feat(lambda-rs): Add Depth tests, stencil tests, and MSAA

Author: vmarcella

crates/lambda-rs-platform/src/wgpu/gpu.rs

@@ -4,6 +4,7 @@ use super::{
   command::CommandBuffer,
   instance::Instance,
   surface::Surface,
+  texture,
 };
 
 #[derive(Clone, Copy, Debug, PartialEq, Eq)]
@@ -197,6 +198,24 @@ pub struct Gpu {
 }
 
 impl Gpu {
+  /// Whether the provided surface format supports the sample count for render attachments.
+  pub fn supports_sample_count_for_surface(
+    &self,
+    format: super::surface::SurfaceFormat,
+    sample_count: u32,
+  ) -> bool {
+    return self.supports_sample_count(format.to_wgpu(), sample_count);
+  }
+
+  /// Whether the provided depth format supports the sample count for render attachments.
+  pub fn supports_sample_count_for_depth(
+    &self,
+    format: texture::DepthFormat,
+    sample_count: u32,
+  ) -> bool {
+    return self.supports_sample_count(format.to_wgpu(), sample_count);
+  }
+
   /// Borrow the adapter used to create the device.
   ///
   /// Crate-visible to avoid exposing raw `wgpu` to higher layers.
@@ -245,11 +264,50 @@ impl Gpu {
     let iter = list.into_iter().map(|cb| cb.into_raw());
     self.queue.submit(iter);
   }
+
+  fn supports_sample_count(
+    &self,
+    format: wgpu::TextureFormat,
+    sample_count: u32,
+  ) -> bool {
+    if sample_count <= 1 {
+      return true;
+    }
+
+    let features = self.adapter.get_texture_format_features(format);
+    if !features
+      .allowed_usages
+      .contains(wgpu::TextureUsages::RENDER_ATTACHMENT)
+    {
+      return false;
+    }
+
+    match sample_count {
+      2 => features
+        .flags
+        .contains(wgpu::TextureFormatFeatureFlags::MULTISAMPLE_X2),
+      4 => features
+        .flags
+        .contains(wgpu::TextureFormatFeatureFlags::MULTISAMPLE_X4),
+      8 => features
+        .flags
+        .contains(wgpu::TextureFormatFeatureFlags::MULTISAMPLE_X8),
+      16 => features
+        .flags
+        .contains(wgpu::TextureFormatFeatureFlags::MULTISAMPLE_X16),
+      _ => false,
+    }
+  }
 }
 
 #[cfg(test)]
 mod tests {
   use super::*;
+  use crate::wgpu::{
+    instance,
+    surface,
+    texture,
+  };
 
   #[test]
   fn gpu_build_error_wraps_request_device_error() {
@@ -260,4 +318,121 @@ mod tests {
     fn assert_from_impl<T: From<wgpu::RequestDeviceError>>() {}
     assert_from_impl::<GpuBuildError>();
   }
+
+  /// Create an offscreen GPU for sample-count support tests.
+  ///
+  /// Returns `None` when no compatible adapter is available so tests can be
+  /// skipped instead of failing.
+  fn create_test_gpu() -> Option<Gpu> {
+    let instance = instance::InstanceBuilder::new()
+      .with_label("gpu-test-instance")
+      .build();
+    return GpuBuilder::new()
+      .with_label("gpu-test-device")
+      .build(&instance, None)
+      .ok();
+  }
+
+  /// Accepts zero or single-sample attachments for any format.
+  #[test]
+  fn single_sample_always_supported() {
+    let gpu = match create_test_gpu() {
+      Some(gpu) => gpu,
+      None => {
+        eprintln!(
+          "Skipping single_sample_always_supported: no compatible GPU adapter"
+        );
+        return;
+      }
+    };
+    let surface_format =
+      surface::SurfaceFormat::from_wgpu(wgpu::TextureFormat::Bgra8UnormSrgb);
+    let depth_format = texture::DepthFormat::Depth32Float;
+
+    assert!(gpu.supports_sample_count_for_surface(surface_format, 1));
+    assert!(gpu.supports_sample_count_for_surface(surface_format, 0));
+    assert!(gpu.supports_sample_count_for_depth(depth_format, 1));
+    assert!(gpu.supports_sample_count_for_depth(depth_format, 0));
+  }
+
+  /// Rejects sample counts that are outside the supported set.
+  #[test]
+  fn unsupported_sample_count_rejected() {
+    let gpu = match create_test_gpu() {
+      Some(gpu) => gpu,
+      None => {
+        eprintln!(
+          "Skipping unsupported_sample_count_rejected: no compatible GPU adapter"
+        );
+        return;
+      }
+    };
+    let surface_format =
+      surface::SurfaceFormat::from_wgpu(wgpu::TextureFormat::Bgra8Unorm);
+    let depth_format = texture::DepthFormat::Depth32Float;
+
+    assert!(!gpu.supports_sample_count_for_surface(surface_format, 3));
+    assert!(!gpu.supports_sample_count_for_depth(depth_format, 3));
+  }
+
+  /// Mirrors the adapter's texture feature flags for surface formats.
+  #[test]
+  fn surface_support_matches_texture_features() {
+    let gpu = match create_test_gpu() {
+      Some(gpu) => gpu,
+      None => {
+        eprintln!(
+          "Skipping surface_support_matches_texture_features: \
+no compatible GPU adapter"
+        );
+        return;
+      }
+    };
+    let surface_format =
+      surface::SurfaceFormat::from_wgpu(wgpu::TextureFormat::Bgra8UnormSrgb);
+    let features = gpu
+      .adapter
+      .get_texture_format_features(surface_format.to_wgpu());
+    let expected = features
+      .allowed_usages
+      .contains(wgpu::TextureUsages::RENDER_ATTACHMENT)
+      && features
+        .flags
+        .contains(wgpu::TextureFormatFeatureFlags::MULTISAMPLE_X4);
+
+    assert_eq!(
+      gpu.supports_sample_count_for_surface(surface_format, 4),
+      expected
+    );
+  }
+
+  /// Mirrors the adapter's texture feature flags for depth formats.
+  #[test]
+  fn depth_support_matches_texture_features() {
+    let gpu = match create_test_gpu() {
+      Some(gpu) => gpu,
+      None => {
+        eprintln!(
+          "Skipping depth_support_matches_texture_features: \
+no compatible GPU adapter"
+        );
+        return;
+      }
+    };
+    let depth_format = texture::DepthFormat::Depth32Float;
+    let features = gpu
+      .adapter
+      .get_texture_format_features(depth_format.to_wgpu());
+    let expected = features
+      .allowed_usages
+      .contains(wgpu::TextureUsages::RENDER_ATTACHMENT)
+      && features
+        .flags
+        .contains(wgpu::TextureFormatFeatureFlags::MULTISAMPLE_X4);
+
+    assert_eq!(
+      gpu.supports_sample_count_for_depth(depth_format, 4),
+      expected
+    );
+  }
 }

