49 lines
2.8 KiB
Plaintext
49 lines
2.8 KiB
Plaintext
/**
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* Copyright (C) 2011 by Morten S. Mikkelsen
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*
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* This software is provided 'as-is', without any express or implied
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* warranty. In no event will the authors be held liable for any damages
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* arising from the use of this software.
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*
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* Permission is granted to anyone to use this software for any purpose,
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* including commercial applications, and to alter it and redistribute it
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* freely, subject to the following restrictions:
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*
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* 1. The origin of this software must not be misrepresented; you must not
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* claim that you wrote the original software. If you use this software
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* in a product, an acknowledgment in the product documentation would be
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* appreciated but is not required.
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* 2. Altered source versions must be plainly marked as such, and must not be
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* misrepresented as being the original software.
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* 3. This notice may not be removed or altered from any source distribution.
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*/
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/* Author: Morten S. Mikkelsen
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* Version: 1.0
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*
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* The files mikktspace.h and mikktspace.c are designed to be
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* stand-alone files and it is important that they are kept this way.
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* Not having dependencies on structures/classes/libraries specific
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* to the program, in which they are used, allows them to be copied
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* and used as is into any tool, program or plugin.
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* The code is designed to consistently generate the same
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* tangent spaces, for a given mesh, in any tool in which it is used.
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* This is done by performing an internal welding step and subsequently an order-independent evaluation
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* of tangent space for meshes consisting of triangles and quads.
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* This means faces can be received in any order and the same is true for
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* the order of vertices of each face. The generated result will not be affected
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* by such reordering. Additionally, whether degenerate (vertices or texture coordinates)
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* primitives are present or not will not affect the generated results either.
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* Once tangent space calculation is done the vertices of degenerate primitives will simply
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* inherit tangent space from neighboring non degenerate primitives.
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* The analysis behind this implementation can be found in my master's thesis
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* which is available for download --> http://image.diku.dk/projects/media/morten.mikkelsen.08.pdf
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* Note that though the tangent spaces at the vertices are generated in an order-independent way,
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* by this implementation, the interpolated tangent space is still affected by which diagonal is
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* chosen to split each quad. A sensible solution is to have your tools pipeline always
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* split quads by the shortest diagonal. This choice is order-independent and works with mirroring.
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* If these have the same length then compare the diagonals defined by the texture coordinates.
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* XNormal which is a tool for baking normal maps allows you to write your own tangent space plugin
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* and also quad triangulator plugin.
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*/
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