openxr changes

src/openxr.rs

@@ -1,16 +1,39 @@
-pub mod extensions;
-pub mod init;
+mod extensions;
+pub mod graphics;
 mod resources;
 pub mod types;
 
 pub use resources::*;
+pub use types::*;
 
 use bevy::app::{App, Plugin};
 
+pub fn xr_entry() -> Result<XrEntry> {
+    #[cfg(windows)]
+    let entry = openxr::Entry::linked();
+    #[cfg(not(windows))]
+    let entry = unsafe { openxr::Entry::load()? };
+    Ok(entry.into())
+}
+
+fn init_xr() -> Result<()> {
+    let entry = xr_entry()?;
+    let instance = entry.create_instance(
+        AppInfo::default(),
+        XrExtensions::default(),
+        GraphicsBackend::Vulkan(()),
+    )?;
+    let system_id = instance.system(openxr::FormFactor::HEAD_MOUNTED_DISPLAY)?;
+
+    instance.create_session(system_id)?;
+    Ok(())
+}
+
 pub struct XrInitPlugin;
 
 impl Plugin for XrInitPlugin {
     fn build(&self, app: &mut App) {
+        let entry = xr_entry();
         todo!()
     }
 }

src/openxr/extensions.rs

@@ -49,40 +49,6 @@ impl Default for XrExtensions {
     }
 }
 
-macro_rules! unavailable_exts {
-    (
-        $exts:ty;
-        $(
-            $(
-                #[$meta:meta]
-            )*
-            $ident:ident
-        ),*
-        $(,)?
-    ) => {
-        impl $exts {
-            /// Returns any extensions needed by `required_exts` that aren't available in `self`
-            pub(crate) fn unavailable_exts(&self, required_exts: &Self) -> Vec<std::borrow::Cow<'static, str>> {
-                let mut exts = vec![];
-                $(
-                    $(
-                        #[$meta]
-                    )*
-                    if required_exts.0.$ident && !self.0.$ident {
-                        exts.push(std::borrow::Cow::Borrowed(stringify!($ident)))
-                    }
-                )*
-                for ext in required_exts.0.other.iter() {
-                    if !self.0.other.contains(ext) {
-                        exts.push(std::borrow::Cow::Owned(ext.clone()))
-                    }
-                }
-                exts
-            }
-        }
-    };
-}
-
 macro_rules! bitor {
     (
         $exts:ty;
@@ -288,4 +254,4 @@ macro_rules! impl_ext {
     };
 }
 
-impl_ext!(bitor, bitand, unavailable_exts);
+impl_ext!(bitor, bitand);

src/openxr/graphics.rs

@@ -0,0 +1,133 @@
+pub mod vulkan;
+
+use bevy::math::UVec2;
+
+use crate::openxr::resources::*;
+use crate::openxr::types::{AppInfo, Result, XrError};
+use crate::types::BlendMode;
+
+trait GraphicWrapper {
+    type Inner<T: GraphicsExt>;
+    type Func: Fn();
+}
+
+pub trait GraphicsExt: openxr::Graphics {
+    fn from_wgpu_format(format: wgpu::TextureFormat) -> Option<Self::Format>;
+    fn to_wgpu_format(format: Self::Format) -> Option<wgpu::TextureFormat>;
+    fn create_session(
+        app_info: &AppInfo,
+        instance: &openxr::Instance,
+        system_id: openxr::SystemId,
+    ) -> Result<(
+        wgpu::Device,
+        wgpu::Queue,
+        wgpu::Adapter,
+        wgpu::Instance,
+        XrSession,
+        XrFrameWaiter,
+        XrFrameStream,
+    )>;
+    unsafe fn to_wgpu_img(
+        image: Self::SwapchainImage,
+        device: &wgpu::Device,
+        format: wgpu::TextureFormat,
+        resolution: UVec2,
+    ) -> Result<wgpu::Texture>;
+    fn required_exts() -> XrExtensions;
+}
+
+#[derive(Clone, Copy, Debug, PartialEq, Eq)]
+pub enum GraphicsWrap<T: GraphicsType> {
+    Vulkan(T::Inner<openxr::Vulkan>),
+}
+
+impl<T: GraphicsType> GraphicsWrap<T> {
+    /// Returns the name of the graphics api this struct is using.
+    pub fn graphics_name(&self) -> &'static str {
+        graphics_match!(
+            self;
+            _ => std::any::type_name::<Api>()
+        )
+    }
+
+    fn graphics_type(&self) -> std::any::TypeId {
+        graphics_match!(
+            self;
+            _ => std::any::TypeId::of::<Api>()
+        )
+    }
+
+    /// Checks if this struct is using the wanted graphics api.
+    pub fn using_graphics<G: GraphicsExt + 'static>(&self) -> bool {
+        self.graphics_type() == std::any::TypeId::of::<G>()
+    }
+}
+
+pub trait GraphicsType {
+    type Inner<G: GraphicsExt>;
+}
+
+impl GraphicsType for () {
+    type Inner<G: GraphicsExt> = ();
+}
+
+macro_rules! graphics_match {
+    (
+        $field:expr;
+        $var:pat => $expr:expr $(=> $($return:tt)*)?
+    ) => {
+        match $field {
+            $crate::openxr::graphics::GraphicsWrap::Vulkan($var) => {
+                #[allow(unused)]
+                type Api = openxr::Vulkan;
+                graphics_match!(@arm_impl Vulkan; $expr $(=> $($return)*)?)
+            },
+        }
+    };
+
+    (
+        @arm_impl
+        $variant:ident;
+        $expr:expr => $wrap_ty:ty
+    ) => {
+        GraphicsWrap::<$wrap_ty>::$variant($expr)
+    };
+
+    (
+        @arm_impl
+        $variant:ident;
+        $expr:expr
+    ) => {
+        $expr
+    };
+}
+
+pub(crate) use graphics_match;
+
+use super::XrExtensions;
+
+impl From<openxr::EnvironmentBlendMode> for BlendMode {
+    fn from(value: openxr::EnvironmentBlendMode) -> Self {
+        use openxr::EnvironmentBlendMode;
+        if value == EnvironmentBlendMode::OPAQUE {
+            BlendMode::Opaque
+        } else if value == EnvironmentBlendMode::ADDITIVE {
+            BlendMode::Additive
+        } else if value == EnvironmentBlendMode::ALPHA_BLEND {
+            BlendMode::AlphaBlend
+        } else {
+            unreachable!()
+        }
+    }
+}
+
+impl From<BlendMode> for openxr::EnvironmentBlendMode {
+    fn from(value: BlendMode) -> Self {
+        use openxr::EnvironmentBlendMode;
+        match value {
+            BlendMode::Opaque => EnvironmentBlendMode::OPAQUE,
+            BlendMode::Additive => EnvironmentBlendMode::ADDITIVE,
+            BlendMode::AlphaBlend => EnvironmentBlendMode::ALPHA_BLEND,
+        }
+    }
+}

