jsketcher/modules/geom/impl/line.ts

import Vector from "math/vector";

export class Line {
  p0: Vector;
  v: Vector;

  private _pointsCache: Map<any, Vector>;
  
  isLine: boolean;

  static fromTwoPlanesIntersection: (plane1, plane2) => Line;
  static fromSegment: (a, b) => Line;

  constructor(p0, v) {
    this.p0 = p0;
    this.v = v;
  }

  intersectSurface(surface) {
    if (surface.isPlane) {
      const s0 = surface.normal.multiply(surface.w);
      return surface.normal.dot(s0.minus(this.p0)) / surface.normal.dot(this.v); // 4.7.4
    } else {
      throw 'unsupported';
      // return super.intersectSurface(surface);
    }
  }

  intersectCurve(curve, surface) {
    if (curve.isLine && surface.isPlane) {
      const otherNormal = surface.normal.cross(curve.v)._normalize();
      return otherNormal.dot(curve.p0.minus(this.p0)) / otherNormal.dot(this.v); // (4.8.3)    
    }
    throw 'unsupported';
    // return super.intersectCurve(curve, surface);
  }

  point(t) {
    return this.p0.plus(this.v.multiply(t));
  }
  
  t(point) {
    return point.minus(this.p0).dot(this.v);
  }
  
  pointOfSurfaceIntersection(surface) {
    if (!this._pointsCache) {
      this._pointsCache = new Map();
    }
    let point = this._pointsCache.get(surface);
    if (!point) {
      const t = this.intersectSurface(surface);
      point = this.point(t);
      this._pointsCache.set(surface, point);
    }
    return point;
  }

  translate(vector) {
    return new Line(this.p0.plus(vector), this.v);
  }

  tessellate(resolution, from, to, path) {
  }
  
  offset() {}
}

Line.prototype.isLine = true;

Line.fromTwoPlanesIntersection = function(plane1, plane2): Line {
  const n1 = plane1.normal;
  const n2 = plane2.normal;
  const v = n1.cross(n2)._normalize();
  const pf1 = plane1.toParametricForm();
  const pf2 = plane2.toParametricForm();
  const r0diff = pf1.r0.minus(pf2.r0);
  const ww = r0diff.minus(n2.multiply(r0diff.dot(n2)));
  const p0 = pf2.r0.plus( ww.multiply( n1.dot(r0diff) / n1.dot(ww)));
  return new Line(p0, v);
};

Line.fromSegment = function(a, b) {
  return new Line(a, b.minus(a)._normalize());
};