flan/examples/models-box-collisions.flan
Joseph Ferano 52e9c92b0f The enum prefix goes uniform across all eleven
The author's ruling: "I think the prefix reads better, keep it" — so two
prefixed enums out of eleven was the inconsistency, not the prefix.
TraceLogLevel takes log-, CameraProjection projection-, CameraMode camera-,
GamepadButton button-, GamepadAxis axis-, Gesture gesture-, MouseCursor
cursor-, TextureFilter filter-, PixelFormat pixel-.

Two of those are judgement. CameraProjection and CameraMode share raylib's
CAMERA_ and deliberately do not share a Flan prefix: they are two questions
asked of the same struct, and :projection-perspective beside :camera-orbital
says which is being answered. GamepadButton and GamepadAxis take the short
stems rather than a shared gamepad-, which keeps :button-left-face-up and
:axis-left-trigger readable.

It is a reading choice and not a collision fix, and bindings, raylib.flan and
docs/BUILT.md all say so: a keyword resolves against the expected type and
nothing else, so :point at a TextureFilter site was never ambiguous. What the
prefix buys is the call site read on its own.

The three constant exception lines are keyed on the member's full Flan
spelling and moved with it. flan generate-c vendor/raylib is green against
raylib-5.5.h, and the check was confirmed non-vacuous by breaking it:
filter-trilinearr reported TEXTURE_FILTER_TRILINEARR rather than passing.
test_flan pins one member of each of the eleven to the C name the rule
reaches, read out of the real bindings file.

sand.flan line 121 is (rl/set-trace-log-level :warning) and is the author's
to respell. TraceLogLevel carries a warning alias beside log-warning, mapped
by name in bindings, so the suite stays green until he does; FIX.org has the
three-edit removal recipe.
2026-09-21 07:59:48 +07:00

