void
ConvexHull::graham() {
if(is_degenerate()) // nothing to do
return;
find_pivot();
angle_sort();
graham_scan();
}
/*** ConvexHull::is_clockwise
* We require that successive pairs of edges always turn right.
* proposed algorithm: walk successive edges and require triangle area is positive.
*/
bool
ConvexHull::is_clockwise() const {
if(is_degenerate())
return true;
Point first = boundary[0];
Point second = boundary[1];
for(std::vector<Point>::const_iterator it(boundary.begin()+2), e(boundary.end());
it != e;) {
if(SignedTriangleArea(first, second, *it) > 0)
return false;
first = second;
second = *it;
++it;
}
return true;
}
Mesh marching_cubes(Grid& grid, double isovalue, SurfaceType surface_type)
{
Mesh mesh;
int offset[8];
Vertex* vertices[12];
unordered_set<Vertex*, vertex_hash, vertex_equals> vertex_set;
compute_offset(grid, offset);
for(int z = 0; z < grid.get_axis(2)-1; z++) {
for(int y = 0; y < grid.get_axis(1)-1; y++) {
for(int x = 0; x < grid.get_axis(0)-1; x++) {
int ic = grid.index(x,y,z);
int table_index = get_index(grid, ic, offset, isovalue);
for(int i = 0; i < 12; i++) {
if(edge_table[table_index] & (1 << i)) {
int v[3], u[3];
get_grid_edge(x, y, z, i, v, u);
double sv = grid[grid.index(v[0],v[1],v[2])];
double su = grid[grid.index(u[0],u[1],u[2])];
double vc[3] = {(v[0]-grid.get_axis(0)/2.0)*grid.get_spacing(0),
(v[1]-grid.get_axis(1)/2.0)*grid.get_spacing(1),
(v[2]-grid.get_axis(2)/2.0)*grid.get_spacing(2)};
double uc[3] = {(u[0]-grid.get_axis(0)/2.0)*grid.get_spacing(0),
(u[1]-grid.get_axis(1)/2.0)*grid.get_spacing(1),
(u[2]-grid.get_axis(2)/2.0)*grid.get_spacing(2)};
if(surface_type == NO_SURFACE) {
vertices[i] = lerp(vc, sv, uc, su, isovalue);
} else {
vertices[i] = find_cut_point(vc, sv, uc, su, isovalue, surface_type);
}
vertices[i] = merge_vertex(vertices[i], vertex_set, mesh);
}
}
for(int i = 0; triangle_table[table_index][i] != -1; i += 3) {
Vertex *v0, *v1, *v2;
v0 = vertices[triangle_table[table_index][i]];
v1 = vertices[triangle_table[table_index][i+1]];
v2 = vertices[triangle_table[table_index][i+2]];
if(!is_degenerate(v0, v1, v2)) {
Face* f = new Face;
f->v.push_back(v0);
f->v.push_back(v1);
f->v.push_back(v2);
v0->f.push_back(f);
v1->f.push_back(f);
v2->f.push_back(f);
Edge* e0 = create_edge(v0, v1, f, mesh);
Edge* e1 = create_edge(v1, v2, f, mesh);
Edge* e2 = create_edge(v2, v0, f, mesh);
f->e.push_back(e0);
f->e.push_back(e1);
f->e.push_back(e2);
mesh.add(f);
}
}
}
}
}
compute_normals(mesh);
return mesh;
}
Line_d<R> Segment_d<R>::supporting_line() const
{ CGAL_assertion_msg((!is_degenerate()),
"Segment_d::supporting_line(): degenerate segment cannot be converted.");
return Line_d<R>(Base(*this));
}
int Face3::split_by_plane(const Plane &p_plane, Face3 p_res[3], bool p_is_point_over[3]) const {
ERR_FAIL_COND_V(is_degenerate(), 0);
Vector3 above[4];
int above_count = 0;
Vector3 below[4];
int below_count = 0;
for (int i = 0; i < 3; i++) {
if (p_plane.has_point(vertex[i], CMP_EPSILON)) { // point is in plane
ERR_FAIL_COND_V(above_count >= 4, 0);
above[above_count++] = vertex[i];
ERR_FAIL_COND_V(below_count >= 4, 0);
below[below_count++] = vertex[i];
} else {
if (p_plane.is_point_over(vertex[i])) {
//Point is over
ERR_FAIL_COND_V(above_count >= 4, 0);
above[above_count++] = vertex[i];
} else {
//Point is under
ERR_FAIL_COND_V(below_count >= 4, 0);
below[below_count++] = vertex[i];
}
/* Check for Intersection between this and the next vertex*/
Vector3 inters;
if (!p_plane.intersects_segment(vertex[i], vertex[(i + 1) % 3], &inters))
continue;
/* Intersection goes to both */
ERR_FAIL_COND_V(above_count >= 4, 0);
above[above_count++] = inters;
ERR_FAIL_COND_V(below_count >= 4, 0);
below[below_count++] = inters;
}
}
int polygons_created = 0;
ERR_FAIL_COND_V(above_count >= 4 && below_count >= 4, 0); //bug in the algo
if (above_count >= 3) {
p_res[polygons_created] = Face3(above[0], above[1], above[2]);
p_is_point_over[polygons_created] = true;
polygons_created++;
if (above_count == 4) {
p_res[polygons_created] = Face3(above[2], above[3], above[0]);
p_is_point_over[polygons_created] = true;
polygons_created++;
}
}
if (below_count >= 3) {
p_res[polygons_created] = Face3(below[0], below[1], below[2]);
p_is_point_over[polygons_created] = false;
polygons_created++;
if (below_count == 4) {
p_res[polygons_created] = Face3(below[2], below[3], below[0]);
p_is_point_over[polygons_created] = false;
polygons_created++;
}
}
return polygons_created;
}
