233 lines
9.2 KiB
C++
233 lines
9.2 KiB
C++
/*
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---------------------------------------------------------------------------
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Free Asset Import Library (ASSIMP)
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---------------------------------------------------------------------------
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Copyright (c) 2006-2008, ASSIMP Development Team
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All rights reserved.
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Redistribution and use of this software in source and binary forms,
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with or without modification, are permitted provided that the following
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conditions are met:
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* Redistributions of source code must retain the above
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copyright notice, this list of conditions and the
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following disclaimer.
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* Redistributions in binary form must reproduce the above
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copyright notice, this list of conditions and the
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following disclaimer in the documentation and/or other
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materials provided with the distribution.
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* Neither the name of the ASSIMP team, nor the names of its
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contributors may be used to endorse or promote products
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derived from this software without specific prior
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written permission of the ASSIMP Development Team.
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THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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---------------------------------------------------------------------------
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*/
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/** @file Implementation of the post processing step to calculate
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* tangents and bitangents for all imported meshes
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*/
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#include <vector>
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#include <assert.h>
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#include "DefaultLogger.h"
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#include "CalcTangentsProcess.h"
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#include "SpatialSort.h"
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#include "../include/aiPostProcess.h"
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#include "../include/aiMesh.h"
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#include "../include/aiScene.h"
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using namespace Assimp;
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// ------------------------------------------------------------------------------------------------
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// Constructor to be privately used by Importer
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CalcTangentsProcess::CalcTangentsProcess()
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{
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// nothing to do here
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}
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// ------------------------------------------------------------------------------------------------
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// Destructor, private as well
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CalcTangentsProcess::~CalcTangentsProcess()
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{
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// nothing to do here
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}
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// ------------------------------------------------------------------------------------------------
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// Returns whether the processing step is present in the given flag field.
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bool CalcTangentsProcess::IsActive( unsigned int pFlags) const
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{
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return (pFlags & aiProcess_CalcTangentSpace) != 0;
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}
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// ------------------------------------------------------------------------------------------------
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// Executes the post processing step on the given imported data.
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void CalcTangentsProcess::Execute( aiScene* pScene)
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{
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DefaultLogger::get()->debug("CalcTangentsProcess begin");
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for( unsigned int a = 0; a < pScene->mNumMeshes; a++)
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ProcessMesh( pScene->mMeshes[a]);
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DefaultLogger::get()->debug("CalcTangentsProcess finished");
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}
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// ------------------------------------------------------------------------------------------------
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// Calculates tangents and bitangents for the given mesh
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void CalcTangentsProcess::ProcessMesh( aiMesh* pMesh)
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{
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// we assume that the mesh is still in the verbose vertex format where each face has its own set
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// of vertices and no vertices are shared between faces. Sadly I don't know any quick test to
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// assert() it here.
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//assert( must be verbose, dammit);
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// what we can check, though, is if the mesh has normals and texture coord. That's a requirement
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if( pMesh->mNormals == NULL || pMesh->mTextureCoords[0] == NULL)
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return;
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// calculate the position bounds so we have a reliable epsilon to check position differences against
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aiVector3D minVec( 1e10f, 1e10f, 1e10f), maxVec( -1e10f, -1e10f, -1e10f);
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for( unsigned int a = 0; a < pMesh->mNumVertices; a++)
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{
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minVec.x = std::min( minVec.x, pMesh->mVertices[a].x);
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minVec.y = std::min( minVec.y, pMesh->mVertices[a].y);
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minVec.z = std::min( minVec.z, pMesh->mVertices[a].z);
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maxVec.x = std::max( maxVec.x, pMesh->mVertices[a].x);
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maxVec.y = std::max( maxVec.y, pMesh->mVertices[a].y);
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maxVec.z = std::max( maxVec.z, pMesh->mVertices[a].z);
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}
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// calculate epsilons border
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const float epsilon = 1e-5f;
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const float posEpsilon = (maxVec - minVec).Length() * epsilon;
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const float angleEpsilon = 0.9999f;
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// create space for the tangents and bitangents
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pMesh->mTangents = new aiVector3D[pMesh->mNumVertices];
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pMesh->mBitangents = new aiVector3D[pMesh->mNumVertices];
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const aiVector3D* meshPos = pMesh->mVertices;
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const aiVector3D* meshNorm = pMesh->mNormals;
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const aiVector3D* meshTex = pMesh->mTextureCoords[0];
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aiVector3D* meshTang = pMesh->mTangents;
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aiVector3D* meshBitang = pMesh->mBitangents;
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// calculate the tangent and bitangent for every face
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for( unsigned int a = 0; a < pMesh->mNumFaces; a++)
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{
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const aiFace& face = pMesh->mFaces[a];
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// triangle or polygon... we always use only the first three indices. A polygon
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// is supposed to be planar anyways....
