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View Full Version : Bump mapping in software?



Syslock
08-30-2002, 03:47 PM
I need to do software bump mapping in OpenGL. No hardware please.
Does not matter if I have to slowly render it in multiple passes.

Where can I find some examples or code to do this?

tinak
08-30-2002, 04:45 PM
You might want to pay a visit to Nehe's tutorial 22 as it seems to cover bump mapping.
http://nehe.gamedev.net/

Tina

Syslock
08-31-2002, 06:54 AM
I already looked at that demo.

From what I can tell, it doesn't do bump mapping.
The box looks totally flat on my computer.

tinak
08-31-2002, 07:48 AM
Hmm, seemed non flat to me when I ran it just now. I can see it working for say a planet requiring the ground to be bumped.

Did you use the letters E, M and B to see the different effects. B changes the bump setting. Flat or not flat. E changes emboss setting and M allows multi-texturing.

Hopefully it isn't the case that your card will not allow you to use the extensions.

Tina

Syslock
08-31-2002, 09:38 PM
I can see all the textures, but I don't see any bump shadows.

The textures have some shadowing to them (as in the actual
texture pixels), but I don't see any exaggerated bump mapping
shadows. It's all flat.

Maybe my card doesn't support these extensions. I wish
a screenshot came with this demo.

tinak
09-01-2002, 07:38 AM
I've incorporated my screenshot routines into the program and dumped the bumped,embossed and normal views of the object on my site so that you can see the effects I have.
http://programming.swangen.co.uk/opengl/bumpmapping.asp

If this is what you get then either we both have no support for this or this is what the lesson is showing us. Perhaps someone who gets a different effect will let us know.

Tina

Syslock
09-01-2002, 08:20 AM
Thanks, I see it now. I changed MAX_EMBOSS to 0.02f.

The problem with the demo is that the bump mapping is so subtle,
you really don't notice the difference, even if it is working
correctly.

If I increase MAX_EMBOSS to 0.05 or higher, the bump mapping
does not look very good. Do you know if hardware bump mapping
does the same thing if I want to use a very exaggerated, but
realistic bump mapping that looks good?

dorbie
09-01-2002, 09:55 AM
To improve the quality you need a higher resolution bump map with filtering like MIPmaps too. You can still displace by the same s&t magnitude

Syslock
09-01-2002, 10:26 AM
Ok, but say if I replaced bump.bmp with a 1024x1024 B&W checker pattern.
The quality is the same as a 256x256 B&W checker pattern. Is that what
you mean by higher resolution?

(Oh, nevermind. You mean if the texture has a wider range of colors,
not necessarily the size of the texture. http://www.opengl.org/discussion_boards/ubb/smile.gif)

BTW, a checker pattern shows off the bump mapping in this demo much better.

[This message has been edited by Syslock (edited 09-01-2002).]