//
// Use point-slope form to determine if the given point is on the line
//
public bool PointLiesOnAndBetweenEndpoints(Point thatPoint)
{
if (thatPoint == null)
{
return(false);
}
return(Segment.Between(thatPoint, Point1, Point2));
}
//
// Creates a flying shape using a CROSSING intersection
// offCross
// |
// ______|______ <--crossingInter
// |
// _____|_____ <--standsInter
//
// Returns <offCross>
//
public Point CreatesFlyingShapeWithCrossing(Intersection thatInter)
{
// A valid transversal is required for this shape
if (!this.CreatesAValidTransversalWith(thatInter))
{
return(null);
}
// We hould not have have endpoint standing as that is handled elsewhere
if (this.StandsOnEndpoint() || thatInter.StandsOnEndpoint())
{
return(null);
}
//
// Determine which is the crossing intersection and which stands on the endpoints
//
Intersection crossingInter = null;
Intersection standsInter = null;
if (this.Crossing() && thatInter.StandsOn())
{
crossingInter = this;
standsInter = thatInter;
}
else if (thatInter.Crossing() && this.StandsOn())
{
crossingInter = thatInter;
standsInter = this;
}
else
{
return(null);
}
Segment transversal = this.AcquireTransversal(thatInter);
// Stands on intersection must have BOTH points not on the transversal line
// |
// ______|______
// |
// |_____
// |
// |
if (!transversal.PointLiesOn(standsInter.CreatesTShape()))
{
return(null);
}
// Success, we have the desired shape
// Acquire return point: offCross
Segment transversalCrossing = crossingInter.GetCollinearSegment(transversal);
return(Segment.Between(crossingInter.intersect, transversalCrossing.Point1, standsInter.intersect) ?
transversalCrossing.Point1 : transversalCrossing.Point2);
}
public void AddCollinearPoint(Point newPt)
{
// Traverse list to find where to insert the new point in the list in the proper order
for (int p = 0; p < points.Count - 1; p++)
{
if (Segment.Between(newPt, points[p], points[p + 1]))
{
points.Insert(p + 1, newPt);
return;
}
}
points.Add(newPt);
}
public bool PointLiesOnAndExactlyBetweenEndpoints(Point thatPoint)
{
if (thatPoint == null)
{
return(false);
}
if (this.HasPoint(thatPoint))
{
return(false);
}
return(Segment.Between(thatPoint, Point1, Point2));
}
//
// Creates a shape like an extended t
// offCross offCross
// | |
// _____|____ ______|______
// | |
// |_____ offStands offStands _____|
//
// Returns <offStands, offCross>
public KeyValuePair <Point, Point> CreatesCrossedTShape(Intersection thatInter)
{
KeyValuePair <Point, Point> nullPair = new KeyValuePair <Point, Point>(null, null);
// A valid transversal is required for this shape
if (!this.CreatesAValidTransversalWith(thatInter))
{
return(nullPair);
}
//
// Determine which is the crossing intersection and which stands on the endpoints
//
Intersection crossingInter = null;
Intersection standsInter = null;
if (this.Crossing() && thatInter.StandsOnEndpoint())
{
crossingInter = this;
standsInter = thatInter;
}
else if (thatInter.Crossing() && this.StandsOnEndpoint())
{
crossingInter = thatInter;
standsInter = this;
}
else
{
return(nullPair);
}
//
// Acquire the returning points
//
Segment transversal = this.AcquireTransversal(thatInter);
Segment parallelStands = standsInter.OtherSegment(transversal);
Point offStands = transversal.PointLiesOn(parallelStands.Point1) ? parallelStands.Point2 : parallelStands.Point1;
Segment transversalCross = crossingInter.GetCollinearSegment(transversal);
Point offCross = Segment.Between(crossingInter.intersect, transversalCross.Point1, standsInter.intersect) ? transversalCross.Point1 : transversalCross.Point2;
return(new KeyValuePair <Point, Point>(offStands, offCross));
}
//
// Angle measure (in degrees) between two vectors in standard position.
//
public static double AngleBetween(Point thisPoint, Point thatPoint)
{
Point origin = new Point("", 0, 0);
if (Segment.Between(origin, thisPoint, thatPoint))
{
return(180);
}
if (Segment.Between(thisPoint, origin, thatPoint))
{
return(0);
}
if (Segment.Between(thatPoint, origin, thisPoint))
{
return(0);
}
return(new Angle(thisPoint, origin, thatPoint).measure);
}
//
// Is this point in the interior of the angle?
