flan/examples/core-input-mouse.flan
Joseph Ferano afec482722 Ten raylib examples, and what they could not say
The first ten of raylib's core list, ported. Seven new bindings and the
named colour palette; nothing else was added, because a binding called
by nothing is the same as not having bound it.

The gaps they found are the point. No number reaches draw-text: i64->bytes
answers [u8], draw-text wants a string, and nothing bridges — five of the
ten wanted TextFormat and got a glyph table instead. And an enum parameter
cannot be driven by a loop variable: the index is an i32, the parameter is
an enum, neither converts, and a second declare-c with an i32 face is
refused because one C function gets one binding. Two correct rules that
compose into a wall.

None of the gaps expected blocked anything: no generics, no allocator, no
Vec, no escaping closure, no block-scoped defer. These are input-and-draw
programs over fixed-size state, which is the shape the language has.
2026-09-12 05:06:01 +07:00

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;;;; raylib [core] example - input mouse
;;;;
;;;; examples/core/core_input_mouse.c. Needed three new bindings — show-cursor,
;;;; hide-cursor and cursor-hidden? — which are now in vendor/raylib.
;;;;
;;;; The C's `else if` chain over the seven mouse buttons is a `cond` here.
;;;; That is not a workaround: `cond` is what Flan has and it is the same
;;;; first-match-wins shape, with `:else` where C falls off the end. The order
;;;; matters in both — two buttons pressed on the same frame give the earlier
;;;; one, which is the C's behaviour and not an accident of the port.
;;;;
;;;; The colour has to be a `defvar` rather than a `let`, for the reason
;;;; core-input-keys' position does: it is state between frames.
(import rl "vendor:raylib")
(defconst screen-width 800)
(defconst screen-height 450)
(defvar ball-color rl/Color)
(defn main []
(rl/init-window screen-width screen-height
"raylib [core] example - input mouse")
(defer (rl/close-window))
;; The C also initialises the ball's POSITION, to {-100,-100} so it starts
;; off-screen. That is dead there and is not here: the first thing the loop
;; does is overwrite it with get-mouse-position, before anything is drawn.
(set ball-color rl/darkblue)
(rl/set-target-fps 60)
(until (rl/window-should-close?)
;; Update
(when (rl/key-pressed? :h)
(if (rl/cursor-hidden?) (rl/show-cursor) (rl/hide-cursor)))
(let [ball (rl/get-mouse-position)]
(set ball-color
(cond
(rl/mouse-button-pressed? :left) rl/maroon
(rl/mouse-button-pressed? :middle) rl/lime
(rl/mouse-button-pressed? :right) rl/darkblue
(rl/mouse-button-pressed? :side) rl/purple
(rl/mouse-button-pressed? :extra) rl/yellow
(rl/mouse-button-pressed? :forward) rl/orange
(rl/mouse-button-pressed? :back) rl/beige
:else ball-color))
;; Draw
(rl/begin-drawing)
(rl/clear-background rl/raywhite)
(rl/draw-circle-v ball 40.0 ball-color)
(rl/draw-text "move ball with mouse and click mouse button to change color"
10 10 20 rl/darkgray)
(rl/draw-text "Press 'H' to toggle cursor visibility" 10 30 20 rl/darkgray)
(if (rl/cursor-hidden?)
(rl/draw-text "CURSOR HIDDEN" 20 60 20 rl/red)
(rl/draw-text "CURSOR VISIBLE" 20 60 20 rl/lime))
(rl/end-drawing))))