flan/vendor/raylib/raylib.flan

;;;; raylib, declared for Flan. The directory is the package (plan.org,
;;;; Modules), and (import rl "vendor:raylib") qualifies all of it as rl/…
;;;;
;;;; Nothing here names a raylib symbol. Every `declare` names a wrapper in
;;;; shim.c, and that is the whole design decision: raylib passes Color by
;;;; value and returns Vector2 by value, and how a small aggregate is passed
;;;; differs between x86-64, arm64 and wasm32. Written in C, clang classifies
;;;; each one correctly per target for free; written in emit.ml it would be
;;;; three calling conventions to reimplement and then maintain forever. This
;;;; is "one narrow host ABI, implemented twice" (plan.org, Targets), and it
;;;; is why the checker rejects an aggregate in a `declare` signature at all.
;;;;
;;;; So each struct that crosses does it through a pointer, and the `-raw`
;;;; declaration is wrapped by an ordinary Flan function just below it. The
;;;; `-raw` names are visible as rl/…-raw because there is no visibility rule
;;;; yet; they are not meant to be called.

;; Layouts are C's — no object headers anywhere — so these are exactly
;; raylib's structs and nothing marshals.
(defstruct Vector2 [x f32  y f32])
(defstruct Color   [r u8  g u8  b u8  a u8])

;; Texture2D is five 4-byte fields in a row, which is the layout most likely
;; to be silently wrong: permute two of them and every field still reads as a
;; plausible number. Rectangle is four floats in x/y/width/height order.
(defstruct Texture2D [id u32  width i32  height i32  mipmaps i32  format i32])
(defstruct Rectangle [x f32  y f32  width f32  height f32])

;; KeyboardKey, the subset sand.flan uses. A keyword at a call site resolves
;; against these members at compile time and a typo is an error there.
(defenum Key
  [space 32  apostrophe 39  comma 44  minus 45  period 46  slash 47
   zero 48  one 49  two 50  three 51  four 52
   five 53  six 54  seven 55  eight 56  nine 57
   a 65  b 66  c 67  d 68  e 69  f 70  g 71  h 72  i 73
   j 74  k 75  l 76  m 77  n 78  o 79  p 80  q 81  r 82
   s 83  t 84  u 85  v 86  w 87  x 88  y 89  z 90
   escape 256  enter 257  tab 258  backspace 259
   right 262  left 263  down 264  up 265])

(defenum MouseButton
  [left 0  right 1  middle 2  side 3  extra 4  forward 5  back 6])

(defenum TraceLogLevel
  [all 0  trace 1  debug 2  info 3  warning 4  error 5  fatal 6  none 7])

;; ── Window ──────────────────────────────────────────────────────────

(declare init-window [width i32  height i32  title string] "flan_rl_init_window")
(declare close-window [] "flan_rl_close_window")
(declare window-should-close? [] bool "flan_rl_window_should_close")
(declare set-target-fps [fps i32] "flan_rl_set_target_fps")
(declare set-trace-log-level [level TraceLogLevel] "flan_rl_set_trace_log_level")

;; ── Input ───────────────────────────────────────────────────────────

(declare key-pressed?  [key Key] bool "flan_rl_is_key_pressed")
(declare key-down?     [key Key] bool "flan_rl_is_key_down")
(declare key-released? [key Key] bool "flan_rl_is_key_released")

(declare mouse-button-pressed?  [button MouseButton] bool
  "flan_rl_is_mouse_button_pressed")
(declare mouse-button-down?     [button MouseButton] bool
  "flan_rl_is_mouse_button_down")
(declare mouse-button-released? [button MouseButton] bool
  "flan_rl_is_mouse_button_released")

(declare get-mouse-position-raw [out (Ptr Vector2)] "flan_rl_get_mouse_position")

(defn get-mouse-position [] Vector2
  (let [v (Vector2 {})]
    (get-mouse-position-raw (addr v))
    v))

;; ── Colours ─────────────────────────────────────────────────────────
;;
;; A Color is four bytes in RGBA order, so it is *not* the little-endian
;; reading of the packed 0xRRGGBBAA integer — that is why get-color is a real
;; call and not a reinterpretation.

