1/*
2---------------------------------------------------------------------------
3Open Asset Import Library (assimp)
4---------------------------------------------------------------------------
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17 following disclaimer.
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41*/
42
43/** @file FindInstancesProcess.cpp
44 * @brief Implementation of the aiProcess_FindInstances postprocessing step
45*/
46
47
48#include "FindInstancesProcess.h"
49#include <memory>
50#include <stdio.h>
51
52using namespace Assimp;
53
54// ------------------------------------------------------------------------------------------------
55// Constructor to be privately used by Importer
56FindInstancesProcess::FindInstancesProcess()
57: configSpeedFlag (false)
58{}
59
60// ------------------------------------------------------------------------------------------------
61// Destructor, private as well
62FindInstancesProcess::~FindInstancesProcess()
63{}
64
65// ------------------------------------------------------------------------------------------------
66// Returns whether the processing step is present in the given flag field.
67bool FindInstancesProcess::IsActive( unsigned int pFlags) const
68{
69 // FindInstances makes absolutely no sense together with PreTransformVertices
70 // fixme: spawn error message somewhere else?
71 return 0 != (pFlags & aiProcess_FindInstances) && 0 == (pFlags & aiProcess_PreTransformVertices);
72}
73
74// ------------------------------------------------------------------------------------------------
75// Setup properties for the step
76void FindInstancesProcess::SetupProperties(const Importer* pImp)
77{
78 // AI_CONFIG_FAVOUR_SPEED
79 configSpeedFlag = (0 != pImp->GetPropertyInteger(AI_CONFIG_FAVOUR_SPEED,0));
80}
81
82// ------------------------------------------------------------------------------------------------
83// Compare the bones of two meshes
84bool CompareBones(const aiMesh* orig, const aiMesh* inst)
85{
86 for (unsigned int i = 0; i < orig->mNumBones;++i) {
87 aiBone* aha = orig->mBones[i];
88 aiBone* oha = inst->mBones[i];
89
90 if (aha->mNumWeights != oha->mNumWeights ||
91 aha->mOffsetMatrix != oha->mOffsetMatrix) {
92 return false;
93 }
94
95 // compare weight per weight ---
96 for (unsigned int n = 0; n < aha->mNumWeights;++n) {
97 if (aha->mWeights[n].mVertexId != oha->mWeights[n].mVertexId ||
98 (aha->mWeights[n].mWeight - oha->mWeights[n].mWeight) < 10e-3f) {
99 return false;
100 }
101 }
102 }
103 return true;
104}
105
106// ------------------------------------------------------------------------------------------------
107// Update mesh indices in the node graph
108void UpdateMeshIndices(aiNode* node, unsigned int* lookup)
109{
110 for (unsigned int n = 0; n < node->mNumMeshes;++n)
111 node->mMeshes[n] = lookup[node->mMeshes[n]];
112
113 for (unsigned int n = 0; n < node->mNumChildren;++n)
114 UpdateMeshIndices(node->mChildren[n],lookup);
115}
116
117// ------------------------------------------------------------------------------------------------
118// Executes the post processing step on the given imported data.
119void FindInstancesProcess::Execute( aiScene* pScene)
120{
121 DefaultLogger::get()->debug("FindInstancesProcess begin");
122 if (pScene->mNumMeshes) {
123
124 // use a pseudo hash for all meshes in the scene to quickly find
125 // the ones which are possibly equal. This step is executed early
126 // in the pipeline, so we could, depending on the file format,
127 // have several thousand small meshes. That's too much for a brute
128 // everyone-against-everyone check involving up to 10 comparisons
129 // each.
130 std::unique_ptr<uint64_t[]> hashes (new uint64_t[pScene->mNumMeshes]);
131 std::unique_ptr<unsigned int[]> remapping (new unsigned int[pScene->mNumMeshes]);
132
133 unsigned int numMeshesOut = 0;
134 for (unsigned int i = 0; i < pScene->mNumMeshes; ++i) {
135
136 aiMesh* inst = pScene->mMeshes[i];
137 hashes[i] = GetMeshHash(inst);
138
139 for (int a = i-1; a >= 0; --a) {
140 if (hashes[i] == hashes[a])
141 {
142 aiMesh* orig = pScene->mMeshes[a];
143 if (!orig)
144 continue;
145
146 // check for hash collision .. we needn't check
147 // the vertex format, it *must* match due to the
148 // (brilliant) construction of the hash
149 if (orig->mNumBones != inst->mNumBones ||
150 orig->mNumFaces != inst->mNumFaces ||
151 orig->mNumVertices != inst->mNumVertices ||
152 orig->mMaterialIndex != inst->mMaterialIndex ||
153 orig->mPrimitiveTypes != inst->mPrimitiveTypes)
154 continue;
155
156 // up to now the meshes are equal. find an appropriate
157 // epsilon to compare position differences against
158 float epsilon = ComputePositionEpsilon(inst);
159 epsilon *= epsilon;
160
161 // now compare vertex positions, normals,
162 // tangents and bitangents using this epsilon.
