Paul, If this was raw OpenGL, I'd be tempted to set up my heightfield as a display list, and then change the modelview matrix for each call to the display list. I'm not quite sure how to force similar behaviour in OSG other than to set up the scenegraph with multiple PATs.
I'm working on a similar problem: rendering a large vector field as several > arrows, all with different positions and orientations. If I multiparent > the Geometry to several PAT nodes, the cull time cost is quite high. > I have the notion that cull times can be improved by not letting the cull traverse go across the PATs. The parent of the PATs probably knows something that could limit the set of PATs that actually needs to be traversed in the draw. In my application that's certainly true - the top "Group" gets the view/projection matrices, and since each tile is the same size, can decide which of it's children really need drawing without having to check the bounding spheres of its many PAT children. Unfortunately, my heightfield does sometimes change and so I haven't really pursued the tradeoff between the cost of display list compiles and other techniques. I'm looking at adding support for ARB_draw_instanced to reduce both the cull > and draw time > If you get anything working, I'd be delighted to test it in my context, time permitting (by then I will have probably got the codepaths for the various other techniques going). David
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