Merge #2224

2224: [mtl] dynamic depth bias, callback coalescence, and more stats r=grovesNL a=kvark

Fixes #2170

Expands our Metal stats to report the number of active and temporary command buffers. Coalesces the completion handlers, and finally fixes the depth bias issue we've been seeing (HAL breaking change).

PR checklist:
- [x] `make` succeeds (on *nix)
- [x] `make reftests` succeeds
- [x] tested examples with the following backends:


Co-authored-by: Dzmitry Malyshau <kvarkus@gmail.com>

src/backend/dx11/src/conv.rs

@@ -1,6 +1,6 @@
 use hal::format::{Format};
 use hal::pso::{
-    BlendDesc, BlendOp, BlendState, ColorBlendDesc, Comparison, DepthStencilDesc,
+    BlendDesc, BlendOp, BlendState, ColorBlendDesc, Comparison, DepthBias, DepthStencilDesc,
     DepthTest, Face, Factor, PolygonMode, Rasterizer, Rect, StencilFace, StencilOp, StencilTest,
     Viewport, Stage, State, StencilValue, FrontFace,
 };
@@ -271,16 +271,20 @@ fn map_cull_mode(mode: Face) -> D3D11_CULL_MODE {
 }
 
 pub(crate) fn map_rasterizer_desc(desc: &Rasterizer) -> D3D11_RASTERIZER_DESC {
+    let bias = match desc.depth_bias { //TODO: support dynamic depth bias
+        Some(State::Static(db)) => db,
+        Some(_) | None => DepthBias::default(),
+    };
     D3D11_RASTERIZER_DESC {
         FillMode: map_fill_mode(desc.polygon_mode),
         CullMode: map_cull_mode(desc.cull_face),
         FrontCounterClockwise: match desc.front_face {
             FrontFace::Clockwise => FALSE,
             FrontFace::CounterClockwise => TRUE,
         },
-        DepthBias: desc.depth_bias.map_or(0, |bias| bias.const_factor as INT),
-        DepthBiasClamp: desc.depth_bias.map_or(0.0, |bias| bias.clamp),
-        SlopeScaledDepthBias: desc.depth_bias.map_or(0.0, |bias| bias.slope_factor),
+        DepthBias: bias.const_factor as INT,
+        DepthBiasClamp: bias.clamp,
+        SlopeScaledDepthBias: bias.slope_factor,
         DepthClipEnable: !desc.depth_clamping as _,
         // TODO:
         ScissorEnable: TRUE,

src/backend/dx12/src/conv.rs

@@ -150,6 +150,11 @@ pub fn map_rasterizer(rasterizer: &pso::Rasterizer) -> D3D12_RASTERIZER_DESC {
     use hal::pso::PolygonMode::*;
     use hal::pso::FrontFace::*;
 
+    let bias = match rasterizer.depth_bias { //TODO: support dynamic depth bias
+        Some(pso::State::Static(db)) => db,
+        Some(_) | None => pso::DepthBias::default(),
+    };
+
     D3D12_RASTERIZER_DESC {
         FillMode: match rasterizer.polygon_mode {
             Point => {
@@ -172,9 +177,9 @@ pub fn map_rasterizer(rasterizer: &pso::Rasterizer) -> D3D12_RASTERIZER_DESC {
             Clockwise => FALSE,
             CounterClockwise => TRUE,
         },
-        DepthBias: rasterizer.depth_bias.map_or(0, |bias| bias.const_factor as INT),
-        DepthBiasClamp: rasterizer.depth_bias.map_or(0.0, |bias| bias.clamp),
-        SlopeScaledDepthBias: rasterizer.depth_bias.map_or(0.0, |bias| bias.slope_factor),
+        DepthBias: bias.const_factor as INT,
+        DepthBiasClamp: bias.clamp,
+        SlopeScaledDepthBias: bias.slope_factor,
         DepthClipEnable: !rasterizer.depth_clamping as _,
         MultisampleEnable: FALSE, // TODO: currently not supported
         ForcedSampleCount: 0, // TODO: currently not supported

src/backend/gl/src/state.rs

@@ -5,7 +5,7 @@ use hal::pso;
 use gl;
 use smallvec::SmallVec;
 
-pub fn bind_polygon_mode(gl: &gl::Gl, mode: pso::PolygonMode, bias: Option<pso::DepthBias>) {
+pub fn bind_polygon_mode(gl: &gl::Gl, mode: pso::PolygonMode, bias: Option<pso::State<pso::DepthBias>>) {
     use hal::pso::PolygonMode::*;
 
     let (gl_draw, gl_offset) = match mode {
@@ -20,11 +20,11 @@ pub fn bind_polygon_mode(gl: &gl::Gl, mode: pso::PolygonMode, bias: Option<pso::
     unsafe { gl.PolygonMode(gl::FRONT_AND_BACK, gl_draw) };
 
     match bias {
-        Some(bias) => unsafe {
+        Some(pso::State::Static(bias)) => unsafe {
             gl.Enable(gl_offset);
             gl.PolygonOffset(bias.slope_factor as _, bias.const_factor as _);
         },
-        None => unsafe {
+        _ => unsafe {
             gl.Disable(gl_offset)
         },
     }