I need some help with shaders and shading

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I'm trying to render a glass and maybe some caustics. Can someone please tell me how to use this things in houdini (btw. they are not documented so well, except ambient occlusion) because I used the glass shader and it's cool as long as I don't render with shadows (the shadow is black no matter which shadow filter I'm using) and when I want to render from inside the glass only the reflection map is rendering (no transparency). I must admit I'm kind of lost here because I don't fully understand the way that Houdini works with ray tracing/transparencies/caustics
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not sure, but i think all the photon stuff is Mental Ray specific so I wouldn't know how to do caustics without shaders, but as for your shadows, use filter shadows and be sure to set opacity to be fully opaque, Play with the Alpha instead
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There's a GI with caustics video here:
http://www.vislab.usyd.edu.au/sidefx/houdini_video/by_topic/rendering/index.html [vislab.usyd.edu.au]
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figures, the one rendering video i don't have
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thx, for the link, caustic works fine now. But I still have the transparent shadow and glass shader BIG problem. If I use a glass shader the shadow is opaque even if I use texture shadow as a shadow shader(too bad there is no video tutorial about shadows and raytracing). Basicaly I have a glass object and inside a opaque object. Now what I expect to see in the shadow is a nice transparent shadow (a little less transparent to the edge of the glass shadow) and a opaque shadow of the opaque object. There must be a way of doing this but I'm affraid I don't know how to do it
Can someone please help me.
I've try to build a vex glass shader from scratch (like connecting facing forward or fresnel to bouth color and opacity) but it was a total fiasco.
In my opinion this capitol (rendering raytracing and some dumb vex shader creation for transparent/translucent objects like glass, water or ice) needs some more tutorials because I find myself a bit lost in the way that houdini renders
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Tutorials on Shadows Rendering and optimisization.
http://www.sidefx.com/community/learn/rendering/index.html [sidefx.com]

Cheers,
Nate Nesler
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