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author | 3gg <3gg@shellblade.net> | 2023-01-03 08:49:54 -0800 |
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committer | 3gg <3gg@shellblade.net> | 2023-01-03 08:49:54 -0800 |
commit | 1e3fcf5b38d67fb54102786be74af42be5c6792f (patch) | |
tree | 88bff4e24121c50d0e3c62f5ddb4eff6a3dfa238 /gfx/contrib/cgltf-tangents/MikkTSpace/mikktspace.h |
Initial commit.
Diffstat (limited to 'gfx/contrib/cgltf-tangents/MikkTSpace/mikktspace.h')
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diff --git a/gfx/contrib/cgltf-tangents/MikkTSpace/mikktspace.h b/gfx/contrib/cgltf-tangents/MikkTSpace/mikktspace.h new file mode 100644 index 0000000..52c44a7 --- /dev/null +++ b/gfx/contrib/cgltf-tangents/MikkTSpace/mikktspace.h | |||
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1 | /** \file mikktspace/mikktspace.h | ||
2 | * \ingroup mikktspace | ||
3 | */ | ||
4 | /** | ||
5 | * Copyright (C) 2011 by Morten S. Mikkelsen | ||
6 | * | ||
7 | * This software is provided 'as-is', without any express or implied | ||
8 | * warranty. In no event will the authors be held liable for any damages | ||
9 | * arising from the use of this software. | ||
10 | * | ||
11 | * Permission is granted to anyone to use this software for any purpose, | ||
12 | * including commercial applications, and to alter it and redistribute it | ||
13 | * freely, subject to the following restrictions: | ||
14 | * | ||
15 | * 1. The origin of this software must not be misrepresented; you must not | ||
16 | * claim that you wrote the original software. If you use this software | ||
17 | * in a product, an acknowledgment in the product documentation would be | ||
18 | * appreciated but is not required. | ||
19 | * 2. Altered source versions must be plainly marked as such, and must not be | ||
20 | * misrepresented as being the original software. | ||
21 | * 3. This notice may not be removed or altered from any source distribution. | ||
22 | */ | ||
23 | |||
24 | #ifndef __MIKKTSPACE_H__ | ||
25 | #define __MIKKTSPACE_H__ | ||
26 | |||
27 | |||
28 | #ifdef __cplusplus | ||
29 | extern "C" { | ||
30 | #endif | ||
31 | |||
32 | /* Author: Morten S. Mikkelsen | ||
33 | * Version: 1.0 | ||
34 | * | ||
35 | * The files mikktspace.h and mikktspace.c are designed to be | ||
36 | * stand-alone files and it is important that they are kept this way. | ||
37 | * Not having dependencies on structures/classes/libraries specific | ||
38 | * to the program, in which they are used, allows them to be copied | ||
39 | * and used as is into any tool, program or plugin. | ||
40 | * The code is designed to consistently generate the same | ||
41 | * tangent spaces, for a given mesh, in any tool in which it is used. | ||
42 | * This is done by performing an internal welding step and subsequently an order-independent evaluation | ||
43 | * of tangent space for meshes consisting of triangles and quads. | ||
44 | * This means faces can be received in any order and the same is true for | ||
45 | * the order of vertices of each face. The generated result will not be affected | ||
46 | * by such reordering. Additionally, whether degenerate (vertices or texture coordinates) | ||
47 | * primitives are present or not will not affect the generated results either. | ||
48 | * Once tangent space calculation is done the vertices of degenerate primitives will simply | ||
49 | * inherit tangent space from neighboring non degenerate primitives. | ||
50 | * The analysis behind this implementation can be found in my master's thesis | ||
51 | * which is available for download --> http://image.diku.dk/projects/media/morten.mikkelsen.08.pdf | ||
52 | * Note that though the tangent spaces at the vertices are generated in an order-independent way, | ||
53 | * by this implementation, the interpolated tangent space is still affected by which diagonal is | ||
54 | * chosen to split each quad. A sensible solution is to have your tools pipeline always | ||
55 | * split quads by the shortest diagonal. This choice is order-independent and works with mirroring. | ||
56 | * If these have the same length then compare the diagonals defined by the texture coordinates. | ||
57 | * XNormal which is a tool for baking normal maps allows you to write your own tangent space plugin | ||
58 | * and also quad triangulator plugin. | ||
59 | */ | ||
60 | |||
61 | |||
62 | typedef int tbool; | ||
63 | typedef struct SMikkTSpaceContext SMikkTSpaceContext; | ||
64 | |||
65 | typedef struct { | ||
66 | // Returns the number of faces (triangles/quads) on the mesh to be processed. | ||
67 | int (*m_getNumFaces)(const SMikkTSpaceContext * pContext); | ||
68 | |||
69 | // Returns the number of vertices on face number iFace | ||
70 | // iFace is a number in the range {0, 1, ..., getNumFaces()-1} | ||
71 | int (*m_getNumVerticesOfFace)(const SMikkTSpaceContext * pContext, const int iFace); | ||
72 | |||
73 | // returns the position/normal/texcoord of the referenced face of vertex number iVert. | ||
74 | // iVert is in the range {0,1,2} for triangles and {0,1,2,3} for quads. | ||
75 | void (*m_getPosition)(const SMikkTSpaceContext * pContext, float fvPosOut[], const int iFace, const int iVert); | ||
