Add MULTISAMPLE_ARRAY feature flag.

CHANGELOG.md

@@ -135,6 +135,7 @@ By @cwfitzgerald in [#8579](https://github.com/gfx-rs/wgpu/pull/8579).
 - Added support for transient textures on Vulkan and Metal. By @opstic in [#8247](https://github.com/gfx-rs/wgpu/pull/8247)
 - Implement shader triangle barycentric coordinate builtins. By @atlv24 in [#8320](https://github.com/gfx-rs/wgpu/pull/8320).
 - Added support for binding arrays of storage textures on Metal. By @msvbg in [#8464](https://github.com/gfx-rs/wgpu/pull/8464)
+- Added support for multisampled texture arrays on Vulkan through adapter feature `MULTISAMPLE_ARRAY`. By @LaylBongers in [#8571](https://github.com/gfx-rs/wgpu/pull/8571).
 
 ### Changes
 

tests/tests/wgpu-gpu/multiview/mod.rs

@@ -9,6 +9,7 @@ pub fn all_tests(vec: &mut Vec<GpuTestInitializer>) {
     vec.push(DRAW_MULTIVIEW_SINGLE);
     vec.push(DRAW_MULTIVIEW);
     vec.push(DRAW_MULTIVIEW_NONCONTIGUOUS);
+    vec.push(DRAW_MULTIVIEW_MULTISAMPLE);
 }
 
 #[gpu_test]
@@ -21,7 +22,7 @@ static DRAW_MULTIVIEW_SINGLE: GpuTestConfiguration = GpuTestConfiguration::new()
                 ..Limits::defaults()
             }),
     )
-    .run_async(|ctx| run_test(ctx, 0b1));
+    .run_async(|ctx| run_test(ctx, 0b1, 1));
 
 #[gpu_test]
 static DRAW_MULTIVIEW: GpuTestConfiguration = GpuTestConfiguration::new()
@@ -33,7 +34,7 @@ static DRAW_MULTIVIEW: GpuTestConfiguration = GpuTestConfiguration::new()
                 ..Limits::defaults()
             }),
     )
-    .run_async(|ctx| run_test(ctx, 0b11));
+    .run_async(|ctx| run_test(ctx, 0b11, 1));
 
 #[gpu_test]
 static DRAW_MULTIVIEW_NONCONTIGUOUS: GpuTestConfiguration = GpuTestConfiguration::new()
@@ -45,9 +46,21 @@ static DRAW_MULTIVIEW_NONCONTIGUOUS: GpuTestConfiguration = GpuTestConfiguration
                 ..Limits::defaults()
             }),
     )
-    .run_async(|ctx| run_test(ctx, 0b1001));
+    .run_async(|ctx| run_test(ctx, 0b1001, 1));
 
-async fn run_test(ctx: TestingContext, layer_mask: u32) {
+#[gpu_test]
+static DRAW_MULTIVIEW_MULTISAMPLE: GpuTestConfiguration = GpuTestConfiguration::new()
+    .parameters(
+        TestParameters::default()
+            .features(Features::MULTIVIEW | Features::MULTISAMPLE_ARRAY)
+            .limits(Limits {
+                max_multiview_view_count: 2,
+                ..Limits::defaults()
+            }),
+    )
+    .run_async(|ctx| run_test(ctx, 0b11, 4));
+
+async fn run_test(ctx: TestingContext, layer_mask: u32, sample_count: u32) {
     let num_layers = 32 - layer_mask.leading_zeros();
 
     let shader_src = include_str!("shader.wgsl");
@@ -79,29 +92,34 @@ async fn run_test(ctx: TestingContext, layer_mask: u32) {
             })],
         }),
         multiview_mask: NonZero::new(layer_mask),
-        multisample: Default::default(),
+        multisample: wgpu::MultisampleState {
+            count: sample_count,
+            ..Default::default()
+        },
         layout: None,
         depth_stencil: None,
         cache: None,
     };
 
