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DarrenGold
06-05-2005, 10:29 AM
Hi Folks,

is it possible to have a UV map with an alpha channel? I'll try to explain what I'm after and maybe some kind soul can point me in the right direction.

I have a simple model and the texture is UV mapped. What I would like to include in the texture is some sparkly/reflective bits. How would I go about doing this?

I initially assumed I'd need to use the same UV map & texture in the reflection channel with an alpha which masked out everything but the reflective portions? The only problem is that UV maps don't appear to allow this. It seems I can do it with an ordinary image map but this wouldn't stay in place when my model was animated, would it?

Any ideas?

Cheers,

Darren.

toby
06-05-2005, 05:17 PM
Make a new map, black with white bits where you want to see reflective spots. Now copy the texture from the color channel, apply it to the reflection channel and replace the color map with this new map.

You also have an option to set a texture layer to 'Alpha', which will affect the layer below it. Use this to mask out parts of the color map if needed.

DarrenGold
06-06-2005, 01:22 AM
Hi toby,

hmmm... but this doesn't work! It works with an ordinary image map but not with a UV map.

And I need to use a UV map in order that my reflective bits are placed correctly on my model and move with the model when animated.

Any other ideas?

Cheers,

Darren.

toby
06-06-2005, 02:23 AM
It has to work! You can use uv maps in the reflection channel, and you can assign different texture maps to any uv map.

The texture in the reflection channel is identical to the one in the color channel, except for the image map, correct? What is it that's not working like you planned?

DarrenGold
06-06-2005, 03:03 AM
Hi toby,

thanks for sticking with this.

I'm doing exactly as you say... the UV map in the reflection channel is identical to the one in the colour channel. And I'm using my new image (black and white) to dictate where the reflective bits will be positioned. But instead of just the white bits showing up as reflective in the render, the whole model (or at least the part that's affected by the respective UV map) is reflective.

I can't figure out why... the reflective bits are very small and don't cover the whole object.

Cheers,

Darren.

DarrenGold
06-06-2005, 03:25 AM
Hi again,

I've just figured out what I'm doing wrong. On comparing your screen grab to my settings again, I notice that Instead of 'Normal' as the blending mode for the Reflection channel, I had it set to 'Alpha'. When I change it back to 'Normal', everything works as it should.

I thought the Alpha blending mode would have been the one to choose? Since what I was trying to do was mask out everything but the white sections of my image.

Ah well. At least it's now working.

Thanks again for your help.

Cheers,

Darren.

toby
06-06-2005, 03:34 AM
Glad it's working -

If you set the reflection to 100%, then set the layer to Alpha it would work, masking out the reflection in the white parts of the image. If you want the image to dictate the value of the channel you can't use alpha, because that only masks out value.

DarrenGold
06-06-2005, 04:26 AM
Ah... OK. That makes sense.

Thanks again.

Darren.