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metal: honor Conf.sample_count for MSAA on iOS + matching pipelines #640

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metal: honor Conf.sample_count for MSAA on iOS + matching pipelines #640

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d084e03
metal: honor Conf.sample_count for MSAA on iOS + matching pipelines
Jun 13, 2026
8fcd91e
metal: pick begin_pass storeAction based on resolve attachment
Jun 13, 2026
7c74c42
metal: preserve multisample texture across passes (StoreAndMultisampl…
Jun 13, 2026
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47 changes: 40 additions & 7 deletions src/graphics/metal.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -715,12 +715,28 @@ impl RenderingBackend for MetalContext {
msg_send_![descriptor, setPixelFormat: pixel_format];
}
msg_send_![descriptor, setStorageMode: MTLStorageMode::Private];
msg_send_![
descriptor,
setUsage: MTLTextureUsage::RenderTarget as u64
| MTLTextureUsage::ShaderRead as u64
| MTLTextureUsage::ShaderWrite as u64
];
if params.sample_count > 1 {
// MSAA target — render-only, no mipmaps, no
// shader-sample (the resolve texture is sampled
// instead).
msg_send_![
descriptor,
setTextureType: MTLTextureType::D2Multisample
];
msg_send_![descriptor, setSampleCount: params.sample_count as u64];
msg_send_![descriptor, setMipmapLevelCount: 1u64];
msg_send_![
descriptor,
setUsage: MTLTextureUsage::RenderTarget as u64
];
} else {
msg_send_![
descriptor,
setUsage: MTLTextureUsage::RenderTarget as u64
| MTLTextureUsage::ShaderRead as u64
| MTLTextureUsage::ShaderWrite as u64
];
}
} else {
#[cfg(target_os = "macos")]
{
Expand Down Expand Up @@ -985,6 +1001,11 @@ impl RenderingBackend for MetalContext {
descriptor,
setStencilAttachmentPixelFormat: MTLPixelFormat::Depth32Float_Stencil8
];
// Pipeline sampleCount must match every render-pass
// color attachment it binds to; use the view's as the
// canonical app-wide value.
let view_sample_count: u64 = msg_send![self.view, sampleCount];
msg_send_![descriptor, setSampleCount: view_sample_count];

let mut error: ObjcId = nil;
let pipeline_state: ObjcId = msg_send![
Expand Down Expand Up @@ -1190,7 +1211,19 @@ impl RenderingBackend for MetalContext {
let color_attachments = msg_send_![descriptor, colorAttachments];
let color_attachment = msg_send_![color_attachments, objectAtIndexedSubscript: 0];

msg_send_![color_attachment, setStoreAction: MTLStoreAction::Store];
// If the attachment has a resolve texture, use
// `StoreAndMultisampleResolve` (not just
// `MultisampleResolve`) so the multisample texture
// survives target-switch boundaries within a frame —
// a later `Load` on the same target would otherwise
// read discarded memory.
let resolve_texture: ObjcId = msg_send![color_attachment, resolveTexture];
let store_action = if resolve_texture.is_null() {
MTLStoreAction::Store
} else {
MTLStoreAction::StoreAndMultisampleResolve
};
msg_send_![color_attachment, setStoreAction: store_action];

match action {
PassAction::Clear { color, .. } => {
Expand Down
5 changes: 4 additions & 1 deletion src/native/ios.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -451,7 +451,7 @@
}
}

unsafe fn create_metal_view(screen_rect: NSRect, _sample_count: i32, _high_dpi: bool) -> View {
unsafe fn create_metal_view(screen_rect: NSRect, sample_count: i32, _high_dpi: bool) -> View {
let mtk_view_obj: ObjcId = msg_send![define_glk_or_mtk_view(class!(MTKView)), alloc];
let mtk_view_obj: ObjcId = msg_send![mtk_view_obj, initWithFrame: screen_rect];

Expand All @@ -470,6 +470,9 @@
let device = MTLCreateSystemDefaultDevice();
msg_send_![mtk_view_obj, setDevice: device];
msg_send_![mtk_view_obj, setUserInteractionEnabled: YES];
if sample_count > 1 {
msg_send_![mtk_view_obj, setSampleCount: sample_count as u64];
}

View {
view: mtk_view_obj,
Expand Down Expand Up @@ -499,7 +502,7 @@
_: ObjcId,
) -> BOOL {
unsafe {
let (f, conf) = RUN_ARGS.take().unwrap();

Check warning on line 505 in src/native/ios.rs

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GitHub Actions / Build (macos-latest, x86_64-apple-ios) 

creating a mutable reference to mutable static

Check warning on line 505 in src/native/ios.rs

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GitHub Actions / Build (macos-latest, aarch64-apple-ios) 

creating a mutable reference to mutable static

let main_screen: ObjcId = msg_send![class!(UIScreen), mainScreen];
let screen_rect: NSRect = msg_send![main_screen, bounds];
Expand Down
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