openxr: support changing overlay opacity

README.md

@@ -100,10 +100,6 @@ or alternatively add the following to `Cargo.toml` to only do basic optimization
 opt-level = 1
 ```
 
-## OpenXR: Overlay opacity
-
-Translucent overlays are not supported on OpenXR yet.
-
 ## Scroll wheel doesn't work
 
 This seems to be an issue specific to Electron apps (Discord, Element, Slack, Spotify) on Wayland. Scrolling will work when using these in your web browser.

src/backend/openvr/input.rs

@@ -4,8 +4,8 @@ use anyhow::bail;
 use ovr_overlay::{
     input::{ActionHandle, ActionSetHandle, ActiveActionSet, InputManager, InputValueHandle},
     sys::{
-        k_unMaxTrackedDeviceCount, ETrackedControllerRole, ETrackedDeviceClass,
-        ETrackedDeviceProperty, ETrackingUniverseOrigin,
+        ETrackedControllerRole, ETrackedDeviceClass, ETrackedDeviceProperty,
+        ETrackingUniverseOrigin,
     },
     system::SystemManager,
     TrackedDeviceIndex,

src/backend/openxr/lines.rs

@@ -135,10 +135,11 @@ impl LinePool {
             if let Some(inner) = line.maybe_line.take() {
                 let quad = xr::CompositionLayerQuad::new()
                     .pose(inner.pose)
-                    .sub_image(
-                        line.swapchain
-                            .acquire_present_release(command_buffer, inner.view),
-                    )
+                    .sub_image(line.swapchain.acquire_present_release(
+                        command_buffer,
+                        inner.view,
+                        1.0,
+                    ))
                     .eye_visibility(xr::EyeVisibility::BOTH)
                     .layer_flags(xr::CompositionLayerFlags::CORRECT_CHROMATIC_ABERRATION)
                     .space(&xr.stage)

src/backend/openxr/overlay.rs

@@ -50,7 +50,7 @@ impl OverlayData<OpenXrOverlayData> {
             srd
         });
 
-        let sub_image = data.acquire_present_release(command_buffer, my_view);
+        let sub_image = data.acquire_present_release(command_buffer, my_view, self.state.alpha);
         let posef = helpers::transform_to_posef(&self.state.transform);
 
         let aspect_ratio = extent[1] as f32 / extent[0] as f32;

src/backend/openxr/swapchain.rs

@@ -87,6 +87,7 @@ impl SwapchainRenderData {
         &mut self,
         command_buffer: &mut WlxCommandBuffer,
         view: Arc<ImageView>,
+        alpha: f32,
     ) -> xr::SwapchainSubImage<xr::Vulkan> {
         let idx = self.swapchain.acquire_image().unwrap() as usize;
         self.swapchain.wait_image(xr::Duration::INFINITE).unwrap();
@@ -95,14 +96,18 @@ impl SwapchainRenderData {
         command_buffer.begin_rendering(render_target.clone());
 
         let target_extent = render_target.image().extent();
-        let set = self
+
+        let set0 = self
             .pipeline
             .uniform_sampler(0, view.clone(), Filter::Linear);
+
+        let set1 = self.pipeline.uniform_buffer(1, vec![alpha]);
+
         let pass = self.pipeline.create_pass(
             [target_extent[0] as _, target_extent[1] as _],
             command_buffer.graphics.quad_verts.clone(),
             command_buffer.graphics.quad_indices.clone(),
-            vec![set],
+            vec![set0, set1],
         );
         command_buffer.run_ref(&pass);
         command_buffer.end_rendering();

src/overlays/watch.rs

@@ -13,7 +13,7 @@ use serde::Deserialize;
 
 use crate::{
     backend::{
-        common::{OverlayContainer, OverlaySelector, TaskType},
+        common::{OverlaySelector, TaskType},
         input::PointerMode,
         overlay::{OverlayData, OverlayState, RelativeTo},
     },

src/shaders/mod.rs

@@ -92,6 +92,10 @@ pub mod frag_srgb {
             layout (location = 0) out vec4 out_color;
 
             layout (set = 0, binding = 0) uniform sampler2D in_texture;
+            layout (set = 1, binding = 0) uniform AlphaBlock {
+                uniform float alpha;
+            };
+
 
             void main()
             {
@@ -102,6 +106,7 @@ pub mod frag_srgb {
                 vec4 lower = out_color/vec4(12.92);
 
                 out_color = mix(higher, lower, cutoff);
+                out_color.a = alpha;
             }
         ",
     }