Mutable bind groups in DX12 and Vulkan within wgpu-hal

CHANGELOG.md

@@ -174,6 +174,9 @@ By @ErichDonGubler in [#6456](https://github.com/gfx-rs/wgpu/pull/6456), [#6148]
 
 - Replace `usage: Range<T>`, for `BufferUses`, `TextureUses`, and `AccelerationStructureBarrier` with a new `StateTransition<T>`. By @atlv24 in [#6703](https://github.com/gfx-rs/wgpu/pull/6703)
 - Change the `DropCallback` API to use `FnOnce` instead of `FnMut`. By @jerzywilczek in [#6482](https://github.com/gfx-rs/wgpu/pull/6482)
+- Mutable bind groups are now supported in DX12 and Vulkan on `wgpu-hal`. When creating a BindGroup using `create_bind_group` in `wgpu-hal`, set the `ALLOW_UPDATES` flag to allow updating the bind group after creation. Update the bind group using `update_bind_group`, similarly to how it's cr
+- DX12 now supports partially bound bind groups, allowing you to skip entries. These will then not get written when calling `create_bind_group`.
+- Added `array_element_offset` to `BindGroupLayoutEntry`, to allow for more free-form creating and updating of mutable bind groups for bindless resources.
 
 ### Bug Fixes
 

wgpu-core/src/device/resource.rs

@@ -2330,6 +2330,7 @@ impl Device {
             hal_entries.push(hal::BindGroupEntry {
                 binding,
                 resource_index: res_index as u32,
+                array_element_offset: None,
                 count: count as u32,
             });
         }
@@ -2344,6 +2345,7 @@ impl Device {
         }
         let hal_desc = hal::BindGroupDescriptor {
             label: desc.label.to_hal(self.instance_flags),
+            flags: hal::BindGroupFlags::empty(),
             layout: layout.raw(),
             entries: &hal_entries,
             buffers: &hal_buffers,

wgpu-core/src/indirect_validation.rs

@@ -234,10 +234,12 @@ impl IndirectValidation {
 
         let dst_bind_group_desc = hal::BindGroupDescriptor {
             label: None,
+            flags: hal::BindGroupFlags::empty(),
             layout: dst_bind_group_layout.as_ref(),
             entries: &[hal::BindGroupEntry {
                 binding: 0,
                 resource_index: 0,
+                array_element_offset: None,
                 count: 1,
             }],
             buffers: &[hal::BufferBinding {
@@ -280,10 +282,12 @@ impl IndirectValidation {
         };
         let hal_desc = hal::BindGroupDescriptor {
             label: None,
+            flags: hal::BindGroupFlags::empty(),
             layout: self.src_bind_group_layout.as_ref(),
             entries: &[hal::BindGroupEntry {
                 binding: 0,
                 resource_index: 0,
+                array_element_offset: None,
                 count: 1,
             }],
             buffers: &[hal::BufferBinding {