//
public bool IsOnInterior(Point pt)
{
// |
// |
// x |_____
// Is the point on either ray such that it is outside the angle? (x in the image above)
if (ray1.PointLiesOn(pt))
{
// Point between the endpoints of the ray.
if (Segment.Between(pt, GetVertex(), ray1.OtherPoint(GetVertex())))
{
return(true);
}
// Point is on the ray, but extended in the right direction.
return(Segment.Between(ray1.OtherPoint(GetVertex()), GetVertex(), pt));
}
if (ray2.PointLiesOn(pt))
{
// Point between the endpoints of the ray.
if (Segment.Between(pt, GetVertex(), ray2.OtherPoint(GetVertex())))
{
return(true);
}
// Point is on the ray, but extended in the right direction.
return(Segment.Between(ray2.OtherPoint(GetVertex()), GetVertex(), pt));
}
Angle newAngle1 = new Angle(A, GetVertex(), pt);
Angle newAngle2 = new Angle(C, GetVertex(), pt);
// This is an angle addition scenario, BUT not with these two angles; that is, one is contained in the other.
if (Utilities.CompareValues(newAngle1.measure + newAngle2.measure, this.measure))
{
return(true);
}
return(newAngle1.measure + newAngle2.measure <= this.measure);
}
//
// PointA
// |
// | X (pt)
// |_____________________ otherSegment
// |
// |
// PointB
//
public Point SameSidePoint(Segment otherSegment, Point pt)
{
// Is the given point on other? If so, we cannot make a determination.
if (otherSegment.PointLiesOn(pt))
{
return(null);
}
// Make a vector out of this vector as well as the vector connecting one of the points to the given pt
Vector thisVector = new Vector(Point1, Point2);
Vector thatVector = new Vector(Point1, pt);
Vector projectionOfOtherOntoThis = thisVector.Projection(thatVector);
// We are interested most in the endpoint of the projection (which is not the
Point projectedEndpoint = projectionOfOtherOntoThis.NonOriginEndpoint();
// Find the intersection between the two lines
Point intersection = FindIntersection(otherSegment);
if (this.PointLiesOn(projectedEndpoint))
{
System.Diagnostics.Debug.WriteLine("Unexpected: Projection does not lie on this line. " + this + " " + projectedEndpoint);
}
// The endpoint of the projection is on this vector. Therefore, we can judge which side of the given segment the given pt lies on.
if (Segment.Between(projectedEndpoint, Point1, intersection))
{
return(Point1);
}
if (Segment.Between(projectedEndpoint, Point2, intersection))
{
return(Point2);
}
return(null);
}
//
// Acquires one or two intercepted arcs from an exterior or interior angle vertex.
//
public static KeyValuePair <Arc, Arc> GetInterceptedArcs(Circle circle, Angle angle)
{
KeyValuePair <Arc, Arc> nullPair = new KeyValuePair <Arc, Arc>(null, null);
//
// Get the intersection points of the rays of the angle.
//
Point interRay11 = null;
Point interRay12 = null;
circle.FindIntersection(angle.ray1, out interRay11, out interRay12);
if (!angle.ray1.PointLiesOnAndBetweenEndpoints(interRay11))
{
interRay11 = null;
}
if (!angle.ray1.PointLiesOnAndBetweenEndpoints(interRay12))
{
interRay12 = null;
}
if (interRay11 == null && interRay12 != null)
{
interRay11 = interRay12;
}
// non-intersection
if (interRay11 == null && interRay12 == null)
{
return(nullPair);
}
Point interRay21 = null;
Point interRay22 = null;
circle.FindIntersection(angle.ray2, out interRay21, out interRay22);
if (!angle.ray2.PointLiesOnAndBetweenEndpoints(interRay21))
{
interRay21 = null;
}
if (!angle.ray2.PointLiesOnAndBetweenEndpoints(interRay22))
{
interRay22 = null;
}
if (interRay21 == null && interRay22 != null)
{
interRay21 = interRay22;
}
// non-intersection
if (interRay21 == null && interRay22 == null)
{
return(nullPair);
}
//
// Split the rays into cases based on if they are secants or not.
//
bool isSecRay1 = angle.ray1.IsSecant(circle);
bool isSecRay2 = angle.ray2.IsSecant(circle);
//
// One Arc: No secants
//
if (!isSecRay1 && !isSecRay2)
{
// This means the endpoints of the ray were on the circle directly for each.
return(new KeyValuePair <Arc, Arc>(Arc.GetFigureMinorArc(circle, interRay11, interRay21), null));
}
//
// One Arc; with one secant and one not.
