From caea233a47870d5477383949057cc9fdc0f7fbca Mon Sep 17 00:00:00 2001
From: Juanperias <136520331+Juanperias@users.noreply.github.com>
Date: Wed, 26 Aug 2026 02:09:32 -0400
Subject: [PATCH] Fix wgpu padding (#8448)
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The Egui web example was throwing an error in WGPU. In this case, the
error was
```
panicked at /home/runner/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/wgpu-30.0.0/src/backend/wgpu_core.rs:1414:26: wgpu error: Validation Error Caused by: In Device::create_render_pipeline, label = ‘egui_pipeline’ In the provided shader, the type given for group 1 binding 2 has a size of 4. Since the device does not support DownlevelFlags::BUFFER_BINDINGS_NOT_16_BYTE_ALIGNED`, the type must have a size that is a multiple of 16 bytes
```

One reference I used was the following Pull Request:
<https://github.com/viridia/quill/pull/14>

The biggest change I made was in `egui-wgpu` to
`r_tex_nearest_filtering`

Shader (`egui.wgsl`)
```wgsl
// Old
@group(1) @binding(2) var<uniform> r_tex_nearest_filtering: u32;

// New
@group(1) @binding(2) var<uniform> r_tex_nearest_filtering: vec4<u32>;
```

And with the corresponding changes in `renderer.rs`, I ran it locally
and it worked perfectly in Firefox 149 and Chromium 151 (Both fail when
attempting to access https://www.egui.rs/#demo, returning the error
described above)

* Closes <https://github.com/emilk/egui/issues/8446>
* Fixes <https://github.com/emilk/egui/issues/8446>
* [X] I have followed the instructions in the PR template

---------

Co-authored-by: Emil Ernerfeldt <emil.ernerfeldt@gmail.com>
Co-authored-by: Claude Fable 5 <noreply@anthropic.com>
---
 crates/egui-wgpu/src/egui.wgsl   | 8 +++++---
 crates/egui-wgpu/src/renderer.rs | 6 ++++--
 2 files changed, 9 insertions(+), 5 deletions(-)

diff --git a/crates/egui-wgpu/src/egui.wgsl b/crates/egui-wgpu/src/egui.wgsl
index bd3b5313e..9567b0d3e 100644
--- a/crates/egui-wgpu/src/egui.wgsl
+++ b/crates/egui-wgpu/src/egui.wgsl
@@ -98,6 +98,7 @@ fn vs_main(
 @group(1) @binding(0) var r_tex_color: texture_2d<f32>;
 @group(1) @binding(1) var r_tex_sampler: sampler;
 
+
 /// Set in bit 0 of `r_tex_flags` if the sampler uses nearest filtering.
 ///
 /// Must match `TEX_FLAG_NEAREST` in `renderer.rs`.
@@ -114,11 +115,11 @@ const WRAP_MODE_MIRRORED_REPEAT: u32 = 2u;
 ///
 /// Bit 0: `TEX_FLAG_NEAREST`.
 /// Bits 1+: one of the `WRAP_MODE_*` constants.
-@group(1) @binding(2) var<uniform> r_tex_flags: u32;
+@group(1) @binding(2) var<uniform> r_tex_flags: vec4<u32>;
 
 /// Map a texel coordinate to a valid texel according to the texture's wrap mode.
 fn wrap_texel_coord(coord: vec2<i32>, texture_size: vec2<i32>) -> vec2<i32> {
-    let wrap_mode = r_tex_flags >> 1u;
+    let wrap_mode = r_tex_flags[0] >> 1u;
     if wrap_mode == WRAP_MODE_REPEAT {
         return ((coord % texture_size) + texture_size) % texture_size;
     } else if wrap_mode == WRAP_MODE_MIRRORED_REPEAT {
@@ -131,6 +132,7 @@ fn wrap_texel_coord(coord: vec2<i32>, texture_size: vec2<i32>) -> vec2<i32> {
     }
 }
 
+
 fn sample_texture(in: VertexOutput) -> vec4<f32> {
     if r_locals.predictable_texture_filtering == 0 {
         // Hardware filtering: fast, but varies across GPUs and drivers.
@@ -139,7 +141,7 @@ fn sample_texture(in: VertexOutput) -> vec4<f32> {
         let texture_size = vec2<i32>(textureDimensions(r_tex_color, 0));
         let texture_size_f = vec2<f32>(texture_size);
 
-        if (r_tex_flags & TEX_FLAG_NEAREST) != 0u {
+        if (r_tex_flags[0] & TEX_FLAG_NEAREST) != 0u {
             // Nearest filtering: load the texel under the sample position.
             let texel = wrap_texel_coord(vec2<i32>(floor(in.tex_coord * texture_size_f)), texture_size);
             return textureLoad(r_tex_color, texel, 0);
diff --git a/crates/egui-wgpu/src/renderer.rs b/crates/egui-wgpu/src/renderer.rs
index cb9f40f18..d5130d5c0 100644
--- a/crates/egui-wgpu/src/renderer.rs
+++ b/crates/egui-wgpu/src/renderer.rs
@@ -357,7 +357,9 @@ impl Renderer {
                         visibility: wgpu::ShaderStages::FRAGMENT,
                         ty: wgpu::BindingType::Buffer {
                             has_dynamic_offset: false,
-                            min_binding_size: NonZeroU64::new(core::mem::size_of::<u32>() as _),
+                            min_binding_size: NonZeroU64::new(
+                                (core::mem::size_of::<u32>() * 4) as _,
+                            ),
                             ty: wgpu::BufferBindingType::Uniform,
                         },
                         count: None,
@@ -370,7 +372,7 @@ impl Renderer {
             let flag = flag as u32;
             device.create_buffer_init(&wgpu::util::BufferInitDescriptor {
                 label: Some(&format!("egui_texture_flags_{flag}")),
-                contents: bytemuck::bytes_of(&flag),
+                contents: bytemuck::bytes_of(&[flag, 0, 0, 0]),
                 usage: wgpu::BufferUsages::UNIFORM,
             })
         });