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Documentation                       Search   tangent_space_build.cpp Go to the documentation of this file. /* Copyright, 2000-2002 Nevrax Ltd. * * This file is part of NEVRAX NEL. * NEVRAX NEL is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation; either version 2, or (at your option) * any later version. * NEVRAX NEL is distributed in the hope that it will be useful, but * WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU * General Public License for more details. * You should have received a copy of the GNU General Public License * along with NEVRAX NEL; see the file COPYING. If not, write to the * Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, * MA 02111-1307, USA. */ #include "std3d.h" #include "3d/tangent_space_build.h" #include "3d/primitive_block.h" #include "3d/vertex_buffer.h" #include "nel/misc/triangle.h" namespace NL3D { //======================================================================================================================== static uint DuplicateMBAndAddTexCoord(CMesh::CMeshBuild &outMeshBuild, const CMesh::CMeshBuild &inMeshBuild) { outMeshBuild = inMeshBuild; uint numTexCoord = 0; for (uint k = CVertexBuffer::FirstTexCoordValue; k <= CVertexBuffer::FirstTexCoordValue; ++k) { if (inMeshBuild.VertexFlags & (1 << k)) numTexCoord = 1 + k - CVertexBuffer::FirstTexCoordValue; } if (numTexCoord == CVertexBuffer::MaxStage) return 0; outMeshBuild.VertexFlags = inMeshBuild.VertexFlags | (1 << (numTexCoord + CVertexBuffer::FirstTexCoordValue)); outMeshBuild.NumCoords[numTexCoord] = 3; return numTexCoord; } //========== Build one tangent space vector ================== static void BuildTGSpaceVect(const NLMISC::CVector &normal, const NLMISC::CVector &sGrad, NLMISC::CUVW &result) { // start normalizing the basis NLMISC::CVector res = (sGrad - ((sGrad * normal) * normal)).normed(); result.U = res.x; result.V = res.y; result.W = res.z; } //========== build one tri from a vb and 3 index in it================= static void BuildTriFromMB(const CMesh::CMeshBuild &mb, const uint index[3], NLMISC::CTriangle &tri) { tri.V0 = mb.Vertices[index[0]]; tri.V1 = mb.Vertices[index[1]]; tri.V2 = mb.Vertices[index[2]]; } //======================================================================================================================== bool BuildTangentSpace(CMesh::CMeshBuild &outMeshBuild, const CMesh::CMeshBuild &inMeshBuild) { static const NLMISC::CUVW NullUVW(0, 0, 0); // todo add this directly in the CUVW class (for next compile ...) nlassert(&outMeshBuild != &inMeshBuild); uint tgSpaceStage = DuplicateMBAndAddTexCoord(outMeshBuild, inMeshBuild); // format the resulting vb if (tgSpaceStage == 0) return false; // unable to create the vb uint l, m, n, k; // some loop counters // Tells for each vertex what faces belong to it std::vector<std::vector<uint> > VertToFace(inMeshBuild.Vertices.size()); // fill VertToFace for (l = 0; l < inMeshBuild.Faces.size(); ++l) { for (m = 0; m < 3; ++m) { outMeshBuild.Faces[l].Corner[m].Uvws[tgSpaceStage] = NLMISC::CUVW(0, 0, 0); VertToFace[outMeshBuild.Faces[l].Corner[m].Vertex].push_back(l); } } /* TODO: debug this version std::vector<NLMISC::CVector> SGradArray(outMeshBuild.Faces.size()); // SGradient for each face // compute sGradient for each face for (k = 0; k < outMeshBuild.Faces.size(); ++k) { CMesh::CFace &f = outMeshBuild.Faces[k]; NLMISC::CTriangle tri; tri.V0 = outMeshBuild.Vertices[f.Corner[0].Vertex]; tri.V1 = outMeshBuild.Vertices[f.Corner[1].Vertex]; tri.V2 = outMeshBuild.Vertices[f.Corner[2].Vertex]; tri.computeGradient(f.Corner[0].Uvws[0].U, f.Corner[1].Uvws[0].U, f.Corner[2].Uvws[0].U, SGradArray[k]); SGradArray[k].normalize(); } // for each triangle, add