Joseph Ferano
afec482722
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.
111 lines
4.6 KiB
Plaintext
111 lines
4.6 KiB
Plaintext
;;;; raylib [core] example - input gestures
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;;;;
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;;;; examples/core/core_input_gestures.c. Needed `fade`, now bound.
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;;;;
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;;;; The C keeps `char gestureStrings[20][32]` and TextCopy's a name into the
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;;;; next slot. Flan has no mutable character buffer and no way to copy into
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;;;; one, but it does not need either: the names are compile-time literals, so
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;;;; the log is a `[20 string]` and a slot holds the literal itself. That is
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;;;; strictly better than the C — no truncation at 32 bytes, no copy — and it
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;;;; is only possible because every string that ever goes into the log is
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;;;; known at compile time. A log of strings the program had BUILT could not be
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;;;; written at all.
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;;;;
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;;;; The C's `switch (currentGesture)` over the ten gesture values is a `cond`
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;;;; of keyword equalities. `get-gesture-detected` answers an `rl/Gesture` and
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;;;; `(= g :tap)` compares against a member by name, checked at compile time —
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;;;; so a typo here is an error and the C's `default: break` has nothing to
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;;;; catch.
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;;;;
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;;;; A slot that has not been written yet holds a zero-length string, because a
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;;;; `defvar` with no initialiser is all-bytes-zero and a string is ptr+len —
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;;;; a null pointer with a length of 0. draw-text draws nothing for it. That is
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;;;; the C's `{ "" }` initialiser arriving by a different route, and it is why
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;;;; resetting the log below only has to reset the counter.
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(import rl "vendor:raylib")
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(defconst screen-width 800)
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(defconst screen-height 450)
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(defconst max-gesture-strings 20)
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(defvar gesture-log [max-gesture-strings string])
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(defvar gestures-count i32)
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(defvar current-gesture rl/Gesture)
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(defvar last-gesture rl/Gesture)
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;; The C's switch, as a function. `:else` is its `default:` — an unnamed
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;; gesture logs the empty string, which draws nothing, which is what falling
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;; through the C's switch without a TextCopy leaves in the slot.
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(defn gesture-name [g rl/Gesture] string
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(cond
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(= g :tap) "GESTURE TAP"
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(= g :double-tap) "GESTURE DOUBLETAP"
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(= g :hold) "GESTURE HOLD"
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(= g :drag) "GESTURE DRAG"
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(= g :swipe-right) "GESTURE SWIPE RIGHT"
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(= g :swipe-left) "GESTURE SWIPE LEFT"
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(= g :swipe-up) "GESTURE SWIPE UP"
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(= g :swipe-down) "GESTURE SWIPE DOWN"
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(= g :pinch-in) "GESTURE PINCH IN"
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(= g :pinch-out) "GESTURE PINCH OUT"
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:else ""))
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(defn main []
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(rl/init-window screen-width screen-height
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"raylib [core] example - input gestures")
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(defer (rl/close-window))
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(rl/set-target-fps 60)
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(let [touch-area (rl/Rectangle {:x 220.0 :y 10.0
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:width (- (f32 screen-width) 230.0)
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:height (- (f32 screen-height) 20.0)})]
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(until (rl/window-should-close?)
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;; Update
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(set last-gesture current-gesture)
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(set current-gesture (rl/get-gesture-detected))
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(let [touch (rl/get-touch-position 0)]
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(when (and (rl/collision-point-rec? touch touch-area)
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(not (= current-gesture :none))
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(not (= current-gesture last-gesture)))
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(set (at gesture-log gestures-count) (gesture-name current-gesture))
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(set gestures-count (+ gestures-count 1))
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;; Full: start over. The stale slots below the counter are never
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;; drawn, so they do not have to be cleared the way the C clears
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;; them — the loop below is bounded by gestures-count.
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(when (>= gestures-count max-gesture-strings)
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(set gestures-count 0)))
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;; Draw
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(rl/begin-drawing)
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(rl/clear-background rl/raywhite)
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(rl/draw-rectangle-rec touch-area rl/gray)
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(rl/draw-rectangle 225 15 (- screen-width 240) (- screen-height 30)
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rl/raywhite)
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(rl/draw-text "GESTURES TEST AREA" (- screen-width 270)
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(- screen-height 40) 20 (rl/fade rl/gray 0.5))
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(dotimes [i gestures-count]
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(if (= 0 (% i 2))
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(rl/draw-rectangle 10 (+ 30 (* 20 i)) 200 20
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(rl/fade rl/lightgray 0.5))
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(rl/draw-rectangle 10 (+ 30 (* 20 i)) 200 20
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(rl/fade rl/lightgray 0.3)))
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;; The newest entry in maroon and the rest in dark grey, as the C
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;; has it.
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(rl/draw-text (at gesture-log i) 35 (+ 36 (* 20 i)) 10
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(if (< i (- gestures-count 1)) rl/darkgray rl/maroon)))
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(rl/draw-rectangle-lines 10 29 200 (- screen-height 50) rl/gray)
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(rl/draw-text "DETECTED GESTURES" 50 15 10 rl/gray)
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(unless (= current-gesture :none)
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(rl/draw-circle-v touch 30.0 rl/maroon))
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(rl/end-drawing)))))
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