Preet, Perhaps the problem is lack of precision in your BillboardRotate uniform (double -> float).
Maybe you can try a different approach: transform your vertex into View space (or Clip space) and then apply the ModelPosition offsets there. Just an idea. Glenn Waldron / @glennwaldron On Sun, Jan 20, 2013 at 5:35 PM, Preet <[email protected]> wrote: > Hiya, > > This is somewhat related to my last thread (maybe I should have just > explained the situation from the beginning). > > I'm trying to create a shader that does billboarding for hundreds of > objects at once (where using AutoTransform is too slow). I merge all these > objects together to reduce the number of draw calls, and pass along > specific vertex attribute data (specifically model-space relative vertex > data when I want the billboard center to be the model's center) and > uniforms (camera vectors) to do the required billboard transform in the > shader. > > This kind of works, but the result is 'jittery' compared to AutoTransform. > I don't know whether its the way I specify the uniform update callback or > if its related to reduced shader precision (the coordinates I used are all > close to the origin though, so I hope that's not the case) or something > else entirely. > > I created a minimal example that reproduces the issue [1]... (just > copy->past->compile). The example shows a square billboarded with > AutoTransform working perfectly, and my not so great example directly > behind it. > > [1] https://gist.github.com/4582261 > > * Does anyone know why my example billboard implementation causes that > jitter/delay? > > * Or, has anyone created a better shader that can do billboarding for > batched geometry (and if so, could they maybe share how)? > > > Preet > > _______________________________________________ > osg-users mailing list > [email protected] > http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org > >
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