the S gradient contribution to any neighbour vertex for which the owning face has TexCoords that do not mirror with that face for (k = 0; k < outMeshBuild.Faces.size(); ++k) { CMesh::CFace &f = outMeshBuild.Faces[k]; for (l = 0; l < 3; ++l) { const std::vector<uint> &neighbours = VertToFace[f.Corner[l].Vertex]; for (m = 0; m < neighbours.size(); ++m) { // other face must share smoothgroups with this one if (f.SmoothGroup & outMeshBuild.Faces[neighbours[m]].SmoothGroup) { // test if the other face UVs are not mirroring the current ones.. float dp = SGradArray[k] * SGradArray[neighbours[m]]; if (dp > 0.f) { f.Corner[l].Uvws[tgSpaceStage] += NLMISC::CUVW(SGradArray[neighbours[m]].x, SGradArray[neighbours[m]].y, SGradArray[neighbours[m]].z); } } } } } // normalize each tangent space vector for (k = 0; k < outMeshBuild.Faces.size(); ++k) { CMesh::CFace &f = outMeshBuild.Faces[k]; for (l = 0; l < 3; ++l) { CMesh::CCorner &c = f.Corner[l]; CVector tgs(c.Uvws[tgSpaceStage].U, c.Uvws[tgSpaceStage].V, c.Uvws[tgSpaceStage].W); tgs = (tgs - (tgs * c.Normal) * c.Normal).normed(); c.Uvws[tgSpaceStage].U = tgs.x; c.Uvws[tgSpaceStage].V = tgs.y; c.Uvws[tgSpaceStage].W = tgs.z; } } */ // Old tangent space version (no support for mirrored textures ..) for (l = 0; l < inMeshBuild.Faces.size(); ++l) { CMesh::CFace &curF = outMeshBuild.Faces[l]; // Build each tangent space vector if needed for (m = 0; m < 3; ++m) { uint vertIndex = outMeshBuild.Faces[l].Corner[m].Vertex; bool found = false; NLMISC::CUVW *tsv=0; // a previously computed tangent space vector // Test wether it hasn't been built before, by looking in each corner of each face that share that vertex for (n = 0; n < VertToFace[vertIndex].size() && !found; ++n) { CMesh::CFace &f = outMeshBuild.Faces[VertToFace[vertIndex][n]]; // ref to the current face for (k = 0; k < 3; ++k) { // can only share with corners that are equal to this one if (f.Corner[k].Vertex == curF.Corner[m].Vertex) // same position { if (f.Corner[k].Uvws[tgSpaceStage] != NullUVW) // must have built the tangent space vector previously. { if (f.Corner[k].Normal == curF.Corner[m].Normal && f.Corner[k].Uvws[0] == curF.Corner[m].Uvws[0] ) { // no texture and normal discontinuity found = true; tsv = &f.Corner[k].Uvws[tgSpaceStage]; } } } } } if (!found) { NLMISC::CVector grad(0, 0, 0); // walk all the triangles around this vertex to sum the gradients // Get the s coordinate gradient over that triangle for (n = 0; n < VertToFace[vertIndex].size(); ++n) { CMesh::CFace &f = outMeshBuild.Faces[VertToFace[vertIndex][n]]; // ref to the current face // before to sum this face gradient, make sure there's no normal or mapping discontinuity bool canShare = true; for (k = 0; k < 3; ++k) { // can only share with corners that are equal to this one if (f.Corner[k].Vertex == curF.Corner[m].Vertex) // same position { if (!(f.Corner[k].Normal == curF.Corner[m].Normal && f.Corner[k].Uvws[0] == curF.Corner[m].Uvws[0] ) ) { canShare = false; break; } } } if (!canShare) continue; // Get indices of vertices of current tri const uint indices[] = { f.Corner[0].Vertex, f.Corner[1].Vertex, f.Corner[2].Vertex }; NLMISC::CTriangle tri; // Build it BuildTriFromMB(outMeshBuild, indices, tri); // Get s coordinates for each corner float s[3]; for (k = 0; k < 3; ++k) { s[k] = f.Corner[k].Uvws[0].U; } NLMISC::CVector sGrad; tri.computeGradient(s[0], s[1], s[2], sGrad); grad += ((tri.V1 - tri.V0) ^ (tri.V2 - tri.V0)).norm() * sGrad; // ponderate by twice the area } grad.normalize(); // build new tangent space vector BuildTGSpaceVect(inMeshBuild.Faces[l].Corner[m].Normal, grad, curF.Corner[m].Uvws[tgSpaceStage]); } else { // use previously built vector curF.Corner[m].Uvws[tgSpaceStage] = *tsv; } } } return true; } }