Texture question about Tron Glow Filter Example

Pipeline
1

I have been looking into creating cg shaders, and am dissecting the example distributed with Panda3D. As I am new to Panda I have many questions, but the main one that has come up pertains to the texturing of 3d models.
From my understanding the Panda3D egg format used does not contain texture data, only a referenced path to the texture.

In the Glow Filter Example a Tron-inspired model is used. Looking at the .egg file I see this model uses a texture file: tronally.png. This is the only image file in the Tron subdirectory of the Example.
The cg shaders provided seem to use the tronally.png texture to define where to put the glow/blur effect. I have opened up this image in photoshop and it consists of only blue lines and an alpha map. However the model being displayed has what must be a second texture that has the face and wrinkly pattern displayed on the body.

My question is: where is this texture coming from? Where is it stored and what part of the program is loading it becuase I find no reference to any other texture aside from the “tronally.png” and that is listed in the text of the tron.egg file itself.

I feel like the answer is right infront of my face but I just can’t see it. Any help would be great.
thanks

2

The shader glowShader.sha uses the alpha channel of the texture (tronally.png) to determine where the glow should be applied. Where the alpha channel is 1.0, you get a glow effect, and where it is 0.0, you get no glow.

The face, wrinkly pattern, and blue lines are all found in tronally.png. However, the alpha channel is non-zero only where the glowing blue lines are located. Since Photoshop assumes the alpha channel is meant to indicate transparency, when you view tronally.png in Photoshop you see only the parts of the texture map that have non-zero alpha; the rest of it are assumed to be transparent. It therefore looks like the image consists only of blue lines. But if you were to remove the alpha channel in Photoshop (or view it using some different program that ignores the alpha channel), you would see the rest of it.

David

3

Excellent!
Based on what you said, I deleted the alpha channel in Photoshop and saved a copy. I opened the copy in firefox the rest of the texture was still missing.
However i opened the original in MS Paint and the entire texture was there, plain as day.
:blush:
thanks much