Am Dienstag, 11. September 2007 10:25:28 schrieb Roderick Colenbrander:
Hi,
This patch adds PBO support for dynamicly locked textures. It greatly improves performance of games that use render target locking a lot.
It looks good to me, here are some suggestions for further improvements in further patches(this patch is good for the start).
The locking flag passed to LockRect could be forwarded to GL. D3DLOCK_DISCARD and D3DLOCK_WRITEONLY(ddraw only) would be GL_WRITE_ONLY, D3DLOCK_READONLY GL_READ_ONLY. However, we have to take care about the upside down swap for render target locking.
D3DLOCK_DISCARD can be implemented(appart of the surface beeing writeonly) by calling glBufferData with a NULL pointer. This tells gl that the old data can be thrown away. This allows the driver to further optimize the map. e.g. if it is a texture that is still used for rendering in some pending calls, it can duplicate the buffer and doesn't have to wait for the rendering to finish. It will have to be tested if that really helps performance. I tried it for vbos, and it made things noticeably worse.
Binding the pbo to 0 after each operation is a good idea for a start, but shouldn't be done in the long term in my opinion.