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.
70 lines
2.9 KiB
Plaintext
70 lines
2.9 KiB
Plaintext
;;;; raylib [core] example - input multitouch
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;;;;
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;;;; examples/core/core_input_multitouch.c. No new bindings: the whole touch
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;;;; surface was already there for sand.flan's read-out.
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;;;;
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;;;; The C keeps `Vector2 touchPositions[MAX_TOUCH_POINTS]`, and this is the
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;;;; first example that needs a fixed array whose element type is a STRUCT
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;;;; rather than a number. That works — `[10 rl/Vector2]` is ten Vector2s laid
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;;;; out flat, no headers, and `(at touch-positions i)` is a place that can be
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;;;; assigned a whole struct. Nothing in the repository used one before, so it
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;;;; is worth saying that it does.
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;;;;
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;;;; It is a top-level `defvar` and not a local, which is NOT a stylistic
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;;;; choice. A `let` binding takes no type annotation, so the only way to make
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;;;; a fixed array inside a function is to initialise it from a literal with
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;;;; every element written out — ten `(rl/Vector2 {:x 0.0 :y 0.0})`s here, and
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;;;; thirty-two in the gestures testbed. A zeroed local array of a given type
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;;;; cannot be spelled. Static storage is what the C's `= { 0 }` gets anyway.
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;;;;
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;;;; On a desktop with no touchscreen get-touch-point-count is 0 and this draws
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;;;; nothing at all, which is correct and is also what the C does. The window
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;;;; opening and the help text appearing is the whole of what can be checked
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;;;; without hardware.
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(import rl "vendor:raylib")
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(import d "digits.flan")
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(defconst screen-width 800)
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(defconst screen-height 450)
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(defconst max-touch-points 10)
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(defvar touch-positions [max-touch-points rl/Vector2])
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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 multitouch")
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(defer (rl/close-window))
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(rl/set-target-fps 60)
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(until (rl/window-should-close?)
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;; Update
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(let [count (min max-touch-points (rl/get-touch-point-count))]
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(dotimes [i count]
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(set (at touch-positions i) (rl/get-touch-position i)))
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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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(dotimes [i count]
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(let [p (at touch-positions i)]
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;; raylib reports (0,0) for a slot that is not being touched, so the
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;; C filters on it and so does this. It means a real touch in the
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;; very top-left corner is dropped; that is raylib's ambiguity, not
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;; something the port introduced.
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(when (and (> (.x p) 0.0) (> (.y p) 0.0))
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(rl/draw-circle-v p 34.0 rl/orange)
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;; The C's TextFormat("%d", i) — one digit, drawn by the shared
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;; helper rather than by a codepoint call, so every number on
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;; screen in these ten files goes through the same path.
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(d/draw-int i (- (i32 (.x p)) 10) (- (i32 (.y p)) 70) 40
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rl/black))))
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(rl/draw-text "touch the screen at multiple locations to get multiple balls"
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10 10 20 rl/darkgray)
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(rl/end-drawing))))
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