src/openxr/graphics/vulkan.rs

@@ -9,14 +9,9 @@ use wgpu_hal::Api;
 
 use crate::openxr::extensions::XrExtensions;
 use crate::openxr::resources::*;
+use crate::openxr::types::Result;
 
-use super::{AppInfo, GraphicsExt, XrInitError};
-
-pub fn required_exts() -> XrExtensions {
-    let mut extensions = openxr::ExtensionSet::default();
-    extensions.khr_vulkan_enable2 = true;
-    extensions.into()
-}
+use super::{AppInfo, GraphicsExt, XrError};
 
 #[cfg(not(target_os = "android"))]
 const VK_TARGET_VERSION: Version = Version::new(1, 2, 0);
@@ -30,35 +25,28 @@ const VK_TARGET_VERSION_ASH: u32 = ash::vk::make_api_version(
     VK_TARGET_VERSION.patch() as u32,
 );
 
-pub fn enumerate_swapchain_formats(
-    session: &openxr::Session<openxr::Vulkan>,
-) -> openxr::Result<Vec<wgpu::TextureFormat>> {
-    let formats = session
-        .enumerate_swapchain_formats()?
-        .into_iter()
-        .filter_map(|f| vulkan_to_wgpu(ash::vk::Format::from_raw(f as _)))
-        .collect();
-    Ok(formats)
+impl GraphicsExt for openxr::Vulkan {
+    fn from_wgpu_format(format: wgpu::TextureFormat) -> Option<Self::Format> {
+        wgpu_to_vulkan(format).map(|f| f.as_raw() as _)
     }
 
-pub fn create_session(
-    app_info: AppInfo,
+    fn to_wgpu_format(format: Self::Format) -> Option<wgpu::TextureFormat> {
+        vulkan_to_wgpu(ash::vk::Format::from_raw(format as _))
+    }
+
+    fn create_session(
+        app_info: &AppInfo,
         instance: &openxr::Instance,
         system_id: openxr::SystemId,
-    format: wgpu::TextureFormat,
-    resolution: UVec2,
-) -> Result<
-    (
+    ) -> Result<(
         wgpu::Device,
         wgpu::Queue,
         wgpu::Adapter,
         wgpu::Instance,
-        openxr::Session<openxr::AnyGraphics>,
-        openxr::FrameWaiter,
-        FrameStreamInner,
-    ),
-    XrInitError,
-> {
+        XrSession,
+        XrFrameWaiter,
+        XrFrameStream,
+    )> {
         let reqs = instance.graphics_requirements::<openxr::Vulkan>(system_id)?;
         if VK_TARGET_VERSION < reqs.min_api_version_supported
             || VK_TARGET_VERSION.major() > reqs.max_api_version_supported.major()
@@ -68,12 +56,15 @@ pub fn create_session(
                 reqs.min_api_version_supported,
                 reqs.max_api_version_supported.major() + 1
             );
-        return Err(XrInitError::FailedGraphicsRequirements);
+            return Err(XrError::FailedGraphicsRequirements);
         };
         let vk_entry = unsafe { ash::Entry::load() }?;
         let flags = wgpu_hal::InstanceFlags::empty();
-    let extensions =
-        <Vulkan as Api>::Instance::required_extensions(&vk_entry, VK_TARGET_VERSION_ASH, flags)?;
+        let extensions = <Vulkan as Api>::Instance::required_extensions(
+            &vk_entry,
+            VK_TARGET_VERSION_ASH,
+            flags,
+        )?;
         let device_extensions = vec![
             ash::extensions::khr::Swapchain::name(),
             ash::extensions::khr::DrawIndirectCount::name(),
@@ -84,7 +75,7 @@ pub fn create_session(
         let vk_instance = unsafe {
             let extensions_cchar: Vec<_> = extensions.iter().map(|s| s.as_ptr()).collect();
 
