[osg-users] Best way to cull object hidden by a mountain

[Sebastian Messerschmidt]

Am 24.06.2016 um 17:14 schrieb Valerian Merkling:
> Hi Robert,
>
> Thanks for your clarification about OccluderNode.
>
> I already looked at the osgocclusionquery example. If I'm right, it just need to add an OcclusionQueryNode to contain the node wich have to be occluded by the rest of the scene graph. I wasn't able to make it works so I may need to dig a bit.
>
> To be honest, I don't know if I will use OcclusionCulling at all, but I want to understand how it works and how it can be used. I don't want to be forced to, in a few month, rebuild all my app because I'm unable to use occlusion culling while really needing it.
>
> I'm also need to support a part of SLD (see here http://docs.geoserver.org/stable/en/user/styling/sld-cookbook/lines.html), the "Line With Border" example.
>
> I want to use PolygonOffset to force the drawing order of my lines, and OcclusionCulling might be a good way to avoid depth buffer issues.
If you are trying to display outlines it might be more efficient to use 
a shader, as your heightfield is most likely a regular grid, for which 
you can calculate barycentric coordinates easily. See [0], I used this 
myself by adding a Barycentric-Visitor which simply put, will add some 
vertex-attributes to the geometry which you then can use to have 
outlines. As the rendering is in the same primitive, there won't be any 
depth-related issues.

Cheers
Sebastian

[0] 
http://codeflow.org/entries/2012/aug/02/easy-wireframe-display-with-barycentric-coordinates/
>
> Anyway, thanks again for your help. And if you have any tips about OcclusionQueryNode I'll take it !
>
> Cheers,
> Valerian
>
> ------------------
> Read this topic online here:
> http://forum.openscenegraph.org/viewtopic.php?p=67798#67798
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