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| Bumpmapping Part II |
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wis Member since: 2/21/2002 From: Germany |
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 Posted - 3/15/2002 6:33:43 AM |
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| Hello, perhaps I'm just bit confused... But anyway here's another question about bumpmapping: The effect Bumpmapping is only influenced by light, right? If my lights are static, so is my bumpmapping effect... (If it's specular also the viewer comes into account... ... but terrain (mud, grass, rock) is not so shiny...) Unfortunately I have a very static light, the sun! What I want to achieve is Bumpmapping completely related to the viewer (camera position), so I see the front of a bump if I stand in Front of the bump (but the back shouldn't be just darkened, it should not be visible) and the back of the bump when I stand in its back. Hope I made myself clear... And please tell me if this is completely impossible! Any answers are strongly appreciated. |
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Gammastrahler Member since: 4/12/2001 From: Germany |
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Posted - 3/15/2002 9:21:09 AM |
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| Was für ein Lichtmodell benutzt du? OpenGL oder ein eigenes? Du kannst dein Sonnenlicht mit einer Specular-Komponente versehen, so das deine Bump Maps sich ensprechend deiner Kameraposition verändern. Dies bedeutet jedoch eine Menge an Rechenaufwand, da die Bump Maps jedes Frame aktualisiert werden müssen. Wenn du eine Geforce3 hast, ist dies allerdings kein Problem, da es dort Hardware mässig unterstützt wird. Sorry, ich kann dir auf deine zweite Frage nicht antworten, da ich nicht genau verstanden hab worum es geht... |
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Yann L Moderator Member since: 2/6/2002 From: Breizh |
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Posted - 3/15/2002 9:53:53 AM |
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quote: If you are using DOT3 bumpmapping, you can't use OGLs internal lighting, you *have* to use your own. quote: I would also suggest that. You should only have the specular component be influenced by the viewer position, not the diffuse. If you don't want specular terrains, then forget about bumpmapping altogether, at least for the sunlight. You *could* have the diffuse component change with viewposition, just do as if the light source was at the position of the camaera. It actually makes the equations for tangent space vectors even a bit simpler. But I'm not sure, if this is want you want to do, since the effect would look *very* weird, and totally unrealistic. |
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wis Member since: 2/21/2002 From: Germany |
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 Posted - 3/15/2002 12:26:34 PM |
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| Thanks for your answers! Unfornately I dont't have a GF3, only a GF2, so Gammastrahlers suggestion is out... And I tried already the thing with the lightsource having the same position as the camera, looks like crap if the scene is not quite dark. I have to say, I'm very disappointed about bumpmapping, I thaught something like cracks or small bumps on terrain would be possible by now on gf2 in a rather realistic manner... One thing last: This one goes out to you Gammastrahler, please post in english language, you've seen that I'm from Germany, and of course I understood you, but this topic might also be interesting for some people how don't, and for my part, i hate it if some guys start posting in french and I can't follow an interesting topic anymore. |
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Yann L Moderator Member since: 2/6/2002 From: Breizh |
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Posted - 3/15/2002 1:49:12 PM |
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quote: Perhaps you tried to use bumpmapping for something it was not designed to do. Bumpmapping is not used to give you more texture details in a static lit scene. Esp. I would stay far away from bumpmapping terrains, this looks like crap (as you discovered). You should use detail-mapping for that purpose. Bumpmapping is only useful on moving objects and/or moving lightsources. And it can be of breathtaking quality, eg. on animated skinned characters in a dynamic light environment. Another use for it are water surfaces, it's almost mandatory there, if you want good looking detailed water pools. quote: That's why I replied in english. Good you mentioned the point, Wis. People, this is an english message board, please post in english. |
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Gammastrahler Member since: 4/12/2001 From: Germany |
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Posted - 3/15/2002 3:03:41 PM |
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okay  |
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zedzeek Member since: 7/8/2000 From: nelson, New Zealand |
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Posted - 3/15/2002 3:23:24 PM |
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| >>I would also suggest that. You should only have the specular component be influenced by the viewer position, not the diffuse. If you don't want specular terrains, then forget about bumpmapping altogether, at least for the sunlight.<< first part is true though i would add 'terrain doesnt really need specular except maybe water' + 'terrain with bumpmaps looks very good even for just sunlight' also bumpmapping with specular can be done on all geforces quite easierly http://uk.geocities.com/sloppyturds/gotterdammerung.html |
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Yann L Moderator Member since: 2/6/2002 From: Breizh |
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Posted - 3/15/2002 4:33:45 PM |
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| > 'terrain with bumpmaps looks very good even for just sunlight' And I will add to that: 'what is a complete waste of resources'. It's absolutely pointless to bumpmap a static object with static light only. You might tweak it to look good, but you can also use pre-bumped detail maps, that take a fraction of the resources needed by bump mapping. The quality will be *exactly* the same (pixel by pixel), if the lightposition doesn't change and the terrain deosn't move/morph. > also bumpmapping with specular can be done on all geforces quite easierly Not really. To do good pixel perfect bumpmapped speculars on low tesselated geometry (such as a terrain) you need 3 texture units. One for the normal map, one for a normalization lookup cubemap, and one for the specular environment EMBM map. You'll also need VPs to efficiently adjust the specular tangent vectors. So, good specular = GF3. But you can do some kind of cheesy vertex speculars on GF2, but they look horrible, IMO. |
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