73 lines
3.1 KiB
Plaintext
73 lines
3.1 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 `defonce` 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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(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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(defonce 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/with-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). This used to need examples/digits.flan
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;; and a table of one-character strings; (string b) makes the
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;; number a string with no instructions, so it is one draw-text and
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;; this file imports nothing but raylib.
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(rl/draw-text (str (i64->bytes (i64 i)))
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(- (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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;; The numbers drawn this frame were formatted into the temp allocator;
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;; this hands that memory back once the frame is drawn.
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(free-temp))))
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