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Old 24-03-2004, 07:23 PM   #1
JimmyC
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Default Alpha Shadows

I have a plane in a scene textured with a texture containing an alpha channel (its basically an object on the middle of the plane, with a fully transparent area around it). I was told that any shadows the plane projects will take the alpha channel into account, but as it is the whole plane is projecting a shadow.

Is there something I'm supposed to do to get a shadow only from the non transparent areas of the texture?
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Old 25-03-2004, 08:25 AM   #2
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have you just got an alpha channel in your image or have you mapped it to the transparency channel? What I would do is get the texture's alpha channel and save it out to another file as a greyscale image. Then map that to the transparency texture channel. That will probably give yo ubetter results.

Let me know how you go.
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Old 25-03-2004, 03:46 PM   #3
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Only raytracing works with alpha-maps so make sure your shadows are raytraced.
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Old 25-03-2004, 04:31 PM   #4
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hmmm I tried it out with raytraced shadows just to see, but it didn't work. Without them, all you have is a shadow of your plane. With them, I can get no shadow at all. hmmm.....

edit*** bah... I see what I did. I just turned on raytraced shadows in the light attributes without turning on raytracing in render globals. =P
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Old 25-03-2004, 09:39 PM   #5
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Yeah i figured out that it only works with raytracing.

The problem is you can still see the outline of the plane in shadow. Ive read a tutorial that says you can fix this with shader networks (which I have no experience with). Is there any easier way?
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