Introduce DynCommandEncoder, implement index & vertex buffer ops on it

wgpu-hal/src/dynamic/command.rs

@@ -0,0 +1,37 @@
+use crate::{BufferBinding, CommandEncoder};
+
+use super::DynBuffer;
+
+pub trait DynCommandEncoder {
+    unsafe fn set_index_buffer<'a>(
+        &mut self,
+        binding: BufferBinding<'a, dyn DynBuffer>,
+        format: wgt::IndexFormat,
+    );
+
+    unsafe fn set_vertex_buffer<'a>(
+        &mut self,
+        index: u32,
+        binding: BufferBinding<'a, dyn DynBuffer>,
+    );
+}
+
+impl<C: CommandEncoder> DynCommandEncoder for C {
+    unsafe fn set_index_buffer<'a>(
+        &mut self,
+        binding: BufferBinding<'a, dyn DynBuffer>,
+        format: wgt::IndexFormat,
+    ) {
+        let binding = binding.expect_downcast();
+        unsafe { self.set_index_buffer(binding, format) };
+    }
+
+    unsafe fn set_vertex_buffer<'a>(
+        &mut self,
+        index: u32,
+        binding: BufferBinding<'a, dyn DynBuffer>,
+    ) {
+        let binding = binding.expect_downcast();
+        unsafe { self.set_vertex_buffer(index, binding) };
+    }
+}

wgpu-hal/src/dynamic/mod.rs

@@ -1,7 +1,13 @@
+mod command;
+
+pub use self::command::DynCommandEncoder;
+
 use std::any::Any;
 
 use wgt::WasmNotSendSync;
 
+use crate::BufferBinding;
+
 /// Base trait for all resources, allows downcasting via [`Any`].
 pub trait DynResource: Any + WasmNotSendSync + 'static {
     fn as_any(&self) -> &dyn Any;
@@ -81,3 +87,13 @@ impl<R: DynResource + ?Sized> DynResourceExt for R {
 }
 
 pub trait DynBuffer: DynResource + std::fmt::Debug {}
+
+impl<'a> BufferBinding<'a, dyn DynBuffer> {
+    pub fn expect_downcast<B: DynBuffer>(self) -> BufferBinding<'a, B> {
+        BufferBinding {
+            buffer: self.buffer.expect_downcast_ref(),
+            offset: self.offset,
+            size: self.size,
+        }
+    }
+}

wgpu-hal/src/lib.rs

@@ -264,8 +264,8 @@ pub mod api {
 
 mod dynamic;
 
-pub use dynamic::DynBuffer;
 pub(crate) use dynamic::{impl_dyn_resource, DynResource};
+pub use dynamic::{DynBuffer, DynCommandEncoder};
 
 use std::{
     borrow::{Borrow, Cow},
@@ -392,7 +392,7 @@ pub trait Api: Clone + fmt::Debug + Sized {
     type Device: Device<A = Self>;
 
     type Queue: Queue<A = Self>;
-    type CommandEncoder: CommandEncoder<A = Self>;
+    type CommandEncoder: DynCommandEncoder + CommandEncoder<A = Self>;
 
     /// This API's command buffer type.
     ///