From e312f3be4374f4684110b0897191f2c0339e9cc4 Mon Sep 17 00:00:00 2001
From: Lukas Matena <lukasmatena@seznam.cz>
Date: Fri, 15 May 2020 14:16:56 +0200
Subject: [PATCH] FDM supports gizmo: caching triangle normals in order to
 increase performance

---
 src/slic3r/GUI/Gizmos/GLGizmoFdmSupports.cpp |  6 ++++--
 src/slic3r/GUI/MeshUtils.cpp                 | 15 +++++----------
 src/slic3r/GUI/MeshUtils.hpp                 |  9 +++++++--
 3 files changed, 16 insertions(+), 14 deletions(-)

diff --git a/src/slic3r/GUI/Gizmos/GLGizmoFdmSupports.cpp b/src/slic3r/GUI/Gizmos/GLGizmoFdmSupports.cpp
index 0fea328bb..6843bab46 100644
--- a/src/slic3r/GUI/Gizmos/GLGizmoFdmSupports.cpp
+++ b/src/slic3r/GUI/Gizmos/GLGizmoFdmSupports.cpp
@@ -506,8 +506,10 @@ void GLGizmoFdmSupports::update_vertex_buffers(const ModelVolume* mv,
             if (status != type)
                 continue;
             for (int i=0; i<3; ++i)
-                iva.push_geometry(mesh->its.vertices[mesh->its.indices[facet_idx](i)].cast<double>(),
-                                  MeshRaycaster::get_triangle_normal(mesh->its, facet_idx).cast<double>());
+                iva.push_geometry(
+                    mesh->its.vertices[mesh->its.indices[facet_idx](i)].cast<double>(),
+                    m_c->raycaster()->raycasters()[mesh_id]->get_triangle_normal(facet_idx).cast<double>()
+                );
             iva.push_triangle(3*triangle_cnt, 3*triangle_cnt+1, 3*triangle_cnt+2);
             ++triangle_cnt;
         }
diff --git a/src/slic3r/GUI/MeshUtils.cpp b/src/slic3r/GUI/MeshUtils.cpp
index 6c4f5e49d..18526d8ce 100644
--- a/src/slic3r/GUI/MeshUtils.cpp
+++ b/src/slic3r/GUI/MeshUtils.cpp
@@ -95,11 +95,9 @@ void MeshClipper::recalculate_triangles()
 }
 
 
-Vec3f MeshRaycaster::get_triangle_normal(const indexed_triangle_set& its, size_t facet_idx)
+Vec3f MeshRaycaster::get_triangle_normal(size_t facet_idx) const
 {
-    Vec3f a(its.vertices[its.indices[facet_idx](1)] - its.vertices[its.indices[facet_idx](0)]);
-    Vec3f b(its.vertices[its.indices[facet_idx](2)] - its.vertices[its.indices[facet_idx](0)]);
-    return Vec3f(a.cross(b)).normalized();
+    return m_normals[facet_idx];
 }
 
 void MeshRaycaster::line_from_mouse_pos(const Vec2d& mouse_pos, const Transform3d& trafo, const Camera& camera,
@@ -218,12 +216,9 @@ Vec3f MeshRaycaster::get_closest_point(const Vec3f& point, Vec3f* normal) const
     int idx = 0;
     Vec3d closest_point;
     m_emesh.squared_distance(point.cast<double>(), idx, closest_point);
-    if (normal) {
-        auto indices = m_emesh.F().row(idx);
-        Vec3d a(m_emesh.V().row(indices(1)) - m_emesh.V().row(indices(0)));
-        Vec3d b(m_emesh.V().row(indices(2)) - m_emesh.V().row(indices(0)));
-        *normal = Vec3f(a.cross(b).cast<float>());
-    }
+    if (normal)
+        *normal = m_normals[idx];
+
     return closest_point.cast<float>();
 }
 
diff --git a/src/slic3r/GUI/MeshUtils.hpp b/src/slic3r/GUI/MeshUtils.hpp
index 92f444f55..8e321730c 100644
--- a/src/slic3r/GUI/MeshUtils.hpp
+++ b/src/slic3r/GUI/MeshUtils.hpp
@@ -108,7 +108,11 @@ public:
     // The pointer can be invalidated after constructor returns.
     MeshRaycaster(const TriangleMesh& mesh)
         : m_emesh(mesh)
-    {}
+    {
+        m_normals.reserve(mesh.stl.facet_start.size());
+        for (const stl_facet& facet : mesh.stl.facet_start)
+            m_normals.push_back(facet.normal);
+    }
 
     void line_from_mouse_pos(const Vec2d& mouse_pos, const Transform3d& trafo, const Camera& camera,
                              Vec3d& point, Vec3d& direction) const;
@@ -140,10 +144,11 @@ public:
 
     Vec3f get_closest_point(const Vec3f& point, Vec3f* normal = nullptr) const;
 
-    static Vec3f get_triangle_normal(const indexed_triangle_set& its, size_t facet_idx);
+    Vec3f get_triangle_normal(size_t facet_idx) const;
 
 private:
     sla::EigenMesh3D m_emesh;
+    std::vector<stl_normal> m_normals;
 };