Make games run on watchOS (FFI stubs, string FFI, file reading, 2D camera)#60
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gen_stubs.js threw on `string` params (rustType only knew f64/i64/void), so it crashed before writing src/ffi_stubs.rs and the checked-in file went stale — a game linking against the watchOS lib failed with undefined `_bloom_*` (post-pass, ssao, wind, …). Map `string` -> i64 (Perry passes string pointers in an integer register) for both params and returns, and add bloom_get_language / bloom_set_direct_2d_mode to OVERRIDES (real impls in lib.rs that regen would otherwise duplicate). Regenerate. Four functions (bloom_set_material_params, bloom_splat_impulse, bloom_profiler_frame_history, bloom_profiler_overlay_text) are declared in the engine's core/index.ts but absent from package.json's nativeLibrary.functions, so gen_stubs can't see them — add hand-written no-op stubs in src/ffi_stubs_manual.rs (perry validates the manifest cross-platform, so the manifest gap is left for a separate change).
Three runtime gaps that kept games from actually rendering on watchOS:
- StringHeader was 16 bytes (4×u32), but Perry 0.5.x's canonical header is 20
bytes (5×u32 incl `flags`, data at +20). `perry_str` read every incoming
string 4 bytes early — text rendered with a 4-null prefix + truncated tail
("BLOOM JUMP" -> "BLOOM") and file paths came back corrupted so levels
never loaded. Add the missing `flags` field.
- bloom_read_file was a stub returning 0 (null); the game's inline `.length`
then dereferenced null and crashed. Implement it: resolve the bundle-relative
path, read the file, and return a real StringHeader via a new
alloc_perry_string (empty string on a miss, never null).
- bloom_begin_mode_2d / bloom_end_mode_2d were no-ops, so world-space draws
(tiles, sprites) rendered at raw coordinates off-screen while the screen-space
HUD showed. Emit BEGIN_2D/END_2D marker commands carrying the camera; the
SwiftUI Canvas applies the matching affine transform (world -> screen) to
every command in between.
Also drop the watchOS `metal_sources` post-fx shader: SCNTechnique/SCNRenderer
is absent from the watchOS SDK so it can't run, and compiling it needs the
separately-downloadable Metal Toolchain. The app renders fine without the
metallib.
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Summary
Brings a real 2D game (Bloom Jump) up on the watchOS simulator — title screen and gameplay (player, ground tiles, coins, HUD) rendering through the SwiftUI-
Canvaspath. Five issues stood between "compiles" and "plays":_bloom_add_post_pass,_bloom_set_wind, …gen_stubs.jsthrew onstringparams soffi_stubs.rswent stale — mapstring→i64, add two real impls to OVERRIDES, regenerate_bloom_*bloom_set_material_params/splat_impulse/profiler_*are declared incore/index.tsbut missing from the manifest — hand-written stubs inffi_stubs_manual.rsStringHeaderwas 16 bytes; Perry 0.5.x's is 20 (missingflags).perry_strread every string 4 bytes early. AddflagsSIGSEGVat…fff8)bloom_read_filereturned null; implement it (resolve bundle path, read, return a real StringHeader viaalloc_perry_string, empty-never-null on miss)bloom_begin/end_mode_2dwere no-ops, so world draws used raw coords. Emit BEGIN_2D/END_2D markers; the Canvas applies the camera's affine transformAlso drops the watchOS
metal_sourcespost-fx shader —SCNTechnique/SCNRendereris absent from the watchOS SDK so it can't run, and compiling it requires the separately-downloadable Metal Toolchain. The app renders fine without the metallib.Validation
Built for
watchos-simulator(--features watchos-swift-app) and ran on an Apple Watch Series 11 (watchOS 26) simulator:Notes
package.json'snativeLibrary.functions, because Perry validates that manifest cross-platform and this change was only validated on watchOS. Adding them to the manifest (sogen_stubs.jsemits them) is a reasonable follow-up for someone who can test the other targets.--features watchos-swift-applink reliability (the_main → __perry_user_mainentry-object rename) — submitted to PerryTS/perry separately.