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Fix game_of_life shader relying on Naga bug (#18951)

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# Objective

The game of life example shader relies on a Naga bug
([6397](https://github.com/gfx-rs/wgpu/issues/6397) /
[4536](https://github.com/gfx-rs/wgpu/issues/4536)). In WGSL certain
arithmetic operations must be explicitly parenthesized
([reference](https://www.w3.org/TR/WGSL/#operator-precedence-associativity)).
Naga doesn't enforce that (and also the precedence order is [messed
up](https://github.com/gfx-rs/wgpu/issues/4536#issuecomment-1780113990)).

So this example may break soon. This is the only sample shader having
this issue.

## Solution

added parentheses

## Testing

ran the example before and after the fix with `cargo run --example
compute_shader_game_of_life`
This commit is contained in:
Mathis Brossier 2025-04-26 23:38:08 +02:00 committed by GitHub
parent 78d9f05d31
commit 119eb51f00
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GPG Key ID: B5690EEEBB952194
1 changed files with 3 additions and 3 deletions
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6
assets/shaders/game_of_life.wgsl
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@ -12,9 +12,9 @@ fn hash(value: u32) -> u32 {
var state = value; var state = value;
state = state ^ 2747636419u; state = state ^ 2747636419u;
state = state * 2654435769u; state = state * 2654435769u;
state = state ^ state >> 16u; state = state ^ (state >> 16u);
state = state * 2654435769u; state = state * 2654435769u;
state = state ^ state >> 16u; state = state ^ (state >> 16u);
state = state * 2654435769u; state = state * 2654435769u;
return state; return state;
} }
@ -27,7 +27,7 @@ fn randomFloat(value: u32) -> f32 {
fn init(@builtin(global_invocation_id) invocation_id: vec3<u32>, @builtin(num_workgroups) num_workgroups: vec3<u32>) { fn init(@builtin(global_invocation_id) invocation_id: vec3<u32>, @builtin(num_workgroups) num_workgroups: vec3<u32>) {
let location = vec2<i32>(i32(invocation_id.x), i32(invocation_id.y)); let location = vec2<i32>(i32(invocation_id.x), i32(invocation_id.y));
let randomNumber = randomFloat(invocation_id.y << 16u | invocation_id.x); let randomNumber = randomFloat((invocation_id.y << 16u) | invocation_id.x);
let alive = randomNumber > 0.9; let alive = randomNumber > 0.9;
let color = vec4<f32>(f32(alive)); let color = vec4<f32>(f32(alive));