import { mat2d, vec2 } from 'gl-matrix';
import { Drawable } from '../drawable';
import { DrawableDescriptor } from '../drawable-descriptor';

export class Circle extends Drawable {
  public static descriptor: DrawableDescriptor = {
    sdf: {
      shader: `
          uniform struct {
              vec2 center;
              float radius;
          }[CIRCLE_COUNT] circles;

          void circleMinDistance(inout float minDistance, inout float color) {
              float myMinDistance = maxMinDistance;
              for (int i = 0; i < CIRCLE_COUNT; i++) {
                  float dist = distance(circles[i].center, position) - circles[i].radius;
                  myMinDistance = min(myMinDistance, dist);
              }
              minDistance = min(minDistance, myMinDistance);
              color = mix(2.0, color, step(
                distanceNdcPixelSize + SURFACE_OFFSET, 
                myMinDistance
              ));
          }
        `,
      distanceFunctionName: 'circleMinDistance',
    },
    uniformName: 'circles',
    uniformCountMacroName: 'CIRCLE_COUNT',
    shaderCombinationSteps: [0, 1, 2, 3, 16, 32],
    empty: new Circle(vec2.fromValues(0, 0), 0),
  };

  constructor(public center: vec2, public radius: number) {
    super();
  }

  public minDistance(target: vec2): number {
    return vec2.dist(this.center, target) - this.radius;
  }

  protected getObjectToSerialize(transform2d: mat2d, transform1d: number): any {
    return {
      center: vec2.transformMat2d(vec2.create(), this.center, transform2d),
      radius: this.radius * transform1d,
    };
  }
}