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253 lines
8.3 KiB
C++
253 lines
8.3 KiB
C++
// NeL - MMORPG Framework <http://dev.ryzom.com/projects/nel/>
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// Copyright (C) 2010 Winch Gate Property Limited
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//
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// This program is free software: you can redistribute it and/or modify
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// it under the terms of the GNU Affero General Public License as
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// published by the Free Software Foundation, either version 3 of the
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// License, or (at your option) any later version.
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//
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// This program is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU Affero General Public License for more details.
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//
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// You should have received a copy of the GNU Affero General Public License
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// along with this program. If not, see <http://www.gnu.org/licenses/>.
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#include "std3d.h"
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#include "nel/3d/tangent_space_build.h"
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#include "nel/3d/index_buffer.h"
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#include "nel/3d/vertex_buffer.h"
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#include "nel/misc/triangle.h"
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namespace NL3D
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{
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//========================================================================================================================
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/** private func : duplicate a mesh build
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* It returns the index of the new texture coordinate or 0 if the conversion couldn't occur..
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*/
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static uint DuplicateMBAndAddTexCoord(CMesh::CMeshBuild &outMeshBuild, const CMesh::CMeshBuild &inMeshBuild)
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{
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outMeshBuild = inMeshBuild;
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uint numTexCoord = 0;
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for (uint k = CVertexBuffer::FirstTexCoordValue; k <= CVertexBuffer::FirstTexCoordValue; ++k)
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{
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if (inMeshBuild.VertexFlags & (1 << k)) numTexCoord = 1 + k - CVertexBuffer::FirstTexCoordValue;
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}
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if (numTexCoord == CVertexBuffer::MaxStage) return 0;
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outMeshBuild.VertexFlags = inMeshBuild.VertexFlags | (1 << (numTexCoord + CVertexBuffer::FirstTexCoordValue));
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outMeshBuild.NumCoords[numTexCoord] = 3;
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return numTexCoord;
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}
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//========== Build one tangent space vector ==================
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static void BuildTGSpaceVect(const NLMISC::CVector &normal, const NLMISC::CVector &sGrad, NLMISC::CUVW &result)
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{
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// start normalizing the basis
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NLMISC::CVector res = (sGrad - ((sGrad * normal) * normal)).normed();
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result.U = res.x;
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result.V = res.y;
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result.W = res.z;
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}
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//========== build one tri from a vb and 3 index in it=================
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static void BuildTriFromMB(const CMesh::CMeshBuild &mb, const uint index[3], NLMISC::CTriangle &tri)
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{
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tri.V0 = mb.Vertices[index[0]];
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tri.V1 = mb.Vertices[index[1]];
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tri.V2 = mb.Vertices[index[2]];
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}
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//========================================================================================================================
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bool BuildTangentSpace(CMesh::CMeshBuild &outMeshBuild, const CMesh::CMeshBuild &inMeshBuild)
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{
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static const NLMISC::CUVW NullUVW(0, 0, 0); // todo add this directly in the CUVW class (for next compile ...)
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/// for each face, we must use a previously computed tangent space vector if other vertex datas are similar
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nlassert(&outMeshBuild != &inMeshBuild);
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uint tgSpaceStage = DuplicateMBAndAddTexCoord(outMeshBuild, inMeshBuild); // format the resulting vb
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if (tgSpaceStage == 0) return false; // unable to create the vb
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uint l, m, n, k; // some loop counters
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// Tells for each vertex what faces belong to it
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std::vector<std::vector<uint> > VertToFace(inMeshBuild.Vertices.size());
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// fill VertToFace
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for (l = 0; l < inMeshBuild.Faces.size(); ++l)
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{
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for (m = 0; m < 3; ++m)
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{
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outMeshBuild.Faces[l].Corner[m].Uvws[tgSpaceStage] = NLMISC::CUVW(0, 0, 0);
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VertToFace[outMeshBuild.Faces[l].Corner[m].Vertex].push_back(l);
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}
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}
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/* TODO: debug this version
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std::vector<NLMISC::CVector> SGradArray(outMeshBuild.Faces.size()); // SGradient for each face
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// compute sGradient for each face
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for (k = 0; k < outMeshBuild.Faces.size(); ++k)
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{
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CMesh::CFace &f = outMeshBuild.Faces[k];
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NLMISC::CTriangle tri;
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tri.V0 = outMeshBuild.Vertices[f.Corner[0].Vertex];
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tri.V1 = outMeshBuild.Vertices[f.Corner[1].Vertex];
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tri.V2 = outMeshBuild.Vertices[f.Corner[2].Vertex];
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tri.computeGradient(f.Corner[0].Uvws[0].U,
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f.Corner[1].Uvws[0].U,
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f.Corner[2].Uvws[0].U, SGradArray[k]);
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SGradArray[k].normalize();
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}
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// 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
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for (k = 0; k < outMeshBuild.Faces.size(); ++k)
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{
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CMesh::CFace &f = outMeshBuild.Faces[k];
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for (l = 0; l < 3; ++l)
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{
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const std::vector<uint> &neighbours = VertToFace[f.Corner[l].Vertex];
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for (m = 0; m < neighbours.size(); ++m)
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{
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// other face must share smoothgroups with this one
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if (f.SmoothGroup & outMeshBuild.Faces[neighbours[m]].SmoothGroup)
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{
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// test if the other face UVs are not mirroring the current ones..
