66 lines
3.0 KiB
Plaintext
66 lines
3.0 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.fln'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 `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 `once` 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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const screen-width = 800
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const screen-height = 450
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const max-touch-points = 10
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once touch-positions: [max-touch-points rl/Vector2]
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fn 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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for i in range(count)
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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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for i in range(count)
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let p = 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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if p.x > 0.0 and p.y > 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.fln
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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))), i32(p.x) - 10, i32(p.y) - 70,
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40, 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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