From 4fe9443feb00e14646b68879df9feed888f30f1d Mon Sep 17 00:00:00 2001
From: Robin KAY <komadori@gekkou.co.uk>
Date: Tue, 23 Aug 2022 22:16:59 +0100
Subject: [PATCH] Add feature to control 16 byte alignment of uniforms.

---
 Cargo.toml           | 3 ++-
 src/outline.wgsl     | 6 ++++++
 src/pipeline.rs      | 9 +++++++--
 src/uniforms.rs      | 2 +-
 src/view_uniforms.rs | 2 +-
 5 files changed, 17 insertions(+), 5 deletions(-)

diff --git a/Cargo.toml b/Cargo.toml
index 011609d..c45bf5c 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -26,7 +26,8 @@ bevy = { version = "0.8", default-features = false, features = [
 ] }
 
 [features]
-default = ["bevy_ui"]
+default = ["align16", "bevy_ui"]
+align16 = []
 bevy_ui = ["bevy/bevy_ui", "bevy/bevy_sprite", "bevy/bevy_text"]
 
 [[example]]
diff --git a/src/outline.wgsl b/src/outline.wgsl
index b6710a2..9f3d54b 100644
--- a/src/outline.wgsl
+++ b/src/outline.wgsl
@@ -6,17 +6,23 @@ struct VertexInput {
 };
 
 struct OutlineViewUniform {
+#ifdef ALIGN_16
     @align(16)
+#endif
     scale: vec2<f32>,
 };
 
 struct OutlineVertexUniform {
+#ifdef ALIGN_16
     @align(16)
+#endif
     width: f32,
 };
 
 struct OutlineFragmentUniform {
+#ifdef ALIGN_16
     @align(16)
+#endif
     colour: vec4<f32>,
 };
 
diff --git a/src/pipeline.rs b/src/pipeline.rs
index ca969f8..2076f46 100644
--- a/src/pipeline.rs
+++ b/src/pipeline.rs
@@ -146,17 +146,22 @@ impl SpecializedMeshPipeline for OutlinePipeline {
                 );
             }
         }
+        let shader_defs = if cfg!(feature = "align16") {
+            vec!["ALIGN_16".to_string()]
+        } else {
+            vec![]
+        };
         let buffers = vec![mesh_layout.get_layout(&buffer_attrs)?];
         Ok(RenderPipelineDescriptor {
             vertex: VertexState {
                 shader: shader.clone().typed::<Shader>(),
                 entry_point: "vertex".into(),
-                shader_defs: vec![],
+                shader_defs: shader_defs.clone(),
                 buffers,
             },
             fragment: Some(FragmentState {
                 shader: shader.typed::<Shader>(),
-                shader_defs: vec![],
+                shader_defs,
                 entry_point: "fragment".into(),
                 targets,
             }),
diff --git a/src/uniforms.rs b/src/uniforms.rs
index 5bcfe4c..14d57c4 100644
--- a/src/uniforms.rs
+++ b/src/uniforms.rs
@@ -17,7 +17,7 @@ use crate::{pipeline::OutlinePipeline, Outline};
 
 #[derive(Clone, Component, ShaderType)]
 pub struct OutlineVertexUniform {
-    #[align(16)]
+    #[cfg_attr(feature = "align16", align(16))]
     pub width: f32,
 }
 
diff --git a/src/view_uniforms.rs b/src/view_uniforms.rs
index 59bce4c..551f206 100644
--- a/src/view_uniforms.rs
+++ b/src/view_uniforms.rs
@@ -15,7 +15,7 @@ use crate::pipeline::OutlinePipeline;
 
 #[derive(Clone, Component, ShaderType)]
 pub struct OutlineViewUniform {
-    #[align(16)]
+    #[cfg_attr(feature = "align16", align(16))]
     scale: Vec2,
 }