Merge pull request #635 from andyleiserson/dual-source-blending

Enable dual-source blending (requires unreleased wgpu changes)

Author: dhardy

crates/kas-wgpu/src/draw/images.rs

@@ -171,12 +171,9 @@ impl Images {
         );
 
         let mut atlas_rgba_mask = None;
-        // FIXME: This is disabled because of a wgpu validation error
-        #[allow(clippy::overly_complex_bool_expr)]
-        if false
-            && device
-                .features()
-                .contains(wgpu::Features::DUAL_SOURCE_BLENDING)
+        if device
+            .features()
+            .contains(wgpu::Features::DUAL_SOURCE_BLENDING)
         {
             atlas_rgba_mask = Some(atlases::Pipeline::new(
                 device,

crates/kas-wgpu/src/draw/shaders/subpixel.frag

@@ -11,8 +11,8 @@ precision mediump float;
 layout(location = 0) in vec2 tex_coord;
 layout(location = 1) in vec4 col;
 
-layout(location = 0) out vec4 frag_color;
-layout(location = 1) out vec4 blend_color;
+layout(location = 0, index = 0) out vec4 frag_color;
+layout(location = 0, index = 1) out vec4 blend_color;
 
 layout(set = 1, binding = 0) uniform texture2D tex;
 layout(set = 1, binding = 1) uniform sampler tex_sampler;