scene: add Scene::pre_render and post_render

This allows actors to perform draw commands in TickDraw(), even
if it’s not exactly what we want in the future.

src/engine/ticker.cpp

@@ -432,6 +432,8 @@ void TickerData::DrawThreadTick()
         scene.EnableDisplay();
         Renderer::Get(idx)->Clear(ClearMask::All);
 
+        scene.pre_render(data->deltatime);
+
         /* Tick objects for the draw loop */
         for (int g = Entity::DRAWGROUP_BEGIN; g < Entity::DRAWGROUP_END && !data->quit /* Stop as soon as required */; ++g)
         {
@@ -470,6 +472,8 @@ void TickerData::DrawThreadTick()
         /* Do the render step */
         scene.render(data->deltatime);
 
+        scene.post_render(data->deltatime);
+
         /* Disable display */
         scene.DisableDisplay();
     }

src/scene.cpp

@@ -622,12 +622,11 @@ void Scene::DisableDisplay()
     data->m_display->Disable();
 }
 
-/* Render everything that the scene contains */
-void Scene::render(float seconds)
-{
-    bool do_pp = true;
+static bool do_pp = true;
 
-    gpu_marker("Start Render");
+void Scene::pre_render(float seconds)
+{
+    gpu_marker("Pre Render");
 
     /* First render into the offline buffer */
     if (do_pp)
@@ -644,12 +643,23 @@ void Scene::render(float seconds)
         }
 
         Renderer::Get()->Clear(ClearMask::Color | ClearMask::Depth);
-
-        // FIXME: get rid of the delta time argument
-        render_primitives();
-        render_tiles();
-        render_lines(seconds);
     }
+}
+
+/* Render everything that the scene contains */
+void Scene::render(float seconds)
+{
+    gpu_marker("Render");
+
+    // FIXME: get rid of the delta time argument
+    render_primitives();
+    render_tiles();
+    render_lines(seconds);
+}
+
+void Scene::post_render(float seconds)
+{
+    gpu_marker("Post Render");
 
     if (do_pp)
     {

src/scene.h

@@ -251,7 +251,9 @@ public:
     void EnableDisplay();
     void DisableDisplay();
 
+    void pre_render(float seconds);
     void render(float seconds);
+    void post_render(float seconds);
 
 private:
     void render_primitives();