Horde3D

Next-Generation Graphics Engine
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PostPosted: 12.09.2010, 23:55 
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Joined: 11.09.2010, 20:21
Posts: 44
Location: Germany
Hi,

I just skimmed over the Horde3D source (trunk), which is btw. very understandable and compact, and saw, that GL_DYNAMIC_DRAW is always used as vbuffer usage. But i think this is usually only needed for models with software skinning or other special dynamic geometries, but most geos should be GL_STATIC_DRAW.

I don't know, if most implementations store GL_DYNAMIC_DRAW in VRAM anyway, but I think GL_STATIC_DRAW is just more appropriate for most cases. One could make a "dynamic" flag in the model or just use GL_DYNAMIC_DRAW for software skinned models only.


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PostPosted: 14.09.2010, 21:26 
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Joined: 10.09.2006, 15:52
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Right, this can be improved in the future, although I never saw a real performance difference in practice.


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PostPosted: 29.09.2010, 18:02 
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Joined: 11.09.2010, 20:21
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I just made a patch (based on Community trunk), where I integrated the buffer usage as a field of RDIBuffer and updated the buffer methods of the RenderDeviceInterface accordingly. At the moment it just uses GL_DYNAMIC_DRAW for vertex buffers and GL_STATIC_DRAW for index buffers. It is just a starting point for further advances. I do not know if it gives any performance boost, but this GL_DYNAMIC_DRAW has always been a thorn in my eye (if I can use this phrase in english).


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Horde3DEngine_buffer_usage.patch [1.55 KiB]
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PostPosted: 29.09.2010, 18:36 
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Joined: 11.09.2010, 20:21
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Location: Germany
I just made a new patch. I added a bool dynamic parameter to the buffer creation functions which selects between GL_DYNAMIC_DRAW and GL_STATIC_DRAW and adapted all usages of those functions in the engine. Now all buffers are created as static except the vertex buffers for the overlays, geometries and terrain. Although one could make the static stream of the geometry (with the joint params and texCoords) static I am not sure if it gives a performance penalty when sourcing vertex attributes from buffers with different usage (and thus possibly different memory locations). In the future it should be made depending on the use of morph targets and software skinning, or a flag in the geo resource.


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Horde3DEngine_buffer_usage2.patch [8.82 KiB]
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PostPosted: 03.10.2010, 19:50 
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Joined: 10.09.2006, 15:52
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Thanks for the patch. We will add this later to the DeviceInterface, along with some more usage hints.


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