Protocol structs registered via registerProtocolDecl carry a new
is_protocol flag; the ?T paths in sizeOf/typeSizeBytes/toLLVMType
recognise it and lay out ?Protocol as the protocol struct itself
(ctx == null IS the "none" state), matching how ?Closure / ?*T are
sentinel-shaped — no extra storage.
Method dispatch on ?Protocol auto-unwraps in lowerCall's field-access
path; the unwrap is structurally a no-op so we just rebind obj_ty to
the payload type. resolveCallParamTypes extended for optional-protocol
receivers so enum-literal args (gpu.create_texture(.r8, ...)) get the
right target_type and don't silently collapse to tag=0 : s32 — same
issue-0031-class bug closed in Session 66, one type-system layer
deeper.
Library: UIRenderer / UIPipeline / GlyphCache migrated from the verbose
gpu: GPU = ---; has_gpu: bool pattern to gpu: ?GPU = null. set_gpu no
longer maintains a parallel bool flag.
Bundled: dock.sx threads delta_time as a struct field rather than via
a global pointer (cleanup unrelated to issue-0028, committed alongside).
Verified: 85/85 regression tests pass; iOS-sim chess + macOS chess
both render correctly post-migration.
Two small cleanups in the Metal text path on top of the buffer-offset
fix from cc71d95:
- Drop the SDF-style `smoothstep(0.5 ± ew, alpha)` from the text mode
branch in UI_MSL_SRC. The glyph atlas stores alpha coverage straight
from stbtt_MakeGlyphBitmap, not signed distance, so the smoothstep
was thinning anti-aliased strokes by mapping mid-coverage values
(0.3–0.7) toward 0/1. Use the sampled value directly as alpha.
- Drop the 16-byte alignment pad on `mtl_buf_offset` in `flush()`. Each
batch's upload_size is already a multiple of UI_VERTEX_BYTES (48), so
the running offset stays vertex-aligned without the extra rounding.
- After `font.shape_text` + `font.flush` in `render_text`, re-bind
`font.texture_id`. If the atlas grew during shaping, the GPU texture
handle changed; without this rebind the next flush samples the old
(smaller) atlas which doesn't have the newly-rasterized glyphs.
- Use explicit s64-pointer arithmetic in `metal_update_buffer_at_ios`
so a future regression in `[*]u8` indexing can't quietly miscompile
the per-flush write offset.
Text at small sizes still renders dim on dark backgrounds — most glyph
pixels sit in 0.1–0.5 coverage and the linear blend doesn't push them
to bright values — tracked separately as the faint-text follow-up.
UIRenderer.flush wrote to mtl_vbuf at byte offset 0 on every flush.
Metal records draw commands but reads the buffer at GPU execution time,
so a frame with multiple flushes ended up rendering whatever the LAST
writer left in the buffer for every draw. Chess UI hit this hard:
each of the 32 pieces in the initial position triggers two bind_texture
flushes (atlas -> pieces -> atlas), so ~64 mid-frame flushes silently
rendered the final info-panel batch over the board and the sprites.
New GPU protocol method update_buffer_at(buf, data, size, byte_offset);
Metal impl writes at offset via [*]u8 arithmetic on [buf contents].
UIRenderer tracks mtl_buf_offset (reset in begin, advanced per flush,
aligned to 16B, wraps on overflow) and draws each batch with
vertex_off = byte_off / UI_VERTEX_BYTES. Metal buffer over-allocated
4x the per-flush max (~3 MB) for headroom. GL path untouched —
glBufferData already orphans the storage.
71/71 regression tests pass. Metal-clear example, macOS GL chess, and
WASM chess all still build.
Step 3b code is wired across UIRenderer + GlyphCache + UIPipeline +
chess game (gpu_mode = .metal on iOS, MetalGPU bound via the GPU
protocol). macOS GL chess, iOS-sim GLES chess, and iOS-sim Metal
triangle (63-metal-clear.sx) all still render.
iOS-sim Metal chess crashes inside replaceRegion uploading the 1MB
font atlas. Bisecting that crash exposed several sx-language issues
where mid-bisect tracers (NSLog inside if/else branch bodies) didn't
produce output, blocking further investigation.