//
else if (!isSecRay1 || !isSecRay2)
{
Segment secant = null;
Segment nonSecant = null;
Point endPtNonSecant = null;
if (isSecRay1)
{
secant = angle.ray1;
nonSecant = angle.ray2;
endPtNonSecant = interRay21;
}
else
{
secant = angle.ray2;
nonSecant = angle.ray1;
endPtNonSecant = interRay11;
}
Segment chordOfSecant = circle.ContainsChord(secant);
Point endptSecant = Segment.Between(chordOfSecant.Point1, angle.GetVertex(), chordOfSecant.Point2) ?
chordOfSecant.Point1 : chordOfSecant.Point2;
return(new KeyValuePair <Arc, Arc>(Arc.GetFigureMinorArc(circle, endPtNonSecant, endptSecant), null));
}
//
// Two arcs
//
else
{
//
// Ensure proper ordering of points
//
Point closeRay1, farRay1;
Point closeRay2, farRay2;
if (Segment.Between(interRay11, angle.GetVertex(), interRay12))
{
closeRay1 = interRay11;
farRay1 = interRay12;
}
else
{
closeRay1 = interRay12;
farRay1 = interRay11;
}
if (Segment.Between(interRay21, angle.GetVertex(), interRay22))
{
closeRay2 = interRay21;
farRay2 = interRay22;
}
else
{
closeRay2 = interRay22;
farRay2 = interRay21;
}
return(new KeyValuePair <Arc, Arc>(Arc.GetFigureMinorArc(circle, closeRay1, closeRay2),
Arc.GetFigureMinorArc(circle, farRay1, farRay2)));
}
}
public static Quadrilateral GenerateQuadrilateral(Segment s1, Segment s2, Segment s3, Segment s4)
{
// ____
// |
// |____
// Check a C shape of 3 segments; the 4th needs to be opposite
Segment top;
Segment bottom;
Segment left = AcquireMiddleSegment(s1, s2, s3, out top, out bottom);
// Check C for the top, bottom, and right sides
if (left == null)
{
return(null);
}
Segment right = s4;
Segment tempOut1, tempOut2;
Segment rightMid = AcquireMiddleSegment(top, bottom, right, out tempOut1, out tempOut2);
// The middle segment we acquired must match the 4th segment
if (!right.StructurallyEquals(rightMid))
{
return(null);
}
//
// The top / bottom cannot cross; bowtie or hourglass shape
// A valid quadrilateral will have the intersections outside of the quad, that is defined
// by the order of the three points: intersection and two endpts of the side
//
Point intersection = top.FindIntersection(bottom);
// Check for parallel lines, then in-betweenness
if (intersection != null && !double.IsNaN(intersection.X) && !double.IsNaN(intersection.Y))
{
if (Segment.Between(intersection, top.Point1, top.Point2))
{
return(null);
}
if (Segment.Between(intersection, bottom.Point1, bottom.Point2))
{
return(null);
}
}
// The left / right cannot cross; bowtie or hourglass shape
intersection = left.FindIntersection(right);
// Check for parallel lines, then in-betweenness
if (intersection != null && !double.IsNaN(intersection.X) && !double.IsNaN(intersection.Y))
{
if (Segment.Between(intersection, left.Point1, left.Point2))
{
return(null);
}
if (Segment.Between(intersection, right.Point1, right.Point2))
{
return(null);
}
}
//
// Verify that we have 4 unique points; And not different shapes (like a star, or triangle with another segment)
//
List <Point> pts = new List <Point>();
pts.Add(left.SharedVertex(top));
pts.Add(left.SharedVertex(bottom));
pts.Add(right.SharedVertex(bottom));
pts.Add(right.SharedVertex(top));
for (int i = 0; i < pts.Count - 1; i++)
{
for (int j = i + 1; j < pts.Count; j++)
{
if (pts[i].StructurallyEquals(pts[j]))
{
return(null);
}
}
}
return(new Quadrilateral(left, right, top, bottom));
}
//
// Assumes our points represent vectors in std position
//
public static bool OppositeVectors(Point first, Point second)
{
Point origin = new Point("", 0, 0);
return(Segment.Between(origin, first, second));
}
// top
// o
// offStands oooooooe
// e
//offEndpoint eeeeeee
// o
// bottom
// Returns: <offEndpoint, offStands>
public KeyValuePair <Point, Point> CreatesSimplePIShape(Intersection thatInter)
{
KeyValuePair <Point, Point> nullPair = new KeyValuePair <Point, Point>(null, null);
// A valid transversal is required for this shape
if (!this.CreatesAValidTransversalWith(thatInter))
{
return(nullPair);
}
// Restrict to desired combination
if (this.StandsOnEndpoint() && thatInter.StandsOnEndpoint())
