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Diffstat (limited to 'intern/mikktspace/mikktspace.hh')
| -rw-r--r-- | intern/mikktspace/mikktspace.hh | 823 |
1 files changed, 823 insertions, 0 deletions
diff --git a/intern/mikktspace/mikktspace.hh b/intern/mikktspace/mikktspace.hh new file mode 100644 index 00000000000..4b45fa86e14 --- /dev/null +++ b/intern/mikktspace/mikktspace.hh @@ -0,0 +1,823 @@ +/* SPDX-License-Identifier: Apache-2.0 + * + * Original C code: + * Copyright 2011 by Morten S. Mikkelsen. + * + * C++ rewrite: + * Copyright 2022 Blender Foundation. All rights reserved. + */ + +/** \file + * \ingroup mikktspace + */ + +#include <algorithm> +#include <cassert> + +#ifdef WITH_TBB +# include <tbb/parallel_for.h> +#endif + +#include "mikk_atomic_hash_set.hh" +#include "mikk_float3.hh" +#include "mikk_util.hh" + +namespace mikk { + +static constexpr uint UNSET_ENTRY = 0xffffffffu; + +template<typename Mesh> class Mikktspace { + struct Triangle { + /* Stores neighboring triangle for group assignment. */ + std::array<uint, 3> neighbor; + /* Stores assigned group of each vertex. */ + std::array<uint, 3> group; + /* Stores vertex indices that make up the triangle. */ + std::array<uint, 3> vertices; + + /* Computed face tangent, will be accumulated into group. */ + float3 tangent; + + /* Index of the face that this triangle belongs to. */ + uint faceIdx; + /* Index of the first of this triangle's vertices' TSpaces. */ + uint tSpaceIdx; + + /* Stores mapping from this triangle's vertices to the original + * face's vertices (relevant for quads). */ + std::array<uint8_t, 3> faceVertex; + + // flags + bool markDegenerate : 1; + bool quadOneDegenTri : 1; + bool groupWithAny : 1; + bool orientPreserving : 1; + + Triangle(uint faceIdx_, uint tSpaceIdx_) + : tangent{0.0f}, + faceIdx{faceIdx_}, + tSpaceIdx{tSpaceIdx_}, + markDegenerate{false}, + quadOneDegenTri{false}, + groupWithAny{true}, + orientPreserving{false} + { + neighbor.fill(UNSET_ENTRY); + group.fill(UNSET_ENTRY); + } + + void setVertices(uint8_t i0, uint8_t i1, uint8_t i2) + { + faceVertex[0] = i0; + faceVertex[1] = i1; + faceVertex[2] = i2; + vertices[0] = pack_index(faceIdx, i0); + vertices[1] = pack_index(faceIdx, i1); + vertices[2] = pack_index(faceIdx, i2); + } + }; + + struct Group { + float3 tangent; + uint vertexRepresentative; + bool orientPreserving; + + Group(uint vertexRepresentative_, bool orientPreserving_) + : tangent{0.0f}, + vertexRepresentative{vertexRepresentative_}, + orientPreserving{orientPreserving_} + { + } + + void normalizeTSpace() + { + tangent = tangent.normalize(); + } + + void accumulateTSpaceAtomic(float3 v_tangent) + { + float_add_atomic(&tangent.x, v_tangent.x); + float_add_atomic(&tangent.y, v_tangent.y); + float_add_atomic(&tangent.z, v_tangent.z); + } + + void accumulateTSpace(float3 v_tangent) + { + tangent += v_tangent; + } + }; + + struct TSpace { + float3 tangent = float3(1.0f, 0.0f, 0.0f); + uint counter = 0; + bool orientPreserving = false; + + void accumulateGroup(const Group &group) + { + assert(counter < 2); + + if (counter == 0) { + tangent = group.tangent; + } + else if (tangent == group.tangent) { + // this if is important. Due to floating point precision + // averaging when ts0==ts1 will cause a slight difference + // which results in tangent space splits later on, so do nothing + } + else { + tangent = (tangent + group.tangent).normalize(); + } + + counter++; + orientPreserving = group.orientPreserving; + } + }; + + Mesh &mesh; + + std::vector<Triangle> triangles; + std::vector<TSpace> tSpaces; + std::vector<Group> groups; + + uint nrTSpaces, nrFaces, nrTriangles, totalTriangles; + + int nrThreads; + bool isParallel; + + public: + Mikktspace(Mesh &mesh_) : mesh(mesh_) + { + } + + void genTangSpace() + { + nrFaces = (uint)mesh.GetNumFaces(); + +#ifdef WITH_TBB + nrThreads = tbb::this_task_arena::max_concurrency(); + isParallel = (nrThreads > 1) && (nrFaces > 10000); +#else + nrThreads = 1; + isParallel = false; +#endif + + // make an initial triangle --> face index list + generateInitialVerticesIndexList(); + + if (nrTriangles == 0) { + return; + } + + // make a welded index list of identical positions and attributes (pos, norm, texc) + generateSharedVerticesIndexList(); + + // mark all triangle pairs that belong to a quad with only one + // good triangle. These need special treatment in degenEpilogue(). + // Additionally, move all good triangles to the start of + // triangles[] without changing order and + // put the degenerate triangles last. + degenPrologue(); + + // evaluate triangle level attributes and neighbor list + initTriangle(); + + // match up edge pairs + buildNeighbors(); + + // based on the 4 rules, identify groups based on connectivity + build4RuleGroups(); + + // make tspaces, each group is split up into subgroups. + // Finally a tangent space is made for every resulting subgroup + generateTSpaces(); + + // degenerate quads with one good triangle will be fixed by copying a space from + // the good triangle to the coinciding vertex. + // all other degenerate triangles will just copy a space from any good triangle + // with the same welded index in vertices[]. + degenEpilogue(); + + uint index = 0; + for (uint f = 0; f < nrFaces; f++) { + const uint verts = mesh.GetNumVerticesOfFace(f); + if (verts != 3 && verts != 4) { + continue; + } + + // set data + for (uint i = 0; i < verts; i++) { + const TSpace &tSpace = tSpaces[index++]; + mesh.SetTangentSpace(f, i, tSpace.tangent, tSpace.orientPreserving); + } + } + } + + protected: + template<typename F> void runParallel(uint start, uint end, F func) + { +#ifdef WITH_TBB + if (isParallel) { + tbb::parallel_for(start, end, func); + } + else +#endif + { + for (uint i = start; i < end; i++) { + func(i); + } + } + } + + /////////////////////////////////////////////////////////////////////////////////////////////////// + /////////////////////////////////////////////////////////////////////////////////////////////////// + + float3 getPosition(uint vertexID) + { + uint f, v; + unpack_index(f, v, vertexID); + return mesh.GetPosition(f, v); + } + + float3 getNormal(uint vertexID) + { + uint f, v; + unpack_index(f, v, vertexID); + return mesh.GetNormal(f, v); + } + + float3 getTexCoord(uint vertexID) + { + uint f, v; + unpack_index(f, v, vertexID); + return mesh.GetTexCoord(f, v); + } + + /////////////////////////////////////////////////////////////////////////////////////////////////// + /////////////////////////////////////////////////////////////////////////////////////////////////// + + void generateInitialVerticesIndexList() + { + nrTriangles = 0; + for (uint f = 0; f < nrFaces; f++) { + const uint verts = mesh.GetNumVerticesOfFace(f); + if (verts == 3) { + nrTriangles += 1; + } + else if (verts == 4) { + nrTriangles += 2; + } + } + + triangles.reserve(nrTriangles); + + nrTSpaces = 0; + for (uint f = 0; f < nrFaces; f++) { + const uint verts = mesh.GetNumVerticesOfFace(f); + if (verts != 3 && verts != 4) + continue; + + uint tA = (uint)triangles.size(); + triangles.emplace_back(f, nrTSpaces); + Triangle &triA = triangles[tA]; + + if (verts == 3) { + triA.setVertices(0, 1, 2); + } + else { + uint tB = (uint)triangles.size(); + triangles.emplace_back(f, nrTSpaces); + Triangle &triB = triangles[tB]; + + // need an order independent way to evaluate + // tspace on quads. This is done by splitting + // along the shortest diagonal. + float distSQ_02 = (mesh.GetTexCoord(f, 2) - mesh.GetTexCoord(f, 0)).length_squared(); + float distSQ_13 = (mesh.GetTexCoord(f, 3) - mesh.GetTexCoord(f, 1)).length_squared(); + bool quadDiagIs_02; + if (distSQ_02 != distSQ_13) + quadDiagIs_02 = (distSQ_02 < distSQ_13); + else { + distSQ_02 = (mesh.GetPosition(f, 2) - mesh.GetPosition(f, 0)).length_squared(); + distSQ_13 = (mesh.GetPosition(f, 3) - mesh.GetPosition(f, 1)).length_squared(); + quadDiagIs_02 = !(distSQ_13 < distSQ_02); + } + + if (quadDiagIs_02) { + triA.setVertices(0, 1, 2); + triB.setVertices(0, 2, 3); + } + else { + triA.setVertices(0, 1, 3); + triB.setVertices(1, 2, 3); + } + } + + nrTSpaces += verts; + } + } + + struct VertexHash { + Mikktspace<Mesh> *mikk; + inline uint operator()(const uint &k) const + { + return hash_float3x3(mikk->getPosition(k), mikk->getNormal(k), mikk->getTexCoord(k)); + } + }; + + struct VertexEqual { + Mikktspace<Mesh> *mikk; + inline bool operator()(const uint &kA, const uint &kB) const + { + return mikk->getTexCoord(kA) == mikk->getTexCoord(kB) && + mikk->getNormal(kA) == mikk->getNormal(kB) && + mikk->getPosition(kA) == mikk->getPosition(kB); + } + }; + + /* Merge identical vertices. + * To find vertices with identical position, normal and texcoord, we calculate a hash of the 9 + * values. Then, by sorting based on that hash, identical elements (having identical hashes) will + * be moved next to each other. Since there might be hash collisions, the elements of each block + * are then compared with each other and duplicates are merged. + */ + template<bool isAtomic> void generateSharedVerticesIndexList_impl() + { + uint numVertices = nrTriangles * 3; + AtomicHashSet<uint, isAtomic, VertexHash, VertexEqual> set(numVertices, {this}, {this}); + runParallel(0u, nrTriangles, [&](uint t) { + for (uint i = 0; i < 3; i++) { + auto res = set.emplace(triangles[t].vertices[i]); + if (!res.second) { + triangles[t].vertices[i] = res.first; + } + } + }); + } + void generateSharedVerticesIndexList() + { + if (isParallel) { + generateSharedVerticesIndexList_impl<true>(); + } + else { + generateSharedVerticesIndexList_impl<false>(); + } + } + + ///////////////////////////////////////////////////////////////////////////////////////////// + /////////////////////////////////// Degenerate triangles //////////////////////////////////// + + void degenPrologue() + { + // Mark all degenerate triangles + totalTriangles = nrTriangles; + std::atomic<uint> degenTriangles(0); + runParallel(0u, totalTriangles, [&](uint t) { + const float3 p0 = getPosition(triangles[t].vertices[0]); + const float3 p1 = getPosition(triangles[t].vertices[1]); + const float3 p2 = getPosition(triangles[t].vertices[2]); + if (p0 == p1 || p0 == p2 || p1 == p2) // degenerate + { + triangles[t].markDegenerate = true; + degenTriangles.fetch_add(1); + } + }); + nrTriangles -= degenTriangles.load(); + + if (totalTriangles == nrTriangles) { + return; + } + + // locate quads with only one good triangle + runParallel(0u, totalTriangles - 1, [&](uint t) { + Triangle &triangleA = triangles[t], &triangleB = triangles[t + 1]; + if (triangleA.faceIdx != triangleB.faceIdx) { + /* Individual triangle, skip. */ + return; + } + if (triangleA.markDegenerate != triangleB.markDegenerate) { + triangleA.quadOneDegenTri = true; + triangleB.quadOneDegenTri = true; + } + }); + + std::stable_partition(triangles.begin(), triangles.end(), [](const Triangle &tri) { + return tri.markDegenerate; + }); + } + + void degenEpilogue() + { + if (nrTriangles == totalTriangles) { + return; + } + + std::unordered_map<uint, uint> goodTriangleMap; + for (uint t = 0; t < nrTriangles; t++) { + for (uint i = 0; i < 3; i++) { + goodTriangleMap.emplace(triangles[t].vertices[i], pack_index(t, i)); + } + } + + // deal with degenerate triangles + // punishment for degenerate triangles is O(nrTriangles) extra memory. + for (uint t = nrTriangles; t < totalTriangles; t++) { + // degenerate triangles on a quad with one good triangle are skipped + // here but processed in the next loop + if (triangles[t].quadOneDegenTri) { + continue; + } + + for (uint i = 0; i < 3; i++) { + const auto entry = goodTriangleMap.find(triangles[t].vertices[i]); + if (entry == goodTriangleMap.end()) { + // Matching vertex from good triangle is not found. + continue; + } + + uint tSrc, iSrc; + unpack_index(tSrc, iSrc, entry->second); + const uint iSrcVert = triangles[tSrc].faceVertex[iSrc]; + const uint iSrcOffs = triangles[tSrc].tSpaceIdx; + const uint iDstVert = triangles[t].faceVertex[i]; + const uint iDstOffs = triangles[t].tSpaceIdx; + // copy tspace + tSpaces[iDstOffs + iDstVert] = tSpaces[iSrcOffs + iSrcVert]; + } + } + + // deal with degenerate quads with one good triangle + for (uint t = 0; t < nrTriangles; t++) { + // this triangle belongs to a quad where the + // other triangle is degenerate + if (!triangles[t].quadOneDegenTri) { + continue; + } + uint vertFlag = (1u << triangles[t].faceVertex[0]) | (1u << triangles[t].faceVertex[1]) | + (1u << triangles[t].faceVertex[2]); + uint missingFaceVertex = 0; + if ((vertFlag & 2) == 0) + missingFaceVertex = 1; + else if ((vertFlag & 4) == 0) + missingFaceVertex = 2; + else if ((vertFlag & 8) == 0) + missingFaceVertex = 3; + + uint faceIdx = triangles[t].faceIdx; + float3 dstP = mesh.GetPosition(faceIdx, missingFaceVertex); + bool found = false; + for (uint i = 0; i < 3; i++) { + const uint faceVertex = triangles[t].faceVertex[i]; + const float3 srcP = mesh.GetPosition(faceIdx, faceVertex); + if (srcP == dstP) { + const uint offset = triangles[t].tSpaceIdx; + tSpaces[offset + missingFaceVertex] = tSpaces[offset + faceVertex]; + found = true; + break; + } + } + assert(found); + (void)found; + } + } + + /////////////////////////////////////////////////////////////////////////////////////////////////// + /////////////////////////////////////////////////////////////////////////////////////////////////// + + // returns the texture area times 2 + float calcTexArea(uint tri) + { + const float3 t1 = getTexCoord(triangles[tri].vertices[0]); + const float3 t2 = getTexCoord(triangles[tri].vertices[1]); + const float3 t3 = getTexCoord(triangles[tri].vertices[2]); + + const