--- /dev/null
+/*
+ * Test glMapBuffer() call immediately after glDrawArrays().
+ * See details below.
+ *
+ * NOTE: Do not use freeglut with this test! It calls the Display()
+ * callback twice right away instead of just once.
+ *
+ * Brian Paul
+ * 27 Feb 2009
+ */
+
+
+#define GL_GLEXT_PROTOTYPES
+#include <stdio.h>
+#include <stdlib.h>
+#include <GL/glut.h>
+
+static GLuint BufferID;
+
+
+static GLuint Win;
+
+
+
+
+/*
+ * Create VBO (position and color) and load with data.
+ */
+static void
+SetupBuffers(void)
+{
+ static const GLfloat data[] = {
+ /* vertex */ /* color */
+ 0, -1, 0, 1, 1, 0,
+ 1, 0, 0, 1, 1, 0,
+ 0, 1, 0, 1, 1, 0,
+ -1, 0, 0, 1, 1, 0
+ };
+
+ glGenBuffersARB(1, &BufferID);
+ glBindBufferARB(GL_ARRAY_BUFFER_ARB, BufferID);
+ glBufferDataARB(GL_ARRAY_BUFFER_ARB, sizeof(data), data,
+ GL_STATIC_DRAW_ARB);
+}
+
+
+static void
+Draw(void)
+{
+ static int count = 1;
+
+ printf("Draw Frame %d\n", count);
+ count++;
+
+ glBindBufferARB(GL_ARRAY_BUFFER_ARB, BufferID);
+ glVertexPointer(3, GL_FLOAT, 24, 0);
+ glEnable(GL_VERTEX_ARRAY);
+
+ glColorPointer(3, GL_FLOAT, 24, (void*) 12);
+ glEnable(GL_COLOR_ARRAY);
+
+ glDrawArrays(GL_TRIANGLE_FAN, 0, 4);
+
+ if (0)
+ glFinish();
+
+ /* Immediately map the color buffer and change something.
+ * This should not effect the first glDrawArrays above, but the
+ * next time we draw we should see a black vertex.
+ */
+ if (1) {
+ GLfloat *m = (GLfloat *) glMapBufferARB(GL_ARRAY_BUFFER_ARB,
+ GL_WRITE_ONLY_ARB);
+ m[3] = m[4] = m[5] = 0.0f; /* black vertex */
+ glUnmapBufferARB(GL_ARRAY_BUFFER_ARB);
+ }
+}
+
+
+static void Display( void )
+{
+ glClear( GL_COLOR_BUFFER_BIT );
+ Draw();
+ glutSwapBuffers();
+}
+
+
+static void Reshape( int width, int height )
+{
+ float ar = (float) width / (float) height;
+ glViewport( 0, 0, width, height );
+ glMatrixMode( GL_PROJECTION );
+ glLoadIdentity();
+ glFrustum( -ar, ar, -1.0, 1.0, 5.0, 25.0 );
+ glMatrixMode( GL_MODELVIEW );
+ glLoadIdentity();
+ glTranslatef( 0.0, 0.0, -15.0 );
+}
+
+
+static void Key( unsigned char key, int x, int y )
+{
+ (void) x;
+ (void) y;
+ if (key == 27) {
+ glutDestroyWindow(Win);
+ exit(0);
+ }
+ glutPostRedisplay();
+}
+
+
+static void Init( void )
+{
+ if (!glutExtensionSupported("GL_ARB_vertex_buffer_object")) {
+ printf("GL_ARB_vertex_buffer_object not found!\n");
+ exit(0);
+ }
+ printf("GL_RENDERER = %s\n", (char *) glGetString(GL_RENDERER));
+
+ SetupBuffers();
+}
+
+
+int main( int argc, char *argv[] )
+{
+ glutInit( &argc, argv );
+ glutInitWindowPosition( 0, 0 );
+ glutInitWindowSize( 300, 300 );
+ glutInitDisplayMode( GLUT_RGB | GLUT_DOUBLE );
+ Win = glutCreateWindow(argv[0]);
+ glutReshapeFunc( Reshape );
+ glutKeyboardFunc( Key );
+ glutDisplayFunc( Display );
+ Init();
+ glutMainLoop();
+ return 0;
+}