trace: make Id serialization nicer

README.md

@@ -17,6 +17,7 @@ The implementation consists of the following parts:
 
   - `wgpu-core` - internal Rust API for WebGPU implementations to use
   - `wgpu-types` - Rust types shared between `wgpu-core`, `wgpu-native`, and `wgpu-rs`
+  - `player` - application for replaying the API traces, uses `winit`
 
 This repository is not meant for direct use by applications.
 If you are looking for the user-facing Rust API, you need [wgpu-rs](https://github.com/gfx-rs/wgpu-rs).

player/README.md

@@ -0,0 +1,12 @@
+# wgpu player
+
+This is application that allows replaying the `wgpu` workloads recorded elsewhere.
+
+Launch as:
+```rust
+player <trace-dir>
+```
+
+When built with "winit" feature, it's able to replay the workloads that operate on a swapchain. It renders each frame consequently, then waits for the user to close the window. When built without "winit", it launches in console mode and can replay any trace that doesn't use swapchains.
+
+Note: replaying is currently restricted to the same backend, as one used for recording a trace. It is straightforward, however, to just replace the backend in RON, since it's serialized as plain text. Valid values are: Vulkan, Metal, Dx12, and Dx11.

wgpu-core/src/command/compute.rs

@@ -33,7 +33,7 @@ pub enum ComputeCommand {
         index: u8,
         num_dynamic_offsets: u8,
         bind_group_id: id::BindGroupId,
-        #[cfg_attr(feature = "serde", serde(skip))]
+        #[cfg_attr(any(feature = "trace", feature = "replay"), serde(skip))]
         phantom_offsets: PhantomSlice<DynamicOffset>,
     },
     SetPipeline(id::ComputePipelineId),

wgpu-core/src/command/render.rs

@@ -63,7 +63,7 @@ pub enum RenderCommand {
         index: u8,
         num_dynamic_offsets: u8,
         bind_group_id: id::BindGroupId,
-        #[cfg_attr(feature = "serde", serde(skip))]
+        #[cfg_attr(any(feature = "trace", feature = "replay"), serde(skip))]
         phantom_offsets: PhantomSlice<DynamicOffset>,
     },
     SetPipeline(id::RenderPipelineId),

wgpu-core/src/id.rs

@@ -11,9 +11,37 @@ const EPOCH_MASK: u32 = (1 << (32 - BACKEND_BITS)) - 1;
 type Dummy = crate::backend::Empty;
 
 #[repr(transparent)]
+#[cfg_attr(feature = "trace", derive(serde::Serialize), serde(into = "SerialId"))]
+#[cfg_attr(
+    feature = "replay",
+    derive(serde::Deserialize),
+    serde(from = "SerialId")
+)]
+pub struct Id<T>(NonZeroU64, PhantomData<T>);
+
+// This type represents Id in a more readable (and editabble) way.
+#[allow(dead_code)]
 #[cfg_attr(feature = "trace", derive(serde::Serialize))]
 #[cfg_attr(feature = "replay", derive(serde::Deserialize))]
-pub struct Id<T>(NonZeroU64, PhantomData<T>);
+enum SerialId {
+    // The only variant forces RON to not ignore "Id"
+    Id(Index, Epoch, Backend),
+}
+#[cfg(feature = "trace")]
+impl<T> From<Id<T>> for SerialId {
+    fn from(id: Id<T>) -> Self {
+        let (index, epoch, backend) = id.unzip();
+        SerialId::Id(index, epoch, backend)
+    }
+}
+#[cfg(feature = "replay")]
+impl<T> From<SerialId> for Id<T> {
+    fn from(id: SerialId) -> Self {
+        match id {
+            SerialId::Id(index, epoch, backend) => TypedId::zip(index, epoch, backend),
+        }
+    }
+}
 
 // required for PeekPoke
 impl<T> Default for Id<T> {