View Full Version : Self illuminated texture maps with AlphaChannels


LoveFest
08 August 2011, 03:41 AM
I can't figure out how to have a self-illuminated texture show through an alpha channel in Maya.

It's easy as pie with the Unreal engine (2.5x). Maybe, if I show you what I'm doing, it will help.

Faking self-illuminated textures.

It works just like a layer in Photoshop. With Unreal you can use an alpha channel to have one surface show through another (like layers in PS).

http://img27.imageshack.us/img27/7151/xansodaunlitalphatextur.jpg (http://imageshack.us/photo/my-images/27/xansodaunlitalphatextur.jpg/)

Same thing here in Unreal Tournament: http://img856.imageshack.us/img856/4418/alphachannel.jpg (http://imageshack.us/photo/my-images/856/alphachannel.jpg/)
An alpha channel is used to allow the unlit (faked self-illuminated) texture to show through, allowing two textures to work as one.

I'm trying to get the same effect with a bullet in Maya (see example of effect below). The tip is self-illuniated. Use an alpha to allow the white hot texture (set to full incandescence) to show through the MR Mia_Material (Copper/Chrome) material.
http://2media.nowpublic.net/images//59/90/5990552f2864211e100d042897952c97.jpg

tobbew
08 August 2011, 07:35 AM
Mia_material_x has the additional color slot under advanced which is the same as incandescense. You could use the mia_light_shader texture in that slot if you want more control over contribution to reflections and FG.

LoveFest
08 August 2011, 08:41 AM
Mia_material_x has the additional color slot under advanced which is the same as incandescense. You could use the mia_light_shader texture in that slot if you want more control over contribution to reflections and FG.

Thanks tobbew for responding. :) I'm looking at the additional color slot, but have no idea what to do with the mia_light shader (or even sure I'm looking at the right one). I tried playing with it, but I'm pretty lost on how to get the same affect as DJ way

I got the tip to glow by following the tutorial "Creating glow maps for the cooling tubes:" It's almost there, but the mia_material I added(using presets, 50% chrome & 50% copper) to the color input of the Maya phongE material causes the color to desaturate. I can't get the color back up, even by making the mia_material's color darker.


http://s2.postimage.org/1iwxjllic/white_hot_bullet_tip_maya.jpg (http://postimage.org/image/1iwxjllic/)

ntashev
08 August 2011, 09:33 AM
You can use the mib_color_mix to mix your shaders - here is some concept network:

mia_x1.result -> mib_color_mix1.color_0
mia_x2.result -> mib_color_mix1.color_1
blendMap.outAlpha -> mib_color_mix1.weight_1
mib_color_mix1.message -> shadingGroup.miMaterialShader
mib_color_mix1.message -> shadingGroup.miShadowShader

key thing is the Num attribute of the mib_color_mix equals the number of input conections or sometimes it doesn't work properly.

tobbew
08 August 2011, 09:48 AM
If you want the tip to glow just use your alpha channel for your lighting in the additional color slot. Otherwise it seems you got another possible solution.

LoveFest
08 August 2011, 09:52 AM
You can use the mib_color_mix to mix your shaders - here is some concept network:

mia_x1.result -> mib_color_mix1.color_0
mia_x2.result -> mib_color_mix1.color_1
blendMap.outAlpha -> mib_color_mix1.weight_1
mib_color_mix1.message -> shadingGroup.miMaterialShader
mib_color_mix1.message -> shadingGroup.miShadowShader

key thing is the Num attribute of the mib_color_mix equals the number of input conections or sometimes it doesn't work properly.
Hi Azrail, Thanks for responding.

Where would I connect the mib_color_mix? Please take a look at the thumbnail below. I showed how far I got. Thanks :)

http://s2.postimage.org/1iwxjllic/white_hot_bullet_tip_maya.jpg (http://postimage.org/image/1iwxjllic/)

LoveFest
08 August 2011, 10:22 AM
Mia_material_x has the additional color slot under advanced which is the same as incandescense. You could use the mia_light_shader texture in that slot if you want more control over contribution to reflections and FG.
That worked! I didn't even need a grey scale. Just used the color map. I can't believe that was easier than Unreal 2.5x. Thanks tobbew. You're golden, man.
http://s2.postimage.org/1jbehvx2c/white_hot_bullet_tip_ryan_johnsond_copper_color.jpg (http://postimage.org/image/1jbehvx2c/)

The only other question I have is how to fix the reflected striation running down the bullet. I have a real one in my hand and they don't "stretch" the clouds or the reflections in the room like pulled/stretched streaks. Would a cube map work better than using straight reflections from an image based map in Mental Ray?

LoveFest
08 August 2011, 10:45 AM
You can use the mib_color_mix to mix your shaders - here is some concept network:

mia_x1.result -> mib_color_mix1.color_0
mia_x2.result -> mib_color_mix1.color_1
blendMap.outAlpha -> mib_color_mix1.weight_1
mib_color_mix1.message -> shadingGroup.miMaterialShader
mib_color_mix1.message -> shadingGroup.miShadowShader

key thing is the Num attribute of the mib_color_mix equals the number of input conections or sometimes it doesn't work properly.
Azrail, you're amazing, good! I just went to your site.

tobbew
08 August 2011, 11:44 AM
The stretching could be due to the anisotropy settings in the mia_material and could then be easily changed. It could be due to distortion depending on your environment setup. Preferrably use a spherical hdr in the native ibl.

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