{
return(nullPair);
}
//
// Determine which is the stands and which is the endpoint
//
Intersection endpointInter = null;
Intersection standsInter = null;
if (this.StandsOnEndpoint() && thatInter.StandsOn())
{
endpointInter = this;
standsInter = thatInter;
}
else if (thatInter.StandsOnEndpoint() && this.StandsOn())
{
endpointInter = this;
standsInter = thatInter;
}
else
{
return(nullPair);
}
//
// Avoid Some shapes
//
Segment transversal = this.AcquireTransversal(thatInter);
Segment transversalStands = standsInter.GetCollinearSegment(transversal);
Point top = null;
Point bottom = null;
if (Segment.Between(standsInter.intersect, transversalStands.Point1, endpointInter.intersect))
{
top = transversalStands.Point1;
bottom = transversalStands.Point2;
}
else
{
top = transversalStands.Point2;
bottom = transversalStands.Point1;
}
// Avoid: ____ Although this shouldn't happen since both intersections do not stand on endpoints
// ____|
//
// Also avoid Simple F-Shape
//
if (transversal.HasPoint(top) || transversal.HasPoint(bottom))
{
return(nullPair);
}
// Determine S shape
Point offStands = standsInter.CreatesTShape();
Segment parallelEndpoint = endpointInter.OtherSegment(transversal);
Point offEndpoint = parallelEndpoint.OtherPoint(endpointInter.intersect);
Segment crossingTester = new Segment(offStands, offEndpoint);
Point intersection = transversal.FindIntersection(crossingTester);
// S-shape // PI-Shape
return(transversal.PointLiesOnAndBetweenEndpoints(intersection) ? nullPair : new KeyValuePair <Point, Point>(offEndpoint, offStands));
}
//
// Creates an F-Shape
// top
// _____ offEnd <--- Stands on Endpt
// |
// |_____ offStands <--- Stands on
// |
// |
// bottom
// Order of non-collinear points is order of intersections: <this, that>
public KeyValuePair <Point, Point> CreatesFShape(Intersection thatInter)
{
KeyValuePair <Point, Point> nullPair = new KeyValuePair <Point, Point>(null, null);
// A valid transversal is required for this shape
if (!this.CreatesAValidTransversalWith(thatInter))
{
return(nullPair);
}
// Avoid both standing on an endpoint
if (this.StandsOnEndpoint() && thatInter.StandsOnEndpoint())
{
return(nullPair);
}
Intersection endpt = null;
Intersection standsOn = null;
if (this.StandsOnEndpoint() && thatInter.StandsOn())
{
endpt = this;
standsOn = thatInter;
}
else if (thatInter.StandsOnEndpoint() && this.StandsOn())
{
endpt = thatInter;
standsOn = this;
}
else
{
return(nullPair);
}
Segment transversal = this.AcquireTransversal(thatInter);
Segment transversalStands = standsOn.GetCollinearSegment(transversal);
//
// Determine Top and bottom to avoid PI shape
//
Point top = null;
Point bottom = null;
if (Segment.Between(standsOn.intersect, transversalStands.Point1, endpt.intersect))
{
bottom = transversalStands.Point1;
top = transversalStands.Point2;
}
else
{
bottom = transversalStands.Point2;
top = transversalStands.Point1;
}
// Avoid: ____ Although this shouldn't happen since both intersections do not stand on endpoints
// ____|
if (transversal.HasPoint(top) && transversal.HasPoint(bottom))
{
return(nullPair);
}
// Also avoid Simple PI-Shape
//
if (!transversal.HasPoint(top) && !transversal.HasPoint(bottom))
{
return(nullPair);
}
// Find the two points that make the points of the F
Segment parallelEndPt = endpt.OtherSegment(transversal);
Segment parallelStands = standsOn.OtherSegment(transversal);
Point offEnd = transversal.PointLiesOn(parallelEndPt.Point1) ? parallelEndPt.Point2 : parallelEndPt.Point1;
Point offStands = transversal.PointLiesOn(parallelStands.Point1) ? parallelStands.Point2 : parallelStands.Point1;
// Check this is not a crazy F
// _____
// |
// ____|
// |
// |
Point intersection = transversal.FindIntersection(new Segment(offEnd, offStands));
if (transversal.PointLiesOnAndBetweenEndpoints(intersection))
{
return(nullPair);
}
// Return in the order of 'off' points: <this, that>
return(this.Equals(endpt) ? new KeyValuePair <Point, Point>(offEnd, offStands) : new KeyValuePair <Point, Point>(offStands, offEnd));
}