     const TEXTURE_SIZE: u32 = 256;
     let pipeline = ctx.device.create_render_pipeline(&pipeline_desc);
-    let texture = ctx.device.create_texture(&wgpu::TextureDescriptor {
+
+    let texture_desc = wgpu::TextureDescriptor {
         label: None,
         size: wgpu::Extent3d {
             width: TEXTURE_SIZE,
             height: TEXTURE_SIZE,
             depth_or_array_layers: 32 - layer_mask.leading_zeros(),
         },
         mip_level_count: 1,
-        sample_count: 1,
+        sample_count,
         dimension: wgpu::TextureDimension::D2,
         format: wgpu::TextureFormat::R8Unorm,
         usage: wgpu::TextureUsages::RENDER_ATTACHMENT | wgpu::TextureUsages::COPY_SRC,
         view_formats: &[],
-    });
-    let entire_texture_view = texture.create_view(&wgpu::TextureViewDescriptor {
+    };
+    let texture = ctx.device.create_texture(&texture_desc);
+    let texture_view_desc = wgpu::TextureViewDescriptor {
         label: None,
         format: Some(wgpu::TextureFormat::R8Unorm),
         dimension: Some(wgpu::TextureViewDimension::D2Array),
@@ -111,7 +129,21 @@ async fn run_test(ctx: TestingContext, layer_mask: u32) {
         mip_level_count: None,
         base_array_layer: 0,
         array_layer_count: Some(num_layers),
-    });
+    };
+    let entire_texture_view = texture.create_view(&texture_view_desc);
+
+    let (resolve_texture, resolve_texture_view) = if sample_count != 1 {
+        let mut texture_desc = texture_desc.clone();
+        texture_desc.sample_count = 1;
+
+        let resolve_texture = ctx.device.create_texture(&texture_desc);
+        let resolve_texture_view = resolve_texture.create_view(&texture_view_desc);
+
+        (Some(resolve_texture), Some(resolve_texture_view))
+    } else {
+        (None, None)
+    };
+
     let readback_buffer = ctx.device.create_buffer(&wgpu::BufferDescriptor {
         label: None,
         size: TEXTURE_SIZE as u64 * TEXTURE_SIZE as u64 * num_layers as u64,
@@ -130,7 +162,7 @@ async fn run_test(ctx: TestingContext, layer_mask: u32) {
             color_attachments: &[Some(wgpu::RenderPassColorAttachment {
                 view: &entire_texture_view,
                 depth_slice: None,
-                resolve_target: None,
+                resolve_target: resolve_texture_view.as_ref(),
                 ops: wgpu::Operations {
                     load: wgpu::LoadOp::Clear(wgpu::Color::TRANSPARENT),
                     store: wgpu::StoreOp::Store,
@@ -146,7 +178,7 @@ async fn run_test(ctx: TestingContext, layer_mask: u32) {
     }
     encoder.copy_texture_to_buffer(
         wgpu::TexelCopyTextureInfo {
-            texture: &texture,
+            texture: resolve_texture.as_ref().unwrap_or(&texture),
             mip_level: 0,
             origin: wgpu::Origin3d { x: 0, y: 0, z: 0 },
             aspect: wgpu::TextureAspect::All,

wgpu-core/src/device/resource.rs

@@ -1436,7 +1436,9 @@ impl Device {
                 });
             }
 
-            if desc.size.depth_or_array_layers != 1 {
+            if desc.size.depth_or_array_layers != 1
+                && !self.features.contains(wgt::Features::MULTISAMPLE_ARRAY)
+            {
                 return Err(CreateTextureError::InvalidDimension(
                     TextureDimensionError::MultisampledDepthOrArrayLayer(
                         desc.size.depth_or_array_layers,
@@ -1741,11 +1743,17 @@ impl Device {
 
         // check if multisampled texture is seen as anything but 2D
         if texture.desc.sample_count > 1 && resolved_dimension != TextureViewDimension::D2 {
-            return Err(
-                resource::CreateTextureViewError::InvalidMultisampledTextureViewDimension(
-                    resolved_dimension,
-                ),
-            );
+            // Multisample is allowed on 2D arrays, only if explicitly supported
+            let multisample_array_exception = resolved_dimension == TextureViewDimension::D2Array
+                && self.features.contains(wgt::Features::MULTISAMPLE_ARRAY);
+
+            if !multisample_array_exception {
+                return Err(
+                    resource::CreateTextureViewError::InvalidMultisampledTextureViewDimension(
+                        resolved_dimension,
+                    ),
+                );
+            }
         }
 