130 lines
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;;;; raylib [models] example - box collisions
;;;;
;;;; examples/models/models_box_collisions.c. The previous lane's finding was
;;;; that the whole models category is refused by the importer for want of a
;;;; defstruct, and that a models example is therefore mostly a binding
;;;; exercise. That is true of the twenty that load a Model — but not of this
;;;; one, which is why it is here: nothing in it is a Model, a Mesh or a
;;;; Material. It is two cubes, a sphere and one aggregate the package did not
;;;; describe.
;;;;
;;;; That aggregate is BoundingBox, and it is two Vector3s and nothing else —
;;;; no owned pointer, no array, no lifetime. One `defstruct` in
;;;; vendor/raylib/raylib.flan un-refuses four raylib functions at once
;;;; (CheckCollisionBoxes, CheckCollisionBoxSphere, DrawBoundingBox and
;;;; GetRayCollisionBox), and that is the cheapest widening of the 3D surface
;;;; available anywhere in the tree. Ray and RayCollision went in beside it
;;;; for examples/core-3d-picking.flan and for the same reason.
;;;;
;;;; So the answer to "is a models example just a binding exercise" is: the
;;;; ones that need Model are, and this one is the counterexample. What
;;;; separates them is not the category, it is whether the struct owns memory.
;;;;
;;;; What it also exercises, and what needed hand-writing rather than
;;;; generating: draw-cube-v, draw-sphere and draw-sphere-wires. All three
;;;; were in the generated half already, and all three moved to the
;;;; hand-written one here on `bindings`'s own rule — they are inside a frame,
;;;; in an example that ships in examples/. draw-cube-v in particular was
;;;; named there as generated *because nothing called it*; something calls it
;;;; now.
;;;;
;;;; The collision maths is written twice in the C, once per test, building
;;;; the player's box inline both times. It is a function here for the reason
;;;; the eyes example gives: two copies of the same eight expressions cannot
;;;; be checked against each other by reading them.
(import rl "vendor:raylib")
(defconst screen-width 800)
(defconst screen-height 450)
(defonce camera rl/Camera3D)
(defonce player-position rl/Vector3)
(defonce player-size rl/Vector3)
(defonce player-color rl/Color)
(defonce enemy-box-pos rl/Vector3)
(defonce enemy-box-size rl/Vector3)
(defonce enemy-sphere-pos rl/Vector3)
(defconst enemy-sphere-size f32 1.5)
;; A box centred on `centre` with the given extents. raylib's BoundingBox is
;; min-corner/max-corner, not centre/size, and every collision call in the
;; family takes the corner form — so this is the conversion the C writes out
;; longhand at each of its two call sites.
;;
;; It used to be eight expressions of field arithmetic here too; it is the
;; half-extent subtracted and added now that the package carries vector
;; arithmetic — see vendor/raylib/vector.flan, which is Flan and not C
;; because raymath is `static inline` and has no symbol to bind.
(defn box-around [centre rl/Vector3 size rl/Vector3] rl/BoundingBox
(let [half (rl/v3-scale size 0.5)]
(rl/BoundingBox {.min (rl/v3-sub centre half)
.max (rl/v3-add centre half)})))
(defn main [] ()
(rl/init-window screen-width screen-height
"raylib [models] example - box collisions")
(defer (rl/close-window))
;; The C writes this camera as a brace initialiser with a trailing 0 for the
;; projection, which is CAMERA_PERSPECTIVE. Named here, because the defenum
;; exists precisely so that the 0 does not have to be remembered.
(set camera (rl/Camera3D {.position (rl/Vector3 {.x 0.0 .y 10.0 .z 10.0})
.target (rl/Vector3 {.x 0.0 .y 0.0 .z 0.0})
.up (rl/Vector3 {.x 0.0 .y 1.0 .z 0.0})
.fovy 45.0
.projection :projection-perspective}))
(set player-position (rl/Vector3 {.x 0.0 .y 1.0 .z 2.0}))
(set player-size (rl/Vector3 {.x 1.0 .y 2.0 .z 1.0}))
(set player-color rl/green)
(set enemy-box-pos (rl/Vector3 {.x -4.0 .y 1.0 .z 0.0}))
(set enemy-box-size (rl/Vector3 {.x 2.0 .y 2.0 .z 2.0}))
(set enemy-sphere-pos (rl/Vector3 {.x 4.0 .y 0.0 .z 0.0}))
(rl/set-target-fps 60)
(until (rl/window-should-close?)
;; Update. The arrow keys move on the XZ plane, and the C's else-if chain
;; means only one direction applies per frame — diagonal movement is not
;; possible, deliberately.
(cond
(rl/key-down? :key-right) (set (.x player-position) (+ (.x player-position) 0.2))
(rl/key-down? :key-left) (set (.x player-position) (- (.x player-position) 0.2))
(rl/key-down? :key-down) (set (.z player-position) (+ (.z player-position) 0.2))
(rl/key-down? :key-up) (set (.z player-position) (- (.z player-position) 0.2)))
(let [player-box (box-around player-position player-size)
hit (or (rl/check-collision-boxes player-box
(box-around enemy-box-pos enemy-box-size))
(rl/check-collision-box-sphere player-box enemy-sphere-pos
enemy-sphere-size))]
(set player-color (if hit rl/red rl/green)))
;; Draw
(rl/with-drawing
(rl/clear-background rl/raywhite)
(rl/with-mode-3d camera
(rl/draw-cube enemy-box-pos (.x enemy-box-size) (.y enemy-box-size)
(.z enemy-box-size) rl/gray)
(rl/draw-cube-wires enemy-box-pos (.x enemy-box-size) (.y enemy-box-size)
(.z enemy-box-size) rl/darkgray)
;; draw-sphere is draw-sphere-ex at 16 rings and 16 slices; the wires form
;; takes them because the tessellation is only visible in the wireframe.
(rl/draw-sphere enemy-sphere-pos enemy-sphere-size rl/gray)
(rl/draw-sphere-wires enemy-sphere-pos enemy-sphere-size 16 16 rl/darkgray)
(rl/draw-cube-v player-position player-size player-color)
(rl/draw-grid 10 1.0))
(rl/draw-text "Move player with arrow keys to collide" 220 40 20 rl/gray)
(rl/draw-fps 10 10))))