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float dp = SGradArray[k] * SGradArray[neighbours[m]];
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if (dp > 0.f)
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{
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f.Corner[l].Uvws[tgSpaceStage] += NLMISC::CUVW(SGradArray[neighbours[m]].x, SGradArray[neighbours[m]].y, SGradArray[neighbours[m]].z);
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}
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}
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}
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}
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}
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// normalize each tangent space vector
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for (k = 0; k < outMeshBuild.Faces.size(); ++k)
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{
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CMesh::CFace &f = outMeshBuild.Faces[k];
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for (l = 0; l < 3; ++l)
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{
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CMesh::CCorner &c = f.Corner[l];
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CVector tgs(c.Uvws[tgSpaceStage].U, c.Uvws[tgSpaceStage].V, c.Uvws[tgSpaceStage].W);
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tgs = (tgs - (tgs * c.Normal) * c.Normal).normed();
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c.Uvws[tgSpaceStage].U = tgs.x;
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c.Uvws[tgSpaceStage].V = tgs.y;
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c.Uvws[tgSpaceStage].W = tgs.z;
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}
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}
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*/
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// Old tangent space version (no support for mirrored textures ..)
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for (l = 0; l < inMeshBuild.Faces.size(); ++l)
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{
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CMesh::CFace &curF = outMeshBuild.Faces[l];
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// Build each tangent space vector if needed
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for (m = 0; m < 3; ++m)
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{
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uint vertIndex = outMeshBuild.Faces[l].Corner[m].Vertex;
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bool found = false;
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NLMISC::CUVW *tsv=0; // a previously computed tangent space vector
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// Test whether it hasn't been built before, by looking in each corner of each face that share that vertex
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for (n = 0; n < VertToFace[vertIndex].size() && !found; ++n)
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{
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CMesh::CFace &f = outMeshBuild.Faces[VertToFace[vertIndex][n]]; // ref to the current face
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for (k = 0; k < 3; ++k)
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{
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// can only share with corners that are equal to this one
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if (f.Corner[k].Vertex == curF.Corner[m].Vertex) // same position
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{
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if (f.Corner[k].Uvws[tgSpaceStage] != NullUVW) // must have built the tangent space vector previously.
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{
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if (f.Corner[k].Normal == curF.Corner[m].Normal
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&& f.Corner[k].Uvws[0] == curF.Corner[m].Uvws[0]
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)
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{
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// no texture and normal discontinuity
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found = true;
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tsv = &f.Corner[k].Uvws[tgSpaceStage];
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}
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}
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}
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}
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}
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if (!found)
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{
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NLMISC::CVector grad(0, 0, 0);
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// walk all the triangles around this vertex to sum the gradients
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// Get the s coordinate gradient over that triangle
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for (n = 0; n < VertToFace[vertIndex].size(); ++n)
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{
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CMesh::CFace &f = outMeshBuild.Faces[VertToFace[vertIndex][n]]; // ref to the current face
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// before to sum this face gradient, make sure there's no normal or mapping discontinuity
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bool canShare = true;
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for (k = 0; k < 3; ++k)
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{
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// can only share with corners that are equal to this one
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if (f.Corner[k].Vertex == curF.Corner[m].Vertex) // same position
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{
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if (!(f.Corner[k].Normal == curF.Corner[m].Normal
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&& f.Corner[k].Uvws[0] == curF.Corner[m].Uvws[0]
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)
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)
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{
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canShare = false;
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break;
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}
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}
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}
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if (!canShare) continue;
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// Get indices of vertices of current tri
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const uint indices[] = { (uint)f.Corner[0].Vertex,
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(uint)f.Corner[1].Vertex,
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(uint)f.Corner[2].Vertex };
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NLMISC::CTriangle tri;
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// Build it
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BuildTriFromMB(outMeshBuild, indices, tri);
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// Get s coordinates for each corner
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float s[3];
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for (k = 0; k < 3; ++k)
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{
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s[k] = f.Corner[k].Uvws[0].U;
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}
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NLMISC::CVector sGrad;
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tri.computeGradient(s[0], s[1], s[2], sGrad);
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grad += ((tri.V1 - tri.V0) ^ (tri.V2 - tri.V0)).norm() * sGrad; // ponderate by twice the area
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}
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grad.normalize();
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// build new tangent space vector
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BuildTGSpaceVect(inMeshBuild.Faces[l].Corner[m].Normal, grad, curF.Corner[m].Uvws[tgSpaceStage]);
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}
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else
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{
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// use previously built vector
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curF.Corner[m].Uvws[tgSpaceStage] = *tsv;
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}
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}
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}
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return true;
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}
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}
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