DeleD Community Edition

Spaddlewit · Last edited by Spaddlewit on Tue Jun 28, 2011 1:41 am; edited 1 time in total

I'm just starting to get into using lightmaps and I want to be sure I understand the file format part correctly:

*) Each material specifies a texture file for lightmapping

*) When rendering a polygon in code, it might look something like this:

Starnick · DeleD PRO user Joined: 28 Jul 2007 Posts: 611

Yeah, each material has three user-defined layers, and a 4th layer reserved for a lightmap texture.

Applying a lightmap is easy if you're using shaders since all you're doing is modulating (multiply) the color of the lightmap with the color of the polygon (e.g. base texture or color or whatever else is specified in the DeleD material). White areas remain the original polygon color, black areas remain black.

If you're using fixed function rendering, you're going to have to look at multitexturing, which would allow you to draw the polygon in one pass, instead of the two passes you mentioned.

Spaddlewit · Posted: Tue Jun 28, 2011 2:36 am Post subject:

Yeah, I'm using fixed-function.
Turns out the V coordinate for lightmaps doesn't need to be flipped like the regular texture materials do.

The only thing I can't figure out now is the proper glBlendFunc to use. I have it looking ALMOST just like DeleD, but there's an issue with alpha blended textures.

Grandmaster B · DeleD PRO user Joined: 03 Jul 2007 Posts: 218

You may use alpha testing for that:

glEnable(GL_ALPHA_TEST)
glAlphaFunc(GL_GREATER, 0.5)

Spaddlewit · Posted: Tue Jun 28, 2011 5:35 pm Post subject:

I'm already using alpha testing like you said... works great for the actual texture, but it's the lightmap texture that's getting drawn where the regular texture dictates transparency.

Edit: Figured it out... For anyone else having this issue, you MUST use multitexture rather than doing multiple passes for the lightmaps to work with alpha blended textures.

AWM Mars · Posted: Wed Jun 29, 2011 8:34 am Post subject:

I came across a similar problem like this. I changed to PNG for transparancies from TGA's, which were the cause. Might be worth a try. Question

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