From 9c365da8285ffdfeee22290e8222d2060702af09 Mon Sep 17 00:00:00 2001
From: Lukas Matena <lukasmatena@seznam.cz>
Date: Thu, 21 May 2020 09:45:10 +0200
Subject: [PATCH] Removed immediate OpenGL mode calls in place on face gizmo

---
 src/slic3r/GUI/Gizmos/GLGizmoFlatten.cpp | 45 +++++++++++++-----------
 src/slic3r/GUI/Gizmos/GLGizmoFlatten.hpp |  3 +-
 2 files changed, 27 insertions(+), 21 deletions(-)

diff --git a/src/slic3r/GUI/Gizmos/GLGizmoFlatten.cpp b/src/slic3r/GUI/Gizmos/GLGizmoFlatten.cpp
index 7f33916cd..3f2c0ea46 100644
--- a/src/slic3r/GUI/Gizmos/GLGizmoFlatten.cpp
+++ b/src/slic3r/GUI/Gizmos/GLGizmoFlatten.cpp
@@ -1,7 +1,6 @@
 // Include GLGizmoBase.hpp before I18N.hpp as it includes some libigl code, which overrides our localization "L" macro.
 #include "GLGizmoFlatten.hpp"
 #include "slic3r/GUI/GLCanvas3D.hpp"
-#include "slic3r/GUI/GUI_App.hpp"
 #include "slic3r/GUI/Gizmos/GLGizmosCommon.hpp"
 
 #include <numeric>
@@ -80,12 +79,7 @@ void GLGizmoFlatten::on_render() const
             else
                 glsafe(::glColor4f(0.9f, 0.9f, 0.9f, 0.5f));
 
-            ::glBegin(GL_POLYGON);
-            for (const Vec3d& vertex : m_planes[i].vertices)
-            {
-                ::glVertex3dv(vertex.data());
-            }
-            glsafe(::glEnd());
+            m_planes[i].vbo.render();
         }
         glsafe(::glPopMatrix());
     }
@@ -112,12 +106,7 @@ void GLGizmoFlatten::on_render_for_picking() const
         for (int i = 0; i < (int)m_planes.size(); ++i)
         {
             glsafe(::glColor4fv(picking_color_component(i).data()));
-            ::glBegin(GL_POLYGON);
-            for (const Vec3d& vertex : m_planes[i].vertices)
-            {
-                ::glVertex3dv(vertex.data());
-            }
-            glsafe(::glEnd());
+            m_planes[i].vbo.render();
         }
         glsafe(::glPopMatrix());
     }
@@ -181,7 +170,7 @@ void GLGizmoFlatten::update_planes()
             if (std::abs(this_normal(0) - (*normal_ptr)(0)) < 0.001 && std::abs(this_normal(1) - (*normal_ptr)(1)) < 0.001 && std::abs(this_normal(2) - (*normal_ptr)(2)) < 0.001) {
                 stl_vertex* first_vertex = ch.stl.facet_start[facet_idx].vertex;
                 for (int j=0; j<3; ++j)
-                    m_planes.back().vertices.emplace_back((double)first_vertex[j](0), (double)first_vertex[j](1), (double)first_vertex[j](2));
+                    m_planes.back().vertices.emplace_back(first_vertex[j].cast<double>());
 
                 facet_visited[facet_idx] = true;
                 for (int j = 0; j < 3; ++ j) {
@@ -193,15 +182,16 @@ void GLGizmoFlatten::update_planes()
         }
         m_planes.back().normal = normal_ptr->cast<double>();
 
+        Pointf3s& verts = m_planes.back().vertices;
         // Now we'll transform all the points into world coordinates, so that the areas, angles and distances
         // make real sense.
-        m_planes.back().vertices = transform(m_planes.back().vertices, inst_matrix);
+        verts = transform(verts, inst_matrix);
 
         // if this is a just a very small triangle, remove it to speed up further calculations (it would be rejected later anyway):
-        if (m_planes.back().vertices.size() == 3 &&
-            ((m_planes.back().vertices[0] - m_planes.back().vertices[1]).norm() < minimal_side
-            || (m_planes.back().vertices[0] - m_planes.back().vertices[2]).norm() < minimal_side
-            || (m_planes.back().vertices[1] - m_planes.back().vertices[2]).norm() < minimal_side))
+        if (verts.size() == 3 &&
+            ((verts[0] - verts[1]).norm() < minimal_side
+            || (verts[0] - verts[2]).norm() < minimal_side
+            || (verts[1] - verts[2]).norm() < minimal_side))
             m_planes.pop_back();
     }
 
@@ -246,7 +236,7 @@ void GLGizmoFlatten::update_planes()
             discard = true;
         else {
             // We also check the inner angles and discard polygons with angles smaller than the following threshold
-            const double angle_threshold = ::cos(10.0 * (double)PI / 180.0);
+            constexpr double angle_threshold = ::cos(10.0 * (double)PI / 180.0);
 
             for (unsigned int i = 0; i < polygon.size(); ++i) {
                 const Vec3d& prec = polygon[(i == 0) ? polygon.size() - 1 : i - 1];
@@ -334,6 +324,21 @@ void GLGizmoFlatten::update_planes()
     m_first_instance_mirror = mo->instances.front()->get_mirror();
     m_old_model_object = mo;
 
+    // And finally create respective VBOs. The polygon is convex with
+    // the vertices in order, so triangulation is trivial.
+    for (auto& plane : m_planes) {
+        plane.vbo.reserve(plane.vertices.size());
+        for (const auto& vert : plane.vertices)
+            plane.vbo.push_geometry(vert, plane.normal);
+        for (size_t i=1; i<plane.vertices.size()-1; ++i)
+            plane.vbo.push_triangle(0, i, i+1); // triangle fan
+        plane.vbo.finalize_geometry(true);
+        // FIXME: vertices should really be local, they need not
+        // persist now when we use VBOs
+        plane.vertices.clear();
+        plane.vertices.shrink_to_fit();
+    }
+
     m_planes_valid = true;
 }
 
diff --git a/src/slic3r/GUI/Gizmos/GLGizmoFlatten.hpp b/src/slic3r/GUI/Gizmos/GLGizmoFlatten.hpp
index 05b4ae4cd..92d36d9d6 100644
--- a/src/slic3r/GUI/Gizmos/GLGizmoFlatten.hpp
+++ b/src/slic3r/GUI/Gizmos/GLGizmoFlatten.hpp
@@ -16,7 +16,8 @@ private:
     mutable Vec3d m_normal;
 
     struct PlaneData {
-        std::vector<Vec3d> vertices;
+        std::vector<Vec3d> vertices; // should be in fact local in update_planes()
+        GLIndexedVertexArray vbo;
         Vec3d normal;
         float area;
     };