grid-cell expects screen coordinates and draws the enclosing cell. size of grid is the size of the cell.

To convert grid coordinates you can call grid/cell->mid or grid/cell->anchor .

I see now that it's not clear enough. I'll update docs and maybe introduce another function for cell coordinates.

(let [grid (grid/grid :flat-hex 20.0)]
  (with-canvas [c (canvas 600 600)]
    (set-background c 0)
    (doseq [q (range 0 20)                    
            r (range 0 20)
            :let [m (grid/cell->anchor grid q r)]]
      (-> c (grid-cell grid (m 0) (m 1) true)))
    (show-window {:canvas c})))

Today I'll deploy a snapshot which will introduce grid-qr-cell function.

(let [grid (grid/grid :flat-hex 20.0)]
  (with-canvas [c (canvas 600 600)]
    (set-background c 0)
    (doseq [q (range 0 20)                    
            r (range 0 20)]
      (-> c (grid-qr-cell grid q r true)))
    (show-window {:canvas c})))

Deployed 1.4.5-SNAPSHOT

Thanks for that! I see how it works now.

Is there some simple way to get the grid to align across the top?

Unfortunately, qr coordinates are skewed

Here is the list of other coordinate systems and conversion methods. Maybe I add them soon: https://www.redblobgames.com/grids/hexagons/#coordinates

I figured out how to do the odd-q layout finally 🙂 Thanks for all the help!