TriangleInt triangle_intersection(const vec3 tri_a[3], const vec3 tri_b[3]) {
if (sat_bbox(tri_a, tri_b)) return TR_INT_NONE;
sat_t norm1 = sat_normal(tri_a, tri_b);
sat_t norm2 = sat_normal(tri_b, tri_a);
if (norm2 == SAT_NONE) return TR_INT_NONE;
if (norm1 == SAT_NONE) return TR_INT_NONE;
if (norm2 == SAT_COPLANAR) return TR_INT_NONE;
if (norm1 == SAT_COPLANAR) return TR_INT_NONE;
if (norm1 == SAT_COPLANAR) {
return triangle_intersection_coplanar(tri_a, tri_b);
}
size_t ia, ib;
int sharing = test_sharing<3>(tri_a, tri_b, ia, ib);
switch (std::abs(sharing)) {
case 0: {
// no shared vertices.
for (size_t i = 0; i < 3; ++i) {
for (size_t j = 0; j < 3; ++j) {
if (sat_plane(tri_a, tri_b, i, j)) return TR_INT_NONE;
if (sat_plane(tri_b, tri_a, i, j)) return TR_INT_NONE;
}
}
return TR_INT_INT;
}
case 1: {
// shared vertex (ia, ib) [but not shared edge, and not coplanar]
size_t ia0 = ia, ia1 = (ia+1)%3, ia2 = (ia+2)%3;
size_t ib0 = ib, ib1 = (ib+1)%3, ib2 = (ib+2)%3;
if (sat_plane(tri_a, tri_b, ia2, ib1, ib2)) return TR_INT_VERT;
if (sat_plane(tri_a, tri_b, ia2, ib2, ib1)) return TR_INT_VERT;
if (sat_plane(tri_a, tri_b, ia0, ib1, ib2)) return TR_INT_VERT;
if (sat_plane(tri_a, tri_b, ia0, ib2, ib1)) return TR_INT_VERT;
if (sat_plane(tri_b, tri_b, ib2, ia1, ia2)) return TR_INT_VERT;
if (sat_plane(tri_b, tri_b, ib2, ia2, ia1)) return TR_INT_VERT;
if (sat_plane(tri_b, tri_b, ib0, ia1, ia2)) return TR_INT_VERT;
if (sat_plane(tri_b, tri_b, ib0, ia2, ia1)) return TR_INT_VERT;
return TR_INT_INT;
}
case 2: {
// shared edge (ia, ib) [not coplanar]
return TR_INT_EDGE;
}
case 3: {
return TR_INT_TRI;
}
default: {
CARVE_FAIL("should not happen.");
}
}
}
TriangleInt triangle_intersection(const vec2 tri_a[3], const vec2 tri_b[3]) {
// triangles must be anticlockwise, or colinear.
CARVE_ASSERT(carve::geom2d::orient2d(tri_a[0], tri_a[1], tri_a[2]) >= 0.0);
CARVE_ASSERT(carve::geom2d::orient2d(tri_b[0], tri_b[1], tri_b[2]) >= 0.0);
size_t ia, ib;
int sharing = test_sharing<2>(tri_a, tri_b, ia, ib);
switch (std::abs(sharing)) {
case 0: {
// no shared vertices.
if (sat_edge(tri_a, tri_b, 0) < 0) return TR_INT_NONE;
if (sat_edge(tri_a, tri_b, 1) < 0) return TR_INT_NONE;
if (sat_edge(tri_a, tri_b, 2) < 0) return TR_INT_NONE;
if (sat_edge(tri_b, tri_a, 0) < 0) return TR_INT_NONE;
if (sat_edge(tri_b, tri_a, 1) < 0) return TR_INT_NONE;
if (sat_edge(tri_b, tri_a, 2) < 0) return TR_INT_NONE;
return TR_INT_INT;
}
case 1: {
// shared vertex (ia, ib) [but not shared edge]
if (sat_edge(tri_a, tri_b, (ia+2)%3, ib) < 0) return TR_INT_VERT;
if (sat_edge(tri_a, tri_b, ia, ib) < 0) return TR_INT_VERT;
if (sat_edge(tri_b, tri_a, (ib+2)%3, ia) < 0) return TR_INT_VERT;
if (sat_edge(tri_b, tri_a, ib, ia) < 0) return TR_INT_VERT;
return TR_INT_INT;
}
case 2: {
// shared edge (ia, ib) -> (ia + 1, ib + (sharing > 0) ? +1 : -1)
size_t pa = (ia + 2) % 3;
size_t pb = (ib + (sharing == +1 ? 2 : 1)) % 3;
double sa = orient2d_exact(tri_a[ia], tri_a[(ia+1)%3], tri_a[pa]);
double sb = orient2d_exact(tri_a[ia], tri_a[(ia+1)%3], tri_b[pb]);
if (sa * sb < 0.0) {
return TR_INT_EDGE;
}
return TR_INT_INT;
}
case 3: {
return TR_INT_TRI;
}
default: {
CARVE_FAIL("should not happen.");
}
}
}
TriangleIntType triangle_intersection_exact(const vec2 tri_a[3], const vec2 tri_b[3]) {
// triangles must be anticlockwise, or colinear.
