# Tangent Space Vectors [T B N]

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Hi, I am trying to implement Cubic Environment Map Bump Mapping for the Utah teapot. The teapot data consists of 32 bezier patches. I had evaluated these bezier patches and calculated the vertices (x, y, z) and their corresponding texture coordinates (s, t). Given 4 vertices and their texture coordinates how to compute the Tangent space (Tangent, Binormal and Normal) at each vertex. All the methods that I found on the internet describe the scheme for triangles. I think I can use the same method but I just want to make sure if that is correct. All comments would be of help! Thanks!

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Hi,

Was my question stupid ? or everybody just sneaked with the triangles ?

Thanks!

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Well, if you have a mathematical representation of the surface, you can calculate the bitangent and tangent vectors directly. If you don't, then you can calculate them from the tesselated vertices - you must have a list of triangles to render them - so the methods relating to calculating it for triangles is valid.

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You should definitely be able to compute this directly from the patch information, since the Bezier patch is a smooth 2D manifold that is at least C2.

Cheers,

Timkin

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Hi Timkin,

Lets say we have 4 vertices and their texture coordinates of a quad (no Bezier or anything). How to find the TBN for this quad ?

Thanks!

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