Implements Device::tlas_instance_to_bytes().

Author: Lichtso

wgpu-hal/Cargo.toml

@@ -75,6 +75,7 @@ metal = [
     "naga/msl-out",
     "dep:arrayvec",
     "dep:block",
+    "dep:bytemuck",
     "dep:core-graphics-types",
     "dep:hashbrown",
     "dep:libc",

wgpu-hal/src/metal/device.rs

@@ -2,6 +2,7 @@ use alloc::{borrow::ToOwned as _, sync::Arc, vec::Vec};
 use core::{ptr::NonNull, sync::atomic};
 use std::{thread, time};
 
+use bytemuck::TransparentWrapper;
 use parking_lot::Mutex;
 
 use super::{conv, PassthroughShader};
@@ -1613,8 +1614,39 @@ impl crate::Device for super::Device {
         // self.counters.acceleration_structures.sub(1);
     }
 
-    fn tlas_instance_to_bytes(&self, _instance: TlasInstance) -> Vec<u8> {
-        unimplemented!()
+    fn tlas_instance_to_bytes(&self, instance: TlasInstance) -> Vec<u8> {
+        let temp = metal::MTLAccelerationStructureInstanceDescriptor {
+            transformation_matrix: [
+                [
+                    instance.transform[0],
+                    instance.transform[4],
+                    instance.transform[8],
+                ],
+                [
+                    instance.transform[1],
+                    instance.transform[5],
+                    instance.transform[9],
+                ],
+                [
+                    instance.transform[2],
+                    instance.transform[6],
+                    instance.transform[10],
+                ],
+                [
+                    instance.transform[3],
+                    instance.transform[7],
+                    instance.transform[11],
+                ],
+            ],
+            options: metal::MTLAccelerationStructureInstanceOptions::None,
+            mask: (instance.custom_data << 8) | instance.mask as u32,
+            intersection_function_table_offset: 0,
+            acceleration_structure_index: instance.blas_address as u32,
+        };
+
+        wgt::bytemuck_wrapper!(unsafe struct Desc(metal::MTLAccelerationStructureInstanceDescriptor));
+
+        bytemuck::bytes_of(&Desc::wrap(temp)).to_vec()
     }
 
     fn get_internal_counters(&self) -> wgt::HalCounters {