implementing better triangulation

engine/canvas_modes.h

@@ -2,6 +2,7 @@
 #include "event.h"
 #include "shape.h"
 #include "brush.h"
+#include <poly2tri.h>
 
 NS_START
 class Canvas;
@@ -100,4 +101,5 @@ public:
     virtual void on_MouseEvent(MouseEvent* me, glm::vec2& loc) override;
     virtual void init() override;
     virtual void leave() override;
+    std::vector<ui::Shape::vertex_t> triangulate(const std::vector<std::shared_ptr<p2t::Point>>& points);
 };