struct VertexOutput {
@builtin(position) position: vec4<f32>,
@location(0) x: f32,
}
const VERTICES: array<vec3<f32>, 3> = array<vec3<f32>, 3>(
vec3<f32>(-1.0, 1.0, 0.0),
vec3<f32>(-1.0, -3.0, 0.0),
vec3<f32>(3.0, 1.0, 0.0),
);
const X: array<f32, 3> = array<f32, 3>(
0.0, 0.0, 1.0,
);
var<immediate> time: f32;
@vertex
fn vs_main(@builtin(vertex_index) idx: u32) -> VertexOutput {
var output: VertexOutput;
output.position = vec4(VERTICES[idx], 1.0);
output.x = X[idx] + fract(time * 3.1416 / 64.0);
return output;
}
fn hue(x: f32) -> vec3<f32> {
let p = abs(fract(x + vec3(1.0, 2.0 / 3.0, 1.0 / 3.0)) * 6.0 - 3.0);
return clamp(p - 1.0, vec3(0.0), vec3(1.0));
}
@fragment
fn fs_main(input: VertexOutput) -> @location(0) vec4<f32> {
let color = hue(input.x);
return vec4(color, 1.0);
}