Transparent texture?

Transparent texture?

Post by Jeff Weise » Tue, 17 Dec 1996 04:00:00



Greetings:

I'm making a transparent texture, and am having some trouble getting
it to look right.  To save geometry, I rendered a .tga image of my
model, with alpha channel, and mapped it to a simple box so I could
make many apparent copies of the model.  In the material, the bitmap
is Texture 1, as a decal, source=RBG.    The same file is used as an
opacity map, source=alpha.

The problem is I'm getting what look like aliased matted lines around
the edges of the model's image in the material.  I've tried rendering
the .tga with both no background and a gradient BG similar to what
will be used in the scene.  Setting Ambient and Diffuse colors in the
material to L=30 helps some, though it seems to me they should have no
effect and not be necessary.    

I thought alpha channels were supposed to prevent things like this.
Have I missed a step?

Thanks,
Jeff Weisend

 
 
 

Transparent texture?

Post by W3 Use » Tue, 17 Dec 1996 04:00:00



> Greetings:

> I'm making a transparent texture, and am having some trouble getting
> it to look right.  To save geometry, I rendered a .tga image of my
> model, with alpha channel, and mapped it to a simple box so I could
> make many apparent copies of the model.  In the material, the bitmap
> is Texture 1, as a decal, source=RBG.    The same file is used as an
> opacity map, source=alpha.

> The problem is I'm getting what look like aliased matted lines around
> the edges of the model's image in the material.  I've tried rendering
> the .tga with both no background and a gradient BG similar to what
> will be used in the scene.  Setting Ambient and Diffuse colors in the
> material to L=30 helps some, though it seems to me they should have no
> effect and not be necessary.

> I thought alpha channels were supposed to prevent things like this.
> Have I missed a step?

> Thanks,
> Jeff Weisend

Hi Jeff,

I think the "Decal" setting makes it work bad. Decal was actually a way
to FAKE Alpha or Mask in the early versions of 3DS. When you activate
Decal, the program takes the color of the Upper Left corner of the image
(Pixel # 1) and makes it transparent. This means that all the colors
used for Anti-aliasing become ... opaque. I would suggest using Tile,
the Alpha of the same picture in the Mask channel, and the Alpha in the
Opacity map slot. Apply planar coordinates to fit the shape (in order
not to have many Tiles) and... it should look better.

--
Hope this will help you!

Greetings,

3DJ Bobo
aka W3 User
http://info.tuwien.ac.at/raumsim/vrb/
========================================================
What's new in VR Boboland? Check
http://info.tuwien.ac.at/raumsim/vrb/WHATSUP.DOC

New revised SUPER ELLIPSOID Version 1.0 available for DOWNLOAD:
http://www.archlab.tuwien.ac.at/w2561/ipas/ELLIPS.HTM
========================================================

 
 
 

1. transparent texture and texture inside a sphere

Dear openInventor netizens,

I have a few questions regarding using textures:

First, how does one apply texture to the interior of a sphere?  I am
thinking of creating a planetarium using star map as the texture.

Secondly, how does one create a texture on a transparent surface so that
the texture is visible on both sides?  One scenario for this is a painted
glass.

Thanks in advance,

Ansel
--
-------------------------------------------------------------------------
Ansel Teng                                            Tel: (818) 393-2705
Jet Propulsion Lab                                    FAX: (818) 393-3134

Pasadena, CA 91109-8099            http://www-msim.jpl.nasa.gov/Who/teng/

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