Method Execute

code/PostProcessing/FindInstancesProcess.cpp:115–272

------------------------------------------------------------------------------------------------ Executes the post processing step on the given imported data.

// ------------------------------------------------------------------------------------------------
// Executes the post processing step on the given imported data.
void FindInstancesProcess::Execute( aiScene* pScene)
{
    ASSIMP_LOG_DEBUG("FindInstancesProcess begin");
    if (pScene->mNumMeshes) {

        // use a pseudo hash for all meshes in the scene to quickly find
        // the ones which are possibly equal. This step is executed early
        // in the pipeline, so we could, depending on the file format,
        // have several thousand small meshes. That's too much for a brute
        // everyone-against-everyone check involving up to 10 comparisons
        // each.
        std::unique_ptr<uint64_t[]> hashes (new uint64_t[pScene->mNumMeshes]);
        std::unique_ptr<unsigned int[]> remapping (new unsigned int[pScene->mNumMeshes]);

        unsigned int numMeshesOut = 0;
        for (unsigned int i = 0; i < pScene->mNumMeshes; ++i) {

            aiMesh* inst = pScene->mMeshes[i];
            hashes[i] = GetMeshHash(inst);

            // Find an appropriate epsilon
            // to compare position differences against
            float epsilon = ComputePositionEpsilon(inst);
            epsilon *= epsilon;

            for (int a = i-1; a >= 0; --a) {
                if (hashes[i] == hashes[a])
                {
                    aiMesh* orig = pScene->mMeshes[a];
                    if (!orig)
                        continue;

                    // check for hash collision .. we needn't check
                    // the vertex format, it *must* match due to the
                    // (brilliant) construction of the hash
                    if (orig->mNumBones       != inst->mNumBones      ||
                        orig->mNumFaces       != inst->mNumFaces      ||
                        orig->mNumVertices    != inst->mNumVertices   ||
                        orig->mMaterialIndex  != inst->mMaterialIndex ||
                        orig->mPrimitiveTypes != inst->mPrimitiveTypes)
                        continue;

                    // up to now the meshes are equal. Now compare vertex positions, normals,
                    // tangents and bitangents using this epsilon.
                    if (orig->HasPositions()) {
                        if(!CompareArrays(orig->mVertices,inst->mVertices,orig->mNumVertices,epsilon))
                            continue;
                    }
                    if (orig->HasNormals()) {
                        if(!CompareArrays(orig->mNormals,inst->mNormals,orig->mNumVertices,epsilon))
                            continue;
                    }
                    if (orig->HasTangentsAndBitangents()) {
                        if (!CompareArrays(orig->mTangents,inst->mTangents,orig->mNumVertices,epsilon) ||
                            !CompareArrays(orig->mBitangents,inst->mBitangents,orig->mNumVertices,epsilon))
                            continue;
                    }