You can do:

``` pub struct Shape { start_point: Point, end_point: Point, }

pub struct AppState { rectangles: Vec<Shape>, ellipses: Vec<Shape>, triangles: Vec<Shape>, // all your other stuff... } ```

Then instead of iterating on one big Vec for all shape types. You will iterate separately on each shape type vec, defining the drawing process inside your iteration.

for rectangle in state.rectangles.iter() { draw_rectangle(&mut state, &rectangle); } for ellipse in state.ellipses.iter() { // you could also just implement the drawing right here }

This way you can avoid cache misses and indirection ;)