What I would do is to have your lightmap algorithm look up for an custom attribute in the scene and see what needs to be eliminated from computation?! This would be a hack to solve your unique rendering requirement ;)
Chris On 14 Aug, 2012, at 9:55 PM, "Rémi ARQUIER" <arqu...@gmail.com<mailto:arqu...@gmail.com>> wrote: You are right, the ICE Particles cloud are not evaluated for the lightmaps (they don't affect lightmap illuminaton). I would want to compute the lightmaps and the final rendering in just one click on "render". Not using two passes. Lets say that mental ray in "one click on render button" decompose the global rendering into two consecutive stages : Stage 1 - Lightmap computation. The lightmaps, applied on polygon meshes compute some custom user data (whatever) and store them into ram. Stage 2 - Tile Rendering. Other shaders read the custom user data from ram and use it for final illumination of the ICE Particle Clouds. In stage 1, the ICE Particle cloud *must not* be presents for casting ray speed optimization. In stage 2, the ICE Particle cloud *need* to be present since they are visible by all rays. 2012/8/14 Chris Chia <chris.c...@autodesk.com<mailto:chris.c...@autodesk.com>> My qn is: why does your point cloud need to exist in your 'light map' pass? Do you mean that the point cloud still needs to be rendered but not evaluated for light map? Clear my doubt... Chris On 14 Aug, 2012, at 8:39 PM, "Rémi ARQUIER" <arqu...@gmail.com<mailto:arqu...@gmail.com><mailto:arqu...@gmail.com<mailto:arqu...@gmail.com>>> wrote: Thank you Chris Breaking the scene into two passes would solve that specific problem but : 1/ Our custom lightmap shader creates custom data (mental ray point clouds, not maps) and keep them into ram. It would be inefficient to save them then reload them using hard disk. 2/ We already use passes in our workflow and it would complicate it to add other ones just for a shader. We need something "transparent" in the user side. 2012/8/14 Chris Chia <chris.c...@autodesk.com<mailto:chris.c...@autodesk.com><mailto:chris.c...@autodesk.com<mailto:chris.c...@autodesk.com>>> Why can't you break your scene into passes? With the point cloud hidden in the "light map pass"? Chris On 13 Aug, 2012, at 10:20 PM, "Rémi ARQUIER" <arqu...@gmail.com<mailto:arqu...@gmail.com><mailto:arqu...@gmail.com<mailto:arqu...@gmail.com>>> wrote: > Hi list > > I would like to know if it is possible to exclude objects in the ligtmap > rendering stage. Specificaly I would like that some of ICE particle clouds > not be seen by object beeing sampled (for reflection rays and shadow rays for > example). > > I have tried combining a mip_rayswitch_stage plus a transparent shader for > the lightmapping rays on the particle material. It works, *but*, the presence > of the clouds considerably slow down the lightmap rendering stage since the > particles are still hit (by shadows and secondary rays and for nothing). A > "rendering lightmap visibilty flag" excluding the cloud for real would be > perfect, but doesn't seem to exist. > > Any idea ? > > I could write some custom MR shaders and custom plugins if necessary. > > Thank you for help > > Rémi
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