private static Vector2 verticalIntersectionPoint(Line verticalLine, Slope nonVerticalSlope)
{
double x = verticalLine.P1.X;
double y = nonVerticalSlope.Value * x + nonVerticalSlope.YIntercept;
return(new Vector2((double)x, (double)y));
}
/// <summary>
/// Checks if slopes are parallel.
/// </summary>
/// <param name="slopeA">First Slope.</param>
/// <param name="slopeB">Second Slope.</param>
/// <returns>True if the slopes are parallel.</returns>
public static bool AreParallel(Slope slopeA, Slope slopeB)
{
if (!slopeA.HasValue && !slopeB.HasValue)
{
return(true);
}
if (slopeA.HasValue && slopeB.HasValue && slopeA.Value == slopeB.Value)
{
//lines are parallel
return(true);
}
return(false);
}
/// <summary>
/// Check for slope equality.
/// </summary>
/// <param name="slopeA">First Slope.</param>
/// <param name="slopeB">Second Slope.</param>
/// <returns>Returns if the two slopes are equal.</returns>
public static bool AreEqual(Slope slopeA, Slope slopeB)
{
if (!AreParallel(slopeA, slopeB))
{
return(false);
}
if (!slopeA.HasValue && !slopeB.HasValue)
{
//lines are both vertical, see if x are the same
return(slopeA.line.P1.X == slopeB.line.P1.X);
}
//lines are parallel, but not vertical, see if y-intercept is the same
return(slopeA.YIntercept == slopeB.YIntercept);
}
/**
* Calculates the intersection of slopes of two lines.
*
* @param lineA First line to use for slope.
* @param lineB Second line to use for slope.
* @param options Optional IPathIntersectionOptions.
* @returns point of intersection of the two slopes, or null if the slopes did not intersect.
*/
internal static Vector2?FromSlopeIntersection(Line lineA, Line lineB, out bool AreOverlapped, bool excludeTangents = false)
{
var slopeA = Slope.Of(lineA.P1, lineA.P2);
var slopeB = Slope.Of(lineB.P1, lineB.P2);
AreOverlapped = false;
//see if slope are parallel
if (Slope.AreParallel(slopeA, slopeB))
{
if (Slope.AreEqual(slopeA, slopeB))
{
//check for overlap
AreOverlapped = Helper.IsLineOverlapping(lineA, lineB, excludeTangents);
}
return(null);
}
Vector2?pointOfIntersection = null;
if (!slopeA.HasValue)
{
pointOfIntersection = verticalIntersectionPoint(lineA, slopeB);
}
else if (!slopeB.HasValue)
{
pointOfIntersection = verticalIntersectionPoint(lineB, slopeA);
}
else
{
// find intersection by line equation
double x = (slopeB.YIntercept - slopeA.YIntercept) / (slopeA.Value - slopeB.Value);
double y = slopeA.Value * x + slopeA.YIntercept;
pointOfIntersection = new Vector2((double)x, (double)y);
}
return(pointOfIntersection);
}
