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View Full Version : Texturing: routing a TGA alpha though a projection node?


JasonA
01-18-2004, 07:38 PM
I'm using a layered texture in a Blinn's color slot. And I have some decals that are TGA files with alphas. I want to use projects so I can place my decals where I want on my model, but I can't figure out how to get the alpha info through the projection node. It strikes me as odd that the projection node doesn't have an alpha node as well as the image node. weird. Well I figured I probably just didn't know where it was, or its named something different etc etc. Anyways, does it exist?

I already have a work around (creating a second projection, tying the place3dtexture node from the color projection and using a seperate alpha file). Anyways I really hate this workaround because I have to clog my shader network with a bunch of extra projection nodes (for the alphas) and also have to create a whole bunch of alpha files. ugh.

Please someone tell me its possible just uing the TGA file and the 1 projection node :):) (well only if its true ok!) Otherwise, any clever workaround that aren't brute force?

CIM
01-18-2004, 09:18 PM
Try using TIF files.

JasonA
01-18-2004, 10:13 PM
nope didn't work :(

I render with mental ray, and as soon as I apply a TIF with transparency, mr aborts before the render is started. I assume this is another limitation of mr in Maya 4.5. But if not, is there something else I need to be doing? I took my TGA file into PS and created the tiff in there, saved it out with transparency.

rollmops
01-19-2004, 02:30 PM
The problem is 3dprojections lose the alpha, they only read the RGB channel.

Workaround set the alpha gain at 0 in the 3d projection and connect the outAllpha of the file to the alpha offset on the projection.

BTW for a better usage of the memory avoid other file type than .iff and .rgb certainly never TIFF!:D

JasonA
01-19-2004, 05:30 PM
hmm I couldn't get that to work either. This is really wierd. Did you omit a step in your instructions? I'm creating an ultra basic example scene to figure out how to get this to work, but it a no go. I get the decal, with everything around it greyed out, and the underlying layers cannot be seen.

JasonA
01-21-2004, 09:16 PM
*bump*

surely there must be a way to do this without a bunch of seperate alpha files and projection nodes??

:cry:

rollmops
01-22-2004, 08:22 AM
As simple as this!
:cool: http://www.redrival.com/rollmops/image/snap.gif

JasonA
01-22-2004, 05:43 PM
I've had a bit more luck now. Its still not quite functional though. Like I mentioned before, I'm using a layered texture in the color slot of a blinn. The decal (a flag) is a projected texture in the second layer of the layered texture. I ran the outalpha of the projection node into the alpha for the second layer. And it *almost* works. Problem is, the transparency around the flag is not %100. its like its about %85 or something. My gradient gets dimmed when I turn on the decal layer. I can see it in the viewports and definitely in the render.

[EDIT] Attached pic, and also I double checked that the flag decal has an alpha channel by opening the it (now an iff file) in fcheck and confirming that it has a mask layer.

This probably makes things a buit clear in terms of what I'm doing. how would you correct this transparency issue?

btw, thanks for taking the time! :)

http://home.comcast.net./~prwsjl/tree.jpg

rollmops
01-23-2004, 07:47 AM
OK!

:wip:
The reason of: the transparency around the flag is not %100
is the default colors stay at 50% by default. It means that around the file1 you'll get a 50% alpha also.

JasonA
01-23-2004, 05:54 PM
Thanks rollmops, that was what fixed it in my quicky setup test file! Cool, something new to add to my workflow

The bad news is that when I try to implement this in my actual project file, it doesn't work. I haven't figured out why the hell there's a difference.. grrr

Anyways, I think its something I'll have to figure out myself at this point. Your suggestions have been a great help though, it would have been awhile before I came across that solution, thanks for posting!:)

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