Alpha Shadows

# 1 24-03-2004 , 08:23 PM

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Join Date: Mar 2003

Posts: 35

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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# 2 25-03-2004 , 09:25 AM

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Location: London, UK

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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.
Alan

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Currently working on: Your Highness

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# 3 25-03-2004 , 04:46 PM

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Only raytracing works with alpha-maps so make sure your shadows are raytraced.

Björn 'santa' Fredriksson

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# 4 25-03-2004 , 05:31 PM

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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

www.Darkware3D.com

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# 5 25-03-2004 , 10:39 PM

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Join Date: Mar 2003

Posts: 35

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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