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plectrum
03-15-2003, 09:13 PM
Hey guys and gals, quick question:

I have a 32-bit tga file (with an alpha channel) applied as a diffuse texture map to a model. The problem is, 3ds seems to be ingnoring the alpha channel, and makes the transparent areas on the texture completely opaque. I've checked, and the tga file is fine, photoshop recognizes the transparent areas etc. Is there anything I can do to have 3ds display the transparancy directly from the tga file, or do I have to load a separate opacity map?

btw, I'm using R5, and I've tried checking and unchecking that pre-multiplied alpha box, no luck. The alpha source is set to "image alpha" under bitmap parameters.

big thanks for any advice you can offer

>>john
MFreywald
03-15-2003, 10:01 PM
If your looking to make the areas that are in the alpha channel see thru you need to stick the map in the opacity slot. In the diffuse slot it'll just allow the diffuse color to appear where the alpha channel is black (or varying degrees of grey).
PokeChop
03-16-2003, 02:03 AM
To see the transparency of a 32bit TGA file in the viewport and have it render correctly here's what I do:

1. Make a material and assign the TGA to the DIFFUSE slot
2. Double-click and open DIFFUSE slot in material editor
3. VERY IMPORTANT - Uncheck "tile" in the Coordinates section of the TGA properties of the DIFFUSE targa material
4. Check ALPHA in the Mono Channel Output area
5. Go back to the maps section in the material editor
6. Drag the DIFFUSE slot contents to the OPACITTY slot and choose INSTANCE for the copy method
7. Make sure you right-click on the active viewport label and choose TRANSPARENCY - BEST to see your results in the viewport

That should get it. I have no idea why unchecking tile in the coordinates section allows you to see the transparency in the viewport, but it works. hope this is what you were asking for...
gaggle
03-16-2003, 02:21 PM
PokeChop's description seems to make sense. For what it's worth though, I've never had to uncheck tileing to get transparency in my viewports.

The overall important thing to remember, as already mentioned, is that placing a map in the Diffuse Colour channel provides you only with the colour-information, gotta go activate the Opacity channel as well if you're looking to making things transparent.

Remember to key the specular with the map as well, to avoid having a specular highlight in areas the bitmap says are transparent.
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