comments on why the flags are split up

bevyengine · Jan 25, 2024 · 4525f3e · 4525f3e
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commit 4525f3e
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Showing 2 changed files with 5 additions and 1 deletion.
diff --git a/crates/bevy_pbr/src/pbr_material.rs b/crates/bevy_pbr/src/pbr_material.rs
@@ -572,6 +572,8 @@ bitflags::bitflags! {
     }
 }
 
+// NOTE: These bitflags are separate from StandardMaterialFlags due to a bug on some older GPUs
+// that are unable to use the last 16 bits of a u32
 bitflags::bitflags! {
     /// Bitflags info about the alpha mode of the material a shader is currently rendering.
     /// This is accessible in the shader in the [`StandardMaterialUniform`]

diff --git a/crates/bevy_pbr/src/render/pbr_types.wgsl b/crates/bevy_pbr/src/render/pbr_types.wgsl
@@ -12,7 +12,9 @@ struct StandardMaterial {
     ior: f32,
     attenuation_distance: f32,
     attenuation_color: vec4<f32>,
-    // 'flags' is a bit field indicating various options. u32 is 32 bits so we have up to 32 options.
+    // 'flags' is a bit field indicating various options.
+    // u32 is 32 bits so we would have up to 32 options. Some lower-end mobile GPUs only support 16-bits
+    // so we can only use half of the u32
     flags: u32,
     alpha_mode_flags: u32,
     alpha_cutoff: f32,