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

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Merged
not-fl3 merged 3 commits into from
Jul 25, 2026
Merged

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

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9fc9fcb
metal: honor Conf.sample_count for MSAA on iOS + matching pipelines
Jun 13, 2026
7b162b6
metal: pick begin_pass storeAction based on resolve attachment
Jun 13, 2026
7ce5c1a
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 @@ -790,12 +790,28 @@ impl RenderingBackend for MetalContext {
msg_send_![descriptor, setPixelFormat: view_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 @@ -1072,6 +1088,11 @@ impl RenderingBackend for MetalContext {
setStencilAttachmentPixelFormat: view_depth_stencil_format
];
}
// 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 @@ -1288,7 +1309,19 @@ 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 @@ -503,7 +503,7 @@ unsafe fn create_opengl_view(screen_rect: NSRect, _sample_count: i32, high_dpi:
}
}

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 @@ -524,6 +524,9 @@ unsafe fn create_metal_view(screen_rect: NSRect, _sample_count: i32, _high_dpi:
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
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