From 90daffccf2b5fa0a5ab21cec8581e8bf1e92e72f Mon Sep 17 00:00:00 2001
From: Enrico Turri <enricoturri@seznam.cz>
Date: Tue, 2 Jul 2019 15:49:18 +0200
Subject: [PATCH] View dependent order of rendering for layers editing visual
 hints to keep the correct transparency

---
 src/slic3r/GUI/Plater.cpp    |  5 +++++
 src/slic3r/GUI/Plater.hpp    |  2 ++
 src/slic3r/GUI/Selection.cpp | 30 +++++++++++++++++-------------
 3 files changed, 24 insertions(+), 13 deletions(-)

diff --git a/src/slic3r/GUI/Plater.cpp b/src/slic3r/GUI/Plater.cpp
index 98b7c1303..0a154034f 100644
--- a/src/slic3r/GUI/Plater.cpp
+++ b/src/slic3r/GUI/Plater.cpp
@@ -4273,6 +4273,11 @@ void Plater::msw_rescale()
     GetParent()->Layout();
 }
 
+const Camera& Plater::get_camera() const
+{
+    return p->camera;
+}
+
 bool Plater::can_delete() const { return p->can_delete(); }
 bool Plater::can_delete_all() const { return p->can_delete_all(); }
 bool Plater::can_increase_instances() const { return p->can_increase_instances(); }
diff --git a/src/slic3r/GUI/Plater.hpp b/src/slic3r/GUI/Plater.hpp
index c3f8927c0..34fd7984e 100644
--- a/src/slic3r/GUI/Plater.hpp
+++ b/src/slic3r/GUI/Plater.hpp
@@ -220,6 +220,8 @@ public:
 
     void msw_rescale();
 
+    const Camera& get_camera() const;
+
 private:
     struct priv;
     std::unique_ptr<priv> p;
diff --git a/src/slic3r/GUI/Selection.cpp b/src/slic3r/GUI/Selection.cpp
index 9939c291e..bea94e2e6 100644
--- a/src/slic3r/GUI/Selection.cpp
+++ b/src/slic3r/GUI/Selection.cpp
@@ -6,7 +6,8 @@
 #include "GUI_ObjectManipulation.hpp"
 #include "GUI_ObjectList.hpp"
 #include "Gizmos/GLGizmoBase.hpp"
-#include "slic3r/GUI/3DScene.hpp"
+#include "3DScene.hpp"
+#include "Camera.hpp"
 
 #include <GL/glew.h>
 
@@ -1761,33 +1762,36 @@ void Selection::render_sidebar_layers_hints(const std::string& sidebar_field) co
     const float min_y = box.min(1) - Margin;
     const float max_y = box.max(1) + Margin;
 
+    // view dependend order of rendering to keep correct transparency
+    bool camera_on_top = wxGetApp().plater()->get_camera().get_theta() <= 90.0f;
+    float z1 = camera_on_top ? min_z : max_z;
+    float z2 = camera_on_top ? max_z : min_z;
+
     glsafe(::glEnable(GL_DEPTH_TEST));
     glsafe(::glDisable(GL_CULL_FACE));
     glsafe(::glEnable(GL_BLEND));
     glsafe(::glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA));
 
-    // Draw the min_z plane
     ::glBegin(GL_QUADS);
-    if (type == 1)
+    if ((camera_on_top && (type == 1)) || (!camera_on_top && (type == 2)))
         ::glColor4f(1.0f, 0.38f, 0.0f, 1.0f);
     else
         ::glColor4f(0.8f, 0.8f, 0.8f, 0.5f);
-    ::glVertex3f(min_x, min_y, min_z);
-    ::glVertex3f(max_x, min_y, min_z);
-    ::glVertex3f(max_x, max_y, min_z);
-    ::glVertex3f(min_x, max_y, min_z);
+    ::glVertex3f(min_x, min_y, z1);
+    ::glVertex3f(max_x, min_y, z1);
+    ::glVertex3f(max_x, max_y, z1);
+    ::glVertex3f(min_x, max_y, z1);
     glsafe(::glEnd());
 
-    // Draw the max_z plane
     ::glBegin(GL_QUADS);
-    if (type == 2)
+    if ((camera_on_top && (type == 2)) || (!camera_on_top && (type == 1)))
         ::glColor4f(1.0f, 0.38f, 0.0f, 1.0f);
     else
         ::glColor4f(0.8f, 0.8f, 0.8f, 0.5f);
-    ::glVertex3f(min_x, min_y, max_z);
-    ::glVertex3f(max_x, min_y, max_z);
-    ::glVertex3f(max_x, max_y, max_z);
-    ::glVertex3f(min_x, max_y, max_z);
+    ::glVertex3f(min_x, min_y, z2);
+    ::glVertex3f(max_x, min_y, z2);
+    ::glVertex3f(max_x, max_y, z2);
+    ::glVertex3f(min_x, max_y, z2);
     glsafe(::glEnd());
 
     glsafe(::glEnable(GL_CULL_FACE));