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Fix for issue #661 (ExPolygons generation)

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This commit is contained in:
Enrico Turri 2018-02-28 11:41:04 +01:00
parent bcc68ca450
commit 0ec68eb35b
1 changed files with 38 additions and 29 deletions
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67
xs/src/libslic3r/TriangleMesh.cpp
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@ -1186,40 +1186,46 @@ void TriangleMeshSlicer::make_expolygons(const Polygons &loops, ExPolygons* slic
loops correctly in some edge cases when original model had overlapping facets
*/
std::vector<double> area;
std::vector<size_t> sorted_area; // vector of indices
for (Polygons::const_iterator loop = loops.begin(); loop != loops.end(); ++ loop) {
area.push_back(loop->area());
sorted_area.push_back(loop - loops.begin());
}
// outer first
std::sort(sorted_area.begin(), sorted_area.end(),
[&area](size_t a, size_t b) { return std::abs(area[a]) > std::abs(area[b]); });
/* The following lines are commented out because they can generate wrong polygons,
see for example issue #661 */
// we don't perform a safety offset now because it might reverse cw loops
Polygons p_slices;
for (std::vector<size_t>::const_iterator loop_idx = sorted_area.begin(); loop_idx != sorted_area.end(); ++ loop_idx) {
/* we rely on the already computed area to determine the winding order
of the loops, since the Orientation() function provided by Clipper
would do the same, thus repeating the calculation */
Polygons::const_iterator loop = loops.begin() + *loop_idx;
if (area[*loop_idx] > +EPSILON)
p_slices.push_back(*loop);
else if (area[*loop_idx] < -EPSILON)
//FIXME This is arbitrary and possibly very slow.
// If the hole is inside a polygon, then there is no need to diff.
// If the hole intersects a polygon boundary, then diff it, but then
// there is no guarantee of an ordering of the loops.
// Maybe we can test for the intersection before running the expensive diff algorithm?
p_slices = diff(p_slices, *loop);
}
//std::vector<double> area;
//std::vector<size_t> sorted_area; // vector of indices
//for (Polygons::const_iterator loop = loops.begin(); loop != loops.end(); ++ loop) {
// area.push_back(loop->area());
// sorted_area.push_back(loop - loops.begin());
//}
//
//// outer first
//std::sort(sorted_area.begin(), sorted_area.end(),
// [&area](size_t a, size_t b) { return std::abs(area[a]) > std::abs(area[b]); });
//// we don't perform a safety offset now because it might reverse cw loops
//Polygons p_slices;
//for (std::vector<size_t>::const_iterator loop_idx = sorted_area.begin(); loop_idx != sorted_area.end(); ++ loop_idx) {
// /* we rely on the already computed area to determine the winding order
// of the loops, since the Orientation() function provided by Clipper
// would do the same, thus repeating the calculation */
// Polygons::const_iterator loop = loops.begin() + *loop_idx;
// if (area[*loop_idx] > +EPSILON)
// p_slices.push_back(*loop);
// else if (area[*loop_idx] < -EPSILON)
// //FIXME This is arbitrary and possibly very slow.
// // If the hole is inside a polygon, then there is no need to diff.
// // If the hole intersects a polygon boundary, then diff it, but then
// // there is no guarantee of an ordering of the loops.
// // Maybe we can test for the intersection before running the expensive diff algorithm?
// p_slices = diff(p_slices, *loop);
//}
// perform a safety offset to merge very close facets (TODO: find test case for this)
double safety_offset = scale_(0.0499);
//FIXME see https://github.com/prusa3d/Slic3r/issues/520
// double safety_offset = scale_(0.0001);
ExPolygons ex_slices = offset2_ex(p_slices, +safety_offset, -safety_offset);
/* The following line is commented out because it can generate wrong polygons,
see for example issue #661 */
//ExPolygons ex_slices = offset2_ex(p_slices, +safety_offset, -safety_offset);
#ifdef SLIC3R_TRIANGLEMESH_DEBUG
size_t holes_count = 0;
@ -1230,7 +1236,10 @@ void TriangleMeshSlicer::make_expolygons(const Polygons &loops, ExPolygons* slic
#endif
// append to the supplied collection
expolygons_append(*slices, ex_slices);
/* Fix for issue #661 { */
expolygons_append(*slices, offset2_ex(union_(loops, false), +safety_offset, -safety_offset));
//expolygons_append(*slices, ex_slices);
/* } */
}
void TriangleMeshSlicer::make_expolygons(std::vector<IntersectionLine> &lines, ExPolygons* slices) const