progs/tests/mapbufrange.c

   1 /*
   2  * Test glMapBuffer() and glMapBufferRange()
   3  *
   4  * Fill a VBO with vertex data to draw several colored quads.
   5  * On each redraw, update the geometry for just one rect in the VBO.
   6  *
   7  * Brian Paul
   8  * 4 March 2009
   9  */
  10
  11
  12 #include <assert.h>
  13 #include <math.h>
  14 #include <stdio.h>
  15 #include <stdlib.h>
  16 #include <string.h>
  17 #include <GL/glew.h>
  18 #include <GL/glew.h>
  19 #include <GL/glut.h>
  20
  21 static GLuint Win;
  22 static const GLuint NumRects = 10;
  23 static GLuint BufferID;
  24 static GLboolean Anim = GL_TRUE;
  25 static GLboolean UseBufferRange = GL_FALSE;
  26
  27
  28
  29 static const float RectData[] = {
  30    /* vertex */    /* color */
  31     0, -1, 0,      1,  0,  0,
  32     1,  0, 0,      1,  1,  0,
  33     0,  1, 0,      0,  1,  1,
  34    -1,  0, 0,      1,  0,  1
  35 };
  36
  37
  38 /**
  39  * The buffer contains vertex positions (float[3]) and colors (float[3])
  40  * for 'NumRects' quads.
  41  * This function updates/rotates one quad in the buffer.
  42  */
  43 static void
  44 UpdateRect(int r, float angle)
  45 {
  46    float *rect;
  47    int i;
  48
  49    assert(r < NumRects);
  50
  51    glBindBufferARB(GL_ARRAY_BUFFER_ARB, BufferID);
  52    if (UseBufferRange) {
  53       GLintptr offset = r * sizeof(RectData);
  54       GLsizeiptr length = sizeof(RectData);
  55       GLbitfield access = GL_MAP_WRITE_BIT | GL_MAP_INVALIDATE_RANGE_BIT;
  56       float *buf = (float *) glMapBufferRange(GL_ARRAY_BUFFER_ARB,
  57                                               offset, length, access);
  58       rect = buf;
  59    }
  60    else {
  61       /* map whole buffer */
  62       float *buf = (float *)
  63          glMapBufferARB(GL_ARRAY_BUFFER_ARB, GL_WRITE_ONLY_ARB);
  64       rect = buf + r * 24;
  65    }
  66
  67    /* set rect verts/colors */
  68    memcpy(rect, RectData, sizeof(RectData));
  69
  70    /* loop over four verts, updating vertices */
  71    for (i = 0; i < 4; i++) {
  72       float x = 0.2 * RectData[i*6+0];
  73       float y = 0.2 * RectData[i*6+1];
  74       float xpos = -2.5 + 0.5 * r;
  75       float ypos = 0.0;
  76
  77       /* translate and rotate vert */
  78       rect[i * 6 + 0] = xpos + x * cos(angle) + y * sin(angle);
  79       rect[i * 6 + 1] = ypos + x * sin(angle) - y * cos(angle);
  80    }
  81
  82    glUnmapBufferARB(GL_ARRAY_BUFFER_ARB);
  83 }
  84
  85
  86 static void
  87 LoadBuffer(void)
  88 {
  89    static int frame = 0;
  90    float angle = glutGet(GLUT_ELAPSED_TIME) * 0.001;
  91    UpdateRect(frame % NumRects, angle);
  92    frame++;
  93 }
  94
  95
  96 static void
  97 Draw(void)
  98 {
  99    glBindBufferARB(GL_ARRAY_BUFFER_ARB, BufferID);
 100    glVertexPointer(3, GL_FLOAT, 24, 0);
 101    glEnableClientState(GL_VERTEX_ARRAY);
 102
 103    glColorPointer(3, GL_FLOAT, 24, (void*) 12);
 104    glEnableClientState(GL_COLOR_ARRAY);
 105
 106    glDrawArrays(GL_QUADS, 0, NumRects * 4);
 107
 108    if (0)
 109       glFinish();
 110 }
 111
 112
 113 static void
 114 Display(void)
 115 {
 116    glClear(GL_COLOR_BUFFER_BIT);
 117    Draw();
 118    glutSwapBuffers();
 119 }
 120
 121
 122 static void
 123 Reshape(int width, int height)
 124 {
 125    glViewport(0, 0, width, height);
 126    glMatrixMode(GL_PROJECTION);
 127    glLoadIdentity();
 128    glOrtho(-3.0, 3.0, -1.0, 1.0, -1.0, 1.0);
 129    glMatrixMode(GL_MODELVIEW);
 130    glLoadIdentity();
 131 }
 132
 133
 134 static void
 135 Idle(void)
 136 {
 137    LoadBuffer();
 138    glutPostRedisplay();
 139 }
 140
 141
 142 static void
 143 Key(unsigned char key, int x, int y)
 144 {
 145    (void) x;
 146    (void) y;
 147    if (key == 'a') {
 148       Anim = !Anim;
 149       glutIdleFunc(Anim ? Idle : NULL);
 150    }
 151    else if (key == 's') {
 152       LoadBuffer();
 153    }
 154    else if (key == 27) {
 155       glutDestroyWindow(Win);
 156       exit(0);
 157    }
 158    glutPostRedisplay();
 159 }
 160
 161
 162 static void
 163 Init(void)
 164 {
 165    GLuint BufferSize = NumRects * sizeof(RectData);
 166    float *buf;
 167
 168    if (!glutExtensionSupported("GL_ARB_vertex_buffer_object")) {
 169       printf("GL_ARB_vertex_buffer_object not found!\n");
 170       exit(0);
 171    }
 172
 173    UseBufferRange = glutExtensionSupported("GL_ARB_map_buffer_range");
 174    printf("Use GL_ARB_map_buffer_range: %c\n", "NY"[UseBufferRange]);
 175
 176    printf("GL_RENDERER = %s\n", (char *) glGetString(GL_RENDERER));
 177
 178    /* initially load buffer with zeros */
 179    buf = (float *) calloc(1, BufferSize);
 180
 181    glGenBuffersARB(1, &BufferID);
 182    glBindBufferARB(GL_ARRAY_BUFFER_ARB, BufferID);
 183    glBufferDataARB(GL_ARRAY_BUFFER_ARB, BufferSize, buf, GL_DYNAMIC_DRAW_ARB);
 184
 185    free(buf);
 186 }
 187
 188
 189 int
 190 main(int argc, char *argv[])
 191 {
 192    glutInit(&argc, argv);
 193    glutInitWindowSize(800, 200);
 194    glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE);
 195    Win = glutCreateWindow(argv[0]);
 196    glewInit();
 197    glewInit();
 198    glutReshapeFunc(Reshape);
 199    glutKeyboardFunc(Key);
 200    glutDisplayFunc(Display);
 201    glutIdleFunc(Anim ? Idle : NULL);
 202    Init();
 203    glutMainLoop();
 204    return 0;
 205 }