/// run mc on one Octnode
/// this generates one or more triangles which are pushed to the GLData
void MarchingCubes::mc_node( Octnode* node) {
assert( node->childcount == 0 ); // don't call this on non-leafs!
assert( node->is_undecided() );
unsigned int edgeTableIndex = mc_edgeTableIndex(node);
unsigned int edges = edgeTable[edgeTableIndex];
std::vector< GLVertex > vertices = interpolated_vertices(node, edges);
for (unsigned int i=0; triTable[edgeTableIndex][i] != -1 ; i+=3 ) {
std::vector< unsigned int > triangle;
GLVertex p1 = vertices[ triTable[edgeTableIndex][i ] ];
GLVertex p2 = vertices[ triTable[edgeTableIndex][i+1 ] ];
GLVertex p3 = vertices[ triTable[edgeTableIndex][i+2 ] ];
GLVertex::set_normal_and_color( p1, p2, p3, node->color );
triangle.push_back( g->addVertex( p1, node ) );
triangle.push_back( g->addVertex( p2, node ) );
triangle.push_back( g->addVertex( p3, node ) );
g->addPolygon(triangle);
node->addIndex( triangle[0] );
node->addIndex( triangle[1] );
node->addIndex( triangle[2] );
}
}
// run mc on one Octnode
std::vector<Triangle> MarchingCubes::mc_node(const Octnode* node) {
assert( node->childcount == 0 ); // don't call this on non-leafs!
std::vector<Triangle> tris;
unsigned int edgeTableIndex = mc_edgeTableIndex(node);
// the index into this table now tells us which edges have the vertices
// for the new triangles
// the lookup returns a 12-bit number, where each bit indicates wether
// the edge is cut by the isosurface
unsigned int edges = edgeTable[edgeTableIndex];
// calculate intersection points by linear interpolation
// there are now 12 different cases:
std::vector<Point> vertices = interpolated_vertices(node, edges);
assert(vertices.size()==12);
// form triangles by lookup in triTable
for (unsigned int i=0; triTable[edgeTableIndex][i] != -1 ; i+=3 ) {
tris.push_back( Triangle( vertices[ triTable[edgeTableIndex][i ] ],
vertices[ triTable[edgeTableIndex][i+1] ],
vertices[ triTable[edgeTableIndex][i+2] ] )
);
}
return tris;
}