[osg-users] VDSM and shadow of 3d Tree

[Daniel Schmid]

Hi all

Until now we had trees made of billboards in our terrain, and used VDSM as a shadow algorithm. Shadows of billboard trees are ok on the ground, but the billboard itself is always half lit and half in shadow which is not very nice.

So I decided to put trees made as a 3d model with solid trunk and branches and leafs made out of surfaces with alpha texture. 

The trees look nice, also the shadow on the ground, but the GPU time of the shadow camera literaly explodes. Trees with dense leafs and therefore lot of alpha overdraw is a huge performance killer. 

But probably I missed something, put bad states or stuff. I imagine I am not the only one that is using VDSM to shadow a terrain and using 3d tree models. 

Do you have some hints or ideas for me?

Thank you!

Cheers,
Daniel

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