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Uriel

Tangent nmaps question

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Hello! I was experimenting with tangent and object space normal maps. While using object space nmaps i was able to add nice "smoothness" to low poly objects, but i was totally unable to do same thing with tangent nmaps. With tangent maps poligon edges are visible ale sharp. As far as i know there are no technical reasons why tangent based nmaps couldnt add smoothness to objects.. Anyone had that problem? Thanks in advance for any help!

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Tangent maps are more than capable of adding detail to a surface, but they require some additional information. A tangent map requires you to transform the coordinates into "tangent space", which essentially is (for lack of a teechnical explanation) just a method of telling the renderer what direction is "up" on the texture in question. This requires a bit of per-vertex math. I'm no good at explaining mathmatics, so I'll just point you to a good resource:

http://www.opengl.org/resources/tutorials/advanced/advanced97/notes/node73.html

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I solved this kind of a problem, with calculating smooth normals/tangents/binormals. I mean, If many vertices share one position in the 3D world, they have same normal/tangent/binormal.

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Thanks for quick anwsers.

Toji, you understimate me ;-) Im doing all the math and i have working tangent maps. Problem is with smooth objects - example: my low poly model is sphere made of.. say 12 faces and hi poly model is the same sphere but utilizing 5k poly. When i render low poly model with nmap i can see edges (not only on silhuette). Seems like tangent space nmaps have some artifacts on edges - objects are not smooth on them.

MePHyst0, it sounds like a good idea to smooth tangents. But it should also affect way in which normal maps are generated i think.. Do You know any software that is capable of computing smooth tangents, saving them in .x file and then generating nmap using those new tangents? (or maybe im totally wrong here and i can use standard nmaps without artifacts?)

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Ah, I'm sorry. I misunderstood the problem. My apologies!

I think we would have to see some code before we could really help.

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Its probably my fault - im doing too many things at the same time and im not explaining clearly. Also, my previous post was pure nonsens, since its enough to smooth normals before tangent map computation to get smooth tangents. And that solves the problem ( there ale still some problesm on edges but not i have tools to fight them!)
Thanks for help MePHyst0 and Toji!

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