-        let app_name = CString::new(app_info.name)?;
+            let app_name = CString::new(app_info.name.clone().into_owned())?;
             let vk_app_info = ash::vk::ApplicationInfo::builder()
                 .application_name(&app_name)
                 .application_version(1)
@@ -127,7 +118,7 @@ pub fn create_session(
                 VK_TARGET_VERSION.minor(),
                 VK_TARGET_VERSION.patch()
             );
-        return Err(XrInitError::FailedGraphicsRequirements);
+            return Err(XrError::FailedGraphicsRequirements);
         }
 
         let wgpu_vk_instance = unsafe {
@@ -151,7 +142,7 @@ pub fn create_session(
 
         let Some(wgpu_exposed_adapter) = wgpu_vk_instance.expose_adapter(vk_physical_device) else {
             error!("WGPU failed to provide an adapter");
-        return Err(XrInitError::FailedGraphicsRequirements);
+            return Err(XrError::FailedGraphicsRequirements);
         };
 
         let enabled_extensions = wgpu_exposed_adapter
@@ -255,40 +246,69 @@ pub fn create_session(
             wgpu_queue,
             wgpu_adapter,
             wgpu_instance,
-        session.into_any_graphics(),
-        frame_wait,
-        FrameStreamInner::Vulkan(frame_stream),
+            XrSession(
+                session.clone().into_any_graphics(),
+                super::GraphicsWrap::Vulkan(session),
+            ),
+            XrFrameWaiter(frame_wait),
+            XrFrameStream(super::GraphicsWrap::Vulkan(frame_stream)),
         ))
     }
 
-impl GraphicsExt for openxr::Vulkan {
-    fn from_wgpu_format(format: wgpu::TextureFormat) -> Option<Self::Format> {
-        wgpu_to_vulkan(format).map(|f| f.as_raw() as _)
-    }
-
-    fn to_wgpu_format(format: Self::Format) -> Option<wgpu::TextureFormat> {
-        vulkan_to_wgpu(ash::vk::Format::from_raw(format as _))
-    }
-
-    fn create_session(
-        app_info: AppInfo,
-        instance: &openxr::Instance,
-        system_id: openxr::SystemId,
+    unsafe fn to_wgpu_img(
+        color_image: Self::SwapchainImage,
+        device: &wgpu::Device,
         format: wgpu::TextureFormat,
         resolution: UVec2,
-    ) -> Result<
-        (
-            wgpu::Device,
-            wgpu::Queue,
-            wgpu::Adapter,
-            wgpu::Instance,
-            openxr::Session<openxr::AnyGraphics>,
-            openxr::FrameWaiter,
-            FrameStreamInner,
-        ),
-        XrInitError,
-    > {
-        create_session(app_info, instance, system_id, format, resolution)
+    ) -> Result<wgpu::Texture> {
+        let color_image = ash::vk::Image::from_raw(color_image);
+        let wgpu_hal_texture = unsafe {
+            <wgpu_hal::vulkan::Api as wgpu_hal::Api>::Device::texture_from_raw(
+                color_image,
+                &wgpu_hal::TextureDescriptor {
+                    label: Some("VR Swapchain"),
+                    size: wgpu::Extent3d {
+                        width: resolution.x,
+                        height: resolution.y,
+                        depth_or_array_layers: 2,
+                    },
+                    mip_level_count: 1,
+                    sample_count: 1,
+                    dimension: wgpu::TextureDimension::D2,
+                    format: format,
+                    usage: wgpu_hal::TextureUses::COLOR_TARGET | wgpu_hal::TextureUses::COPY_DST,
+                    memory_flags: wgpu_hal::MemoryFlags::empty(),
+                    view_formats: vec![],
+                },
+                None,
+            )
+        };
+        let texture = unsafe {
+            device.create_texture_from_hal::<wgpu_hal::vulkan::Api>(
+                wgpu_hal_texture,
+                &wgpu::TextureDescriptor {
+                    label: Some("VR Swapchain"),
+                    size: wgpu::Extent3d {
+                        width: resolution.x,
+                        height: resolution.y,
+                        depth_or_array_layers: 2,
+                    },
+                    mip_level_count: 1,
+                    sample_count: 1,
+                    dimension: wgpu::TextureDimension::D2,
+                    format: format,
+                    usage: wgpu::TextureUsages::RENDER_ATTACHMENT | wgpu::TextureUsages::COPY_DST,
+                    view_formats: &[],
+                },
+            )
+        };
+        Ok(texture)
+    }
+
+    fn required_exts() -> XrExtensions {
+        let mut extensions = openxr::ExtensionSet::default();
+        extensions.khr_vulkan_enable2 = true;
+        extensions.into()
     }
 }
 

