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Alpha Channels
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Alpha Channels // Archive: Tech Forum
Post by Chester Desmond // Oct 20, 2006, 6:11am
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Chester Desmond
Total Posts: 323
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I'm using TS 6.6.
Many of the supported 2d image formats like TGA, PNG and DDS can have an alpha channel. Can tS use this alpha info in any way, ie for transparency purposes etc? It seems that anywhere grayscale is used (bump, transparency) it is using the gray levels of the image and the alpha stuff is ignored. I can understand their use as an export format, but not as an import.
While on the 2d subject, is there any advantage to using DDS format in 6.6? I think it is used for normal maps in TS 7 for realtime display but what other uses might it have? I have been doing some reading and it seems like normal maps are superior to bump maps for 'displacement' effects on surfaces but seems to be more Direct X\game related. The main use that I can figure is to put high detail on low poly models. Can I use normal maps in TS 6.6?
I have the Ipak and it has normal map export, but according to the Multipass course this seems more useful for just special effects in 2d programs.
Any suggestions or tips or ideas are welcome.
Thanks |
Post by Tiles // Oct 20, 2006, 6:46am
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Tiles
Total Posts: 1037
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As far as i know Alpha Channel is nothing else than a greyscale mask. White: not transparent. Black: fully transparent. Everything between semitransparent.
In the material editor have a look at the top of the colour panel. There is a small button where you can choose between None, Transparency map and Plain transparency.
Choose Transparency map. Then load your PNG or TGA also in the now available transparency panel. Then your material makes use of the Alpha Channel if there is one. |
Post by spacekdet // Oct 20, 2006, 9:02am
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spacekdet
Total Posts: 1360
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In addition to overall transparency effects, you can also use alpha maps to create multi-layer materials.
Create your first layer- red in the example.
Right click on the main preview window in the Material Editor and choose 'Add New Layer' or 'Duplicate Layer'.
Click small 'Layer 2' "eyeball" icon to select layer for editing.
Change color to green. (this can also be a texture, not just a color)
Click and hold small 'Color Blend' icon in color channel and choose 'Color Blend: mask alpha'. An additional image input box will appear in the color shannel stack.
Choose a 32 bit alpha mask image (tga, png, etc) In the example I used the default '3DFoot.TGA' included with tS.
Click 'Paint Object'.
(In the example I also applied Cubic UV Mapping to the object.)
White areas are transparent and allow the base layer to be visible.
Black areas are opaque and show the second layer.
In this fashion you can build up layers of material on an object to simulate areas where one material has worn away, or paint chipping, or moss growing on a wall, etc.
(Edit) AFAIK, 6.6 can't do normal mapping. That was introduced with 7. |
Post by GraySho // Oct 20, 2006, 9:02am
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GraySho
Total Posts: 695
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As far as i know Alpha Channel is nothing else than a greyscale mask. White: not transparent. Black: fully transparent. Everything between semitransparent.
In the material editor have a look at the top of the colour panel. There is a small button where you can choose between None, Transparency map and Plain transparency.
Choose Transparency map. Then load your PNG or TGA also in the now available transparency panel. Then your material makes use of the Alpha Channel if there is one.
I've massivly used TGA's with alpha channel in my latest project, and it worked exactly like Tiles described. |
Post by Chester Desmond // Oct 20, 2006, 9:20am
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Chester Desmond
Total Posts: 323
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Thanks for the replies... I did some experimenting after tiles post and it did work as described in the transp. channel.
In Spacekdet's example, though, it is simply using the greyscale info (in this case it happens to be Black and White) as the transparency info... ie the alpha channel is ignored ... seems like only the base layer uses alpha info. I added some grey dots to the TGA (but left the alpha channel alone) to illustrate my point: |
Post by SteveBe // Oct 20, 2006, 10:42am
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SteveBe
Total Posts: 282
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It seems any layer after the base layer is treated as greyscale Alpha.
Good for tinting or dirtying textures. |
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