diff options
Diffstat (limited to 'thirdparty/misc/mikktspace.h')
| -rw-r--r-- | thirdparty/misc/mikktspace.h | 145 |
1 files changed, 145 insertions, 0 deletions
diff --git a/thirdparty/misc/mikktspace.h b/thirdparty/misc/mikktspace.h new file mode 100644 index 0000000000..52c44a713c --- /dev/null +++ b/thirdparty/misc/mikktspace.h @@ -0,0 +1,145 @@ +/** \file mikktspace/mikktspace.h + * \ingroup mikktspace + */ +/** + * Copyright (C) 2011 by Morten S. Mikkelsen + * + * This software is provided 'as-is', without any express or implied + * warranty. In no event will the authors be held liable for any damages + * arising from the use of this software. + * + * Permission is granted to anyone to use this software for any purpose, + * including commercial applications, and to alter it and redistribute it + * freely, subject to the following restrictions: + * + * 1. The origin of this software must not be misrepresented; you must not + * claim that you wrote the original software. If you use this software + * in a product, an acknowledgment in the product documentation would be + * appreciated but is not required. + * 2. Altered source versions must be plainly marked as such, and must not be + * misrepresented as being the original software. + * 3. This notice may not be removed or altered from any source distribution. + */ + +#ifndef __MIKKTSPACE_H__ +#define __MIKKTSPACE_H__ + + +#ifdef __cplusplus +extern "C" { +#endif + +/* Author: Morten S. Mikkelsen + * Version: 1.0 + * + * The files mikktspace.h and mikktspace.c are designed to be + * stand-alone files and it is important that they are kept this way. + * Not having dependencies on structures/classes/libraries specific + * to the program, in which they are used, allows them to be copied + * and used as is into any tool, program or plugin. + * The code is designed to consistently generate the same + * tangent spaces, for a given mesh, in any tool in which it is used. + * This is done by performing an internal welding step and subsequently an order-independent evaluation + * of tangent space for meshes consisting of triangles and quads. + * This means faces can be received in any order and the same is true for + * the order of vertices of each face. The generated result will not be affected + * by such reordering. Additionally, whether degenerate (vertices or texture coordinates) + * primitives are present or not will not affect the generated results either. + * Once tangent space calculation is done the vertices of degenerate primitives will simply + * inherit tangent space from neighboring non degenerate primitives. + * The analysis behind this implementation can be found in my master's thesis + * which is available for download --> http://image.diku.dk/projects/media/morten.mikkelsen.08.pdf + * Note that though the tangent spaces at the vertices are generated in an order-independent way, + * by this implementation, the interpolated tangent space is still affected by which diagonal is + * chosen to split each quad. A sensible solution is to have your tools pipeline always + * split quads by the shortest diagonal. This choice is order-independent and works with mirroring. + * If these have the same length then compare the diagonals defined by the texture coordinates. + * XNormal which is a tool for baking normal maps allows you to write your own tangent space plugin + * and also quad triangulator plugin. + */ + + +typedef int tbool; +typedef struct SMikkTSpaceContext SMikkTSpaceContext; + +typedef struct { + // Returns the number of faces (triangles/quads) on the mesh to be processed. + int (*m_getNumFaces)(const SMikkTSpaceContext * pContext); + + // Returns the number of vertices on face number iFace + // iFace is a number in the range {0, 1, ..., getNumFaces()-1} + int (*m_getNumVerticesOfFace)(const SMikkTSpaceContext * pContext, const int iFace); + + // returns the position/normal/texcoord of the referenced face of vertex number iVert. + // iVert is in the range {0,1,2} for triangles and {0,1,2,3} for quads. + void (*m_getPosition)(const SMikkTSpaceContext * pContext, float fvPosOut[], const int iFace, const int iVert); + void (*m_getNormal)(const SMikkTSpaceContext * pContext, float fvNormOut[], const int iFace, const int iVert); + void (*m_getTexCoord)(const SMikkTSpaceContext * pContext, float