/// <summary>
/// Returns the distance between the closest points on the segments
/// </summary>
public static float SegmentSegment(Vector2 segment1A, Vector2 segment1B, Vector2 segment2A, Vector2 segment2B)
{
Vector2 from2ATo1A = segment1A - segment2A;
Vector2 direction1 = segment1B - segment1A;
Vector2 direction2 = segment2B - segment2A;
float segment1Length = direction1.Length();
float segment2Length = direction2.Length();
bool segment1IsAPoint = segment1Length < Geometry.Epsilon;
bool segment2IsAPoint = segment2Length < Geometry.Epsilon;
if (segment1IsAPoint && segment2IsAPoint)
{
return(segment1A.DistanceTo(segment2A));
}
if (segment1IsAPoint)
{
direction2.Normalized();
return(PointSegment(segment1A, segment2A, segment2B, direction2, segment2Length));
}
if (segment2IsAPoint)
{
direction1.Normalized();
return(PointSegment(segment2A, segment1A, segment1B, direction1, segment1Length));
}
direction1.Normalized();
direction2.Normalized();
float denominator = VectorE.PerpDot(direction1, direction2);
float perpDot1 = VectorE.PerpDot(direction1, from2ATo1A);
float perpDot2 = VectorE.PerpDot(direction2, from2ATo1A);
if (Mathf.Abs(denominator) < Geometry.Epsilon)
{
// Parallel
if (Mathf.Abs(perpDot1) > Geometry.Epsilon || Mathf.Abs(perpDot2) > Geometry.Epsilon)
{
// Not collinear
float segment2AProjection = -direction1.Dot(from2ATo1A);
if (segment2AProjection > -Geometry.Epsilon &&
segment2AProjection < segment1Length + Geometry.Epsilon)
{
float distanceSqr = from2ATo1A.LengthSquared() - segment2AProjection * segment2AProjection;
// distanceSqr can be negative
return(distanceSqr <= 0 ? 0 : Mathf.Sqrt(distanceSqr));
}
Vector2 from1ATo2B = segment2B - segment1A;
float segment2BProjection = direction1.Dot(from1ATo2B);
if (segment2BProjection > -Geometry.Epsilon &&
segment2BProjection < segment1Length + Geometry.Epsilon)
{
float distanceSqr = from1ATo2B.LengthSquared() - segment2BProjection * segment2BProjection;
// distanceSqr can be negative
return(distanceSqr <= 0 ? 0 : Mathf.Sqrt(distanceSqr));
}
if (segment2AProjection < 0 && segment2BProjection < 0)
{
if (segment2AProjection > segment2BProjection)
{
return(segment1A.DistanceTo(segment2A));
}
return(segment1A.DistanceTo(segment2B));
}
if (segment2AProjection > 0 && segment2BProjection > 0)
{
if (segment2AProjection < segment2BProjection)
{
return(segment1B.DistanceTo(segment2A));
}
return(segment1B.DistanceTo(segment2B));
}
float segment1AProjection = direction2.Dot(from2ATo1A);
Vector2 segment2Point = segment2A + direction2 * segment1AProjection;
return(segment1A.DistanceTo(segment2Point));
}
// Collinear
bool codirected = direction1.Dot(direction2) > 0;
if (codirected)
{
// Codirected
float segment2AProjection = -direction1.Dot(from2ATo1A);
if (segment2AProjection > -Geometry.Epsilon)
{
// 1A------1B
// 2A------2B
return(SegmentSegmentCollinear(segment1A, segment1B, segment2A));
}
else
{
// 1A------1B
// 2A------2B
return(SegmentSegmentCollinear(segment2A, segment2B, segment1A));
}
}
else
{
// Contradirected
float segment2BProjection = direction1.Dot(segment2B - segment1A);
if (segment2BProjection > -Geometry.Epsilon)
{
// 1A------1B
// 2B------2A
return(SegmentSegmentCollinear(segment1A, segment1B, segment2B));
}
else
{
// 1A------1B
// 2B------2A
return(SegmentSegmentCollinear(segment2B, segment2A, segment1A));
}
}
}
// Not parallel
float distance1 = perpDot2 / denominator;
float distance2 = perpDot1 / denominator;
