Members - Reputation: 117
Posted 19 October 2012 - 07:47 AM
you have lots of meshes each with multiple materials
1 -have each mesh build it's own vertex/index buffers for each material. Sort by material and then issue one draw command per mesh-section.
Have each mesh stores it's own vertex/index buffer in main memory
Sort by material
Dynamically build a vertex/index buffer on the GPU for all relevant mesh-sections
Issue a draw call
Both cases minimize the number of render state changes
The second case also minimizes the number of draw calls, but at the cost of the CPU constantly regenerating the vertex buffer each frame. Not reasonable to assume you could reuse the vertex buffer much from frame to frame as the specific meshes in view will change Yes frame coherence will generally keep the same meshes around. But again, to detect that case you are spending CPU time working out if the vertex buffer can be reused in whole or in part.
I recognize the specifics will vary. But "in general" is it a best practice to dynamically create vertex/index buffer each frame, or is the cost of doing it each frame not worth the potential gain?
Crossbones+ - Reputation: 5689
Posted 19 October 2012 - 09:12 AM
Edited by Erik Rufelt, 19 October 2012 - 09:12 AM.
Moderators - Reputation: 16820
Crossbones+ - Reputation: 11097
Posted 19 October 2012 - 05:50 PM
It appears that the gentleman thought C++ was extremely difficult and he was overjoyed that the machine was absorbing it; he understood that good C++ is difficult but the best C++ is well-nigh unintelligible.