;;;; raylib [core] example - input mouse wheel
;;;;
;;;; examples/core/core_input_mouse_wheel.c. Needed get-mouse-wheel-move, now
;;;; bound.
;;;;
;;;; This is the first example with a `TextFormat` in it. The C draws
;;;;
;;;;     DrawText(TextFormat("Box position Y: %03i", boxPositionY), ...)
;;;;
;;;; and the number half of that is now sayable: (string (i64->bytes n)).
;;;; What is not is the "%03" — i64->bytes has no field width — so the label
;;;; is drawn with draw-text and the number with draw-int-padded from
;;;; examples/digits.flan, which draws the leading zeroes itself and then the
;;;; number in one call. A number wider than three digits is drawn in full,
;;;; exactly as printf's minimum-width means.
;;;;
;;;; The position is signed and goes negative as soon as the box scrolls past
;;;; the top, which is why draw-int-padded handles a sign at all.

(import rl "vendor:raylib")
(import d  "digits.flan")

(defconst screen-width  800)
(defconst screen-height 450)

(defconst scroll-speed 4)

(defvar box-y i32)

(defn main [] ()
  (rl/init-window screen-width screen-height
                  "raylib [core] example - input mouse wheel")
  (defer (rl/close-window))

  (set box-y (- (/ screen-height 2) 40))

  (rl/set-target-fps 60)

  (until (rl/window-should-close?)
    ;; Update. The wheel reading is a per-frame delta, so it is 0.0 on every
    ;; frame the wheel did not turn and this is a no-op then.
    (set box-y (- box-y (i32 (* (rl/get-mouse-wheel-move) (f32 scroll-speed)))))

    ;; Draw
    (rl/with-drawing
      (rl/clear-background rl/raywhite)
      (rl/draw-rectangle (- (/ screen-width 2) 40) box-y 80 80 rl/maroon)
      (rl/draw-text "Use mouse wheel to move the cube up and down!" 10 10 20
                    rl/gray)
      ;; The two halves of the C's one TextFormat call: the literal, measured,
      ;; and then the number starting where it ended.
      (rl/draw-text "Box position Y: " 10 40 20 rl/lightgray)
      (d/draw-int-padded box-y 3 (+ 10 (rl/measure-text "Box position Y: " 20))
                         40 20 rl/lightgray))))