if (distance1 < -Geometry.Epsilon || distance1 > segment1Length + Geometry.Epsilon ||
distance2 < -Geometry.Epsilon || distance2 > segment2Length + Geometry.Epsilon)
{
// No intersection
bool codirected = direction1.Dot(direction2) > 0;
Vector2 from1ATo2B;
if (!codirected)
{
PTUtils.Swap(ref segment2A, ref segment2B);
direction2 = -direction2;
from1ATo2B = -from2ATo1A;
from2ATo1A = segment1A - segment2A;
distance2 = segment2Length - distance2;
}
else
{
from1ATo2B = segment2B - segment1A;
}
Vector2 segment1Point;
Vector2 segment2Point;
float segment2AProjection = -direction1.Dot(from2ATo1A);
float segment2BProjection = direction1.Dot(from1ATo2B);
bool segment2AIsAfter1A = segment2AProjection > -Geometry.Epsilon;
bool segment2BIsBefore1B = segment2BProjection < segment1Length + Geometry.Epsilon;
bool segment2AOnSegment1 = segment2AIsAfter1A && segment2AProjection < segment1Length + Geometry.Epsilon;
bool segment2BOnSegment1 = segment2BProjection > -Geometry.Epsilon && segment2BIsBefore1B;
if (segment2AOnSegment1 && segment2BOnSegment1)
{
if (distance2 < -Geometry.Epsilon)
{
segment1Point = segment1A + direction1 * segment2AProjection;
segment2Point = segment2A;
}
else
{
segment1Point = segment1A + direction1 * segment2BProjection;
segment2Point = segment2B;
}
}
else if (!segment2AOnSegment1 && !segment2BOnSegment1)
{
if (!segment2AIsAfter1A && !segment2BIsBefore1B)
{
segment1Point = distance1 < -Geometry.Epsilon ? segment1A : segment1B;
}
else
{
// Not on segment
segment1Point = segment2AIsAfter1A ? segment1B : segment1A;
}
float segment1PointProjection = direction2.Dot(segment1Point - segment2A);
segment1PointProjection = Mathf.Clamp(segment1PointProjection, 0, segment2Length);
segment2Point = segment2A + direction2 * segment1PointProjection;
}
else if (segment2AOnSegment1)
{
if (distance2 < -Geometry.Epsilon)
{
segment1Point = segment1A + direction1 * segment2AProjection;
segment2Point = segment2A;
}
else
{
segment1Point = segment1B;
float segment1PointProjection = direction2.Dot(segment1Point - segment2A);
segment1PointProjection = Mathf.Clamp(segment1PointProjection, 0, segment2Length);
segment2Point = segment2A + direction2 * segment1PointProjection;
}
}
else
{
if (distance2 > segment2Length + Geometry.Epsilon)
{
segment1Point = segment1A + direction1 * segment2BProjection;
segment2Point = segment2B;
}
else
{
segment1Point = segment1A;
float segment1PointProjection = direction2.Dot(segment1Point - segment2A);
segment1PointProjection = Mathf.Clamp(segment1PointProjection, 0, segment2Length);
segment2Point = segment2A + direction2 * segment1PointProjection;
}
}
return(segment1Point.DistanceTo(segment2Point));
}
// Point intersection
return(0);
}
/// <summary>
/// Returns the distance between the closest points on the ray and the segment
/// </summary>
public static float RaySegment(Vector2 rayOrigin, Vector2 rayDirection, Vector2 segmentA, Vector2 segmentB)
{
Vector2 segmentAToOrigin = rayOrigin - segmentA;
Vector2 segmentDirection = segmentB - segmentA;
float denominator = VectorE.PerpDot(rayDirection, segmentDirection);
float perpDotA = VectorE.PerpDot(rayDirection, segmentAToOrigin);
// Normalized direction gives more stable results
float perpDotB = VectorE.PerpDot(segmentDirection.Normalized(), segmentAToOrigin);
if (Mathf.Abs(denominator) < Geometry.Epsilon)
{
// Parallel
float segmentAProjection = -rayDirection.Dot(segmentAToOrigin);