src/openxr/init.rs

@@ -1,224 +0,0 @@
-pub mod vulkan;
-
-use bevy::log::{info, warn};
-use bevy::math::{uvec2, UVec2};
-use thiserror::Error;
-
-use crate::openxr::resources::*;
-use crate::types::BlendMode;
-
-use super::extensions::XrExtensions;
-
-#[derive(Clone, Copy, Debug, Default, PartialEq)]
-pub struct Version(pub u8, pub u8, pub u16);
-
-impl Version {
-    pub const BEVY: Self = Self(0, 12, 1);
-
-    pub const fn to_u32(self) -> u32 {
-        let major = (self.0 as u32) << 24;
-        let minor = (self.1 as u32) << 16;
-        self.2 as u32 | major | minor
-    }
-}
-
-#[derive(Clone, Copy, Debug, Default, PartialEq)]
-pub struct AppInfo<'a> {
-    pub name: &'a str,
-    pub version: Version,
-}
-
-#[derive(Clone, Copy, Debug)]
-pub enum GraphicsBackend {
-    Vulkan,
-}
-
-impl GraphicsBackend {
-    const ALL: &'static [Self] = &[Self::Vulkan];
-
-    pub fn available_backends(exts: &XrExtensions) -> Vec<Self> {
-        Self::ALL
-            .iter()
-            .copied()
-            .filter(|backend| backend.is_available(exts))
-            .collect()
-    }
-
-    pub fn is_available(&self, exts: &XrExtensions) -> bool {
-        self.required_exts().is_available(exts)
-    }
-
-    pub fn required_exts(&self) -> XrExtensions {
-        match self {
-            GraphicsBackend::Vulkan => vulkan::required_exts(),
-        }
-    }
-}
-
-#[derive(Error, Debug)]
-pub enum XrInitError {
-    #[error("OpenXR error: {0}")]
-    OpenXrError(#[from] openxr::sys::Result),
-    #[error("OpenXR loading error: {0}")]
-    OpenXrLoadingError(#[from] openxr::LoadError),
-    #[error("WGPU instance error: {0}")]
-    WgpuInstanceError(#[from] wgpu_hal::InstanceError),
-    #[error("WGPU device error: {0}")]
-    WgpuDeviceError(#[from] wgpu_hal::DeviceError),
-    #[error("WGPU request device error: {0}")]
-    WgpuRequestDeviceError(#[from] wgpu::RequestDeviceError),
-    #[error("Unsupported texture format: {0:?}")]
-    UnsupportedTextureFormat(wgpu::TextureFormat),
-    #[error("Vulkan error: {0}")]
-    VulkanError(#[from] ash::vk::Result),
-    #[error("Vulkan loading error: {0}")]
-    VulkanLoadingError(#[from] ash::LoadingError),
-    #[error("Graphics backend '{0:?}' is not available")]
-    UnavailableBackend(GraphicsBackend),
-    #[error("Could not meet graphics requirements for platform. See console for details")]
-    FailedGraphicsRequirements,
-    #[error("Failed to create CString: {0}")]
-    NulError(#[from] std::ffi::NulError),
-}
-
-pub trait GraphicsExt: openxr::Graphics {
-    fn from_wgpu_format(format: wgpu::TextureFormat) -> Option<Self::Format>;
-    fn to_wgpu_format(format: Self::Format) -> Option<wgpu::TextureFormat>;
-    fn create_session(
-        app_info: AppInfo,
-        instance: &openxr::Instance,
-        system_id: openxr::SystemId,
-        format: wgpu::TextureFormat,
-        resolution: UVec2,
-    ) -> Result<
-        (
-            wgpu::Device,
-            wgpu::Queue,
-            wgpu::Adapter,
-            wgpu::Instance,
-            openxr::Session<openxr::AnyGraphics>,
-            openxr::FrameWaiter,
-            FrameStreamInner,
-        ),
-        XrInitError,
-    >;
-}
-
-fn xr_entry() -> Result<openxr::Entry, XrInitError> {
-    #[cfg(windows)]
-    let entry = Some(openxr::Entry::linked());
-    #[cfg(not(windows))]
-    let entry = unsafe { openxr::Entry::load()? };
-    Ok(entry)
-}
-
-// pub fn init_xr(
-//     app_info: AppInfo,
-//     requested_exts: XrExtensions,
-//     format: wgpu::TextureFormat,
-//     preferred_blend_mode: BlendMode,
-// ) -> Result<
-//     (
-//         wgpu::Device,
-//         wgpu::Queue,
-//         wgpu::Adapter,
-//         wgpu::Instance,
-//         openxr::Instance,
-//         openxr::Session<openxr::AnyGraphics>,
-//         openxr::FrameWaiter,
-//         FrameStreamInner,
-//         XrSwapchain,
-//     ),
-//     XrInitError,
-// > {
-//     let entry = xr_entry().unwrap();
-
-//     let required_exts = vulkan::required_exts() | requested_exts;
-//     let available_exts: XrExtensions = entry.enumerate_extensions()?.into();
-//     for ext in available_exts.unavailable_exts(&required_exts) {
-//         warn!("OpenXR extension '{ext}' is not supported by the current OpenXR runtime")
-//     }
-//     let enabled_exts = required_exts & available_exts;
-
-//     let instance = entry.create_instance(
-//         &openxr::ApplicationInfo {
-//             application_name: app_info.name,
-//             application_version: app_info.version.to_u32(),
-//             engine_name: "Bevy",
-//             engine_version: Version::BEVY.to_u32(),
-//         },
-//         &enabled_exts.into(),
-//         &[],
-//     )?;
-//     info!("Created OpenXR Instance: {:#?}", instance.properties()?);
-
-//     let system_id = instance.system(openxr::FormFactor::HEAD_MOUNTED_DISPLAY)?;
-//     info!(
-//         "Using system: {:#?}",
-//         instance.system_properties(system_id)?
-//     );
-
-//     let view = instance
-//         .enumerate_view_configurations(system_id)?
-//         .first()
-//         .copied()
-//         .unwrap_or(openxr::ViewConfigurationType::PRIMARY_STEREO);
-
-//     let resolution = instance
-//         .enumerate_view_configuration_views(system_id, view)?
-//         .first()
-//         .map(|c| {
-//             uvec2(
-//                 c.recommended_image_rect_width,
-//                 c.recommended_image_rect_height,
-//             )
-//         })
-//         .unwrap();
-
-//     let (wgpu_device, wgpu_queue, wgpu_adapter, wgpu_instance, session, frame_waiter, frame_stream) =
-//         vulkan::create_session(app_info, &instance, system_id, format, resolution)?;
-
-//     let blend_modes = instance.enumerate_environment_blend_modes(system_id, view)?;
-
-//     let blend_mode = if blend_modes.contains(&preferred_blend_mode.into()) {
-//         preferred_blend_mode.into()
-//     } else {
-//         warn!(
-//             "Runtime does not support blend mode '{:?}'",
-//             preferred_blend_mode
-//         );
-//         blend_modes
-//             .first()
-//             .copied()
-//             .unwrap_or(openxr::EnvironmentBlendMode::OPAQUE)
-//     };
-//     info!("Using blend mode '{:?}'", blend_mode);
-
-//     todo!()
-// }
-
-impl From<openxr::EnvironmentBlendMode> for BlendMode {
-    fn from(value: openxr::EnvironmentBlendMode) -> Self {
-        use openxr::EnvironmentBlendMode;
-        if value == EnvironmentBlendMode::OPAQUE {
-            BlendMode::Opaque
-        } else if value == EnvironmentBlendMode::ADDITIVE {
-            BlendMode::Additive
-        } else if value == EnvironmentBlendMode::ALPHA_BLEND {
-            BlendMode::AlphaBlend
-        } else {
-            unreachable!()
-        }
-    }
-}
-
-impl From<BlendMode> for openxr::EnvironmentBlendMode {
-    fn from(value: BlendMode) -> Self {
-        use openxr::EnvironmentBlendMode;
-        match value {
-            BlendMode::Opaque => EnvironmentBlendMode::OPAQUE,
-            BlendMode::Additive => EnvironmentBlendMode::ADDITIVE,
-            BlendMode::AlphaBlend => EnvironmentBlendMode::ALPHA_BLEND,
-        }
-    }
-}

