runtime: Disable default link feature on metal crate (#21)

Since we're only using a few types from the `metal` crate, this helper
library has no reason or need to link against framework libraries (i.e.
we don't call global static functions on them). Disable the `link`
feature on the `metal` crate.

> [!CAUTION]
> For now this won't disable it on the `core-graphics-types` crate until
gfx-rs/metal-rs#330 is merged.

runtime/Cargo.toml

@@ -20,4 +20,4 @@ targets = [
 ]
 
 [dependencies]
-metal = "0.29"
+metal = { version = "0.29", default-features = false }

runtime/README.md

@@ -8,7 +8,7 @@
 
 [![Banner](../banner.png)](https://traverseresearch.nl)
 
-[`saxaboom-runtime`] provides the runtime structures and interop with the [`metal`] crate needed to make use of the `metallib` shaders generated by [`saxaboom`] (bindings for [Metal shader converter]).
+[`saxaboom-runtime`] provides the runtime `repr(C)` definitions for structures and interop with the [`metal`] crate needed to make use of the `metallib` shaders generated by [`saxaboom`] (bindings for [Metal shader converter]).
 
 ## Usage
 
@@ -21,11 +21,13 @@ Add this to your `Cargo.toml`:
 saxaboom-runtime = "0.1.0"
 ```
 
+Example to create a descriptor to a buffer:
+
 ```rust,no_run
 use saxaboom_runtime::ffi::IRDescriptorTableEntry;
 
 let gpu_address = 0; // TODO: Read from metal::Buffer::gpu_address()
-let metadata = IRDescriptorTableEntry::buffer_metadata(&todo!("Fill saxaboom_runtime::BufferView"));
+let metadata = IRDescriptorTableEntry::buffer_metadata(todo!("Fill saxaboom_runtime::BufferView"));
 let buffer_descriptor = IRDescriptorTableEntry::buffer(gpu_address, metadata);
 ```
 

runtime/src/lib.rs

@@ -1,4 +1,4 @@
-//! Contains `repr(C)` definitions for structures used at runtime.
+#![doc = include_str!("../README.md")]
 
 #[allow(
     clippy::useless_transmute,
@@ -30,8 +30,12 @@ impl ffi::IRDescriptorTableEntry {
     ///
     /// This function is a port of the `IRDescriptorTableSetBuffer` function in the `metal_irconverter_runtime.h` header.
     /// See <https://developer.apple.com/metal/shader-converter/> for more info.
-    // TODO: The docs say  "buffer view" for metadata: can we take a BufferView struct and set `Self::buffer_metadata()` instead?
-    // There are special constructors for atomic/counter buffers after all...
+    // TODO: This function seems to have no reason to exist, in favour of `buffer_view()` the
+    // `metadata` argument here needs to be constructed in the exact same way.  However, for a
+    // full buffer descriptor, setting the metadata to `0` seems to be fine?
+    // TODO: The docs say  "buffer view" for metadata: can we take a BufferView struct and set
+    // `Self::buffer_metadata()` instead? There are special constructors for atomic/counter buffers
+    // after all...
     #[doc(alias = "IRDescriptorTableSetBuffer")]
     pub fn buffer(gpu_address: u64, metadata: u64) -> Self {
         Self {