On Fri, Aug 19, 2011 at 2:20 PM, Stefan Dösinger stefandoesinger@gmx.at wrote:
Am 19.08.2011 um 14:04 schrieb Michael Mc Donnell:
Ok I see that in dlls/d3d9/tests/buffers.c. So it will fail to lock on Win7 if D3DLOCK_DISCARD is specified and the vertex buffer wasn't created with D3DUSAGE_DYNAMIC?
Yes, unless Microsoft changed this again.
Am I correct in D3DLOCK_DISCARD makes a copy of the vertex buffer so that the video card can keep reading the old one, and the old vertex buffer memory is released after the video card releases its lock [1]?
Sort of. It doesn't copy the old data, it just gives you a fresh, uninitialized block of memory. So if you read from the pointer you get from a DISCARD lock you'll get garbage.
In that case it does not make sense to use D3DLOCK_DISCARD at all in CloneMesh, as the video card has not begun to use the new vertex buffer, and it will just add memory overhead. The easiest fix would be to just pass 0 instead of D3DLOCK_DISCARD. I've done that in the updated patch.
Right, the buffer is newly created in CloneMesh. Just not using DISCARD is the best fix then.
I noticed a few more D3DLOCK_DISCARD locks in the mesh.c code.
I guess the other methods should check the mesh options for D3DXMESH_DYNAMIC, D3DXMESH_VB_DYNAMIC, and D3DXMESH_IB_DYNAMIC [2] before using D3DLOCK_DISCARD? I'll write patches for those.
Most likely yes. I haven't looked at the details. If the buffer is new in those situations as well just don't pass any flags, otherwise pass DISCARD if you lock a dynamic buffer and are going to rewrite the entire buffer contents.
All of the places with D3DLOCK_DISCARD in mesh.c were working on newly created meshes or vertex buffers, so they should all pass 0. I've attached patches for it.