[osg-users] [About VertexArrayObject Branch] FeedBack and Insight

[Jannik Heller]

Hi,


> 
> I have 
> done this to avoid the extra checks required against the individual 
> arrays to see if they are dirty or not - I have done it for 
> performance reasons as I want to keep the CPU overhead for draw 
> dispatch as low as possible. 
> 

Have you done benchmarking to see if avoiding these if checks makes a difference? Have you considered checking the individual arrays could be advantageous if not all arrays have changed? For example, with a skeletally animated model, you would update only the vertices (and possibly normals) every frame while the texture coordinates, indices and colors will remain static. Here we could save a whole bunch of GL calls (possibly even buffer uploads?) by testing the arrays individually.

Perhaps we could have one "dirty" flag for the whole VAO, and if it's dirty, we start testing the arrays individually to see which ones changed. If VAO isn't dirty, no need to test the arrays.

Cheers,
Jannik

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http://forum.openscenegraph.org/viewtopic.php?p=68419#68419