fix: openxr swapchain banding

src/backend/openxr/swapchain.rs

@@ -6,6 +6,7 @@ use openxr as xr;
 
 use smallvec::SmallVec;
 use vulkano::{
+    format::Format,
     image::{sys::RawImage, view::ImageView, ImageCreateInfo, ImageUsage},
     pipeline::graphics::color_blend::AttachmentBlend,
     Handle,
@@ -23,7 +24,7 @@ pub(super) fn create_swapchain_render_data(
     let swapchain = xr.session.create_swapchain(&xr::SwapchainCreateInfo {
         create_flags: xr::SwapchainCreateFlags::EMPTY,
         usage_flags: xr::SwapchainUsageFlags::COLOR_ATTACHMENT | xr::SwapchainUsageFlags::SAMPLED,
-        format: graphics.native_format as _,
+        format: Format::R8G8B8A8_SRGB as _,
         sample_count: 1,
         width: extent[0],
         height: extent[1],
@@ -37,8 +38,8 @@ pub(super) fn create_swapchain_render_data(
     };
     let pipeline = graphics.create_pipeline_dynamic(
         shaders.get("vert_common").unwrap().clone(), // want panic
-        shaders.get("frag_srgb").unwrap().clone(),   // want panic
-        graphics.native_format,
+        shaders.get("frag_swapchain").unwrap().clone(), // want panic
+        Format::R8G8B8A8_UNORM,
         Some(AttachmentBlend::alpha()),
     )?;
 
@@ -53,7 +54,7 @@ pub(super) fn create_swapchain_render_data(
                     graphics.device.clone(),
                     vk_image,
                     ImageCreateInfo {
-                        format: graphics.native_format,
+                        format: Format::R8G8B8A8_UNORM, // actually SRGB but we lie
                         extent,
                         usage: ImageUsage::COLOR_ATTACHMENT,
                         ..Default::default()

src/shaders/mod.rs

@@ -97,7 +97,7 @@ pub mod frag_screen {
 
                 // linear to srgb
                 bvec4 cutoff = lessThan(out_color, vec4(0.0031308));
-                vec4 higher = (pow(out_color, vec4(0.41666)) * vec4(1.055)) - vec4(0.055);
+                vec4 higher = (pow(out_color, vec4(0.4166667)) * vec4(1.055)) - vec4(0.055);
                 vec4 lower = out_color*vec4(12.92);
                 out_color = mix(higher, lower, cutoff);
                 out_color.a = 1.0;
@@ -135,3 +135,26 @@ pub mod frag_srgb {
         ",
     }
 }
+
+pub mod frag_swapchain {
+    vulkano_shaders::shader! {
+        ty: "fragment",
+        src: r"#version 310 es
+            precision highp float;
+
+            layout (location = 0) in vec2 in_uv;
+            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()
+            {
+                out_color = texture(in_texture, in_uv);
+                out_color.a = alpha;
+            }
+        ",
+    }
+}

src/state.rs

@@ -15,7 +15,7 @@ use crate::{
     gui::font::FontCache,
     hid::HidProvider,
     overlays::toast::{DisplayMethod, ToastTopic},
-    shaders::{frag_color, frag_glyph, frag_screen, frag_sprite, frag_srgb, vert_common},
+    shaders::{frag_color, frag_glyph, frag_screen, frag_sprite, frag_swapchain, vert_common},
 };
 
 pub struct AppState {
@@ -53,8 +53,8 @@ impl AppState {
             let shader = frag_screen::load(graphics.device.clone())?;
             shaders.insert("frag_screen", shader);
 
-            let shader = frag_srgb::load(graphics.device.clone())?;
-            shaders.insert("frag_srgb", shader);
+            let shader = frag_swapchain::load(graphics.device.clone())?;
+            shaders.insert("frag_swapchain", shader);
         }
 
         let session = AppSession::load();