float t21x = t2.x - t1.x; + const float t21y = t2.y - t1.y; + const float t31x = t3.x - t1.x; + const float t31y = t3.y - t1.y; + + const float signedAreaSTx2 = t21x * t31y - t21y * t31x; + return fabsf(signedAreaSTx2); + } + + void initTriangle() + { + // triangles[f].iFlag is cleared in generateInitialVerticesIndexList() + // which is called before this function. + + // evaluate first order derivatives + runParallel(0u, nrTriangles, [&](uint t) { + Triangle &triangle = triangles[t]; + + // initial values + const float3 v1 = getPosition(triangle.vertices[0]); + const float3 v2 = getPosition(triangle.vertices[1]); + const float3 v3 = getPosition(triangle.vertices[2]); + const float3 t1 = getTexCoord(triangle.vertices[0]); + const float3 t2 = getTexCoord(triangle.vertices[1]); + const float3 t3 = getTexCoord(triangle.vertices[2]); + + const float t21x = t2.x - t1.x; + const float t21y = t2.y - t1.y; + const float t31x = t3.x - t1.x; + const float t31y = t3.y - t1.y; + const float3 d1 = v2 - v1, d2 = v3 - v1; + + const float signedAreaSTx2 = t21x * t31y - t21y * t31x; + const float3 vOs = (t31y * d1) - (t21y * d2); // eq 18 + const float3 vOt = (-t31x * d1) + (t21x * d2); // eq 19 + + triangle.orientPreserving = (signedAreaSTx2 > 0); + + if (not_zero(signedAreaSTx2)) { + const float lenOs2 = vOs.length_squared(); + const float lenOt2 = vOt.length_squared(); + const float fS = triangle.orientPreserving ? 1.0f : (-1.0f); + if (not_zero(lenOs2)) + triangle.tangent = vOs * (fS / sqrtf(lenOs2)); + + // if this is a good triangle + if (not_zero(lenOs2) && not_zero(lenOt2)) + triangle.groupWithAny = false; + } + }); + + // force otherwise healthy quads to a fixed orientation + runParallel(0u, nrTriangles - 1, [&](uint t) { + Triangle &triangleA = triangles[t], &triangleB = triangles[t + 1]; + if (triangleA.faceIdx != triangleB.faceIdx) { + // this is not a quad + return; + } + + // bad triangles should already have been removed by + // degenPrologue(), but just in case check that neither are degenerate + if (!(triangleA.markDegenerate || triangleB.markDegenerate)) { + // if this happens the quad has extremely bad mapping!! + if (triangleA.orientPreserving != triangleB.orientPreserving) { + bool chooseOrientFirstTri = false; + if (triangleB.groupWithAny) + chooseOrientFirstTri = true; + else if (calcTexArea(t) >= calcTexArea(t + 1)) + chooseOrientFirstTri = true; + + // force match + const uint t0 = chooseOrientFirstTri ? t : (t + 1); + const uint t1 = chooseOrientFirstTri ? (t + 1) : t; + triangles[t1].orientPreserving = triangles[t0].orientPreserving; + } + } + }); + } + + ///////////////////////////////////////////////////////////////////////////////////////////// + /////////////////////////////////////////// Edges /////////////////////////////////////////// + + struct NeighborShard { + struct Entry { + Entry(uint32_t key_, uint data_) : key(key_), data(data_) + { + } + uint key, data; + }; + std::vector<Entry> entries; + + NeighborShard(size_t capacity) + { + entries.reserve(capacity); + } + + void buildNeighbors(Mikktspace<Mesh> *mikk) + { + /* Entries are added by iterating over t, so by using a stable sort, + * we don't have to compare based on t as well. */ + { + std::vector<Entry> tempEntries(entries.size(), {0, 0}); + radixsort(entries, tempEntries, [](const Entry &e) { return e.key; }); + } + + for (uint i = 0; i < entries.size(); i++) { + const Entry &a = entries[i]; + uint tA, iA; + unpack_index(tA, iA, a.data); + Mikktspace<Mesh>::Triangle &triA = mikk->triangles[tA]; + + if (triA.neighbor[iA] != UNSET_ENTRY) { + continue; + } + + uint i0A = triA.vertices[iA], i1A = triA.vertices[(iA != 2) ? (iA + 1) : 0]; + for (uint j = i + 1; j < entries.size(); j++) { + const Entry &b = entries[j]; + uint tB, iB; + unpack_index(tB, iB, b.data); + Mikktspace<Mesh>::Triangle &triB = mikk->triangles[tB]; + + if (b.key != a.key) + break; + + if (triB.neighbor[iB] != UNSET_ENTRY) { + continue; + } + + uint i1B = triB.vertices[iB], i0B = triB.vertices[(iB != 2) ? (iB + 1) : 0]; + if (i0A == i0B && i1A == i1B) { + triA.neighbor[iA] = tB; + triB.neighbor[iB] = tA; + break; + } + } + } + } + }; + + void buildNeighbors() + { + /* In order to parallelize the processing, we divide the vertices into shards. + * Since only vertex pairs with the same key will be checked, we can process + * shards independently as long as we ensure that all vertices with the same + * key go into the same shard. + * This is done by hashing the key to get the shard index of each vertex. + */ + // TODO: Two-step filling that first counts and then fills? Could be parallel then. + uint targetNrShards = isParallel ? uint(4 * nrThreads) : 1; + uint nrShards = 1, hashShift = 32; + while (nrShards < targetNrShards) { + nrShards *= 2; + hashShift -= 1; + } + + /* Reserve 25% extra to account for variation due to hashing. */ + size_t reserveSize = size_t(double(3 * nrTriangles) * 1.25 / nrShards); + std::vector<NeighborShard> shards(nrShards, {reserveSize}); + + for (uint t = 0; t < nrTriangles; t++) { + Triangle &triangle = triangles[t]; + for (uint i = 0; i < 3; i++) { + const uint i0 = triangle.vertices[i]; + const uint i1 = triangle.vertices[(i != 2) ? (i + 1) : 0]; + const uint high = std::max(i0, i1), low = std::min(i0, i1); + const uint hash = hash_uint3(high, low, 0); + /* TODO: Reusing the hash here means less hash space inside each shard. + * Computing a second hash with a different seed it probably not worth it? */ + const uint shard = isParallel ? (hash >> hashShift) : 0; + shards[shard].entries.emplace_back(hash, pack_index(t, i)); + } + } + + runParallel(0u, nrShards, [&](uint s) { shards[s].buildNeighbors(this); }); + } + + /////////////////////////////////////////////////////////////////////////////////////////////////// + /////////////////////////////////////////////////////////////////////////////////////////////////// + + void assignRecur(const uint t, uint groupId) + { + if (t == UNSET_ENTRY) { + return; + } + + Triangle &triangle = triangles[t]; + Group &group = groups[groupId]; + + // track down vertex + const uint vertRep = group.vertexRepresentative; + uint i = 3; + if (triangle.vertices[0] == vertRep) + i = 0; + else if (triangle.vertices[1] == vertRep) + i = 1; + else if (triangle.vertices[2] == vertRep) + i = 2; + assert(i < 3); + + // early out + if (triangle.group[i] != UNSET_ENTRY) + return; + + if (triangle.groupWithAny) { + // first to group with a group-with-anything triangle + // determines its orientation. + // This is the only existing order dependency in the code!! + if (triangle.group[0] == UNSET_ENTRY && triangle.group[1] == UNSET_ENTRY && + triangle.group[2] == UNSET_ENTRY) { + triangle.orientPreserving = group.orientPreserving; + } + } + + if (triangle.orientPreserving != group.orientPreserving) + return; + + triangle.group[i] = groupId; + + const uint t_L = triangle.neighbor[i]; + const uint t_R = triangle.neighbor[i > 0 ? (i - 1) : 2]; + assignRecur(t_L, groupId); + assignRecur(t_R, groupId); + } + + void build4RuleGroups() + { + /* Note: This could be parallelized by grouping all [t, i] pairs into + * shards by hash(triangles[t].vertices[i]). This way, each shard can be processed + * independently and in parallel. + * However, the groupWithAny logic needs special handling (e.g. lock a mutex when + * encountering a groupWithAny triangle, then sort it out, then unlock and proceed). + */ + for (uint t = 0; t < nrTriangles; t++) { + Triangle &triangle = triangles[t]; + for (uint i = 0; i < 3; i++) { + // if not assigned to a group + if (triangle.groupWithAny || triangle.group[i] != UNSET_ENTRY) { + continue; + } + + const uint newGroupId = (uint)groups.size(); + triangle.group[i] = newGroupId; + + groups.emplace_back(triangle.vertices[i], bool(triangle.orientPreserving)); + + const uint t_L = triangle.neighbor[i]; + const uint t_R = triangle.neighbor[i > 0 ? (i - 1) : 2]; + assignRecur(t_L, newGroupId); + assignRecur(t_R, newGroupId); + } + } + } + + /////////////////////////////////////////////////////////////////////////////////////////////////// + /////////////////////////////////////////////////////////////////////////////////////////////////// + + template<bool atomic> void accumulateTSpaces(uint t) + { + const Triangle &triangle = triangles[t]; + // only valid triangles get to add their contribution + if (triangle.groupWithAny) { + return; + } + + /* Todo: Vectorize? + * Also: Could add special case for flat shading, when all normals are equal half of the fCos + * projections and two of the three tangent projections are unnecessary. */ + std::array<float3, 3> n, p; + for (uint i = 0; i < 3; i++) { + n[i] = getNormal(triangle.vertices[i]); + p[i] = getPosition(triangle.vertices[i]); + } + + std::array<float, 3> fCos = {dot(project(n[0], p[1] - p[0]), project(n[0], p[2] - p[0])), + dot(project(n[1], p[2] - p[1]), project(n[1], p[0] - p[1])), + dot(project(n[2], p[0] - p[2]), project(n[2], p[1] - p[2]))}; + + for (uint i = 0; i < 3; i++) { + uint groupId = triangle.group[i]; + if (groupId != UNSET_ENTRY) { + float3 tangent = project(n[i], triangle.tangent) * + fast_acosf(std::clamp(fCos[i], -1.0f, 1.0f)); + if constexpr (atomic) { + groups[groupId].accumulateTSpaceAtomic(tangent); + } + else { + groups[groupId].accumulateTSpace(tangent); + } + } + } + } + + void generateTSpaces() + { + if (isParallel) { + runParallel(0u, nrTriangles, [&](uint t) { accumulateTSpaces<true>(t); }); + } + else { + for (uint t = 0; t < nrTriangles; t++) { + accumulateTSpaces<false>(t); + } + } + + /* TODO: Worth parallelizing? Probably not. */ + for (Group &group : groups) { + group.normalizeTSpace(); + } + + tSpaces.resize(nrTSpaces); + + for (uint t = 0; t < nrTriangles; t++) { + Triangle &triangle = triangles[t]; + for (uint i = 0; i < 3; i++) { + uint groupId = triangle.group[i]; + if (groupId == UNSET_ENTRY) { + continue; + } + const Group group = groups[groupId]; + assert(triangle.orientPreserving == group.orientPreserving); + + // output tspace + const uint offset = triangle.tSpaceIdx; + const uint faceVertex = triangle.faceVertex[i]; + tSpaces[offset + faceVertex].accumulateGroup(group); + } + } + } +}; + +} // namespace mikk |