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// FIXME: (thom) create correct calculation for multi-vertex polygons maybe?
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const unsigned int p0 = face.mIndices[0], p1 = face.mIndices[1], p2 = face.mIndices[2];
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// position differences p1->p2 and p1->p3
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aiVector3D v = meshPos[p1] - meshPos[p0], w = meshPos[p2] - meshPos[p0];
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// texture offset p1->p2 and p1->p3
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float sx = meshTex[p1].x - meshTex[p0].x, sy = meshTex[p1].y - meshTex[p0].y;
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float tx = meshTex[p2].x - meshTex[p0].x, ty = meshTex[p2].y - meshTex[p0].y;
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float dirCorrection = (tx * sy - ty * sx) < 0.0f ? -1.0f : 1.0f;
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// tangent points in the direction where to positive X axis of the texture coords would point in model space
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// bitangents points along the positive Y axis of the texture coords, respectively
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aiVector3D tangent, bitangent;
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tangent.x = (w.x * sy - v.x * ty) * dirCorrection;
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tangent.y = (w.y * sy - v.y * ty) * dirCorrection;
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tangent.z = (w.z * sy - v.z * ty) * dirCorrection;
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bitangent.x = (w.x * sx - v.x * tx) * dirCorrection;
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bitangent.y = (w.y * sx - v.y * tx) * dirCorrection;
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bitangent.z = (w.z * sx - v.z * tx) * dirCorrection;
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// store for every vertex of that face
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for( unsigned int b = 0; b < face.mNumIndices; b++)
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{
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unsigned int p = face.mIndices[b];
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// project tangent and bitangent into the plane formed by the vertex' normal
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aiVector3D localTangent = tangent - meshNorm[p] * (tangent * meshNorm[p]);
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aiVector3D localBitangent = bitangent - meshNorm[p] * (bitangent * meshNorm[p]);
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localTangent.Normalize(); localBitangent.Normalize();
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// and write it into the mesh.
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meshTang[p] = localTangent;
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meshBitang[p] = localBitangent;
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}
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}
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// create a helper to quickly find locally close vertices among the vertex array
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SpatialSort vertexFinder( meshPos, pMesh->mNumVertices, sizeof( aiVector3D));
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std::vector<unsigned int> verticesFound;
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// in the second pass we now smooth out all tangents and bitangents at the same local position
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// if they are not too far off.
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std::vector<bool> vertexDone( pMesh->mNumVertices, false);
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for( unsigned int a = 0; a < pMesh->mNumVertices; a++)
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{
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if( vertexDone[a])
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continue;
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const aiVector3D& origPos = pMesh->mVertices[a];
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const aiVector3D& origNorm = pMesh->mNormals[a];
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const aiVector3D& origTang = pMesh->mTangents[a];
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const aiVector3D& origBitang = pMesh->mBitangents[a];
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std::vector<unsigned int> closeVertices;
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closeVertices.push_back( a);
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// find all vertices close to that position
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vertexFinder.FindPositions( origPos, posEpsilon, verticesFound);
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// look among them for other vertices sharing the same normal and a close-enough tangent/bitangent
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static const float MAX_DIFF_ANGLE = 0.701f;
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for( unsigned int b = 0; b < verticesFound.size(); b++)
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{
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unsigned int idx = verticesFound[b];
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if( vertexDone[idx])
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continue;
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if( meshNorm[idx] * origNorm < angleEpsilon)
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continue;
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if( meshTang[idx] * origTang < MAX_DIFF_ANGLE)
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continue;
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if( meshBitang[idx] * origBitang < MAX_DIFF_ANGLE)
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continue;
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// it's similar enough -> add it to the smoothing group
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closeVertices.push_back( idx);
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vertexDone[idx] = true;
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}
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// smooth the tangents and bitangents of all vertices that were found to be close enough
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aiVector3D smoothTangent( 0, 0, 0), smoothBitangent( 0, 0, 0);
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for( unsigned int b = 0; b < closeVertices.size(); b++)
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{
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smoothTangent += meshTang[ closeVertices[b] ];
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smoothBitangent += meshBitang[ closeVertices[b] ];
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}
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smoothTangent.Normalize();
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smoothBitangent.Normalize();
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// and write it back into all affected tangents
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for( unsigned int b = 0; b < closeVertices.size(); b++)
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{
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meshTang[ closeVertices[b] ] = smoothTangent;
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meshBitang[ closeVertices[b] ] = smoothBitangent;
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}
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}
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}
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