(declare get-color-raw [hex u32  out (Ptr Color)] "flan_rl_get_color")

(defn get-color [hex u32] Color
  (let [c (Color {})]
    (get-color-raw hex (addr c))
    c))

(defconst black (Color {:r 0 :g 0 :b 0 :a 255}))
(defconst white (Color {:r 255 :g 255 :b 255 :a 255}))

;; ── Drawing ─────────────────────────────────────────────────────────

(declare begin-drawing [] "flan_rl_begin_drawing")
(declare end-drawing [] "flan_rl_end_drawing")
(declare draw-fps [x i32  y i32] "flan_rl_draw_fps")

(declare clear-background-raw [color (Ptr Color)] "flan_rl_clear_background")

(defn clear-background [color Color]
  ;; The copy is not ceremony: a parameter is not an assignable place
  ;; (spec-memory.md), so there is no address to take without one.
  (let [c color]
    (clear-background-raw (addr c))))

(declare draw-rectangle-raw
  [x i32  y i32  width i32  height i32  color (Ptr Color)]
  "flan_rl_draw_rectangle")

(defn draw-rectangle [x i32  y i32  width i32  height i32  color Color]
  (let [c color]
    (draw-rectangle-raw x y width height (addr c))))

;; ── Shapes texture ──────────────────────────────────────────────────
;;
;; raylib draws every shape from one atlas texture, and this pair sets and
;; reads it. It is bound here for a second reason: it is the only part of the
;; API that stores a Texture2D and a Rectangle and hands them back without
;; touching the GPU, so it is how the acceptance table checks both layouts
;; headlessly. Everything else that takes a texture needs a GL context.
;;
;; raylib substitutes a default ({1,1,1,1,7} / {0,0,1,1}) when the id or the
;; source's width or height is not positive, so a caller — and the test —
;; should keep clear of those values if it wants its own back.

(declare set-shapes-texture-raw
  [texture (Ptr Texture2D)  source (Ptr Rectangle)]
  "flan_rl_set_shapes_texture")

(defn set-shapes-texture [texture Texture2D  source Rectangle]
  (let [t texture
        r source]
    (set-shapes-texture-raw (addr t) (addr r))))

(declare get-shapes-texture-raw [out (Ptr Texture2D)] "flan_rl_get_shapes_texture")

(defn get-shapes-texture [] Texture2D
  (let [t (Texture2D {})]
    (get-shapes-texture-raw (addr t))
    t))

(declare get-shapes-texture-rectangle-raw
  [out (Ptr Rectangle)] "flan_rl_get_shapes_texture_rectangle")

(defn get-shapes-texture-rectangle [] Rectangle
  (let [r (Rectangle {})]
    (get-shapes-texture-rectangle-raw (addr r))
    r))

;; ── Camera2D ────────────────────────────────────────────────────────
;;
;; The 2D camera: everything drawn between begin-mode-2d and end-mode-2d is
;; transformed by it. `offset` is where the camera's target lands on screen —
;; half the window size is what centres it — `target` is the world point that
;; goes there, and rotation is in degrees.
;;
;; `zoom` of 0 makes the transform singular and both conversions below hand
;; back NaN rather than failing. raylib does not guard it and neither does
;; this; 1.0 is the identity and a fresh (Camera2D {}) is therefore NOT usable
;; as one — it has to be given a zoom.

(defstruct Camera2D [offset Vector2  target Vector2  rotation f32  zoom f32])

(declare begin-mode-2d-raw [camera (Ptr Camera2D)] "flan_rl_begin_mode_2d")

(defn begin-mode-2d [camera Camera2D]
  (let [c camera]
    (begin-mode-2d-raw (addr c))))

(declare end-mode-2d [] "flan_rl_end_mode_2d")

;; The two conversions are pure arithmetic over every field of the camera, so
;; unlike the rest of the camera they run with no window and no GL context.
;; That is what the acceptance table uses to pin Camera2D's layout, and — via
;; a rotated camera, which is the only call here that mixes x into y — it is
;; also the only thing that pins Vector2's two fields against each other.