Filing each finding as examples/issue-NNNN.sx rather than working
around piecemeal:
Bugs:
- 0024 NSLog/foreign-call inside if/else body not producing output
- 0025 C-ABI param coercion incomplete for composites >16B
(combined direct-call abiCoerceParamType TODO + call_indirect
path that doesn't apply C-ABI coercion at all)
- 0026 replaceRegion 1MB upload crash (likely downstream of 0025)
Features needed for step 4 + cleanup:
- 0027 Obj-C block bridge (^{...}) for animateWithDuration:
- 0028 Optional protocol box (?GPU = null) replaces T = ---; has_T: bool
- 0029 destroy_texture/buffer/shader on GPU protocol
- 0030 extern cross-file globals
Library-side: renderer.sx + glyph_cache.sx + pipeline.sx gain a
`gpu: GPU = ---; has_gpu: bool` field pair + branches that route every
GL touchpoint through the protocol when has_gpu. glyph_cache.init
saves/restores those fields around its memset. pipeline.set_gpu()
propagates to renderer + font. Renderer's MSL shader source added as
UI_MSL_SRC using packed_float2/packed_float4 to keep the 12-float
interleaved vertex layout tight (48 bytes).
metal.sx: dual-phase init (init(null, 0, 0) for eager device+queue,
re-init with the layer once UIKit installs the SxMetalView).
setStorageMode:.shared on every texture descriptor to ensure CPU-
writable atlas pixels on Apple Silicon iOS-sim.
Regression suite: 68 passing, 0 failed. WASM chess build currently
broken under step 3b state (silent compiler crash); documented in
CHECKPOINT.md, likely fallout from one of the filed issues (probably
0028 — the verbose protocol-box pattern). Step 3b resumes after
0024-0030 land.
What works on iOS sim now:
- pure-UIKit boot via UIApplicationMain (no SDL3 on iOS)
- SxGLView (CAEAGLLayer) + EAGLContext(GLES3) + CADisplayLink
- GLES3 shader path in modules/ui/renderer.sx (was wasm-only; now
wasm-OR-ios)
- UITouch -> ui.Event translation (mouse_down/moved/up) on touchesBegan/
Moved/Ended/Cancelled. Verified by tapping the chess board: the
expected pawn highlights and its legal moves show as green dots.
- chdir to NSBundle.mainBundle.resourcePath inside UIKitPlatform.init so
the game's relative fopen("assets/...") calls resolve.
Required restructuring to fix four problems discovered along the way:
1. GL context + load_gl must happen BEFORE UIApplicationMain so the
game's pipeline.init (which compiles shaders) doesn't crash on null
function pointers. Pulled EAGLContext creation + load_gl out of
didFinishLaunching: into UIKitPlatform.init via uikit_create_gl_context.
2. UIScreen.nativeScale returns CGFloat (=double on 64-bit Apple).
Reading it through a `(*void, *void) -> f32` msgSend signature
clobbers the value to 0 — the upper 32 bits of d0 land where the f32
reads from. Replaced msg_f with msg_d returning f64 (and added
msg_odbl for setContentScaleFactor: which takes CGFloat).
3. `xx <f64-call-result>` directly assigned to an f32 field through a
sema path lowers as `sitofp` (integer→float) on the double — LLVM
verification rejects it. Workaround: hoist into an `f64` local first.
4. The renderer was selecting the GLSL 330 core shader on every non-wasm
target, including iOS GLES3 where it silently fails to compile and
no quads render. Added OS == .ios to the GLES branch.
Game changes:
- main.sx: g_plat is now a boxed `Platform` (not concrete *SdlPlatform).
Backend chosen per-target via `inline if OS == .ios { ... }`. The
ESC-to-stop handling is OS-guarded (mobile apps don't quit on key
press, and SDL_Keycode references would force-link SDL on iOS).
- build.sx: iOS no longer adds SDL3; it adds UIKit + OpenGLES +
QuartzCore instead.
- delta_time and viewport dims are now mirrored to free globals so the
dock subsystem (`g_dock_delta_time = @g_delta_time`) and build_ui
layout decisions don't need a pointer through the boxed protocol.
Other:
- Added `stop()` to the Platform protocol (no-op on UIKitPlatform).
- examples/66-uikit-platform.sx updated: taps advance the clear color
(red → green → blue) — smoke test for the touch IMP wiring.
- shutdown() on UIKitPlatform is a no-op (mobile apps don't tear down).
Outstanding for next session:
- The Dynamic Island notch overlaps the top of the board because we
haven't read UIView.safeAreaInsets yet (CGRect/UIEdgeInsets struct
returns require a different msgSend ABI than we currently express).
- Keyboard observer (UIKeyboardWillChangeFrameNotification + animation
duration) — the load-bearing iOS feature.
- Real-device codesigning workflow for the new build.
Two more sx compiler bugs to file out of this work:
- xx(f64 call result) → f32 emits sitofp (problem #3 above).
- Inline `#import` inside `inline if` fails to parse (we worked around
by importing both backends unconditionally; the unused-backend's
Obj-C calls are gated by `inline if OS == .ios`).
20 files (~3,830 lines): view protocol, layout, renderer, glyph cache,
fonts, gestures, animation, scroll, stacks, modifiers, etc.
Internal imports rewritten from "ui/..." to "modules/ui/...".
Consumers now `#import "modules/ui"` from any project; no symlink
hacks needed. Verified by compiling game/main.sx without its local
ui/ — resolves via the Phase 6 stdlib fallback.
