struct Configuration {
  viewProj: mat4x4f,
  lightViewProj: mat4x4f,
  lightPosition: vec4f,
  eyePosition: vec4f,
  aspect: f32,
};

struct Bone {
  position: vec4f,
  velocity: vec4f,
};

struct BoneConfiguration {
  a: vec4f,
};

@group(0) @binding(0) var<uniform> config: Configuration;
@group(1) @binding(0) var<storage> bones: array<Bone>;
@group(1) @binding(1) var<uniform> boneConfig: BoneConfiguration;

struct VertexInput {
  @builtin(vertex_index) vertex_index: u32,
};

struct VertexOutput {
  @builtin(position) position: vec4f,
  @location(0) texture: vec2f,
};

const vertices = array(
  vec2f(1.0, 0.0),
  vec2f(0.0, 1.0),
  vec2f(0.0, 0.0),
  vec2f(1.0, 1.0),
);

@vertex
fn vertexMain(input: VertexInput) -> VertexOutput
{
  let texture = vertices[input.vertex_index];

  let position = texture * 2.0 - 1.0;

  var output: VertexOutput;
  output.position = vec4f(position, 0.0, 1.0);
  output.texture = position * vec2f(config.aspect, 1);
  return output;
}

fn sdCircle(center: vec2f, sample: vec2f) -> f32
{
  let distance = length(center - sample);
  return distance;
}

fn sdSegment(p: vec2f, a: vec2f, b: vec2f) -> f32
{
  let ba = b - a;
  let pa = p - a;
  let h = clamp(dot(pa, ba) / dot(ba, ba), 0.0, 1.0);
  return length(pa - h * ba);
}

@fragment
fn fragmentMain(input: VertexOutput) -> @location(0) vec4f
{
  var color = vec3f(input.texture.xy, 0);

  for (var i: u32 = 0; i < u32(boneConfig.a.x); i++) {
    if (sdCircle(input.texture.xy, bones[i].position.xy) < 0.01) {
      color = vec3f(1, 1, 1);
    }

    /*
    if (sdSegment(input.texture.xy,
                  bones[i].position.xy,
                  bones[i].position.xy + bones[i].velocity.xy * 0.05) < 0.002) {
      color = vec3(0, 0, 1);
    }
    */
    /*
    if (i == 1 && sdCircle(input.texture.xy, bones[i].velocity.xy) < 0.05) {
      color = vec3(0, 0, 1);
    }
    */
  }

  return vec4f(color, 1);
}