From d5271220464fb8da07bdc805c68318ece201d3bb Mon Sep 17 00:00:00 2001
From: tamasmeszaros <meszaros.q@gmail.com>
Date: Fri, 4 Sep 2020 20:20:06 +0200
Subject: [PATCH] Performance optimizations and bugfix

---
 src/libslic3r/SLA/Rotfinder.cpp        | 16 ++++++++++++++--
 src/slic3r/GUI/Jobs/RotoptimizeJob.cpp |  3 ++-
 2 files changed, 16 insertions(+), 3 deletions(-)

diff --git a/src/libslic3r/SLA/Rotfinder.cpp b/src/libslic3r/SLA/Rotfinder.cpp
index e033009aa..db8c0b9a8 100644
--- a/src/libslic3r/SLA/Rotfinder.cpp
+++ b/src/libslic3r/SLA/Rotfinder.cpp
@@ -76,12 +76,20 @@ inline Face facestats(const std::array<Vec3d, 3> &triangle)
 inline const Vec3d DOWN = {0., 0., -1.};
 constexpr double POINTS_PER_UNIT_AREA = 1.;
 
+// The score function for a particular face
 inline double get_score(const Face &fc)
 {
+    // Simply get the angle (acos of dot product) between the face normal and
+    // the DOWN vector.
     double phi = 1. - std::acos(fc.normal.dot(DOWN)) / PI;
+
+    // Only consider faces that have have slopes below 90 deg:
     phi = phi * (phi > 0.5);
+
+    // Make the huge slopes more significant than the smaller slopes
     phi = phi * phi * phi;
 
+    // Multiply with the area of the current face
     return fc.area * POINTS_PER_UNIT_AREA * phi;
 }
 
@@ -176,6 +184,8 @@ std::vector<XYRotation> get_chull_rotations(const TriangleMesh &mesh)
 {
     TriangleMesh chull = mesh.convex_hull_3d();
     chull.require_shared_vertices();
+    double chull2d_area = chull.convex_hull().area();
+    double area_threshold =  chull2d_area / (scaled<double>(1e3) * scaled(1.));
 
     size_t facecount = chull.its.indices.size();
     auto inputs = reserve_vector<XYRotation>(facecount);
@@ -183,8 +193,10 @@ std::vector<XYRotation> get_chull_rotations(const TriangleMesh &mesh)
     for (size_t fi = 0; fi < facecount; ++fi) {
         Face fc = facestats(get_triangle_vertices(chull, fi));
 
-        auto q = Eigen::Quaterniond{}.FromTwoVectors(fc.normal, DOWN);
-        inputs.emplace_back(from_transform3d(Transform3d::Identity() * q));
+        if (fc.area > area_threshold)  {
+            auto q = Eigen::Quaterniond{}.FromTwoVectors(fc.normal, DOWN);
+            inputs.emplace_back(from_transform3d(Transform3d::Identity() * q));
+        }
     }
 
     return inputs;
diff --git a/src/slic3r/GUI/Jobs/RotoptimizeJob.cpp b/src/slic3r/GUI/Jobs/RotoptimizeJob.cpp
index 91a67cfa2..10c09275c 100644
--- a/src/slic3r/GUI/Jobs/RotoptimizeJob.cpp
+++ b/src/slic3r/GUI/Jobs/RotoptimizeJob.cpp
@@ -13,7 +13,8 @@ namespace Slic3r { namespace GUI {
 void RotoptimizeJob::process()
 {
     int obj_idx = m_plater->get_selected_object_idx();
-    if (obj_idx < 0) { return; }
+    if (obj_idx < 0 || m_plater->sla_print().objects().size() <= obj_idx)
+        return;
     
     ModelObject *o = m_plater->model().objects[size_t(obj_idx)];
     const SLAPrintObject *po = m_plater->sla_print().objects()[size_t(obj_idx)];