void ZoaDebugFunctions::calculateTriMeshNormals( ci::TriMesh &mesh )
{
const std::vector<ci::Vec3f>& vertices = mesh.getVertices();
const std::vector<uint32_t>& indices = mesh.getIndices();
// remove all current normals
std::vector<ci::Vec3f>& normals = mesh.getNormals();
normals.reserve( mesh.getNumVertices() );
normals.clear();
// set the normal for each vertex to (0, 0, 0)
for(size_t i=0; i < mesh.getNumVertices(); ++i)
normals.push_back( ci::Vec3f::zero() );
// Average out the normal for each vertex at an index
for(size_t i=0; i< mesh.getNumTriangles(); ++i)
{
ci::Vec3f v0 = vertices[ indices[i * 3] ];
ci::Vec3f v1 = vertices[ indices[i * 3 + 1] ];
ci::Vec3f v2 = vertices[ indices[i * 3 + 2] ];
// calculate normal and normalize it, so each of the normals equally contributes to the final result
ci::Vec3f e0 = v2 - v0;
ci::Vec3f e1 = v2 - v1;
ci::Vec3f n = e0.cross(e1).normalized();
// add the normal to the final result, so we get an average of the normals of each triangle
normals[ indices[i * 3] ] += n;
normals[ indices[i * 3 + 1] ] += n;
normals[ indices[i * 3 + 2] ] += n;
}
// the normals are probably not normalized by now, so make sure their lengths will be 1.0 as expected
for(size_t i=0;i< normals.size();++i) {
normals[i].normalize();
}
}
TriMesh MeshHelper::subdivide( const ci::TriMesh &triMesh, uint32_t division, bool normalize )
{
if ( division <= 1 || triMesh.getNumIndices() == 0 || triMesh.getNumVertices() == 0 ) {
return triMesh;
}
vector<uint32_t> indices = triMesh.getIndices();
vector<Vec3f> normals = triMesh.getNormals();
vector<Vec3f> positions = triMesh.getVertices();
vector<Vec2f> texCoords = triMesh.getTexCoords();
vector<uint32_t> indicesBuffer( indices );
indices.clear();
indices.reserve( indicesBuffer.size() * 4 );
uint32_t index0;
uint32_t index1;
uint32_t index2;
uint32_t index3;
uint32_t index4;
uint32_t index5;
for ( vector<uint32_t>::const_iterator iter = indicesBuffer.begin(); iter != indicesBuffer.end(); ) {
index0 = *iter;
++iter;
index1 = *iter;
++iter;
index2 = *iter;
++iter;
if ( normalize ) {
index3 = positions.size();
positions.push_back( positions.at( index0 ).lerp( 0.5f, positions.at( index1 ) ).normalized() * 0.5f );
index4 = positions.size();
positions.push_back( positions.at( index1 ).lerp( 0.5f, positions.at( index2 ) ).normalized() * 0.5f );
index5 = positions.size();
positions.push_back( positions.at( index2 ).lerp( 0.5f, positions.at( index0 ) ).normalized() * 0.5f );
} else {
index3 = positions.size();
positions.push_back( positions.at( index0 ).lerp( 0.5f, positions.at( index1 ) ) );
index4 = positions.size();
positions.push_back( positions.at( index1 ).lerp( 0.5f, positions.at( index2 ) ) );
index5 = positions.size();
positions.push_back( positions.at( index2 ).lerp( 0.5f, positions.at( index0 ) ) );
}
if ( !normals.empty() ) {
normals.push_back( normals.at( index0 ).lerp( 0.5f, normals.at( index1 ) ) );
normals.push_back( normals.at( index1 ).lerp( 0.5f, normals.at( index2 ) ) );
normals.push_back( normals.at( index2 ).lerp( 0.5f, normals.at( index0 ) ) );
}
if ( !texCoords.empty() ) {
texCoords.push_back( texCoords.at( index0 ).lerp( 0.5f, texCoords.at( index1 ) ) );
texCoords.push_back( texCoords.at( index1 ).lerp( 0.5f, texCoords.at( index2 ) ) );
texCoords.push_back( texCoords.at( index2 ).lerp( 0.5f, texCoords.at( index0 ) ) );
}
indices.push_back( index0 );
indices.push_back( index3 );
indices.push_back( index5 );
indices.push_back( index3 );
indices.push_back( index1 );
indices.push_back( index4 );
indices.push_back( index5 );
indices.push_back( index4 );
indices.push_back( index2 );
indices.push_back( index3 );
indices.push_back( index4 );
indices.push_back( index5 );
}
ci::TriMesh mesh = create( indices, positions, normals, texCoords );
indices.clear();
normals.clear();
positions.clear();
texCoords.clear();
return subdivide( mesh, division - 1, normalize );
}