Hi Graham - Finally got around in looking this a bit more.
First off, it was a bug in my code; Basically before creating a buffer using glGenBuffers I'm binding an invalid buffer in my GL state cache code. (I'm binding GL_INVALID_INDEX).
However, there's still some inconsistencies.
To reproduce this case use this code here (posted below).
Case #1 is creating a buffer first, then binding an invalid buffer and the driver continues to assign buffers in the correct order.
Case #2 however binds an invalid buffer first (0xdeadbeef), the next glGenBuffers will return 0xdeadb000, and all consecutive calls will assign buffers starting at 1.
#if 0
{ // Case #1
// [Create GL context]
GLuint dummy = 0;
glGenBuffers(1, &dummy);
printf("genBuffers=%X\n", dummy); // returns 1 - as expected
glBindBuffer(GL_ARRAY_BUFFER, dummy); // bind valid buffer first...
dummy = 0; glGenBuffers(1, &dummy); // create new buffer
printf("genBuffers=%X\n", dummy); // returns 2 - still OK
glBindBuffer(GL_ARRAY_BUFFER, 0xdeadbeef); // bind invalid buffer
dummy = 0; glGenBuffers(1, &dummy); // create new buffer
printf("genBuffers=%X\n", dummy); // returns 3 - still OK
}
#else
{ // Case #2
// [Create GL context]
glBindBuffer(GL_ARRAY_BUFFER, 0xdeadbeef); // bind invalid buffer first...
GLuint dummy = 0;
glGenBuffers(1, &dummy);
printf("genBuffers=%X\n", dummy); // returns != 1, in this case: 0xDEADB000
dummy = 0; glGenBuffers(1, &dummy);
printf("genBuffers=%X\n", dummy); // returns 1
}
#endif
Cheers
