;;;; raylib [core] example - input multitouch
;;;;
;;;; examples/core/core_input_multitouch.c. No new bindings: the whole touch
;;;; surface was already there for sand.flan's read-out.
;;;;
;;;; The C keeps `Vector2 touchPositions[MAX_TOUCH_POINTS]`, and this is the
;;;; first example that needs a fixed array whose element type is a STRUCT
;;;; rather than a number. That works — `[10 rl/Vector2]` is ten Vector2s laid
;;;; out flat, no headers, and `(at touch-positions i)` is a place that can be
;;;; assigned a whole struct. Nothing in the repository used one before, so it
;;;; is worth saying that it does.
;;;;
;;;; It is a top-level `defvar` and not a local, which is NOT a stylistic
;;;; choice. A `let` binding takes no type annotation, so the only way to make
;;;; a fixed array inside a function is to initialise it from a literal with
;;;; every element written out — ten `(rl/Vector2 {.x 0.0 .y 0.0})`s here, and
;;;; thirty-two in the gestures testbed. A zeroed local array of a given type
;;;; cannot be spelled. Static storage is what the C's `= { 0 }` gets anyway.
;;;;
;;;; On a desktop with no touchscreen get-touch-point-count is 0 and this draws
;;;; nothing at all, which is correct and is also what the C does. The window
;;;; opening and the help text appearing is the whole of what can be checked
;;;; without hardware.

(import rl "vendor:raylib")

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

(defconst max-touch-points 10)

(defvar touch-positions [max-touch-points rl/Vector2])

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

  (rl/set-target-fps 60)

  (until (rl/window-should-close?)
    ;; Update
    (let [count (min max-touch-points (rl/get-touch-point-count))]
      (dotimes [i count]
        (set (at touch-positions i) (rl/get-touch-position i)))

      ;; Draw
      (rl/with-drawing
        (rl/clear-background rl/raywhite)

        (dotimes [i count]
          (let [p (at touch-positions i)]
            ;; raylib reports (0,0) for a slot that is not being touched, so the
            ;; C filters on it and so does this. It means a real touch in the
            ;; very top-left corner is dropped; that is raylib's ambiguity, not
            ;; something the port introduced.
            (when (and (> (.x p) 0.0) (> (.y p) 0.0))
              (rl/draw-circle-v p 34.0 rl/orange)
              ;; The C's TextFormat("%d", i). This used to need examples/digits.flan
              ;; and a table of one-character strings; (string b) makes the
              ;; number a string with no instructions, so it is one draw-text and
              ;; this file imports nothing but raylib.
              (rl/draw-text (string (i64->bytes (i64 i)))
                            (- (i32 (.x p)) 10) (- (i32 (.y p)) 70) 40
                            rl/black))))

        (rl/draw-text "touch the screen at multiple locations to get multiple balls"
                      10 10 20 rl/darkgray)))))