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3Open Asset Import Library (assimp)
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41
42/** @file Generation of normal vectors basing on smoothing groups */
43
44#pragma once
45#ifndef AI_SMOOTHINGGROUPS_INL_INCLUDED
46#define AI_SMOOTHINGGROUPS_INL_INCLUDED
47
48#ifdef __GNUC__
49#   pragma GCC system_header
50#endif
51
52#include <assimp/SGSpatialSort.h>
53
54#include <algorithm>
55
56using namespace Assimp;
57
58// ------------------------------------------------------------------------------------------------
59template <class T>
60void ComputeNormalsWithSmoothingsGroups(MeshWithSmoothingGroups<T>& sMesh)
61{
62    // First generate face normals
63    sMesh.mNormals.resize(sMesh.mPositions.size(),aiVector3D());
64    for( unsigned int a = 0; a < sMesh.mFaces.size(); a++)
65    {
66        T& face = sMesh.mFaces[a];
67
68        aiVector3D* pV1 = &sMesh.mPositions[face.mIndices[0]];
69        aiVector3D* pV2 = &sMesh.mPositions[face.mIndices[1]];
70        aiVector3D* pV3 = &sMesh.mPositions[face.mIndices[2]];
71
72        aiVector3D pDelta1 = *pV2 - *pV1;
73        aiVector3D pDelta2 = *pV3 - *pV1;
74        aiVector3D vNor = pDelta1 ^ pDelta2;
75
76        for (unsigned int c = 0; c < 3;++c)
77            sMesh.mNormals[face.mIndices[c]] = vNor;
78    }
79
80    // calculate the position bounds so we have a reliable epsilon to check position differences against
81    aiVector3D minVec( 1e10f, 1e10f, 1e10f), maxVec( -1e10f, -1e10f, -1e10f);
82    for( unsigned int a = 0; a < sMesh.mPositions.size(); a++)
83    {
84        minVec.x = std::min( minVec.x, sMesh.mPositions[a].x);
85        minVec.y = std::min( minVec.y, sMesh.mPositions[a].y);
86        minVec.z = std::min( minVec.z, sMesh.mPositions[a].z);
87        maxVec.x = std::max( maxVec.x, sMesh.mPositions[a].x);
88        maxVec.y = std::max( maxVec.y, sMesh.mPositions[a].y);
89        maxVec.z = std::max( maxVec.z, sMesh.mPositions[a].z);
90    }
91    const float posEpsilon = (maxVec - minVec).Length() * 1e-5f;
92    std::vector<aiVector3D> avNormals;
93    avNormals.resize(sMesh.mNormals.size());
94
95    // now generate the spatial sort tree
96    SGSpatialSort sSort;
97    for( typename std::vector<T>::iterator i =  sMesh.mFaces.begin();
98        i != sMesh.mFaces.end();++i)
99    {
100        for (unsigned int c = 0; c < 3;++c)
101            sSort.Add(sMesh.mPositions[(*i).mIndices[c]],(*i).mIndices[c],(*i).iSmoothGroup);
102    }
103    sSort.Prepare();
104
105    std::vector<bool> vertexDone(sMesh.mPositions.size(),false);
106    for( typename std::vector<T>::iterator i =  sMesh.mFaces.begin();
107        i != sMesh.mFaces.end();++i)
108    {
109        std::vector<unsigned int> poResult;
110        for (unsigned int c = 0; c < 3;++c)
111        {
112            unsigned int idx = (*i).mIndices[c];
113            if (vertexDone[idx])continue;
114
115            sSort.FindPositions(sMesh.mPositions[idx],(*i).iSmoothGroup,
116                posEpsilon,poResult);
117
118            aiVector3D vNormals;
119            for (std::vector<unsigned int>::const_iterator
120                a =  poResult.begin();
121                a != poResult.end();++a)
122            {
123                vNormals += sMesh.mNormals[(*a)];
124            }
125            vNormals.NormalizeSafe();
126
127            // write back into all affected normals
128            for (std::vector<unsigned int>::const_iterator
129                a =  poResult.begin();
130                a != poResult.end();++a)
131            {
132                idx = *a;
133                avNormals [idx] = vNormals;
134                vertexDone[idx] = true;
135            }
136        }
137    }
138    sMesh.mNormals = avNormals;
139}
140
141#endif // !! AI_SMOOTHINGGROUPS_INL_INCLUDED
142