pattern offset, invert and flip(xy)

src/node_panel_brush.h

@@ -157,6 +157,7 @@ class NodePanelBrushPreset : public Node
         float m_pattern_scale = .25f;
         float m_pattern_brightness = 0.5f;
         float m_pattern_contrast = 0.5f;
+        bool m_pattern_rand_offset = false;
     };
 public:
     std::function<void(Node* target, std::shared_ptr<Brush>& brush)> on_brush_changed;