@group(0) @binding(0) var smplr: sampler;
@group(0) @binding(1) var txt: texture_2d<f32>;

struct CommonUniforms {
    resolution: vec2<f32>,
    aspect_ratio: f32,
    time: f32,
    beat: f32,
    audio_intensity: f32,
};
struct EffectParams {
    offset_scale: f32,
    angle: f32,
};

@group(0) @binding(2) var<uniform> common: CommonUniforms;
@group(0) @binding(3) var<uniform> params: EffectParams;

@vertex fn vs_main(@builtin(vertex_index) i: u32) -> @builtin(position) vec4<f32> {
    var pos = array<vec2<f32>, 3>(
        vec2<f32>(-1, -1),
        vec2<f32>(3, -1),
        vec2<f32>(-1, 3)
    );
    return vec4<f32>(pos[i], 0.0, 1.0);
}

@fragment fn fs_main(@builtin(position) p: vec4<f32>) -> @location(0) vec4<f32> {
    let uv = p.xy / common.resolution;

    // Compute offset magnitude and direction
    let offset_mag = params.offset_scale * common.audio_intensity;
    let offset_dir = vec2<f32>(cos(params.angle), sin(params.angle));
    let offset = offset_mag * offset_dir;

    // Sample RGB channels with chromatic aberration
    let r = textureSample(txt, smplr, uv + offset).r;
    let g = textureSample(txt, smplr, uv).g;
    let b = textureSample(txt, smplr, uv - offset).b;
    return vec4<f32>(r, g, b, 1.0);
}