[osg-users] Swapping out geometry in the cull visitor for just the shadow camera?

[Christian Buchner]

Hey all,

I have a shadowed scene that hosts a detailed city model and some 15000
objects using instanced geometry that also casts shadows. The instance
positions are provided through a 2D float texture (128x128) to the vertex
shader.

To reduce the render times I was thinking that I should maybe replace the
geometry of these instanced geometries with something much simpler. My
shadow resolution is coarse and observers likely wouldn't notice the
difference.

Could it be a good idea to install a NodeCallback on the instanced geometry
that replaces the Geometry of the geode with a cube while we're in the
shadow camera pass, and reinstalls the original object when we're in the
main camera pass? If possible I would like to avoid the overhead of having
a second instanced geometry for just the shadow casters, as updating this
128x128 comes with some costs - and simply swapping out the geometry should
accomplish that.

Christian
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Re: [osg-users] Swapping out geometry in the cull visitor for just the shadow camera?

[Sebastian Messerschmidt]

Hi Christion,

you could use a switch above the 2 geometries or different cullmasks for 
the geodes and control it via the cameras cullmask/setting the switch 
before culling

Hey all,

I have a shadowed scene that hosts a detailed city model and some 
15000 objects using instanced geometry that also casts shadows. The 
instance positions are provided through a 2D float texture (128x128) 
to the vertex shader.


To reduce the render times I was thinking that I should maybe replace 
the geometry of these instanced geometries with something much 
simpler. My shadow resolution is coarse and observers likely wouldn't 
notice the difference.


Could it be a good idea to install a NodeCallback on the instanced 
geometry that replaces the Geometry of the geode with a cube while 
we're in the shadow camera pass, and reinstalls the original object 
when we're in the main camera pass? If possible I would like to avoid 
the overhead of having a second instanced geometry for just the shadow 
casters, as updating this 128x128 comes with some costs - and simply 
swapping out the geometry should accomplish that.


Christian



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