void TriMesh::computeNormals() {
// skip
// Calculate triangle normals
for(int i = 0; i < m_triangles.size(); i++){
glm::vec3 v1; glm::vec3 v2; glm::vec3 v3;
HalfEdge* tempLeader = m_triangles[i]->getLeadingHalfEdge();
v1 = tempLeader->getSourceNode()->m_pos_;
tempLeader = tempLeader->getNext();
v2 = tempLeader->getSourceNode()->m_pos_;
tempLeader = tempLeader->getNext();
v3 = tempLeader->getSourceNode()->m_pos_;
m_triangles[i]->m_N_ = calculateNormal(v1,v2,v3);
}
// Calculate vertex normals by averaging triange normals
for(int i = 0; i < m_nodes.size(); i++){
Node n = m_nodes[i];
HalfEdge* startEdge = n.getLeadingHalfEdge();
Triangle* startTriangle = startEdge->getTriangle();
glm::vec3 accNormal = startTriangle->m_N_;
int triangleCount = 1;
for(HalfEdge* tempEdge = startEdge->getVtxRingNext(); tempEdge != startEdge; tempEdge = tempEdge->getVtxRingNext()){
if (tempEdge == NULL)
break;
accNormal += tempEdge->getTriangle()->m_N_;
triangleCount++;
}
glm::vec3 count = glm::vec3(triangleCount);
m_nodes[i].m_N_ = accNormal/count;
}
// unskip
}
TriMesh* TriMesh::subdivideSqrt3() {
vector<glm::vec3> points;
vector<int> indices;
for (int i = 0; i < m_nodes.size(); i++){
HalfEdge* start_edge = m_nodes[i].getLeadingHalfEdge();
int surroundingPoints = 0;
glm::vec3 new_point = glm::vec3(0);
points.push_back(m_nodes[i].m_pos_); //Pushing node vertex to points.
m_nodes[i].index = points.size() - 1; //Setting node index.
HalfEdge* he = start_edge;
do{
int center_of_triangle;
//Checking if triangle center already exists.
if (he->getTriangle()->getCenter() == -1){
points.push_back(he->getTriangle()->calculateBarycenter());
he->getTriangle()->setCenter(points.size() - 1);
}
center_of_triangle = he->getTriangle()->getCenter();
/*Boundary case*/
if (he->isBoundary()){
points.push_back(glm::lerp(m_nodes[i].m_pos_, he->getDestinationNode()->m_pos_, 0.5f)); //Pushing mid-edge point.
int middle_of_edge = points.size() - 1;
int end_of_edge;
//Checking if end point on edge already exists.
if (he->getDestinationNode()->index == -1){
points.push_back(he->getDestinationNode()->m_pos_); //Pushing if not.
he->getDestinationNode()->index = points.size() - 1;
}
end_of_edge = he->getDestinationNode()->index;
//Pushing boundary triangle 1.
indices.push_back(middle_of_edge);
indices.push_back(center_of_triangle);
indices.push_back(m_nodes[i].index);
//Pushing boundary triangle 2.
indices.push_back(middle_of_edge);
indices.push_back(end_of_edge);
indices.push_back(center_of_triangle);
}
/*Normal non-boundary edge*/
else{
int center_of_twin_triangle;
Triangle* twin_triangle = he->getTwin()->getTriangle();
//Checking if triangle center already exists.
if (twin_triangle->getCenter() == -1){
points.push_back(twin_triangle->calculateBarycenter());
twin_triangle->setCenter(points.size() - 1);
}
center_of_twin_triangle = twin_triangle->getCenter();
//Pushing new triangle
indices.push_back(m_nodes[i].index);
indices.push_back(center_of_twin_triangle);
indices.push_back(center_of_triangle);
}
surroundingPoints++;
new_point += he->getDestinationNode()->m_pos_;
he = he->getVtxRingNext();
} while (he != start_edge);
glm::vec3 beta = glm::vec3((4 - 2*cos(2*M_PI/surroundingPoints))/(9*surroundingPoints));
new_point = (1 - surroundingPoints * beta.x)*m_nodes[i].m_pos_ + beta*new_point;
points[m_nodes[i].index] = new_point;
}
// skip
// Generate a new set of points and indices using the sqrt(3) subdivision scheme
// unskip
return new TriMesh(points, indices);
}