src/openxr/resources.rs

@@ -1,15 +1,8 @@
-use std::sync::{Arc, Mutex};
-
-use ash::vk::Handle;
 use bevy::prelude::*;
 
-use openxr::{AnyGraphics, Vulkan};
+use openxr::AnyGraphics;
 
-use crate::openxr::init::Version;
-
-use super::extensions::XrExtensions;
-use super::init::{self, AppInfo, GraphicsBackend, GraphicsExt, XrInitError};
-type Result<T> = std::result::Result<T, XrInitError>;
+use super::graphics::{graphics_match, GraphicsExt, GraphicsType, GraphicsWrap};
 use super::types::*;
 
 #[derive(Deref, Clone)]
@@ -21,22 +14,22 @@ impl XrEntry {
     }
 
     pub fn create_instance(
-        entry: XrEntry,
+        &self,
         app_info: AppInfo,
         exts: XrExtensions,
         backend: GraphicsBackend,
     ) -> Result<XrInstance> {
-        let available_exts = entry.enumerate_extensions()?;
+        let available_exts = self.enumerate_extensions()?;
 
         if !backend.is_available(&available_exts) {
-            return Err(XrInitError::UnavailableBackend(backend));
+            return Err(XrError::UnavailableBackend(backend));
         }
 
         let required_exts = exts | backend.required_exts();
 
-        let instance = entry.create_instance(
+        let instance = self.0.create_instance(
             &openxr::ApplicationInfo {
-                application_name: app_info.name,
+                application_name: &app_info.name,
                 application_version: app_info.version.to_u32(),
                 engine_name: "Bevy",
                 engine_version: Version::BEVY.to_u32(),
@@ -45,7 +38,7 @@ impl XrEntry {
             &[],
         )?;
 
-        Ok(XrInstance(instance, backend))
+        Ok(XrInstance(instance, backend, app_info))
     }
 
     pub fn available_backends(&self) -> Result<Vec<GraphicsBackend>> {
@@ -65,187 +58,148 @@ impl From<openxr::Entry> for XrEntry {
 pub struct XrInstance(
     #[deref] pub(crate) openxr::Instance,
     pub(crate) GraphicsBackend,
+    pub(crate) AppInfo,
 );
 
 impl XrInstance {
     pub fn create_session(
         &self,
-        app_info: AppInfo,
         system_id: openxr::SystemId,
-        format: wgpu::TextureFormat,
-        resolution: UVec2,
     ) -> Result<(
         wgpu::Device,
         wgpu::Queue,
         wgpu::Adapter,
         wgpu::Instance,
-        openxr::Session<openxr::AnyGraphics>,
-        openxr::FrameWaiter,
-        FrameStreamInner,
+        XrSession,
+        XrFrameWaiter,
+        XrFrameStream,
     )> {
-        match self.1 {
-            GraphicsBackend::Vulkan => {
-                openxr::Vulkan::create_session(app_info, &self.0, system_id, format, resolution)
-            }
+        graphics_match!(
+            self.1;
+            _ => Api::create_session(&self.2, &self.0, system_id)
+        )
     }
 }
+
+impl GraphicsType for XrSession {
+    type Inner<G: GraphicsExt> = openxr::Session<G>;
 }
 
 #[derive(Resource, Deref, Clone)]
 pub struct XrSession(
     #[deref] pub(crate) openxr::Session<AnyGraphics>,
-    pub(crate) TypedSession,
+    pub(crate) GraphicsWrap<Self>,
 );
 
 impl XrSession {
     pub fn enumerate_swapchain_formats(&self) -> Result<Vec<wgpu::TextureFormat>> {
-        self.1.enumerate_swapchain_formats()
+        graphics_match!(
+            &self.1;
+            session => Ok(session.enumerate_swapchain_formats()?.into_iter().filter_map(Api::to_wgpu_format).collect())
+        )
     }
 
     pub fn create_swapchain(&self, info: SwapchainCreateInfo) -> Result<XrSwapchain> {
-        self.1.create_swapchain(info)
+        Ok(XrSwapchain(graphics_match!(
+            &self.1;
+            session => session.create_swapchain(&info.try_into()?)? => XrSwapchain
+        )))
     }
 }
 
-#[derive(Clone)]
-pub enum TypedSession {
-    Vulkan(openxr::Session<Vulkan>),
+pub struct XrFrameStream(pub(crate) GraphicsWrap<Self>);
+
+impl GraphicsType for XrFrameStream {
+    type Inner<G: GraphicsExt> = openxr::FrameStream<G>;
 }
 
