// #include //ly.img.cesdk/shader/common/ubq_constants

// Inputs
uniform shader image;
uniform float2 imageSize;
uniform float dots;
uniform float size;
uniform float blur;

half4 main(float2 coord) {
  float2 uv = coord / imageSize;
  float dotSize = 1.0 / dots;
  float2 samplePos = uv - mod(uv, dotSize) + 0.5 * dotSize;
  float distanceFromSamplePoint = distance(samplePos, uv);
  float4 imageColor = image.eval(samplePos * imageSize);

  float4 backgroundColor = float4(0.0);
  
  // Adjust blur value to avoid sharp transitions between image color and background color.
  // Reasoning: when both lower and upper edge values are the same, smoothstep no longer provides
  // a gradual transition between them (either immediatelly returs 0 or 1).
  // This causes mix() to output imageColor or backgroundColor instead of doing a linear interpolation between them.
  float adjustedBlur = max(blur, EPSILON);

  float4 color =
    mix(imageColor, backgroundColor,
        smoothstep(dotSize * size, dotSize * (size + adjustedBlur), distanceFromSamplePoint));
  return color;
}