diff --git a/include/twn_draw.h b/include/twn_draw.h
index 3016507..137c406 100644
--- a/include/twn_draw.h
+++ b/include/twn_draw.h
@@ -47,6 +47,7 @@ TWN_API void draw_line(Vec2 start,
                        float thickness, /* optional, default: 1 */
                        Color color);    /* optional, default: all 255 */
 
+/* TODO: combine with draw_rectangle()? */
 TWN_API void draw_box(Rect rect,
                       float thickness,  /* optional, default: 1 */
                       Color color);     /* optional, default: all 255 */
@@ -64,6 +65,7 @@ TWN_API void draw_triangle(char const *texture,
                            Color       c1,      /* optional, default: all 255 */
                            Color       c2);     /* optional, default: all 255 */
 
+/* TODO: double sided option */
 TWN_API void draw_quad(char const *texture,
                        Vec3        v0,          /* upper-left */
                        Vec3        v1,          /* bottom-left */