-impl TypedSession {
-    pub fn into_any_graphics(&self) -> openxr::Session<AnyGraphics> {
-        match self {
-            TypedSession::Vulkan(session) => session.clone().into_any_graphics(),
+impl XrFrameStream {
+    pub fn begin(&mut self) -> openxr::Result<()> {
+        graphics_match!(
+            &mut self.0;
+            stream => stream.begin()
+        )
+    }
+
+    pub fn end(
+        &mut self,
+        display_time: openxr::Time,
+        environment_blend_mode: openxr::EnvironmentBlendMode,
+        layers: &[&dyn CompositionLayer],
+    ) -> Result<()> {
+        graphics_match!(
+            &mut self.0;
+            stream => {
+                let mut new_layers = vec![];
+
+                for (i, layer) in layers.into_iter().enumerate() {
+                    if let Some(swapchain) = layer.swapchain() {
+                        if !swapchain.0.using_graphics::<Api>() {
+                            warn!(
+                                "composition layer {i} is using graphics api '{}', expected graphics api '{}'. Excluding layer from frame submission.",
+                                swapchain.0.graphics_name(),
+                                std::any::type_name::<Api>(),
+                            );
+                            continue;
+                        }
+                    }
+                    new_layers.push(unsafe { std::mem::transmute(layer.header()) });
+                }
+
+                Ok(stream.end(display_time, environment_blend_mode, new_layers.as_slice())?)
+            }
+        )
     }
 }
 
-    pub fn enumerate_swapchain_formats(&self) -> Result<Vec<wgpu::TextureFormat>> {
-        Ok(match self {
-            TypedSession::Vulkan(session) => init::vulkan::enumerate_swapchain_formats(session),
-        }?)
-    }
+#[derive(Deref, DerefMut)]
+pub struct XrFrameWaiter(pub openxr::FrameWaiter);
 
-    pub fn create_swapchain(&self, info: SwapchainCreateInfo) -> Result<XrSwapchain> {
-        Ok(match self {
-            TypedSession::Vulkan(session) => {
-                XrSwapchain::Vulkan(session.create_swapchain(&info.try_into()?)?)
-            }
-        })
-    }
-}
+pub struct XrSwapchain(pub(crate) GraphicsWrap<Self>);
 
-#[derive(Resource, Default, Deref)]
-pub struct Framebuffers(pub Vec<wgpu::Texture>);
-
-#[derive(Clone)]
-pub struct Swapchain {
-    pub inner: Arc<Mutex<XrSwapchain>>,
-    pub format: wgpu::TextureFormat,
-    pub resolution: UVec2,
-}
-
-pub enum FrameStreamInner {
-    Vulkan(openxr::FrameStream<openxr::Vulkan>),
-}
-
-pub enum XrSwapchain {
-    Vulkan(openxr::Swapchain<openxr::Vulkan>),
+impl GraphicsType for XrSwapchain {
+    type Inner<G: GraphicsExt> = openxr::Swapchain<G>;
 }
 
 impl XrSwapchain {
     pub fn acquire_image(&mut self) -> Result<u32> {
-        Ok(match self {
-            XrSwapchain::Vulkan(swap) => swap.acquire_image()?,
-        })
+        graphics_match!(
+            &mut self.0;
+            swap => Ok(swap.acquire_image()?)
+        )
     }
 
     pub fn wait_image(&mut self, timeout: openxr::Duration) -> Result<()> {
-        Ok(match self {
-            XrSwapchain::Vulkan(swap) => swap.wait_image(timeout)?,
-        })
+        graphics_match!(
+            &mut self.0;
+            swap => Ok(swap.wait_image(timeout)?)
+        )
     }
 
     pub fn release_image(&mut self) -> Result<()> {
-        Ok(match self {
-            XrSwapchain::Vulkan(swap) => swap.release_image()?,
-        })
+        graphics_match!(
+            &mut self.0;
+            swap => Ok(swap.release_image()?)
+        )
     }
 
     pub fn enumerate_images(
         &mut self,
-        device: wgpu::Device,
+        device: &wgpu::Device,
         format: wgpu::TextureFormat,
         resolution: UVec2,
     ) -> Result<Vec<wgpu::Texture>> {
-        match self {
-            XrSwapchain::Vulkan(swap) => swap.enumerate_imgs(device, format, resolution),
+        graphics_match!(
+            &mut self.0;
+            swap => {
+                let mut images = vec![];
+                for image in swap.enumerate_images()? {
+                    unsafe {
+                        images.push(Api::to_wgpu_img(image, device, format, resolution)?);
                     }
                 }
+                Ok(images)
             }
-
-trait EnumerateImages {
-    fn enumerate_imgs(
-        &mut self,
-        device: wgpu::Device,
-        format: wgpu::TextureFormat,
-        resolution: UVec2,
-    ) -> Result<Vec<wgpu::Texture>>;
-}
-
-impl EnumerateImages for openxr::Swapchain<openxr::Vulkan> {
-    fn enumerate_imgs(
-        &mut self,
-        device: wgpu::Device,
-        format: wgpu::TextureFormat,
-        resolution: UVec2,
-    ) -> Result<Vec<wgpu::Texture>> {
-        let images = self.enumerate_images()?;
-        let images = images.into_iter().map(|color_image| {
-            let color_image = ash::vk::Image::from_raw(color_image);
-            let wgpu_hal_texture = unsafe {
-                <wgpu_hal::vulkan::Api as wgpu_hal::Api>::Device::texture_from_raw(
-                    color_image,
-                    &wgpu_hal::TextureDescriptor {
-                        label: Some("VR Swapchain"),
-                        size: wgpu::Extent3d {
-                            width: resolution.x,
-                            height: resolution.y,
-                            depth_or_array_layers: 2,
-                        },
-                        mip_level_count: 1,
-                        sample_count: 1,
-                        dimension: wgpu::TextureDimension::D2,
-                        format: format,
-                        usage: wgpu_hal::TextureUses::COLOR_TARGET
-                            | wgpu_hal::TextureUses::COPY_DST,
-                        memory_flags: wgpu_hal::MemoryFlags::empty(),
-                        view_formats: vec![],
-                    },
-                    None,
         )
-            };
-            let texture = unsafe {
-                device.create_texture_from_hal::<wgpu_hal::vulkan::Api>(
-                    wgpu_hal_texture,
-                    &wgpu::TextureDescriptor {
-                        label: Some("VR Swapchain"),
-                        size: wgpu::Extent3d {
-                            width: resolution.x,
-                            height: resolution.y,
-                            depth_or_array_layers: 2,
-                        },
-                        mip_level_count: 1,
-                        sample_count: 1,
-                        dimension: wgpu::TextureDimension::D2,
-                        format: format,
-                        usage: wgpu::TextureUsages::RENDER_ATTACHMENT
-                            | wgpu::TextureUsages::COPY_DST,
-                        view_formats: &[],
-                    },
-                )
-            };
-            texture
-        });
-        Ok(images.collect())
     }
 }