crates/lambda-rs-platform/src/wgpu/pipeline.rs

@@ -81,6 +81,95 @@ pub struct VertexAttributeDesc {
   pub format: ColorFormat,
 }
 
+/// Compare function used for depth and stencil tests.
+#[derive(Clone, Copy, Debug)]
+pub enum CompareFunction {
+  Never,
+  Less,
+  LessEqual,
+  Greater,
+  GreaterEqual,
+  Equal,
+  NotEqual,
+  Always,
+}
+
+impl CompareFunction {
+  fn to_wgpu(self) -> wgpu::CompareFunction {
+    match self {
+      CompareFunction::Never => wgpu::CompareFunction::Never,
+      CompareFunction::Less => wgpu::CompareFunction::Less,
+      CompareFunction::LessEqual => wgpu::CompareFunction::LessEqual,
+      CompareFunction::Greater => wgpu::CompareFunction::Greater,
+      CompareFunction::GreaterEqual => wgpu::CompareFunction::GreaterEqual,
+      CompareFunction::Equal => wgpu::CompareFunction::Equal,
+      CompareFunction::NotEqual => wgpu::CompareFunction::NotEqual,
+      CompareFunction::Always => wgpu::CompareFunction::Always,
+    }
+  }
+}
+
+/// Stencil operation applied when the stencil test or depth test passes/fails.
+#[derive(Clone, Copy, Debug)]
+pub enum StencilOperation {
+  Keep,
+  Zero,
+  Replace,
+  Invert,
+  IncrementClamp,
+  DecrementClamp,
+  IncrementWrap,
+  DecrementWrap,
+}
+
+impl StencilOperation {
+  fn to_wgpu(self) -> wgpu::StencilOperation {
+    match self {
+      StencilOperation::Keep => wgpu::StencilOperation::Keep,
+      StencilOperation::Zero => wgpu::StencilOperation::Zero,
+      StencilOperation::Replace => wgpu::StencilOperation::Replace,
+      StencilOperation::Invert => wgpu::StencilOperation::Invert,
+      StencilOperation::IncrementClamp => {
+        wgpu::StencilOperation::IncrementClamp
+      }
+      StencilOperation::DecrementClamp => {
+        wgpu::StencilOperation::DecrementClamp
+      }
+      StencilOperation::IncrementWrap => wgpu::StencilOperation::IncrementWrap,
+      StencilOperation::DecrementWrap => wgpu::StencilOperation::DecrementWrap,
+    }
+  }
+}
+
+/// Per-face stencil state.
+#[derive(Clone, Copy, Debug)]
+pub struct StencilFaceState {
+  pub compare: CompareFunction,
+  pub fail_op: StencilOperation,
+  pub depth_fail_op: StencilOperation,
+  pub pass_op: StencilOperation,
+}
+
+impl StencilFaceState {
+  fn to_wgpu(self) -> wgpu::StencilFaceState {
+    wgpu::StencilFaceState {
+      compare: self.compare.to_wgpu(),
+      fail_op: self.fail_op.to_wgpu(),
+      depth_fail_op: self.depth_fail_op.to_wgpu(),
+      pass_op: self.pass_op.to_wgpu(),
+    }
+  }
+}
+
+/// Full stencil state (front/back + masks).
+#[derive(Clone, Copy, Debug)]
+pub struct StencilState {
+  pub front: StencilFaceState,
+  pub back: StencilFaceState,
+  pub read_mask: u32,
+  pub write_mask: u32,
+}
+
 /// Wrapper around `wgpu::ShaderModule` that preserves a label.
 #[derive(Debug)]
 pub struct ShaderModule {
@@ -202,6 +291,10 @@ impl RenderPipeline {
   pub(crate) fn into_raw(self) -> wgpu::RenderPipeline {
     return self.raw;
   }
+  /// Pipeline label if provided.
+  pub fn label(&self) -> Option<&str> {
+    return self.label.as_deref();
+  }
 }
 
