Joseph Ferano
25f56c24a8
vendor/raylib/modes.flan: five macros over the five pairs the package binds -- with-drawing, with-mode-2d, with-mode-3d, with-texture-mode, with-scissor-mode. A second file with no declare-c in it, split out on vector.flan's reasoning: raylib.flan is the package's statement about C and nothing here names C, so nothing here can be made wrong by raylib changing. Each expands to (do (begin-... args) body... (end-...)) -- the calls the author used to type, in the order they typed them. No let, no gensym: nothing binds a name, so there is nothing for a caller's name to collide with. What it removes is the End* that is missing, wrong, or no longer beside its Begin*. What it cannot remove is a body leaving through the unwind path: a return or an invoke-restart skips the rest of the do and the End* with it. defer is the obvious fix and is refused inside a loop body, which is where a pair always lives -- checked, not assumed. So sand.flan's discipline stays: keep the restart boundary outside the pair. 35 call sites converted across examples/ and sand.flan. The one left is core-scissor-test.flan, whose Begin and End sit in two separate `when`s with the drawing between them -- a conditional pair is a shape a bracketing macro cannot express. test/programs/rl-with.flan covers with-scissor-mode, which no example can, with a frame function unreachable from main so it needs no libraylib; rl-with-reject.flan is the arity half.
75 lines
3.1 KiB
Plaintext
75 lines
3.1 KiB
Plaintext
;;;; raylib [text] example - text writing anim
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;;;;
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;;;; examples/text/text_writing_anim.c. Sixty lines of C whose whole substance
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;;;; is one call this package cannot bind:
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;;;;
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;;;; DrawText(TextSubtext(message, 0, framesCounter/10), ...)
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;;;;
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;;;; TextSubtext is in raylib.h and is not in the bindings, on the rule
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;;;; raylib.flan states for the whole Text* family: it answers a `char *` into
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;;;; a rotating static buffer, and declare-c refuses a returned pointer to
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;;;; memory the caller does not own. There is no missing line to add — the
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;;;; binding would be wrong at any signature.
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;;;;
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;;;; And it does not matter, because Flan has the operation as a primitive.
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;;;; `(slice a lo hi)` takes a view of an array, `(string b)` reinterprets the
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;;;; bytes as a string at no cost, and `(string (slice message 0 n))` is
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;;;; TextSubtext with the static buffer removed — no copy, no shared state, no
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;;;; rotation to run out of. Porting the example is therefore how the gap gets
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;;;; *closed* rather than reported: the C's workaround for not having slices
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;;;; is the thing Flan did not need.
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;;;;
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;;;; The one place they differ, and it is why the clamp below is here rather
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;;;; than in the C: TextSubtext clips its length to the string, so the C can
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;;;; pass a counter that runs past the end for ever and see nothing happen.
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;;;; `slice` does not clip — an out-of-range bound is an error, and a bound
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;;;; computed at run time is checked at run time — so the length has to be
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;;;; brought inside the string before the call. That is a better failure than
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;;;; the C's, and it costs one `min`.
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;;;;
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;;;; The message is a `[u8]` and not a `string` because `slice` takes an array
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;;;; or a slice; `(bytes "…")` is the bridge in the other direction from
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;;;; `(string …)` and costs nothing either. The embedded newline is written as
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;;;; an escape, and raylib's draw-text breaks the line on it.
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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 message
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"This sample illustrates a text writing\nanimation effect! Check it out! ;)")
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(defvar frames-counter i32)
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(defn main [] ()
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(rl/init-window screen-width screen-height
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"raylib [text] example - text writing anim")
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(defer (rl/close-window))
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(set frames-counter 0)
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(rl/set-target-fps 60)
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(until (rl/window-should-close?)
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;; Update. Holding space runs the counter eight times faster; enter starts
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;; it over.
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(if (rl/key-down? :space)
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(set frames-counter (+ frames-counter 8))
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(set frames-counter (+ frames-counter 1)))
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(when (rl/key-pressed? :enter) (set frames-counter 0))
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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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;; One character every ten frames. The clamp is the whole difference from
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;; the C — see the header comment.
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(let [b (bytes message)
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n (min (i32 (len b)) (/ frames-counter 10))]
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(rl/draw-text (string (slice b 0 n)) 210 160 20 rl/maroon))
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(rl/draw-text "PRESS [ENTER] to RESTART!" 240 260 20 rl/lightgray)
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(rl/draw-text "HOLD [SPACE] to SPEED UP!" 239 300 20 rl/lightgray))))
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