src/openxr/types.rs

@@ -1,6 +1,83 @@
-pub use openxr::{SwapchainCreateFlags, SwapchainUsageFlags, SystemId};
+use std::borrow::Cow;
+use thiserror::Error;
 
-use super::init::{GraphicsExt, XrInitError};
+use super::graphics::{graphics_match, GraphicsExt, GraphicsWrap};
+
+pub use super::extensions::XrExtensions;
+pub use openxr::{
+    Extent2Di, Offset2Di, Rect2Di, SwapchainCreateFlags, SwapchainUsageFlags, SystemId,
+};
+pub type Result<T> = std::result::Result<T, XrError>;
+
+#[derive(Clone, Copy, Debug, Default, PartialEq)]
+pub struct Version(pub u8, pub u8, pub u16);
+
+impl Version {
+    pub const BEVY: Self = Self(0, 12, 1);
+
+    pub const fn to_u32(self) -> u32 {
+        let major = (self.0 as u32) << 24;
+        let minor = (self.1 as u32) << 16;
+        self.2 as u32 | major | minor
+    }
+}
+
+#[derive(Clone, Debug, Default, PartialEq)]
+pub struct AppInfo {
+    pub name: Cow<'static, str>,
+    pub version: Version,
+}
+
+pub type GraphicsBackend = GraphicsWrap<()>;
+
+impl GraphicsBackend {
+    const ALL: &'static [Self] = &[Self::Vulkan(())];
+
+    pub fn available_backends(exts: &XrExtensions) -> Vec<Self> {
+        Self::ALL
+            .iter()
+            .copied()
+            .filter(|backend| backend.is_available(exts))
+            .collect()
+    }
+
+    pub fn is_available(&self, exts: &XrExtensions) -> bool {
+        self.required_exts().is_available(exts)
+    }
+
+    pub fn required_exts(&self) -> XrExtensions {
+        graphics_match!(
+            self;
+            _ => Api::required_exts()
+        )
+    }
+}
+
+#[derive(Error, Debug)]
+pub enum XrError {
+    #[error("OpenXR error: {0}")]
+    OpenXrError(#[from] openxr::sys::Result),
+    #[error("OpenXR loading error: {0}")]
+    OpenXrLoadingError(#[from] openxr::LoadError),
+    #[error("WGPU instance error: {0}")]
+    WgpuInstanceError(#[from] wgpu_hal::InstanceError),
+    #[error("WGPU device error: {0}")]
+    WgpuDeviceError(#[from] wgpu_hal::DeviceError),
+    #[error("WGPU request device error: {0}")]
+    WgpuRequestDeviceError(#[from] wgpu::RequestDeviceError),
+    #[error("Unsupported texture format: {0:?}")]
+    UnsupportedTextureFormat(wgpu::TextureFormat),
+    #[error("Vulkan error: {0}")]
+    VulkanError(#[from] ash::vk::Result),
+    #[error("Vulkan loading error: {0}")]
+    VulkanLoadingError(#[from] ash::LoadingError),
+    #[error("Graphics backend '{0:?}' is not available")]
+    UnavailableBackend(GraphicsBackend),
+    #[error("Could not meet graphics requirements for platform. See console for details")]
+    FailedGraphicsRequirements,
+    #[error("Failed to create CString: {0}")]
+    NulError(#[from] std::ffi::NulError),
+}
 
 #[derive(Debug, Copy, Clone)]
 pub struct SwapchainCreateInfo {
@@ -16,14 +93,14 @@ pub struct SwapchainCreateInfo {
 }
 
 impl<G: GraphicsExt> TryFrom<SwapchainCreateInfo> for openxr::SwapchainCreateInfo<G> {
-    type Error = XrInitError;
+    type Error = XrError;
 
