Add quad drawing utilities

include/window.h

@@ -10,6 +10,7 @@
 typedef struct point point_t;
 typedef struct line line_t;
 typedef struct triangle triangle_t;
+typedef struct gquad gquad_t;
 typedef struct rect rect_t;
 typedef struct window window_t;
 
@@ -29,6 +30,13 @@ struct triangle {
   point_t p2;
 };
 
+struct gquad {
+  point_t p0;
+  point_t p1;
+  point_t p2;
+  point_t p3;
+};
+
 struct rect {
   point_t topleft;
   i32 w;
@@ -63,6 +71,8 @@ void draw_point(const window_t *wnd, point_t p, colour_t colour);
 void draw_line(const window_t *wnd, const line_t *ln, colour_t colour);
 void draw_triangle(const window_t *wnd, triangle_t triangle, colour_t colour);
 void fill_triangle(const window_t *wnd, triangle_t triangle, colour_t colour);
+void draw_gquad(const window_t *wnd, gquad_t gquad, colour_t colour);
+void fill_gquad(const window_t *wnd, gquad_t gquad, colour_t colour);
 void draw_rect(const window_t *wnd, rect_t rect, colour_t colour);
 void fill_rect(const window_t *wnd, rect_t rect, colour_t colour);