         // check if the dimension is compatible with the texture

wgpu-hal/src/dx12/adapter.rs

@@ -403,7 +403,8 @@ impl super::Adapter {
             | wgt::Features::FLOAT32_FILTERABLE
             | wgt::Features::TEXTURE_ATOMIC
             | wgt::Features::EXPERIMENTAL_PASSTHROUGH_SHADERS
-            | wgt::Features::EXTERNAL_TEXTURE;
+            | wgt::Features::EXTERNAL_TEXTURE
+            | wgt::Features::MULTISAMPLE_ARRAY;
 
         //TODO: in order to expose this, we need to run a compute shader
         // that extract the necessary statistics out of the D3D12 result.

wgpu-hal/src/vulkan/adapter.rs

@@ -130,6 +130,11 @@ pub struct PhysicalDeviceFeatures {
 
     /// Features provided by `VK_KHR_fragment_shader_barycentric`
     shader_barycentrics: Option<vk::PhysicalDeviceFragmentShaderBarycentricFeaturesKHR<'static>>,
+
+    /// Features provided by `VK_KHR_portability_subset`.
+    ///
+    /// Strictly speaking this tells us what features we *don't* have compared to core.
+    portability_subset: Option<vk::PhysicalDevicePortabilitySubsetFeaturesKHR<'static>>,
 }
 
 impl PhysicalDeviceFeatures {
@@ -206,6 +211,9 @@ impl PhysicalDeviceFeatures {
         if let Some(ref mut feature) = self.shader_barycentrics {
             info = info.push_next(feature);
         }
+        if let Some(ref mut feature) = self.portability_subset {
+            info = info.push_next(feature);
+        }
         info
     }
 
@@ -551,6 +559,17 @@ impl PhysicalDeviceFeatures {
             } else {
                 None
             },
+            portability_subset: if enabled_extensions.contains(&khr::portability_subset::NAME) {
+                let multisample_array_needed =
+                    requested_features.intersects(wgt::Features::MULTISAMPLE_ARRAY);
+
+                Some(
+                    vk::PhysicalDevicePortabilitySubsetFeaturesKHR::default()
+                        .multisample_array_image(multisample_array_needed),
+                )
+            } else {
+                None
+            },
         }
     }
 
@@ -927,6 +946,15 @@ impl PhysicalDeviceFeatures {
                 mesh_shader.multiview_mesh_shader != 0,
             );
         }
+
+        // Not supported by default by `VK_KHR_portability_subset`, which we use on apple platforms.
+        features.set(
+            F::MULTISAMPLE_ARRAY,
+            self.portability_subset
+                .map(|p| p.multisample_array_image == vk::TRUE)
+                .unwrap_or(true),
+        );
+
         (features, dl_flags)
     }
 }
@@ -1698,6 +1726,13 @@ impl super::InstanceShared {
                 features2 = features2.push_next(next);
             }
 
+            if capabilities.supports_extension(khr::portability_subset::NAME) {
+                let next = features
+                    .portability_subset
+                    .insert(vk::PhysicalDevicePortabilitySubsetFeaturesKHR::default());
+                features2 = features2.push_next(next);
+            }
+
             unsafe { get_device_properties.get_physical_device_features2(phd, &mut features2) };
             features2.features
         } else {

wgpu-types/src/features.rs

@@ -1263,6 +1263,16 @@ bitflags_array! {
         ///
         /// This is a native only feature.
         const EXPERIMENTAL_MESH_SHADER_POINTS = 1 << 55;
+
+        /// Enables creating texture arrays that are also multisampled.
+        ///
+        /// Without this feature, you cannot create a texture that has both a `sample_count` higher
+        /// than 1, and a `depth_or_array_layers` higher than 1.
+        ///
+        /// Supported platforms:
+        /// - Vulkan (except VK_KHR_portability_subset if multisampleArrayImage is not available)
+        /// - DX12
+        const MULTISAMPLE_ARRAY = 1 << 56;
     }
 
     /// Features that are not guaranteed to be supported.