-    fn try_from(value: SwapchainCreateInfo) -> Result<Self, Self::Error> {
+    fn try_from(value: SwapchainCreateInfo) -> Result<Self> {
         Ok(openxr::SwapchainCreateInfo {
             create_flags: value.create_flags,
             usage_flags: value.usage_flags,
             format: G::from_wgpu_format(value.format)
-                .ok_or(XrInitError::UnsupportedTextureFormat(value.format))?,
+                .ok_or(XrError::UnsupportedTextureFormat(value.format))?,
             sample_count: value.sample_count,
             width: value.width,
             height: value.height,
@@ -33,3 +110,177 @@ impl<G: GraphicsExt> TryFrom<SwapchainCreateInfo> for openxr::SwapchainCreateInf
         })
     }
 }
+
+pub use builder::*;
+
+/// Copied with modification from the openxr crate to allow for a safe, graphics agnostic api to work with Bevy.
+mod builder {
+    use std::mem;
+
+    use openxr::{sys, CompositionLayerFlags, Fovf, Posef, Rect2Di, Space};
+
+    use crate::openxr::{graphics::graphics_match, XrSwapchain};
+
+    #[derive(Copy, Clone)]
+    pub struct SwapchainSubImage<'a> {
+        inner: sys::SwapchainSubImage,
+        swapchain: Option<&'a XrSwapchain>,
+    }
+
+    impl<'a> SwapchainSubImage<'a> {
+        #[inline]
+        pub fn new() -> Self {
+            Self {
+                inner: sys::SwapchainSubImage {
+                    ..unsafe { mem::zeroed() }
+                },
+                swapchain: None,
+            }
+        }
+        #[inline]
+        pub fn into_raw(self) -> sys::SwapchainSubImage {
+            self.inner
+        }
+        #[inline]
+        pub fn as_raw(&self) -> &sys::SwapchainSubImage {
+            &self.inner
+        }
+        #[inline]
+        pub fn swapchain(mut self, value: &'a XrSwapchain) -> Self {
+            graphics_match!(
+                &value.0;
+                swap => self.inner.swapchain = swap.as_raw()
+            );
+            self.swapchain = Some(value);
+            self
+        }
+        #[inline]
+        pub fn image_rect(mut self, value: Rect2Di) -> Self {
+            self.inner.image_rect = value;
+            self
+        }
+        #[inline]
+        pub fn image_array_index(mut self, value: u32) -> Self {
+            self.inner.image_array_index = value;
+            self
+        }
+    }
+
+    impl<'a> Default for SwapchainSubImage<'a> {
+        fn default() -> Self {
+            Self::new()
+        }
+    }
+
+    #[derive(Copy, Clone)]
+    pub struct CompositionLayerProjectionView<'a> {
+        inner: sys::CompositionLayerProjectionView,
+        swapchain: Option<&'a XrSwapchain>,
+    }
+
+    impl<'a> CompositionLayerProjectionView<'a> {
+        #[inline]
+        pub fn new() -> Self {
+            Self {
+                inner: sys::CompositionLayerProjectionView {
+                    ty: sys::StructureType::COMPOSITION_LAYER_PROJECTION_VIEW,
+                    ..unsafe { mem::zeroed() }
+                },
+                swapchain: None,
+            }
+        }
+        #[inline]
+        pub fn into_raw(self) -> sys::CompositionLayerProjectionView {
+            self.inner
+        }
+        #[inline]
+        pub fn as_raw(&self) -> &sys::CompositionLayerProjectionView {
+            &self.inner
+        }
+        #[inline]
+        pub fn pose(mut self, value: Posef) -> Self {
+            self.inner.pose = value;
+            self
+        }
+        #[inline]
+        pub fn fov(mut self, value: Fovf) -> Self {
+            self.inner.fov = value;
+            self
+        }
+        #[inline]
+        pub fn sub_image(mut self, value: SwapchainSubImage<'a>) -> Self {
+            self.inner.sub_image = value.inner;
+            self.swapchain = value.swapchain;
+            self
+        }
+    }
+    impl<'a> Default for CompositionLayerProjectionView<'a> {
+        fn default() -> Self {
+            Self::new()
+        }
+    }
+    pub unsafe trait CompositionLayer<'a> {
+        fn swapchain(&self) -> Option<&'a XrSwapchain>;
+        fn header(&self) -> &'a sys::CompositionLayerBaseHeader;
+    }
+    #[derive(Clone)]
+    pub struct CompositionLayerProjection<'a> {
+        inner: sys::CompositionLayerProjection,
+        swapchain: Option<&'a XrSwapchain>,
+        views: Vec<sys::CompositionLayerProjectionView>,
+    }
+    impl<'a> CompositionLayerProjection<'a> {
+        #[inline]
+        pub fn new() -> Self {
+            Self {
+                inner: sys::CompositionLayerProjection {
+                    ty: sys::StructureType::COMPOSITION_LAYER_PROJECTION,
+                    ..unsafe { mem::zeroed() }
+                },
+                swapchain: None,
+                views: Vec::new(),
+            }
+        }
+        #[inline]
+        pub fn into_raw(self) -> sys::CompositionLayerProjection {
+            self.inner
+        }
+        #[inline]
+        pub fn as_raw(&self) -> &sys::CompositionLayerProjection {
+            &self.inner
+        }
+        #[inline]
+        pub fn layer_flags(mut self, value: CompositionLayerFlags) -> Self {
+            self.inner.layer_flags = value;
+            self
+        }
+        #[inline]
+        pub fn space(mut self, value: &'a Space) -> Self {
+            self.inner.space = value.as_raw();
+            self
+        }
+        #[inline]
+        pub fn views(mut self, value: &'a [CompositionLayerProjectionView<'a>]) -> Self {
+            for view in value {
+                self.views.push(view.inner.clone());
+            }
+            self.inner.views = self.views.as_slice().as_ptr() as *const _ as _;
+            self.inner.view_count = value.len() as u32;
+            self
+        }
+    }
+    unsafe impl<'a> CompositionLayer<'a> for CompositionLayerProjection<'a> {
+        fn swapchain(&self) -> Option<&'a XrSwapchain> {
+            self.swapchain
+        }
+
+        fn header(&self) -> &'a sys::CompositionLayerBaseHeader {
+            unsafe { std::mem::transmute(&self.inner) }
+        }
+    }
+    impl<'a> Default for CompositionLayerProjection<'a> {
+        fn default() -> Self {
+            Self::new()
+        }
+    }
+}