| /* |
| * Test glMapBuffer() and glMapBufferRange() |
| * |
| * Fill a VBO with vertex data to draw several colored quads. |
| * On each redraw, update the geometry for just one rect in the VBO. |
| * |
| * Brian Paul |
| * 4 March 2009 |
| */ |
| |
| |
| #include <assert.h> |
| #include <math.h> |
| #include <stdio.h> |
| #include <stdlib.h> |
| #include <string.h> |
| #include <GL/glew.h> |
| #include <GL/glew.h> |
| #include <GL/glut.h> |
| |
| static GLuint Win; |
| static const GLuint NumRects = 10; |
| static GLuint BufferID; |
| static GLboolean Anim = GL_TRUE; |
| static GLboolean UseBufferRange = GL_FALSE; |
| |
| |
| |
| static const float RectData[] = { |
| /* vertex */ /* color */ |
| 0, -1, 0, 1, 0, 0, |
| 1, 0, 0, 1, 1, 0, |
| 0, 1, 0, 0, 1, 1, |
| -1, 0, 0, 1, 0, 1 |
| }; |
| |
| |
| /** |
| * The buffer contains vertex positions (float[3]) and colors (float[3]) |
| * for 'NumRects' quads. |
| * This function updates/rotates one quad in the buffer. |
| */ |
| static void |
| UpdateRect(int r, float angle) |
| { |
| float *rect; |
| int i; |
| |
| assert(r < NumRects); |
| |
| glBindBufferARB(GL_ARRAY_BUFFER_ARB, BufferID); |
| if (UseBufferRange) { |
| GLintptr offset = r * sizeof(RectData); |
| GLsizeiptr length = sizeof(RectData); |
| GLbitfield access = GL_MAP_WRITE_BIT | GL_MAP_INVALIDATE_RANGE_BIT; |
| float *buf = (float *) glMapBufferRange(GL_ARRAY_BUFFER_ARB, |
| offset, length, access); |
| rect = buf; |
| } |
| else { |
| /* map whole buffer */ |
| float *buf = (float *) |
| glMapBufferARB(GL_ARRAY_BUFFER_ARB, GL_WRITE_ONLY_ARB); |
| rect = buf + r * 24; |
| } |
| |
| /* set rect verts/colors */ |
| memcpy(rect, RectData, sizeof(RectData)); |
| |
| /* loop over four verts, updating vertices */ |
| for (i = 0; i < 4; i++) { |
| float x = 0.2 * RectData[i*6+0]; |
| float y = 0.2 * RectData[i*6+1]; |
| float xpos = -2.5 + 0.5 * r; |
| float ypos = 0.0; |
| |
| /* translate and rotate vert */ |
| rect[i * 6 + 0] = xpos + x * cos(angle) + y * sin(angle); |
| rect[i * 6 + 1] = ypos + x * sin(angle) - y * cos(angle); |
| } |
| |
| glUnmapBufferARB(GL_ARRAY_BUFFER_ARB); |
| } |
| |
| |
| static void |
| LoadBuffer(void) |
| { |
| static int frame = 0; |
| float angle = glutGet(GLUT_ELAPSED_TIME) * 0.001; |
| UpdateRect(frame % NumRects, angle); |
| frame++; |
| } |
| |
| |
| static void |
| Draw(void) |
| { |
| glBindBufferARB(GL_ARRAY_BUFFER_ARB, BufferID); |
| glVertexPointer(3, GL_FLOAT, 24, 0); |
| glEnableClientState(GL_VERTEX_ARRAY); |
| |
| glColorPointer(3, GL_FLOAT, 24, (void*) 12); |
| glEnableClientState(GL_COLOR_ARRAY); |
| |
| glDrawArrays(GL_QUADS, 0, NumRects * 4); |
| |
| if (0) |
| glFinish(); |
| } |
| |
| |
| static void |
| Display(void) |
| { |
| glClear(GL_COLOR_BUFFER_BIT); |
| Draw(); |
| glutSwapBuffers(); |
| } |
| |
| |
| static void |
| Reshape(int width, int height) |
| { |
| glViewport(0, 0, width, height); |
| glMatrixMode(GL_PROJECTION); |
| glLoadIdentity(); |
| glOrtho(-3.0, 3.0, -1.0, 1.0, -1.0, 1.0); |
| glMatrixMode(GL_MODELVIEW); |
| glLoadIdentity(); |
| } |
| |
| |
| static void |
| Idle(void) |
| { |
| LoadBuffer(); |
| glutPostRedisplay(); |
| } |
| |
| |
| static void |
| Key(unsigned char key, int x, int y) |
| { |
| (void) x; |
| (void) y; |
| if (key == 'a') { |
| Anim = !Anim; |
| glutIdleFunc(Anim ? Idle : NULL); |
| } |
| else if (key == 's') { |
| LoadBuffer(); |
| } |
| else if (key == 27) { |
| glutDestroyWindow(Win); |
| exit(0); |
| } |
| glutPostRedisplay(); |
| } |
| |
| |
| static void |
| Init(void) |
| { |
| GLuint BufferSize = NumRects * sizeof(RectData); |
| float *buf; |
| |
| if (!glutExtensionSupported("GL_ARB_vertex_buffer_object")) { |
| printf("GL_ARB_vertex_buffer_object not found!\n"); |
| exit(0); |
| } |
| |
| UseBufferRange = glutExtensionSupported("GL_ARB_map_buffer_range"); |
| printf("Use GL_ARB_map_buffer_range: %c\n", "NY"[UseBufferRange]); |
| |
| printf("GL_RENDERER = %s\n", (char *) glGetString(GL_RENDERER)); |
| |
| /* initially load buffer with zeros */ |
| buf = (float *) calloc(1, BufferSize); |
| |
| glGenBuffersARB(1, &BufferID); |
| glBindBufferARB(GL_ARRAY_BUFFER_ARB, BufferID); |
| glBufferDataARB(GL_ARRAY_BUFFER_ARB, BufferSize, buf, GL_DYNAMIC_DRAW_ARB); |
| |
| free(buf); |
| } |
| |
| |
| int |
| main(int argc, char *argv[]) |
| { |
| glutInit(&argc, argv); |
| glutInitWindowSize(800, 200); |
| glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE); |
| Win = glutCreateWindow(argv[0]); |
| glewInit(); |
| glewInit(); |
| glutReshapeFunc(Reshape); |
| glutKeyboardFunc(Key); |
| glutDisplayFunc(Display); |
| glutIdleFunc(Anim ? Idle : NULL); |
| Init(); |
| glutMainLoop(); |
| return 0; |
| } |