From 36416d77b8f0db6692ffbafd56abf753e51d074f Mon Sep 17 00:00:00 2001
From: bubnikv <bubnikv@gmail.com>
Date: Thu, 30 Mar 2017 10:25:52 +0200
Subject: Fixes of VBO rendering on Linux with wxWidgets & GTK

---
 lib/Slic3r/GUI/3DScene.pm     | 12 +++++++++++-
 xs/src/slic3r/GUI/3DScene.hpp |  6 ++++++
 xs/xsp/GUI_3DScene.xsp        |  1 +
 3 files changed, 18 insertions(+), 1 deletion(-)

diff --git a/lib/Slic3r/GUI/3DScene.pm b/lib/Slic3r/GUI/3DScene.pm
index b95e8777f..d4eb1eaea 100644
--- a/lib/Slic3r/GUI/3DScene.pm
+++ b/lib/Slic3r/GUI/3DScene.pm
@@ -906,13 +906,16 @@ sub UseVBOs {
     my ($self) = @_;
 
     if (! defined ($self->{use_VBOs})) {
+        # This is a special path for wxWidgets on GTK, where an OpenGL context is initialized
+        # first when an OpenGL widget is shown for the first time. How ugly.
+        return 0 if (! $self->init && $^O eq 'linux');
         # Don't use VBOs if anything fails.
         $self->{use_VBOs} = 0;
         if ($self->GetContext) {
             $self->SetCurrent($self->GetContext);
             my @gl_version = split(/\./, glGetString(GL_VERSION));
             $self->{use_VBOs} = int($gl_version[0]) >= 2;
-            # print "InitGL $self OpenGL major: $gl_version[0], minor: $gl_version[1]. Use VBOs: ", $self->{use_VBOs}, "\n";
+            # print "UseVBOs $self OpenGL major: $gl_version[0], minor: $gl_version[1]. Use VBOs: ", $self->{use_VBOs}, "\n";
         }
     }
     return $self->{use_VBOs};
@@ -968,6 +971,13 @@ sub InitGL {
     return unless $self->GetContext;
     $self->init(1);
 
+    # This is a special path for wxWidgets on GTK, where an OpenGL context is initialized
+    # first when an OpenGL widget is shown for the first time. How ugly.
+    # In that case the volumes are wainting to be moved to Vertex Buffer Objects
+    # after the OpenGL context is being initialized.
+    $self->volumes->finalize_geometry(1) 
+        if ($^O eq 'linux' && $self->UseVBOs);
+
     glClearColor(0, 0, 0, 1);
     glColor3f(1, 0, 0);
     glEnable(GL_DEPTH_TEST);
diff --git a/xs/src/slic3r/GUI/3DScene.hpp b/xs/src/slic3r/GUI/3DScene.hpp
index 1e5b968ba..ed992754d 100644
--- a/xs/src/slic3r/GUI/3DScene.hpp
+++ b/xs/src/slic3r/GUI/3DScene.hpp
@@ -264,6 +264,7 @@ public:
 
     void                set_range(coordf_t low, coordf_t high);
     void                render() const;
+    void                finalize_geometry(bool use_VBOs) { this->indexed_vertex_array.finalize_geometry(use_VBOs); }
     void                release_geometry() { this->indexed_vertex_array.release_geometry(); }
 
     /************************************************ Layer height texture ****************************************************/
@@ -312,6 +313,11 @@ public:
     // Render the volumes by OpenGL.
     void render_VBOs() const;
     void render_legacy() const;
+
+    // Finalize the initialization of the geometry & indices,
+    // upload the geometry and indices to OpenGL VBO objects
+    // and shrink the allocated data, possibly relasing it if it has been loaded into the VBOs.
+    void finalize_geometry(bool use_VBOs) { for (auto *v : volumes) v->finalize_geometry(use_VBOs); }
     // Release the geometry data assigned to the volumes.
     // If OpenGL VBOs were allocated, an OpenGL context has to be active to release them.
     void release_geometry() { for (auto *v : volumes) v->release_geometry(); }
diff --git a/xs/xsp/GUI_3DScene.xsp b/xs/xsp/GUI_3DScene.xsp
index 06ae7ce13..06b042f3b 100644
--- a/xs/xsp/GUI_3DScene.xsp
+++ b/xs/xsp/GUI_3DScene.xsp
@@ -87,6 +87,7 @@
 
     void render_VBOs() const;
     void render_legacy() const;
+    void finalize_geometry(bool use_VBOs);
     void release_geometry();
 %{
 
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