163 if (orig->HasPositions()) {
164 if(!CompareArrays(orig->mVertices,inst->mVertices,orig->mNumVertices,epsilon))
165 continue;
166 }
167 if (orig->HasNormals()) {
168 if(!CompareArrays(orig->mNormals,inst->mNormals,orig->mNumVertices,epsilon))
169 continue;
170 }
171 if (orig->HasTangentsAndBitangents()) {
172 if (!CompareArrays(orig->mTangents,inst->mTangents,orig->mNumVertices,epsilon) ||
173 !CompareArrays(orig->mBitangents,inst->mBitangents,orig->mNumVertices,epsilon))
174 continue;
175 }
176
177 // use a constant epsilon for colors and UV coordinates
178 static const float uvEpsilon = 10e-4f;
179 {
180 unsigned int i, end = orig->GetNumUVChannels();
181 for(i = 0; i < end; ++i) {
182 if (!orig->mTextureCoords[i]) {
183 continue;
184 }
185 if(!CompareArrays(orig->mTextureCoords[i],inst->mTextureCoords[i],orig->mNumVertices,uvEpsilon)) {
186 break;
187 }
188 }
189 if (i != end) {
190 continue;
191 }
192 }
193 {
194 unsigned int i, end = orig->GetNumColorChannels();
195 for(i = 0; i < end; ++i) {
196 if (!orig->mColors[i]) {
197 continue;
198 }
199 if(!CompareArrays(orig->mColors[i],inst->mColors[i],orig->mNumVertices,uvEpsilon)) {
200 break;
201 }
202 }
203 if (i != end) {
204 continue;
205 }
206 }
207
208 // These two checks are actually quite expensive and almost *never* required.
209 // Almost. That's why they're still here. But there's no reason to do them
210 // in speed-targeted imports.
211 if (!configSpeedFlag) {
212
213 // It seems to be strange, but we really need to check whether the
214 // bones are identical too. Although it's extremely unprobable
215 // that they're not if control reaches here, we need to deal
216 // with unprobable cases, too. It could still be that there are
217 // equal shapes which are deformed differently.
218 if (!CompareBones(orig,inst))
219 continue;
220
221 // For completeness ... compare even the index buffers for equality
222 // face order & winding order doesn't care. Input data is in verbose format.
223 std::unique_ptr<unsigned int[]> ftbl_orig(new unsigned int[orig->mNumVertices]);
224 std::unique_ptr<unsigned int[]> ftbl_inst(new unsigned int[orig->mNumVertices]);
225
226 for (unsigned int tt = 0; tt < orig->mNumFaces;++tt) {
227 aiFace& f = orig->mFaces[tt];
228 for (unsigned int nn = 0; nn < f.mNumIndices;++nn)
229 ftbl_orig[f.mIndices[nn]] = tt;
230
231 aiFace& f2 = inst->mFaces[tt];
232 for (unsigned int nn = 0; nn < f2.mNumIndices;++nn)
233 ftbl_inst[f2.mIndices[nn]] = tt;
234 }
235 if (0 != ::memcmp(ftbl_inst.get(),ftbl_orig.get(),orig->mNumVertices*sizeof(unsigned int)))
236 continue;
237 }
238
239 // We're still here. Or in other words: 'inst' is an instance of 'orig'.
240 // Place a marker in our list that we can easily update mesh indices.
241 remapping[i] = remapping[a];
242
243 // Delete the instanced mesh, we don't need it anymore
244 delete inst;
245 pScene->mMeshes[i] = NULL;
246 break;
247 }
248 }
249
250 // If we didn't find a match for the current mesh: keep it
251 if (pScene->mMeshes[i]) {
252 remapping[i] = numMeshesOut++;
253 }
254 }
255 ai_assert(0 != numMeshesOut);
256 if (numMeshesOut != pScene->mNumMeshes) {
257
258 // Collapse the meshes array by removing all NULL entries
259 for (unsigned int real = 0, i = 0; real < numMeshesOut; ++i) {
260 if (pScene->mMeshes[i])
261 pScene->mMeshes[real++] = pScene->mMeshes[i];
262 }
263
264 // And update the node graph with our nice lookup table
265 UpdateMeshIndices(pScene->mRootNode,remapping.get());
266
267 // write to log
268 if (!DefaultLogger::isNullLogger()) {
269
270 char buffer[512];
271 ::ai_snprintf(buffer,512,"FindInstancesProcess finished. Found %i instances",pScene->mNumMeshes-numMeshesOut);
272 DefaultLogger::get()->info(buffer);
273 }
274 pScene->mNumMeshes = numMeshesOut;
275 }
276 else DefaultLogger::get()->debug("FindInstancesProcess finished. No instanced meshes found");
277 }
278}
279