Multi-rendering with 4 textures + 4 alpha masks

DaN1maL · 2004-08-10T00:41:08

Ok, I'm working with splatting-like technique with my terrain and I want to be able to have up to 4 layers per quad. (ex: dirt, grass, rock...etc) .... In my example I'll be using 3 layers. Each texture layer has a corresponding alpha texture (8bit.. GL_ALPHA) say i have these... dirt texture + dirt alpha mask grass texture + grass alpha mask rock texture + rock alpha mask I don't want to have to use 6 texture units... and I don't know if I'd even be able to set it up correctly with multi-texturing if I used six units. What I'd like to do is first combine the dirt texture with its alpha mask, then the grass with its alpha mask, then the rock with its alpha mask... Once they are all combined, I want to render the 3 results together using three texture units. Is this possible? ... All I really want to do is take the alpha right out of the mask and apply it to the texture just before I render. Can this be done? Do I have to just manually copy out the alpha from the mask into the texture? And if so, is that even possible? I know there is some solution to this... Because games such as FarCry are doing this.

Graphics and GPU Programming Programming

Started by DaN1maL August 04, 2004 05:53 AM

11 comments, last by DaN1maL 19 years, 8 months ago

Anonymous

August 06, 2004 02:04 AM

I want to also....

zedzeek,can you sent to yjh1982yjh@yahoo.com.cn?
thanks very much!

DaN1maL

136

Author

August 06, 2004 11:05 PM

I got the code working in my project... But I found out most of my problems were because of the way I was creating my alpha mask texture. I was using GL_ALPHA for the format.. Even though that should work, it doesn't. So I had to put GL_LUMINANCE.

I have everything working, only problem is that it's too slow. Is there anyway to get this all in one pass?

[Edited by - DaN1maL on August 10, 2004 12:05:09 AM]

DaN1maL

136

Author

August 10, 2004 12:41 AM

I'm going to be using a pbuffer now to cache the quads around my position so i dont have to do all the rendering every frame....

But I'd still like to get all the layers rendered in one pass using a texture unit per layer. Do you know how this could be accomplished? Possible?

Multi-rendering with 4 textures + 4 alpha masks

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Multi-rendering with 4 textures + 4 alpha masks

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