  28  */
  29 static void
  30 SetupBuffers(void)
  31 {
  32    static const GLfloat data[] = {
  33       /* vertex */     /* color */
  34       0, -1,  0,      1,    1,   0,
  35       1,  0,  0,      1,    1,   0,
  36       0,  1,  0,      1,    1,   0,
  37       -1, 0,  0,      1,    1,   0
  38    };
  39
  40    glGenBuffersARB(1, &BufferID);
  41    glBindBufferARB(GL_ARRAY_BUFFER_ARB, BufferID);
  42    glBufferDataARB(GL_ARRAY_BUFFER_ARB, sizeof(data), data,
  43                    GL_STATIC_DRAW_ARB);
  44 }
  45
  46
  47 static void
  48 Draw(void)
  49 {
  50    static int count = 1;
  51
  52    printf("Draw Frame %d\n", count);
  53    count++;
  54
  55    glBindBufferARB(GL_ARRAY_BUFFER_ARB, BufferID);
  56    glVertexPointer(3, GL_FLOAT, 24, 0);
  57    glEnableClientState(GL_VERTEX_ARRAY);
  58
  59    glColorPointer(3, GL_FLOAT, 24, (void*) 12);
  60    glEnableClientState(GL_COLOR_ARRAY);
  61
  62    glDrawArrays(GL_TRIANGLE_FAN, 0, 4);
  63
  64    if (0)
  65       glFinish();
  66
  67    /* Immediately map the color buffer and change something.
  68     * This should not effect the first glDrawArrays above, but the
  69     * next time we draw we should see a black vertex.
  70     */
  71    if (1) {
  72       GLfloat *m = (GLfloat *) glMapBufferARB(GL_ARRAY_BUFFER_ARB,
  73                                               GL_WRITE_ONLY_ARB);
  74       m[3] = m[4] = m[5] = 0.0f; /* black vertex */
  75       glUnmapBufferARB(GL_ARRAY_BUFFER_ARB);
  76    }
  77 }
  78
  79
  80 static void Display( void )
  81 {
  82    glClear( GL_COLOR_BUFFER_BIT );
  83    Draw();
  84    glutSwapBuffers();
  85 }
  86
  87
  88 static void Reshape( int width, int height )
  89 {
  90    float ar = (float) width / (float) height;
  91    glViewport( 0, 0, width, height );
  92    glMatrixMode( GL_PROJECTION );
  93    glLoadIdentity();
  94    glFrustum( -ar, ar, -1.0, 1.0, 5.0, 25.0 );
  95    glMatrixMode( GL_MODELVIEW );
  96    glLoadIdentity();
  97    glTranslatef( 0.0, 0.0, -15.0 );
  98 }
  99
 100
 101 static void Key( unsigned char key, int x, int y )
 102 {
 103    (void) x;
 104    (void) y;
 105    if (key == 27) {
 106       glutDestroyWindow(Win);
 107       exit(0);
 108    }
 109    glutPostRedisplay();
 110 }
 111
 112
 113 static void Init( void )
 114 {
 115    if (!glutExtensionSupported("GL_ARB_vertex_buffer_object")) {
 116       printf("GL_ARB_vertex_buffer_object not found!\n");
 117       exit(0);
 118    }
 119    printf("GL_RENDERER = %s\n", (char *) glGetString(GL_RENDERER));
 120
 121    SetupBuffers();
 122 }
 123
 124
 125 int main( int argc, char *argv[] )
 126 {
 127    glutInit( &argc, argv );
 128    glutInitWindowPosition( 0, 0 );
 129    glutInitWindowSize( 300, 300 );
 130    glutInitDisplayMode( GLUT_RGB | GLUT_DOUBLE );
 131    Win = glutCreateWindow(argv[0]);
 132    glewInit();
 133    glutReshapeFunc( Reshape );
 134    glutKeyboardFunc( Key );
 135    glutDisplayFunc( Display );
 136    Init();
 137    glutMainLoop();
 138    return 0;
 139 }