// Circle mask render shader
// Samples mask and draws green outside the circle

@group(0) @binding(0) var mask_tex: texture_2d<f32>;
@group(0) @binding(1) var mask_sampler: sampler;

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

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

struct VSOutput {
  @builtin(position) position: vec4<f32>,
};

@vertex fn vs_main(@builtin(vertex_index) i: u32) -> VSOutput {
  var pos = array<vec2<f32>, 3>(
    vec2<f32>(-1, -1), vec2<f32>(3, -1), vec2<f32>(-1, 3));
  return VSOutput(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 / uniforms.resolution;
  let mask_value = textureSample(mask_tex, mask_sampler, uv).r;

  if (mask_value > 0.5) {
    discard;
  }

  return vec4<f32>(0.0, 1.0, 0.0, 1.0);
}