 /// Builder for creating a graphics render pipeline.
@@ -212,6 +305,7 @@ pub struct RenderPipelineBuilder<'a> {
   cull_mode: CullingMode,
   color_target_format: Option<wgpu::TextureFormat>,
   depth_stencil: Option<wgpu::DepthStencilState>,
+  sample_count: u32,
 }
 
 impl<'a> RenderPipelineBuilder<'a> {
@@ -224,6 +318,7 @@ impl<'a> RenderPipelineBuilder<'a> {
       cull_mode: CullingMode::Back,
       color_target_format: None,
       depth_stencil: None,
+      sample_count: 1,
     };
   }
 
@@ -275,6 +370,56 @@ impl<'a> RenderPipelineBuilder<'a> {
     return self;
   }
 
+  /// Set the depth compare function. Requires depth to be enabled.
+  pub fn with_depth_compare(mut self, compare: CompareFunction) -> Self {
+    let ds = self.depth_stencil.get_or_insert(wgpu::DepthStencilState {
+      format: wgpu::TextureFormat::Depth32Float,
+      depth_write_enabled: true,
+      depth_compare: wgpu::CompareFunction::Less,
+      stencil: wgpu::StencilState::default(),
+      bias: wgpu::DepthBiasState::default(),
+    });
+    ds.depth_compare = compare.to_wgpu();
+    return self;
+  }
+
+  /// Enable or disable depth writes. Requires depth-stencil enabled.
+  pub fn with_depth_write_enabled(mut self, enabled: bool) -> Self {
+    let ds = self.depth_stencil.get_or_insert(wgpu::DepthStencilState {
+      format: wgpu::TextureFormat::Depth32Float,
+      depth_write_enabled: true,
+      depth_compare: wgpu::CompareFunction::Less,
+      stencil: wgpu::StencilState::default(),
+      bias: wgpu::DepthBiasState::default(),
+    });
+    ds.depth_write_enabled = enabled;
+    return self;
+  }
+
+  /// Configure stencil state (front/back ops and masks). Requires depth-stencil enabled.
+  pub fn with_stencil(mut self, stencil: StencilState) -> Self {
+    let ds = self.depth_stencil.get_or_insert(wgpu::DepthStencilState {
+      format: wgpu::TextureFormat::Depth24PlusStencil8,
+      depth_write_enabled: true,
+      depth_compare: wgpu::CompareFunction::Less,
+      stencil: wgpu::StencilState::default(),
+      bias: wgpu::DepthBiasState::default(),
+    });
+    ds.stencil = wgpu::StencilState {
+      front: stencil.front.to_wgpu(),
+      back: stencil.back.to_wgpu(),
+      read_mask: stencil.read_mask,
+      write_mask: stencil.write_mask,
+    };
+    return self;
+  }
+
+  /// Configure multisampling. Count MUST be >= 1 and supported by the device.
+  pub fn with_sample_count(mut self, count: u32) -> Self {
+    self.sample_count = count.max(1);
+    return self;
+  }
+
   /// Build the render pipeline from provided shader modules.
   pub fn build(
     self,
@@ -351,7 +496,10 @@ impl<'a> RenderPipelineBuilder<'a> {
           vertex: vertex_state,
           primitive: primitive_state,
           depth_stencil: self.depth_stencil,
-          multisample: wgpu::MultisampleState::default(),
+          multisample: wgpu::MultisampleState {
+            count: self.sample_count,
+            ..wgpu::MultisampleState::default()
+          },
           fragment,
           multiview: None,
           cache: None,