fvTexcOut[], const int iFace, const int iVert); + + // either (or both) of the two setTSpace callbacks can be set. + // The call-back m_setTSpaceBasic() is sufficient for basic normal mapping. + + // This function is used to return the tangent and fSign to the application. + // fvTangent is a unit length vector. + // For normal maps it is sufficient to use the following simplified version of the bitangent which is generated at pixel/vertex level. + // bitangent = fSign * cross(vN, tangent); + // Note that the results are returned unindexed. It is possible to generate a new index list + // But averaging/overwriting tangent spaces by using an already existing index list WILL produce INCRORRECT results. + // DO NOT! use an already existing index list. + void (*m_setTSpaceBasic)(const SMikkTSpaceContext * pContext, const float fvTangent[], const float fSign, const int iFace, const int iVert); + + // This function is used to return tangent space results to the application. + // fvTangent and fvBiTangent are unit length vectors and fMagS and fMagT are their + // true magnitudes which can be used for relief mapping effects. + // fvBiTangent is the "real" bitangent and thus may not be perpendicular to fvTangent. + // However, both are perpendicular to the vertex normal. + // For normal maps it is sufficient to use the following simplified version of the bitangent which is generated at pixel/vertex level. + // fSign = bIsOrientationPreserving ? 1.0f : (-1.0f); + // bitangent = fSign * cross(vN, tangent); + // Note that the results are returned unindexed. It is possible to generate a new index list + // But averaging/overwriting tangent spaces by using an already existing index list WILL produce INCRORRECT results. + // DO NOT! use an already existing index list. + void (*m_setTSpace)(const SMikkTSpaceContext * pContext, const float fvTangent[], const float fvBiTangent[], const float fMagS, const float fMagT, + const tbool bIsOrientationPreserving, const int iFace, const int iVert); +} SMikkTSpaceInterface; + +struct SMikkTSpaceContext +{ + SMikkTSpaceInterface * m_pInterface; // initialized with callback functions + void * m_pUserData; // pointer to client side mesh data etc. (passed as the first parameter with every interface call) +}; + +// these are both thread safe! +tbool genTangSpaceDefault(const SMikkTSpaceContext * pContext); // Default (recommended) fAngularThreshold is 180 degrees (which means threshold disabled) +tbool genTangSpace(const SMikkTSpaceContext * pContext, const float fAngularThreshold); + + +// To avoid visual errors (distortions/unwanted hard edges in lighting), when using sampled normal maps, the +// normal map sampler must use the exact inverse of the pixel shader transformation. +// The most efficient transformation we can possibly do in the pixel shader is +// achieved by using, directly, the "unnormalized" interpolated tangent, bitangent and vertex normal: vT, vB and vN. +// pixel shader (fast transform out) +// vNout = normalize( vNt.x * vT + vNt.y * vB + vNt.z * vN ); +// where vNt is the tangent space normal. The normal map sampler must likewise use the +// interpolated and "unnormalized" tangent, bitangent and vertex normal to be compliant with the pixel shader. +// sampler does (exact inverse of pixel shader): +// float3 row0 = cross(vB, vN); +// float3 row1 = cross(vN, vT); +// float3 row2 = cross(vT, vB); +// float fSign = dot(vT, row0)<0 ? -1 : 1; +// vNt = normalize( fSign * float3(dot(vNout,row0), dot(vNout,row1), dot(vNout,row2)) ); +// where vNout is the sampled normal in some chosen 3D space. +// +// Should you choose to reconstruct the bitangent in the pixel shader instead +// of the vertex shader, as explained earlier, then be sure to do this in the normal map sampler also. +// Finally, beware of quad triangulations. If the normal map sampler doesn't use the same triangulation of +// quads as your renderer then problems will occur since the interpolated tangent spaces will differ +// eventhough the vertex level tangent spaces match. This can be solved either by triangulating before +// sampling/exporting or by using the order-independent choice of diagonal for splitting quads suggested earlier. +// However, this must be used both by the sampler and your tools/rendering pipeline. + +#ifdef __cplusplus +} +#endif + +#endif |