From f22961edaed244337f463fefad1634a0883c727f Mon Sep 17 00:00:00 2001
From: Lukas Matena <lukasmatena@seznam.cz>
Date: Thu, 9 Jan 2020 14:06:39 +0100
Subject: [PATCH] Fixed a raycaster problem with handling duplicate hits from
 igl

The duplicate hits confused winding number calculations in the raycaster, which in turn returned incorrect hit.
---
 src/libslic3r/SLA/Common.cpp          | 14 +++++++++-----
 tests/sla_print/sla_raycast_tests.cpp |  3 +--
 2 files changed, 10 insertions(+), 7 deletions(-)

diff --git a/src/libslic3r/SLA/Common.cpp b/src/libslic3r/SLA/Common.cpp
index a0fc2f3bb..3d31c5522 100644
--- a/src/libslic3r/SLA/Common.cpp
+++ b/src/libslic3r/SLA/Common.cpp
@@ -297,7 +297,14 @@ EigenMesh3D::query_ray_hits(const Vec3d &s, const Vec3d &dir) const
     // The sort is necessary, the hits are not always sorted.
     std::sort(hits.begin(), hits.end(),
               [](const igl::Hit& a, const igl::Hit& b) { return a.t < b.t; });
-    
+
+    // Remove duplicates. They sometimes appear, for example when the ray is cast
+    // along an axis of a cube due to floating-point approximations in igl (?)
+    hits.erase(std::unique(hits.begin(), hits.end(),
+                           [](const igl::Hit& a, const igl::Hit& b)
+                              { return a.t == b.t; }),
+               hits.end());
+
     //  Convert the igl::Hit into hit_result
     outs.reserve(hits.size());
     for (const igl::Hit& hit : hits) {
@@ -342,14 +349,11 @@ EigenMesh3D::hit_result EigenMesh3D::filter_hits(
     for (const sla::DrainHole& hole : m_holes) {
         std::array<std::pair<float, Vec3d>, 2> isects;
         if (hole.get_intersections(sf, dirf, isects)) {
+            // Ignore hole hits behind the source
             if (isects[0].first > 0.f) hole_isects.emplace_back(isects[0].first, isects[0].second, true);
             if (isects[1].first > 0.f) hole_isects.emplace_back(isects[1].first, isects[1].second, false);
         }
     }
-//    // Remove hole hits behind the source
-//    for (int i=0; i<int(hole_isects.size()); ++i)
-//        if (hole_isects[i].t < 0.f)
-//            hole_isects.erase(hole_isects.begin() + (i--));
 
     // Holes can intersect each other, sort the hits by t
     std::sort(hole_isects.begin(), hole_isects.end(),
diff --git a/tests/sla_print/sla_raycast_tests.cpp b/tests/sla_print/sla_raycast_tests.cpp
index c50aa1f2f..c60f4c8ee 100644
--- a/tests/sla_print/sla_raycast_tests.cpp
+++ b/tests/sla_print/sla_raycast_tests.cpp
@@ -48,11 +48,10 @@ TEST_CASE("Raycaster with loaded drillholes", "[sla_raycast]")
         REQUIRE(hit.distance() == Approx(radius));
     }
     
-    // Shouldn't this hit the inside wall through the hole?
     SECTION("Fire from outside, hit the back side of the hole cylinder.") {
         s.y() = -1.;
         auto hit = emesh.query_ray_hit(s, {0, 1., 0.});
-        REQUIRE(hit.distance() == Approx(hole_length + 1.f));
+        REQUIRE(hit.distance() == Approx(boxbb.size().y() - hcfg.min_thickness + 1.));
     }
     
     SECTION("Check for support tree correctness") {