// Flash shader for visual sync testing
// Pulses white on beat
#include "sequence_uniforms"

@group(0) @binding(2) var<uniform> uniforms: UniformsSequenceParams;

struct VertexOutput {
    @builtin(position) position: vec4<f32>,
    @location(0) uv: vec2<f32>,
};

@vertex fn vs_main(@builtin(vertex_index) vid: u32) -> VertexOutput {
    var out: VertexOutput;
    let x = f32((vid & 1u) << 1u);
    let y = f32((vid & 2u));
    out.position = vec4<f32>(x * 2.0 - 1.0, 1.0 - y * 2.0, 0.0, 1.0);
    out.uv = vec2<f32>(x, y);
    return out;
}

@fragment fn fs_main(in: VertexOutput) -> @location(0) vec4<f32> {
  // Strong flash on beat, fades quickly
  let intensity = pow(1.0 - uniforms.beat_phase, 4.0);
  // Add audio intensity for extra punch
  let final_intensity = intensity * (1.0 + uniforms.audio_intensity * 0.5);
  return vec4<f32>(final_intensity, final_intensity, final_intensity, 1.0);
}