Implement occlusion culling

Added an occlusion culling system with support for static occluder meshes.
It can be enabled via `Project Settings > Rendering > Occlusion Culling > Use Occlusion Culling`.

Occluders are defined via the new `Occluder3D` resource and instanced using the new
`OccluderInstance3D` node. The occluders can also be automatically baked from a
scene using the built-in editor plugin.

1 files changed, 12 insertions, 0 deletions

diff --git a/editor/node_3d_editor_gizmos.h b/editor/node_3d_editor_gizmos.h
index 6f98d3a08c..95344176ad 100644
--- a/editor/node_3d_editor_gizmos.h
+++ b/editor/node_3d_editor_gizmos.h
@@ -100,6 +100,18 @@ public:
 	MeshInstance3DGizmoPlugin();
 };
 
+class OccluderInstance3DGizmoPlugin : public EditorNode3DGizmoPlugin {
+	GDCLASS(OccluderInstance3DGizmoPlugin, EditorNode3DGizmoPlugin);
+
+public:
+	bool has_gizmo(Node3D *p_spatial) override;
+	String get_gizmo_name() const override;
+	int get_priority() const override;
+	void redraw(EditorNode3DGizmo *p_gizmo) override;
+
+	OccluderInstance3DGizmoPlugin();
+};
+
 class Sprite3DGizmoPlugin : public EditorNode3DGizmoPlugin {
 	GDCLASS(Sprite3DGizmoPlugin, EditorNode3DGizmoPlugin);