Plane::Plane( const cc::Vec3f& a, const cc::Vec3f& b, const cc::Vec3f& c ) {
const cc::Vec3f ab = b - a;
const cc::Vec3f ac = c - a;
const cc::Vec3f cross = ab.cross(ac);
_normal = cross.normalized();
_d = -_normal.dot(a);
}
cc::Vec3f GeometricPlane::getNormal() {
const cc::Vec3f p0 = (_xform.getWorld() * cc::Vec4f(_verts[0].position, 1.0f)).truncated();
const cc::Vec3f p1 = (_xform.getWorld() * cc::Vec4f(_verts[1].position, 1.0f)).truncated();
const cc::Vec3f p2 = (_xform.getWorld() * cc::Vec4f(_verts[2].position, 1.0f)).truncated();
const cc::Vec3f p3 = (_xform.getWorld() * cc::Vec4f(_verts[3].position, 1.0f)).truncated();
const cc::Vec3f a = p1 - p0;
const cc::Vec3f b = p3 - p0;
return a.cross(b).normalized();
}
bool ClipMesh::getTriangles( std::vector<int>& indices ) {
const size_t numFaces = _faces.size();
for( size_t currFace = 0; currFace < numFaces; ++currFace ) {
CFace& face = _faces[currFace];
if( !face.visible ) {
continue;
}
const size_t numEdges = face.edges.size();
//assert(numEdges >= 3); // unexpected condition
if( numEdges < 3 ) {
return false;
}
std::vector<int> vOrdered(numEdges+1);
if( !orderVertices(face, vOrdered) ) {
return false;
}
const int v0 = vOrdered[0];
const int v2 = vOrdered[numEdges - 1];
const int v1 = vOrdered[(numEdges - 1) >> 1];
const cc::Vec3f diff1 = _vertices[v1].point - _vertices[v0].point;
const cc::Vec3f diff2 = _vertices[v2].point - _vertices[v0].point;
const float sgnVolume = face.normal.dot(diff1.cross(diff2));
if( sgnVolume < 0.0f ) { // feel free to invert this test
// clockwise, need to swap
for( unsigned int i = 1; i + 1 < numEdges; ++i ) {
indices.push_back(v0);
indices.push_back(vOrdered[i + 1]);
indices.push_back(vOrdered[i]);
}
} else {
// counterclockwise
for( unsigned int i = 1; i + 1 < numEdges; ++i ) {
indices.push_back(v0);
indices.push_back(vOrdered[i]);
indices.push_back(vOrdered[i + 1]);
}
}
}
return true;
}
