/// <summary>
/// Tests if a segment intersects a rectangle</summary>
/// <param name="seg">The segment</param>
/// <param name="rect">Rectangle, in Windows coordinates, such that the top y has
/// a lower value than the bottom Y</param>
/// <returns>True iff the segment intersects the rectangle</returns>
public static bool Intersects(Seg2F seg, RectangleF rect)
{
// Quick acceptance
if (rect.Contains(seg.P1) ||
rect.Contains(seg.P2))
{
return(true);
}
// Check if both segment points are on same side of rectangle.
if (seg.P1.X < rect.Left &&
seg.P2.X < rect.Left)
{
return(false);
}
if (seg.P1.Y < rect.Top &&
seg.P2.Y < rect.Top)
{
return(false);
}
if (seg.P1.X > rect.Right &&
seg.P2.X > rect.Right)
{
return(false);
}
if (seg.P1.Y > rect.Bottom &&
seg.P2.Y > rect.Bottom)
{
return(false);
}
// Check if all four rectangle points are on the same side of the line.
Vec2F dir = new Vec2F(seg.P2.X - seg.P1.X, seg.P2.Y - seg.P1.Y);
if (dir.LengthSquared > Seg2F.DegenerateLength * Seg2F.DegenerateLength)
{
Vec2F normal = dir.Perp;
float dot1 = Vec2F.Dot(new Vec2F(rect.Left, rect.Top) - seg.P1, normal);
float dot2 = Vec2F.Dot(new Vec2F(rect.Right, rect.Top) - seg.P1, normal);
if (dot1 * dot2 > 0) // both are < 0 or both are > 0
{
dot2 = Vec2F.Dot(new Vec2F(rect.Left, rect.Bottom) - seg.P1, normal);
if (dot1 * dot2 > 0) // both are < 0 or both are > 0
{
dot2 = Vec2F.Dot(new Vec2F(rect.Right, rect.Bottom) - seg.P1, normal);
if (dot1 * dot2 > 0) // both are < 0 or both are > 0
{
return(false);
}
}
}
}
// Must intersect.
return(true);
}
/// <summary>
/// Returns the angle to the vector v in radians
/// </summary>
/// <param name="v">Vector v</param>
public double AngleToRAD(Vec2F v)
{
Vec2F n1 = new Vec2F(x, y);
Vec2F n2 = new Vec2F(v);
n1.Normalize();
n2.Normalize();
double ndn = n1.Dot(n2);
if (ndn < -1)
{
ndn = -1;
}
if (ndn > 1)
{
ndn = 1;
}
return(Math.Acos(ndn));
}
