/// <summary>
/// Calculates the intersection of a ray with a segment. Returns the result as the lambdas of the intersection
/// point along the ray and the segment. If there is no intersection returns double.NaN in both lambdas.</summary>
public static void RayWithSegment(ref EdgeD ray, ref EdgeD segment, out double rayL, out double segmentL)
{
Intersect.LineWithLine(ref ray, ref segment, out rayL, out segmentL);
if (!double.IsNaN(rayL) && ((rayL < 0) || (segmentL < 0) || (segmentL > 1)))
{
rayL = segmentL = double.NaN;
}
}
private void AssertRayWithCircle(double frX, double frY, double toX, double toY, double cX, double cY, double cR, double expL1, double expL2)
{
EdgeD ray = new EdgeD(frX, frY, toX, toY);
CircleD cir = new CircleD(cX, cY, cR);
double l1, l2;
Intersect.RayWithCircle(ref ray, ref cir, out l1, out l2);
Assert.AreEqual(expL1, l1, 0.001);
Assert.AreEqual(expL2, l2, 0.001);
}
private void AssertLineWithCircle(double frX, double frY, double toX, double toY, double cX, double cY, double cR, double expL1, double expL2)
{
EdgeD lin = new EdgeD(frX, frY, toX, toY);
CircleD cir = new CircleD(cX, cY, cR);
double l1, l2;
Intersect.LineWithCircle(ref lin, ref cir, out l1, out l2);
Assert.AreEqual(MinTO(expL1, expL2), MinTO(l1, l2), 0.001);
Assert.AreEqual(MaxTO(expL1, expL2), MaxTO(l1, l2), 0.001);
}
/// <summary>
/// Finds intersections between a ray and a rectangle. Returns the lambdas of intersections, if any, or NaN
/// otherwise. Guarantees that lambda1 < lambda2, and if only one of them is NaN then it's lambda2. Lambda is
/// such that ray.Start + lambda * (ray.End - ray.Start) gives the point of intersection.</summary>
public static void RayWithRectangle(ref EdgeD ray, ref RectangleD rect, out double lambda1, out double lambda2)
{
double lambda, dummy;
bool done1 = false;
lambda1 = lambda2 = double.NaN;
for (int i = 0; i < 4; i++)
{
EdgeD segment;
switch (i)
{
case 0: segment = new EdgeD(rect.Left, rect.Top, rect.Right, rect.Top); break;
case 1: segment = new EdgeD(rect.Right, rect.Top, rect.Right, rect.Bottom); break;
case 2: segment = new EdgeD(rect.Right, rect.Bottom, rect.Left, rect.Bottom); break;
case 3: segment = new EdgeD(rect.Left, rect.Bottom, rect.Left, rect.Top); break;
default: throw new InternalErrorException("fsvxhfhj"); // unreachable
}
Intersect.RayWithSegment(ref ray, ref segment, out lambda, out dummy);
if (!double.IsNaN(lambda))
{
if (!done1)
{
lambda1 = lambda;
done1 = true;
}
else if (lambda != lambda1)
{
if (lambda > lambda1)
{
lambda2 = lambda;
}
else
{
lambda2 = lambda1;
lambda1 = lambda;
}
return;
}
}
}
}
/// <summary>Returns a polygon formed by intersecting an arbitrary polygon with a convex polygon.</summary>
public static PolygonD PolygonWithConvexPolygon(PolygonD mainPoly, PolygonD clipPoly)
{
if (mainPoly.Vertices.Count <= 2 || clipPoly.Vertices.Count <= 2)
{
throw new InvalidOperationException("One of the polygons has 2 vertices or fewer.");
}
var result = new List <PointD>();
var resultVertices = mainPoly.Vertices.ToList();
foreach (var clipEdge in clipPoly.ToEdges())
{
var newVertices = new List <PointD>();
var vertexStart = resultVertices[resultVertices.Count - 1];
foreach (var vertexEnd in resultVertices)
{
if (clipEdge.CrossZ(vertexStart) > 0)
{
if (clipEdge.CrossZ(vertexEnd) > 0)
{
newVertices.Add(vertexEnd);
}
else
{
newVertices.Add(Intersect.LineWithLine(clipEdge, new EdgeD(vertexStart, vertexEnd)));
}
}
else
{
if (clipEdge.CrossZ(vertexEnd) > 0)
{
newVertices.Add(Intersect.LineWithLine(clipEdge, new EdgeD(vertexStart, vertexEnd)));
newVertices.Add(vertexEnd);
}
}
vertexStart = vertexEnd;
}
resultVertices = newVertices;
}
return(new PolygonD(resultVertices));
}
/// <summary>Returns true if this bounding box intersects with the specified bounding box.</summary>
public bool IntersectsWithBoundingBox(BoundingBoxD box)
{
return(Intersect.BoundingBoxWithBoundingBox(ref this, ref box));
}
/// <summary>Returns true if this bounding box intersects with the specified ray.</summary>
public bool IntersectsWithRay(EdgeD ray)
{
return(Intersect.RayWithBoundingBox(ref ray, ref this));
}