Vector2 originToSegmentB = segmentB - rayOrigin;
float segmentBProjection = rayDirection.Dot(originToSegmentB);
if (Mathf.Abs(perpDotA) > Geometry.Epsilon || Mathf.Abs(perpDotB) > Geometry.Epsilon)
{
// Not collinear
if (segmentAProjection > -Geometry.Epsilon)
{
float distanceSqr = segmentAToOrigin.LengthSquared() - segmentAProjection * segmentAProjection;
// distanceSqr can be negative
return(distanceSqr <= 0 ? 0 : Mathf.Sqrt(distanceSqr));
}
if (segmentBProjection > -Geometry.Epsilon)
{
float distanceSqr = originToSegmentB.LengthSquared() - segmentBProjection * segmentBProjection;
// distanceSqr can be negative
return(distanceSqr <= 0 ? 0 : Mathf.Sqrt(distanceSqr));
}
if (segmentAProjection > segmentBProjection)
{
return(rayOrigin.DistanceTo(segmentA));
}
return(rayOrigin.DistanceTo(segmentB));
}
// Collinear
if (segmentAProjection > -Geometry.Epsilon || segmentBProjection > -Geometry.Epsilon)
{
// Point or segment intersection
return(0);
}
// No intersection
return(segmentAProjection > segmentBProjection ? -segmentAProjection : -segmentBProjection);
}
// Not parallel
float rayDistance = perpDotB / denominator;
float segmentDistance = perpDotA / denominator;
if (rayDistance < -Geometry.Epsilon ||
segmentDistance < -Geometry.Epsilon || segmentDistance > 1 + Geometry.Epsilon)
{
// No intersection
bool codirected = rayDirection.Dot(segmentDirection) > 0;
Vector2 segmentBToOrigin;
if (!codirected)
{
PTUtils.Swap(ref segmentA, ref segmentB);
segmentDirection = -segmentDirection;
segmentBToOrigin = segmentAToOrigin;
segmentAToOrigin = rayOrigin - segmentA;
segmentDistance = 1 - segmentDistance;
}
else
{
segmentBToOrigin = rayOrigin - segmentB;
}
float segmentAProjection = -rayDirection.Dot(segmentAToOrigin);
float segmentBProjection = -rayDirection.Dot(segmentBToOrigin);
bool segmentAOnRay = segmentAProjection > -Geometry.Epsilon;
bool segmentBOnRay = segmentBProjection > -Geometry.Epsilon;
if (segmentAOnRay && segmentBOnRay)
{
if (segmentDistance < 0)
{
Vector2 rayPoint = rayOrigin + rayDirection * segmentAProjection;
Vector2 segmentPoint = segmentA;
return(rayPoint.DistanceTo(segmentPoint));
}
else
{
Vector2 rayPoint = rayOrigin + rayDirection * segmentBProjection;
Vector2 segmentPoint = segmentB;
return(rayPoint.DistanceTo(segmentPoint));
}
}
else if (!segmentAOnRay && segmentBOnRay)
{
if (segmentDistance < 0)
{
Vector2 rayPoint = rayOrigin;
Vector2 segmentPoint = segmentA;
return(rayPoint.DistanceTo(segmentPoint));
}
else if (segmentDistance > 1 + Geometry.Epsilon)
{
Vector2 rayPoint = rayOrigin + rayDirection * segmentBProjection;
Vector2 segmentPoint = segmentB;
return(rayPoint.DistanceTo(segmentPoint));
}
else
{
Vector2 rayPoint = rayOrigin;
float originProjection = segmentDirection.Dot(segmentAToOrigin);
Vector2 segmentPoint = segmentA + segmentDirection * originProjection / segmentDirection.LengthSquared();
return(rayPoint.DistanceTo(segmentPoint));
}
}
else
{
// Not on ray
Vector2 rayPoint = rayOrigin;
float originProjection = segmentDirection.Dot(segmentAToOrigin);
float sqrSegmentLength = segmentDirection.LengthSquared();
if (originProjection < 0)
{
return(rayPoint.DistanceTo(segmentA));
}
else if (originProjection > sqrSegmentLength)
{
return(rayPoint.DistanceTo(segmentB));
}
else
{
Vector2 segmentPoint = segmentA + segmentDirection * originProjection / sqrSegmentLength;
return(rayPoint.DistanceTo(segmentPoint));
}
}
}
// Point intersection
return(0);
}
