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View Full Version : lighting through a transparency map

wedge
05-12-2002, 06:15 PM
I'm doing a low-poly stadium for a short animation. I needed a set of girders (diagnol crossing support beams), so I did them up in photoshop. I also created a black and white transparency map in photoshop. I applied the colored girders to a flat plane color node, then applied the transparency map to the plane as well. I rendered a test image and yay it worked. Then I set up a little spotlight aimed at the grandstand on the other side of the girders. This was the only lightsource. I rendered this test image, and the shadow the girders cast was completely dark. How can I make light go through the clear parts of this plane?
wedge
05-12-2002, 06:21 PM
I have attached an image of my situation.
svenip
05-12-2002, 07:13 PM
just turn on raytraced shadows and in the render globals raytracing of course. then you can render part-transparent objects with shadows.
there is another way if you don't wanna use raytracing (rendering time maybe). you can then map the shadow color of the light, but this is sometimes difficult. (at least as i figured out, maybe someone has a good tip on that)
wedge
05-12-2002, 07:30 PM
thanks for the tip. if anyone has any tips on setting this up with dmaps i'm all ears. i rendered that little scene with dmaps in 13seconds, and with raytraced shadows in 24seconds... i fear that once i add a lot of detail that will lag a lot more.
svenip
05-12-2002, 07:40 PM
the principe for that is easy. just put a map on the shadowcolor. for instances the crosses you have in your surface. but what if i translate my light somewhere else. then the shadow usually changes on the floor !?!? and that's the problem.

another thing you could do. just convert the shader on the floor to a file texture and turn on bake shadows. :)
wedge
05-12-2002, 11:00 PM
i don't think i'm up to speed on this bake shadows concept... if all the textures in a scene are file textures (i.e. texture1.jpg, texture2.jpg) then Maya only has to render the shadows 1 time, speeding up all the remaining frame renders?
svenip
05-13-2002, 07:25 AM
no, the shadow will be baked into the file texture. you don't need your lights after that. problems oocure then you move the lights, then the shadows would be different on the surfaces but now they are baked in.
wedge
05-13-2002, 07:37 AM
no lights at all? then won't maya use the default light? or does having baked textures disable the default light. are there an tutorials on this?

EDIT: Actually, nevermind... this scene is going to have colored spotlights that move around the stadium, so baked textures definately wont' work.
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