CARVE_ASSERT(orient2d_exact(tri_a[0], tri_a[1], tri_a[2]) >= 0.0);
CARVE_ASSERT(orient2d_exact(tri_b[0], tri_b[1], tri_b[2]) >= 0.0);
int curr = +1;
for (size_t i = 0; curr != -1 && i < 3; ++i) {
curr = std::min(curr, sat_edge(tri_a, tri_b, i));
}
for (size_t i = 0; curr != -1 && i < 3; ++i) {
curr = std::min(curr, sat_edge(tri_b, tri_a, i));
}
switch (curr) {
case -1: return TR_TYPE_NONE;
case 0: return TR_TYPE_TOUCH;
case +1: return TR_TYPE_INT;
default: CARVE_FAIL("should not happen.");
}
}
std::vector<std::pair<size_t, size_t> >
carve::triangulate::incorporateHolesIntoPolygon(const std::vector<std::vector<carve::geom2d::P2> > &poly) {
#if 1
std::vector<std::pair<size_t, size_t> > result;
std::vector<size_t> hole_indices;
hole_indices.reserve(poly.size() - 1);
for (size_t i = 1; i < poly.size(); ++i) {
hole_indices.push_back(i);
}
incorporateHolesIntoPolygon(poly, result, 0, hole_indices);
return result;
#else
typedef std::vector<carve::geom2d::P2> loop_t;
size_t N = poly[0].size();
//
// work out how much space to reserve for the patched in holes.
for (size_t i = 0; i < poly.size(); i++) {
N += 2 + poly[i].size();
}
// this is the vector that we will build the result in.
std::vector<std::pair<size_t, size_t> > current_f_loop;
current_f_loop.reserve(N);
// this is a heap of current_f_loop indices that defines the vertex test order.
std::vector<size_t> f_loop_heap;
f_loop_heap.reserve(N);
// add the poly loop to current_f_loop.
for (size_t i = 0; i < poly[0].size(); ++i) {
current_f_loop.push_back(std::make_pair((size_t)0, i));
}
if (poly.size() == 1) {
return current_f_loop;
}
std::vector<std::pair<size_t, size_t> > h_loop_min_vertex;
h_loop_min_vertex.reserve(poly.size() - 1);
// find the major axis for the holes - this is the axis that we
// will sort on for finding vertices on the polygon to join
// holes up to.
//
// it might also be nice to also look for whether it is better
// to sort ascending or descending.
//
// another trick that could be used is to modify the projection
// by 90 degree rotations or flipping about an axis. just as
// long as we keep the carve::geom3d::Vector pointers for the
// real data in sync, everything should be ok. then we wouldn't
// need to accomodate axes or sort order in the main loop.
// find the bounding box of all the holes.
double min_x, min_y, max_x, max_y;
min_x = max_x = poly[1][0].x;
min_y = max_y = poly[1][0].y;
for (size_t i = 1; i < poly.size(); ++i) {
const loop_t &hole = poly[i];
for (size_t j = 0; j < hole.size(); ++j) {
min_x = std::min(min_x, hole[j].x);
min_y = std::min(min_y, hole[j].y);
max_x = std::max(max_x, hole[j].x);
max_y = std::max(max_y, hole[j].y);
}
}
// choose the axis for which the bbox is largest.
int axis = (max_x - min_x) > (max_y - min_y) ? 0 : 1;
// for each hole, find the minimum vertex in the chosen axis.
for (size_t i = 1; i < poly.size(); ++i) {
const loop_t &hole = poly[i];
size_t best, curr;
best = 0;
for (curr = 1; curr != hole.size(); ++curr) {
if (detail::axisOrdering(hole[curr], hole[best], axis)) {
best = curr;
}
}
h_loop_min_vertex.push_back(std::make_pair(i, best));
}
// sort the holes by the minimum vertex.
std::sort(h_loop_min_vertex.begin(), h_loop_min_vertex.end(), order_h_loops_2d(poly, axis));
// now, for each hole, find a vertex in the current polygon loop that it can be joined to.
for (unsigned i = 0; i < h_loop_min_vertex.size(); ++i) {
// the index of the vertex in the hole to connect.
size_t hole_i = h_loop_min_vertex[i].first;
size_t hole_i_connect = h_loop_min_vertex[i].second;
carve::geom2d::P2 hole_min = poly[hole_i][hole_i_connect];
f_loop_heap.clear();
// we order polygon loop vertices that may be able to be connected
// to the hole vertex by their distance to the hole vertex
heap_ordering_2d _heap_ordering(poly, current_f_loop, hole_min, axis);
const size_t SZ = current_f_loop.size();
for (size_t j = 0; j < SZ; ++j) {
// it is guaranteed that there exists a polygon vertex with
// coord < the min hole coord chosen, which can be joined to
// the min hole coord without crossing the polygon
// boundary. also, because we merge holes in ascending
// order, it is also true that this join can never cross
// another hole (and that doesn't need to be tested for).
if (pvert(poly, current_f_loop[j]).v[axis] <= hole_min.v[axis]) {
f_loop_heap.push_back(j);
std::push_heap(f_loop_heap.begin(), f_loop_heap.end(), _heap_ordering);
}
}
// we are going to test each potential (according to the
// previous test) polygon vertex as a candidate join. we order
// by closeness to the hole vertex, so that the join we make
// is as small as possible. to test, we need to check the
// joining line segment does not cross any other line segment
// in the current polygon loop (excluding those that have the
// vertex that we are attempting to join with as an endpoint).
size_t attachment_point = current_f_loop.size();
while (f_loop_heap.size()) {
std::pop_heap(f_loop_heap.begin(), f_loop_heap.end(), _heap_ordering);
size_t curr = f_loop_heap.back();
f_loop_heap.pop_back();
// test the candidate join from current_f_loop[curr] to hole_min
if (!testCandidateAttachment(poly, current_f_loop, curr, hole_min)) {
continue;
}
attachment_point = curr;
break;
}
if (attachment_point == current_f_loop.size()) {
CARVE_FAIL("didn't manage to link up hole!");
}
patchHoleIntoPolygon_2d(current_f_loop, attachment_point, hole_i, hole_i_connect, poly[hole_i].size());
}
return current_f_loop;
#endif
}