76 | void (*m_getNormal)(const SMikkTSpaceContext * pContext, float fvNormOut[], const int iFace, const int iVert); | ||
77 | void (*m_getTexCoord)(const SMikkTSpaceContext * pContext, float fvTexcOut[], const int iFace, const int iVert); | ||
78 | |||
79 | // either (or both) of the two setTSpace callbacks can be set. | ||
80 | // The call-back m_setTSpaceBasic() is sufficient for basic normal mapping. | ||
81 | |||
82 | // This function is used to return the tangent and fSign to the application. | ||
83 | // fvTangent is a unit length vector. | ||
84 | // For normal maps it is sufficient to use the following simplified version of the bitangent which is generated at pixel/vertex level. | ||
85 | // bitangent = fSign * cross(vN, tangent); | ||
86 | // Note that the results are returned unindexed. It is possible to generate a new index list | ||
87 | // But averaging/overwriting tangent spaces by using an already existing index list WILL produce INCRORRECT results. | ||
88 | // DO NOT! use an already existing index list. | ||
89 | void (*m_setTSpaceBasic)(const SMikkTSpaceContext * pContext, const float fvTangent[], const float fSign, const int iFace, const int iVert); | ||
90 | |||
91 | // This function is used to return tangent space results to the application. | ||
92 | // fvTangent and fvBiTangent are unit length vectors and fMagS and fMagT are their | ||
93 | // true magnitudes which can be used for relief mapping effects. | ||
94 | // fvBiTangent is the "real" bitangent and thus may not be perpendicular to fvTangent. | ||
95 | // However, both are perpendicular to the vertex normal. | ||
96 | // For normal maps it is sufficient to use the following simplified version of the bitangent which is generated at pixel/vertex level. | ||
97 | // fSign = bIsOrientationPreserving ? 1.0f : (-1.0f); | ||
98 | // bitangent = fSign * cross(vN, tangent); | ||
99 | // Note that the results are returned unindexed. It is possible to generate a new index list | ||
100 | // But averaging/overwriting tangent spaces by using an already existing index list WILL produce INCRORRECT results. | ||
101 | // DO NOT! use an already existing index list. | ||
102 | void (*m_setTSpace)(const SMikkTSpaceContext * pContext, const float fvTangent[], const float fvBiTangent[], const float fMagS, const float fMagT, | ||
103 | const tbool bIsOrientationPreserving, const int iFace, const int iVert); | ||
104 | } SMikkTSpaceInterface; | ||
105 | |||
106 | struct SMikkTSpaceContext | ||
107 | { | ||
108 | SMikkTSpaceInterface * m_pInterface; // initialized with callback functions | ||
109 | void * m_pUserData; // pointer to client side mesh data etc. (passed as the first parameter with every interface call) | ||
110 | }; | ||
111 | |||
112 | // these are both thread safe! | ||
113 | tbool genTangSpaceDefault(const SMikkTSpaceContext * pContext); // Default (recommended) fAngularThreshold is 180 degrees (which means threshold disabled) | ||
114 | tbool genTangSpace(const SMikkTSpaceContext * pContext, const float fAngularThreshold); | ||
115 | |||
116 | |||
117 | // To avoid visual errors (distortions/unwanted hard edges in lighting), when using sampled normal maps, the | ||
118 | // normal map sampler must use the exact inverse of the pixel shader transformation. | ||
119 | // The most efficient transformation we can possibly do in the pixel shader is | ||
120 | // achieved by using, directly, the "unnormalized" interpolated tangent, bitangent and vertex normal: vT, vB and vN. | ||
121 | // pixel shader (fast transform out) | ||
122 | // vNout = normalize( vNt.x * vT + vNt.y * vB + vNt.z * vN ); | ||
123 | // where vNt is the tangent space normal. The normal map sampler must likewise use the | ||
124 | // interpolated and "unnormalized" tangent, bitangent and vertex normal to be compliant with the pixel shader. | ||
125 | // sampler does (exact inverse of pixel shader): | ||
126 | // float3 row0 = cross(vB, vN); | ||
127 | // float3 row1 = cross(vN, vT); | ||
128 | // float3 row2 = cross(vT, vB); | ||
129 | // float fSign = dot(vT, row0)<0 ? -1 : 1; | ||
130 | // vNt = normalize( fSign * float3(dot(vNout,row0), dot(vNout,row1), dot(vNout,row2)) ); | ||
131 | // where vNout is the sampled normal in some chosen 3D space. | ||
132 | // | ||
133 | // Should you choose to reconstruct the bitangent in the pixel shader instead | ||
134 | // of the vertex shader, as explained earlier, then be sure to do this in the normal map sampler also. | ||
135 | // Finally, beware of quad triangulations. If the normal map sampler doesn't use the same triangulation of | ||
136 | // quads as your renderer then problems will occur since the interpolated tangent spaces will differ | ||
137 | // eventhough the vertex level tangent spaces match. This can be solved either by triangulating before | ||
138 | // sampling/exporting or by using the order-independent choice of diagonal for splitting quads suggested earlier. | ||
139 | // However, this must be used both by the sampler and your tools/rendering pipeline. | ||
140 | |||
141 | #ifdef __cplusplus | ||
142 | } | ||
143 | #endif | ||
144 | |||
145 | #endif | ||