/// <summary>
///
/// </summary>
/// <param name="line1Start"></param>
/// <param name="line1End"></param>
/// <param name="line2Start"></param>
/// <param name="line2End"></param>
/// <returns></returns>
public static double AngleLineSegments(
Point2 line1Start, Point2 line1End,
Point2 line2Start, Point2 line2End)
{
double angle1 = Math.Atan2(line1Start.Y - line1End.Y, line1Start.X - line1End.X);
double angle2 = Math.Atan2(line2Start.Y - line2End.Y, line2Start.X - line2End.X);
double result = (angle2 - angle1) * 180.0 / Math.PI;
if (result < 0)
result += 360.0;
return result;
}
/// <summary>
///
/// </summary>
/// <param name="centerPoint"></param>
/// <param name="angleInDegrees"></param>
/// <returns></returns>
public Point2 RotateAt(
Point2 centerPoint,
double angleInDegrees)
{
double angleInRadians = angleInDegrees * (Math.PI / 180.0);
double cosTheta = Math.Cos(angleInRadians);
double sinTheta = Math.Sin(angleInRadians);
return new Point2
{
X = (cosTheta * (this.X - centerPoint.X) - sinTheta * (this.Y - centerPoint.Y) + centerPoint.X),
Y = (sinTheta * (this.X - centerPoint.X) + cosTheta * (this.Y - centerPoint.Y) + centerPoint.Y)
};
}
/// <summary>
///
/// </summary>
/// <param name="point"></param>
/// <returns></returns>
public double Distance(Point2 point)
{
double dx = this.X - point.X;
double dy = this.Y - point.Y;
return Math.Sqrt(dx * dx + dy * dy);
}
/// <summary>
///
/// </summary>
/// <param name="tl"></param>
/// <param name="br"></param>
/// <param name="dx"></param>
/// <param name="dy"></param>
/// <returns></returns>
public static Rect2 Create(
Point2 tl, Point2 br,
double dx = 0.0, double dy = 0.0)
{
return Rect2.Create(tl.X, tl.Y, br.X, br.Y, dx, dy);
}
/// <summary>
///
/// </summary>
/// <param name="rect"></param>
/// <param name="p1"></param>
/// <param name="p2"></param>
/// <param name="onlySegment"></param>
/// <returns></returns>
public static IList<Point2> FindEllipseSegmentIntersections(
Rect2 rect,
Point2 p1, Point2 p2,
bool onlySegment)
{
if ((rect.Width == 0) || (rect.Height == 0) || ((p1.X == p2.X) && (p1.Y == p2.Y)))
return new Point2[] { };
if (rect.Width < 0)
{
rect.X = rect.Right;
rect.Width = -rect.Width;
}
if (rect.Height < 0)
{
rect.Y = rect.Bottom;
rect.Height = -rect.Height;
}
double cx = rect.Left + rect.Width / 2.0;
double cy = rect.Top + rect.Height / 2.0;
rect.X -= cx;
rect.Y -= cy;
p1.X -= cx;
p1.Y -= cy;
p2.X -= cx;
p2.Y -= cy;
double a = rect.Width / 2.0;
double b = rect.Height / 2.0;
double A = (p2.X - p1.X) * (p2.X - p1.X) / a / a + (p2.Y - p1.Y) * (p2.Y - p1.Y) / b / b;
double B = 2 * p1.X * (p2.X - p1.X) / a / a + 2 * p1.Y * (p2.Y - p1.Y) / b / b;
double C = p1.X * p1.X / a / a + p1.Y * p1.Y / b / b - 1;
var solutions = new List<double>();
double discriminant = B * B - 4 * A * C;
if (discriminant == 0)
{
solutions.Add(-B / 2 / A);
}
else if (discriminant > 0)
{
solutions.Add((-B + Math.Sqrt(discriminant)) / 2 / A);
solutions.Add((-B - Math.Sqrt(discriminant)) / 2 / A);
}
var points = new List<Point2>();
foreach (var t in solutions)
{
if (!onlySegment || ((t >= 0f) && (t <= 1f)))
{
double x = p1.X + (p2.X - p1.X) * t + cx;
double y = p1.Y + (p2.Y - p1.Y) * t + cy;
points.Add(Point2.Create(x, y));
}
}
return points;
}
/// <summary>
/// Check if line intersects with rectangle using Liang-Barsky line clipping algorithm.
/// </summary>
/// <param name="rect"></param>
/// <param name="p0"></param>
/// <param name="p1"></param>
/// <returns>True if line intersects with rectangle.</returns>
public static bool LineIntersectsWithRect(Rect2 rect, Point2 p0, Point2 p1)
{
double left = rect.Left;
double right = rect.Right;
double bottom = rect.Bottom;
double top = rect.Top;
double x0 = p0.X;
double y0 = p0.Y;
double x1 = p1.X;
double y1 = p1.Y;
double t0 = 0.0;
double t1 = 1.0;
double dx = x1 - x0;
double dy = y1 - y0;
double p = 0.0, q = 0.0, r;
for (int edge = 0; edge < 4; edge++)
{
if (edge == 0)
{
p = -dx;
q = -(left - x0);
}
if (edge == 1)
{
p = dx;
q = (right - x0);
}
if (edge == 2)
{
p = dy;
q = (bottom - y0);
}
if (edge == 3)
{
p = -dy;
q = -(top - y0);
}
r = q / p;
if (p == 0.0 && q < 0.0)
{
return false;
}
if (p < 0.0)
{
if (r > t1)
{
return false;
}
else if (r > t0)
{
t0 = r;
}
}
else if (p > 0.0)
{
if (r < t0)
{
return false;
}
else if (r < t1)
{
t1 = r;
}
}
}
// to calulate clipped line position
// x0clip = x0 + t0 * dx;
// y0clip = y0 + t0 * dy;
// x1clip = x0 + t1 * dx;
// y1clip = y0 + t1 * dy;
return true;
}