(declare get-screen-to-world-2d-raw
  [position (Ptr Vector2)  camera (Ptr Camera2D)  out (Ptr Vector2)]
  "flan_rl_get_screen_to_world_2d")

(defn get-screen-to-world-2d [position Vector2  camera Camera2D] Vector2
  (let [p position
        c camera
        out (Vector2 {})]
    (get-screen-to-world-2d-raw (addr p) (addr c) (addr out))
    out))

(declare get-world-to-screen-2d-raw
  [position (Ptr Vector2)  camera (Ptr Camera2D)  out (Ptr Vector2)]
  "flan_rl_get_world_to_screen_2d")

(defn get-world-to-screen-2d [position Vector2  camera Camera2D] Vector2
  (let [p position
        c camera
        out (Vector2 {})]
    (get-world-to-screen-2d-raw (addr p) (addr c) (addr out))
    out))

;; ── Shapes ──────────────────────────────────────────────────────────
;;
;; Rectangle intersection, which raylib computes from all four fields in
;; different ways. It is the one Rectangle call that needs no GPU, so it is
;; also how the acceptance table pins the layout: a store-and-return check is
;; symmetric and a permuted layout survives it untouched.

(declare get-collision-rec-raw
  [a (Ptr Rectangle)  b (Ptr Rectangle)  out (Ptr Rectangle)]
  "flan_rl_get_collision_rec")

(defn get-collision-rec [a Rectangle  b Rectangle] Rectangle
  (let [x a
        y b
        out (Rectangle {})]
    (get-collision-rec-raw (addr x) (addr y) (addr out))
    out))

;; ── Textures ────────────────────────────────────────────────────────
;;
;; Everything here needs a GL context, so a window has to be open first —
;; load-texture before init-window returns an id of 0 and raylib says so on
;; the log. texture-valid? is how that is noticed in the program rather than
;; only in the log; raylib 5.5 spells it IsTextureValid, and IsTextureReady,
;; which older code calls, does not exist in this version.

(declare load-texture-raw [path string  out (Ptr Texture2D)] "flan_rl_load_texture")

(defn load-texture [path string] Texture2D
  (let [t (Texture2D {})]
    (load-texture-raw path (addr t))
    t))

(declare texture-valid?-raw [texture (Ptr Texture2D)] bool "flan_rl_is_texture_valid")

(defn texture-valid? [texture Texture2D] bool
  (let [t texture]
    (texture-valid?-raw (addr t))))

(declare unload-texture-raw [texture (Ptr Texture2D)] "flan_rl_unload_texture")

(defn unload-texture [texture Texture2D]
  (let [t texture]
    (unload-texture-raw (addr t))))

(declare draw-texture-raw
  [texture (Ptr Texture2D)  x i32  y i32  tint (Ptr Color)]
  "flan_rl_draw_texture")

(defn draw-texture [texture Texture2D  x i32  y i32  tint Color]
  (let [t texture
        c tint]
    (draw-texture-raw (addr t) x y (addr c))))

(declare draw-texture-v-raw
  [texture (Ptr Texture2D)  position (Ptr Vector2)  tint (Ptr Color)]
  "flan_rl_draw_texture_v")

(defn draw-texture-v [texture Texture2D  position Vector2  tint Color]
  (let [t texture
        p position
        c tint]
    (draw-texture-v-raw (addr t) (addr p) (addr c))))

(declare draw-texture-ex-raw
  [texture (Ptr Texture2D)  position (Ptr Vector2)  rotation f32  scale f32
   tint (Ptr Color)]
  "flan_rl_draw_texture_ex")

(defn draw-texture-ex [texture Texture2D  position Vector2  rotation f32
                       scale f32  tint Color]
  (let [t texture
        p position
        c tint]
    (draw-texture-ex-raw (addr t) (addr p) rotation scale (addr c))))

;; A negative source width or height flips the sprite, which is how a sheet is
;; drawn facing the other way without a second image.
(declare draw-texture-rec-raw
  [texture (Ptr Texture2D)  source (Ptr Rectangle)  position (Ptr Vector2)
   tint (Ptr Color)]
  "flan_rl_draw_texture_rec")

(defn draw-texture-rec [texture Texture2D  source Rectangle  position Vector2
                        tint Color]
  (let [t texture
        s source
        p position
        c tint]
    (draw-texture-rec-raw (addr t) (addr s) (addr p) (addr c))))