| private LocateProjection ( DoublePoint point ) : ProjectionLocation | ||
| point | DoublePoint | |
| return | ProjectionLocation | |
/// <summary>
/// Finds, provided it exists, the intersection point with the specified <see cref="LineSegment"/>.
/// </summary>
///
/// <param name="other"><see cref="LineSegment"/> to find intersection with.</param>
///
/// <returns>Returns intersection point with the specified <see cref="LineSegment"/>, or <see langword="null"/>, if
/// the two segments do not intersect.</returns>
///
/// <remarks><para>If the two segments do not intersect, the method returns <see langword="null"/>. If the two
/// segments share multiple points, this throws an <see cref="InvalidOperationException"/>.
/// </para></remarks>
///
/// <exception cref="InvalidOperationException">Thrown if the segments overlap - if they have
/// multiple points in common.</exception>
///
public Point?GetIntersectionWith(LineSegment other)
{
Point?result = null;
if ((line.Slope == other.line.Slope) || (line.IsVertical && other.line.IsVertical))
{
if (line.Intercept == other.line.Intercept)
{
// Collinear segments. Inspect and handle.
// Consider this segment AB and other as CD. (start/end in both cases)
// There are three cases:
// 0 shared points: C and D both project onto the same ray of AB
// 1 shared point: One of A or B equals one of C or D, and the other of C/D
// projects on the correct ray.
// Many shared points.
ProjectionLocation projC = LocateProjection(other.start), projD = LocateProjection(other.end);
if ((projC != ProjectionLocation.SegmentAB) && (projC == projD))
{
// no shared points
result = null;
}
else if (((start == other.start) && (projD == ProjectionLocation.RayA)) ||
((start == other.end) && (projC == ProjectionLocation.RayA)))
{
// shared start point
result = start;
}
else if (((end == other.start) && (projD == ProjectionLocation.RayB)) ||
((end == other.end) && (projC == ProjectionLocation.RayB)))
{
// shared end point
result = end;
}
else
{
// overlapping
throw new InvalidOperationException("Overlapping segments do not have a single intersection point.");
}
}
}
else
{
result = GetIntersectionWith(other.line);
if ((result.HasValue) && (other.LocateProjection(result.Value) != ProjectionLocation.SegmentAB))
{
// the intersection is on the extended line of this segment
result = null;
}
}
return(result);
}
public Point?GetIntersectionWith(LineSegment other)
{
Point?result = null;
if (line.Slope == other.line.Slope || (line.IsVertical && other.line.IsVertical))
{
if (line.Intercept == other.line.Intercept)
{
ProjectionLocation projectionLocation = LocateProjection(other.start);
ProjectionLocation projectionLocation2 = LocateProjection(other.end);
if (projectionLocation != ProjectionLocation.SegmentAB && projectionLocation == projectionLocation2)
{
result = null;
}
else if ((start == other.start && projectionLocation2 == ProjectionLocation.RayA) || (start == other.end && projectionLocation == ProjectionLocation.RayA))
{
result = start;
}
else
{
if ((!(end == other.start) || projectionLocation2 != ProjectionLocation.RayB) && (!(end == other.end) || projectionLocation != ProjectionLocation.RayB))
{
throw new InvalidOperationException("Overlapping segments do not have a single intersection point.");
}
result = end;
}
}
}
else
{
result = GetIntersectionWith(other.line);
if (result.HasValue && other.LocateProjection(result.Value) != ProjectionLocation.SegmentAB)
{
result = null;
}
}
return(result);
}
/// <summary>
/// Finds, provided it exists, the intersection point with the specified <see cref="LineSegment"/>.
/// </summary>
///
/// <param name="other"><see cref="LineSegment"/> to find intersection with.</param>
///
/// <returns>Returns intersection point with the specified <see cref="LineSegment"/>, or <see langword="null"/>, if
/// the two segments do not intersect.</returns>
///
/// <remarks><para>If the two segments do not intersect, the method returns <see langword="null"/>. If the two
/// segments share multiple points, this throws an <see cref="InvalidOperationException"/>.
/// </para></remarks>
///
/// <exception cref="InvalidOperationException">Thrown if the segments overlap - if they have
/// multiple points in common.</exception>
///
public DoublePoint? GetIntersectionWith( LineSegment other )
{
DoublePoint? result = null;
if ( ( line.Slope == other.line.Slope ) || ( line.IsVertical && other.line.IsVertical ) )
{
if ( line.Intercept == other.line.Intercept )
{
// Collinear segments. Inspect and handle.
// Consider this segment AB and other as CD. (start/end in both cases)
// There are three cases:
// 0 shared points: C and D both project onto the same ray of AB
// 1 shared point: One of A or B equals one of C or D, and the other of C/D
// projects on the correct ray.
// Many shared points.
ProjectionLocation projC = LocateProjection( other.start ), projD = LocateProjection( other.end );
if ( ( projC != ProjectionLocation.SegmentAB ) && ( projC == projD ) )
{
// no shared points
result = null;
}
else if ( ( ( start == other.start ) && ( projD == ProjectionLocation.RayA ) ) ||
( ( start == other.end ) && ( projC == ProjectionLocation.RayA ) ) )
{
// shared start point
result = start;
}
else if ( ( ( end == other.start ) && ( projD == ProjectionLocation.RayB ) ) ||
( ( end == other.end ) && ( projC == ProjectionLocation.RayB ) ) )
{
// shared end point
result = end;
}
else
{
// overlapping
throw new InvalidOperationException( "Overlapping segments do not have a single intersection point." );
}
}
}
else
{
result = GetIntersectionWith( other.line );
if ( ( result.HasValue ) && ( other.LocateProjection( result.Value ) != ProjectionLocation.SegmentAB ) )
{
// the intersection is on the extended line of this segment
result = null;
}
}
return result;
}
