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.
154 lines
7.0 KiB
Plaintext
154 lines
7.0 KiB
Plaintext
;;;; raylib [core] example - 3d picking
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;;;;
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;;;; examples/core/core_3d_picking.c. The one `core` example in this batch,
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;;;; and it is here for surface and not for category: it is the only example
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;;;; anywhere upstream that uses Ray and RayCollision without also loading a
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;;;; Model, so it is the only way those two structs get a caller at all.
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;;;;
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;;;; Picking is the round trip the corpus was missing. core-world-screen.flan
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;;;; already runs get-world-to-screen — a point in the scene to a pixel. This
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;;;; is the inverse and it is a different shape: a pixel does not name a
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;;;; point, it names a *line* through the scene, which is what a Ray is, and
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;;;; the answer to "what did I click on" is where that line first meets
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;;;; something, which is what a RayCollision is. Two structs the package could
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;;;; not describe, for one operation that cannot be written without them.
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;;;;
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;;;; What was added, all in vendor/raylib/raylib.flan:
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;;;;
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;;;; - `Ray` — two Vector3s, origin and direction.
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;;;; - `RayCollision` — a C `bool`, a float and two Vector3s. This is the
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;;;; one of the three new structs a layout check can actually fail:
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;;;; `hit` is one byte and `distance` is four, so there are three padding
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;;;; bytes between them that a permutation destroys. BoundingBox's two
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;;;; Vector3s are interchangeable and nothing would catch swapping them.
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;;;; - `BoundingBox` — shared with examples/models-box-collisions.flan.
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;;;; - get-screen-to-world-ray and draw-ray, hand-written beside
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;;;; get-world-to-screen and the cube draws for the reasons `bindings`
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;;;; gives: the first reads the same camera as its inverse, and the second
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;;;; is inside a frame.
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;;;;
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;;;; get-ray-collision-box came free out of the generated half the moment Ray
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;;;; and BoundingBox existed, along with the sphere, triangle and quad forms.
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;;;; get-ray-collision-mesh is still refused and will stay refused: Mesh owns
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;;;; seven arrays and a GPU handle, and describing it is a different job.
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;;;;
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;;;; raylib 5.5 renamed GetMouseRay to GetScreenToWorldRay and left the old
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;;;; name as a #define. A #define is not a symbol, so there is nothing to bind
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;;;; it to and nothing lost by not trying.
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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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(defvar camera rl/Camera3D)
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(defvar cube-position rl/Vector3)
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(defvar cube-size rl/Vector3)
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;; The picking ray, kept between frames because draw-ray draws it every frame
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;; whether or not it hit anything — that is how the example shows where the
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;; click went.
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(defvar ray rl/Ray)
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(defvar collision rl/RayCollision)
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;; The same centre/size to min/max conversion as in
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;; examples/models-box-collisions.flan. Written out here rather than shared
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;; because an example is a single file the reader can follow end to end.
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;;
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;; It used to be eight expressions of field arithmetic; it is the half-extent
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;; subtracted and added, which is what the C means, now that the package
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;; carries vector arithmetic — see vendor/raylib/vector.flan. That file
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;; exists because raymath is `static inline` and has no symbol to bind, so
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;; v3-sub and v3-add are Flan and not C.
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(defn box-around [centre rl/Vector3 size rl/Vector3] rl/BoundingBox
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(let [half (rl/v3-scale size 0.5)]
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(rl/BoundingBox {.min (rl/v3-sub centre half)
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.max (rl/v3-add centre half)})))
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(defn main [] ()
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(rl/init-window screen-width screen-height
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"raylib [core] example - 3d picking")
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(defer (rl/close-window))
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(set camera (rl/Camera3D {.position (rl/Vector3 {.x 10.0 .y 10.0 .z 10.0})
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.target (rl/Vector3 {.x 0.0 .y 0.0 .z 0.0})
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.up (rl/Vector3 {.x 0.0 .y 1.0 .z 0.0})
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.fovy 45.0
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.projection :perspective}))
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(set cube-position (rl/Vector3 {.x 0.0 .y 1.0 .z 0.0}))
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(set cube-size (rl/Vector3 {.x 2.0 .y 2.0 .z 2.0}))
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;; Both start zeroed, which is the C's `= { 0 }`. A zero Ray draws as a
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;; degenerate line at the origin and a zero RayCollision has hit false, so
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;; neither needs a "not yet" flag beside it.
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(set ray (rl/Ray {.position (rl/Vector3 {.x 0.0 .y 0.0 .z 0.0})
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.direction (rl/Vector3 {.x 0.0 .y 0.0 .z 0.0})}))
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(set collision (rl/RayCollision {.hit false .distance 0.0
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.point (rl/Vector3 {.x 0.0 .y 0.0 .z 0.0})
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.normal (rl/Vector3 {.x 0.0 .y 0.0 .z 0.0})}))
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(rl/set-target-fps 60)
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(until (rl/window-should-close?)
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;; Update. The first-person controls only run while the cursor is
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;; captured, which is what the right button toggles — otherwise the mouse
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;; could not be used to aim at anything.
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(when (rl/cursor-hidden?) (rl/update-camera (addr camera) :first-person))
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(when (rl/mouse-button-pressed? :right)
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(if (rl/cursor-hidden?) (rl/enable-cursor) (rl/disable-cursor)))
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(when (rl/mouse-button-pressed? :left)
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(if (not (.hit collision))
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;; The pixel under the pointer, as a line through the scene, tested
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;; against the cube's bounds.
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(do
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(set ray (rl/get-screen-to-world-ray (rl/get-mouse-position) camera))
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(set collision
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(rl/get-ray-collision-box ray (box-around cube-position cube-size))))
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;; A second click deselects. Only `hit` is cleared; the ray stays put
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;; and keeps being drawn, as in the C.
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(set (.hit collision) false)))
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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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(rl/with-mode-3d camera
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(if (.hit collision)
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(do
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(rl/draw-cube cube-position (.x cube-size) (.y cube-size) (.z cube-size)
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rl/red)
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(rl/draw-cube-wires cube-position (.x cube-size) (.y cube-size)
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(.z cube-size) rl/maroon)
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;; A slightly larger wireframe around the selection, which is the
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;; whole visual feedback of the example.
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(rl/draw-cube-wires cube-position (+ (.x cube-size) 0.2)
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(+ (.y cube-size) 0.2) (+ (.z cube-size) 0.2)
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rl/green))
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(do
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(rl/draw-cube cube-position (.x cube-size) (.y cube-size) (.z cube-size)
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rl/gray)
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(rl/draw-cube-wires cube-position (.x cube-size) (.y cube-size)
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(.z cube-size) rl/darkgray)))
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;; raylib draws the ray a thousand units long, so it reads as a line
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;; crossing the scene rather than as a segment with an end.
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(rl/draw-ray ray rl/maroon)
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(rl/draw-grid 10 1.0))
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(rl/draw-text "Try clicking on the box with your mouse!" 240 10 20
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rl/darkgray)
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(when (.hit collision)
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(rl/draw-text "BOX SELECTED"
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(/ (- screen-width (rl/measure-text "BOX SELECTED" 30)) 2)
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(i32 (* (f32 screen-height) 0.1)) 30 rl/green))
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(rl/draw-text "Right click mouse to toggle camera controls" 10 430 10
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rl/gray)
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(rl/draw-fps 10 10))))
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