opengl 3.3 renderer integration, minor renderer tweaks

material.cpp

@@ -315,6 +315,15 @@ float opengl_material::get_or_guess_opacity() const {
     return 0.0f;
 }
 
+bool
+opengl_material::is_translucent() const {
+
+    return (
+        textures[ 0 ] != null_handle ?
+            GfxRenderer->Texture( textures[ 0 ] ).has_alpha :
+            false );
+}
+
 // create material object from data stored in specified file.
 // NOTE: the deferred load parameter is passed to textures defined by material, the material itself is always loaded immediately
 material_handle