3DPrinting/PrusaSlicer-NonPlainar
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Speed up of libigl SelfIntersectMesh:

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The test for intersection of two triangles sharing a common edge
has been optimized to reject non-overlaping triangles with
the least amount of exact arithmetics predicates.

Cherry pick of
d367762468
This commit is contained in:
bubnikv 2020-02-03 14:01:35 +01:00
parent 992a0c3d7a
commit 73f69f3387
1 changed files with 27 additions and 22 deletions
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49
src/libigl/igl/copyleft/cgal/SelfIntersectMesh.h
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@ -635,13 +635,30 @@ inline bool igl::copyleft::cgal::SelfIntersectMesh<
{
using namespace std;
// must be co-planar
if(
A.supporting_plane() != B.supporting_plane() &&
A.supporting_plane() != B.supporting_plane().opposite())
{
return false;
auto opposite_vertex = [](const Index a0, const Index a1) {
// get opposite index of A
int a2=-1;
for(int c=0;c<3;++c)
if(c!=a0 && c!=a1) {
a2 = c;
break;
}
assert(a2 != -1);
return a2;
};
// must be co-planar
Index a2 = opposite_vertex(shared[0].first, shared[1].first);
if (! B.supporting_plane().has_on(A.vertex(a2)))
return false;
Index b2 = opposite_vertex(shared[0].second, shared[1].second);
if (int(CGAL::coplanar_orientation(A.vertex(shared[0].first), A.vertex(shared[1].first), A.vertex(a2))) *
int(CGAL::coplanar_orientation(B.vertex(shared[0].second), B.vertex(shared[1].second), B.vertex(b2))) < 0)
// There is certainly no self intersection as the non-shared triangle vertices lie on opposite sides of the shared edge.
return false;
// Since A and B are non-degenerate the intersection must be a polygon
// (triangle). Either
// - the vertex of A (B) opposite the shared edge of lies on B (A), or
@ -650,22 +667,10 @@ inline bool igl::copyleft::cgal::SelfIntersectMesh<
// Determine if the vertex opposite edge (a0,a1) in triangle A lies in
// (intersects) triangle B
const auto & opposite_point_inside = [](
const Triangle_3 & A, const Index a0, const Index a1, const Triangle_3 & B)
const Triangle_3 & A, const Index a2, const Triangle_3 & B)
-> bool
{
// get opposite index
Index a2 = -1;
for(int c = 0;c<3;c++)
{
if(c != a0 && c != a1)
{
a2 = c;
break;
}
}
assert(a2 != -1);
bool ret = CGAL::do_intersect(A.vertex(a2),B);
return ret;
return CGAL::do_intersect(A.vertex(a2),B);
};
// Determine if edge opposite vertex va in triangle A intersects edge
@ -681,8 +686,8 @@ inline bool igl::copyleft::cgal::SelfIntersectMesh<
};
if(
!opposite_point_inside(A,shared[0].first,shared[1].first,B) &&
!opposite_point_inside(B,shared[0].second,shared[1].second,A) &&
!opposite_point_inside(A,a2,B) &&
!opposite_point_inside(B,b2,A) &&
!opposite_edges_intersect(A,shared[0].first,B,shared[1].second) &&
!opposite_edges_intersect(A,shared[1].first,B,shared[0].second))
{