//private
private CohenSutherlandBitCode ComputeOutCode(PreciseRectangle r, PrecisePoint p, double epsilon)
{
CohenSutherlandBitCode code = CohenSutherlandBitCode.INSIDE;
if (r.Left - p.X >= epsilon)
{
code |= CohenSutherlandBitCode.LEFT;
}
else if (p.X - r.Right >= epsilon)
{
code |= CohenSutherlandBitCode.RIGHT;
}
if (r.Top - p.Y >= epsilon)
{
code |= CohenSutherlandBitCode.BOTTOM;
}
else if (p.Y - r.Bottom >= epsilon)
{
code |= CohenSutherlandBitCode.TOP;
}
return(code);
}
public PrecisePoint Intersects(PreciseRectangle rectangle, double epsilon = 1e-4)
{
if (epsilon <= 0.0d)
{
throw new InvalidOperationException("epsilon cannot be <= 0");
}
PrecisePoint p0 = (PrecisePoint)start.Clone();
PrecisePoint p1 = (PrecisePoint)end.Clone();
CohenSutherlandBitCode outCode0 = ComputeOutCode(rectangle, p0, epsilon);
CohenSutherlandBitCode outCode1 = ComputeOutCode(rectangle, p1, epsilon);
while (true)
{
if (0 == (outCode0 | outCode1))
{
// Both points are inside
return((!p0.Equals(start) || Intersects(p0, epsilon)) ? p0 : null);
}
else if (0 != (outCode0 & outCode1))
{
// Both points are outside and does not intersect
return((!p0.Equals(start) || Intersects(p0, epsilon)) ? p0 : null);
}
else
{
PrecisePoint p = new PrecisePoint();
CohenSutherlandBitCode outCodeOut = (outCode0 != 0) ? outCode0 : outCode1;
if (0 != (outCodeOut & CohenSutherlandBitCode.TOP))
{
p.X = p0.X + (p1.X - p0.X) * (rectangle.Bottom - p0.Y) / (p1.Y - p0.Y);
p.Y = rectangle.Bottom;
}
else if (0 != (outCodeOut & CohenSutherlandBitCode.BOTTOM))
{
p.X = p0.X + (p1.X - p0.X) * (rectangle.Top - p0.Y) / (p1.Y - p0.Y);
p.Y = rectangle.Top;
}
else if (0 != (outCodeOut & CohenSutherlandBitCode.RIGHT))
{
p.Y = p0.Y + (p1.Y - p0.Y) * (rectangle.Right - p0.X) / (p1.X - p0.X);
p.X = rectangle.Right;
}
else if (0 != (outCodeOut & CohenSutherlandBitCode.LEFT))
{
p.Y = p0.Y + (p1.Y - p0.Y) * (rectangle.Left - p0.X) / (p1.X - p0.X);
p.X = rectangle.Left;
}
if (outCodeOut == outCode0)
{
outCode0 = ComputeOutCode(rectangle, p0 = p, epsilon);
}
else
{
outCode1 = ComputeOutCode(rectangle, p1 = p, epsilon);
}
}
}
}
