public override bool Equals(object o) { if (!(o is Segment)) { return(false); } Segment other = ( Segment )o; // empty segments are always considered equal if (this.IsEmpty) { return(other.IsEmpty); } // segments are considered equal if // 1) the endpoints are equal and equally excluded // 2) the opposing endpoints are equal and equally excluded if (DoubleHelper.AreVirtuallyEqual(_p1, other._p1)) { return(DoubleHelper.AreVirtuallyEqual(_p2, other._p2) && _isP1Excluded == other._isP1Excluded && _isP2Excluded == other._isP2Excluded); } else { return(DoubleHelper.AreVirtuallyEqual(_p1, other._p2) && DoubleHelper.AreVirtuallyEqual(_p2, other._p1) && _isP1Excluded == other._isP2Excluded && _isP2Excluded == other._isP1Excluded); } }
public bool Contains(Point point) { if (IsEmpty) { return(false); } // if the point is an endpoint, ensure that it is not excluded if (DoubleHelper.AreVirtuallyEqual(_p1, point)) { return(_isP1Excluded); } if (DoubleHelper.AreVirtuallyEqual(_p2, point)) { return(_isP2Excluded); } bool result = false; // ensure that a line through P1 and the point is parallel to the current segment if (DoubleHelper.AreVirtuallyEqual(Slope, new Segment(_p1, point).Slope)) { // finally, ensure that the point is between the segment's endpoints result = (point.X >= Math.Min(_p1.X, _p2.X)) && (point.X <= Math.Max(_p1.X, _p2.X)) && (point.Y >= Math.Min(_p1.Y, _p2.Y)) && (point.Y <= Math.Max(_p1.Y, _p2.Y)); } return(result); }
public Segment Intersection(Segment segment) { // if either segment is empty, the intersection is also empty if (this.IsEmpty || segment.IsEmpty) { return(Segment.Empty); } // if the segments are equal, just return a new equal segment if (this == segment) { return(new Segment(this._p1, this._p2, this._isP1Excluded, this._isP2Excluded)); } // if either segment is a Point, just see if the point is contained in the other segment if (this.IsPoint) { return(segment.Contains(this._p1) ? new Segment(this._p1) : Segment.Empty); } if (segment.IsPoint) { return(this.Contains(segment._p1) ? new Segment(segment._p1) : Segment.Empty); } // okay, no easy answer, so let's do the math... Point p1 = this._p1; Vector v1 = this._p2 - this._p1; Point p2 = segment._p1; Vector v2 = segment._p2 - segment._p1; Vector endpointVector = p2 - p1; double xProd = Vector.CrossProduct(v1, v2); // if segments are not parallel, then look for intersection on each segment if (!DoubleHelper.AreVirtuallyEqual(Slope, segment.Slope)) { // check for intersection on other segment double s = (Vector.CrossProduct(endpointVector, v1)) / xProd; if (s < 0 || s > 1) { return(Segment.Empty); } // check for intersection on this segment s = (Vector.CrossProduct(endpointVector, v2)) / xProd; if (s < 0 || s > 1) { return(Segment.Empty); } // intersection of segments is a point return(new Segment(p1 + s * v1)); } // segments are parallel xProd = Vector.CrossProduct(endpointVector, v1); if (xProd * xProd > 1.0e-06 * v1.LengthSquared * endpointVector.LengthSquared) { // segments do not intersect return(Segment.Empty); } // intersection is overlapping segment Segment result = new Segment(); // to determine the overlapping segment, create reference segments where the endpoints are *not* excluded Segment refThis = new Segment(this._p1, this._p2); Segment refSegment = new Segment(segment._p1, segment._p2); // check whether this segment is contained in the other segment bool includeThisP1 = refSegment.Contains(refThis._p1); bool includeThisP2 = refSegment.Contains(refThis._p2); if (includeThisP1 && includeThisP2) { result._p1 = this._p1; result._p2 = this._p2; result._isP1Excluded = this._isP1Excluded || !segment.Contains(this._p1); result._isP2Excluded = this._isP2Excluded || !segment.Contains(this._p2); return(result); } // check whether the other segment is contained in this segment bool includeSegmentP1 = refThis.Contains(refSegment._p1); bool includeSegmentP2 = refThis.Contains(refSegment._p2); if (includeSegmentP1 && includeSegmentP2) { result._p1 = segment._p1; result._p2 = segment._p2; result._isP1Excluded = segment._isP1Excluded || !this.Contains(segment._p1); result._isP2Excluded = segment._isP2Excluded || !this.Contains(segment._p2); return(result); } // the intersection must include one endpoint from this segment and one endpoint from the other segment if (includeThisP1) { result._p1 = this._p1; result._isP1Excluded = this._isP1Excluded || !segment.Contains(this._p1); } else { result._p1 = this._p2; result._isP1Excluded = this._isP2Excluded || !segment.Contains(this._p2); } if (includeSegmentP1) { result._p2 = segment._p1; result._isP2Excluded = segment._isP1Excluded || !this.Contains(segment._p1); } else { result._p2 = segment._p2; result._isP2Excluded = segment._isP2Excluded || !this.Contains(segment._p2); } return(result); }