/// <summary>
/// Projects a point onto a circle</summary>
/// <param name="p">Point to project</param>
/// <param name="c">Circle to project onto</param>
/// <param name="projection">Projected point</param>
/// <returns>True iff projection is well defined</returns>
public static bool Project(Vec2F p, CircleF c, ref Vec2F projection)
{
Vec2F d = Vec2F.Sub(p, c.Center);
float length = d.Length;
bool wellDefined = false;
if (length > 0.000001f * c.Radius)
{
wellDefined = true;
float scale = c.Radius / length;
projection = Vec2F.Add(c.Center, Vec2F.Mul(d, scale));
}
return(wellDefined);
}
/// <summary>
/// Constructs the circle containing 3 points</summary>
/// <param name="p1">Point 1</param>
/// <param name="p2">Point 2</param>
/// <param name="p3">Point 3</param>
public CircleF(Vec2F p1, Vec2F p2, Vec2F p3)
{
Vec2F o1 = Vec2F.Add(p1, p2); o1 *= 0.5f;
Vec2F o2 = Vec2F.Add(p3, p2); o2 *= 0.5f;
Vec2F d1 = Vec2F.Sub(p2, p1); d1 = d1.Perp;
Vec2F d2 = Vec2F.Sub(p3, p2); d2 = d2.Perp;
double t1 = 0;
double t2 = 0;
if (Ray2F.Intersect(new Ray2F(o1, d1), new Ray2F(o2, d2), ref t1, ref t2))
{
Center = o1 + d1 * (float)t1;
Radius = Vec2F.Distance(Center, p1);
}
else
{
Center = new Vec2F(float.PositiveInfinity, float.PositiveInfinity);
Radius = float.PositiveInfinity;
}
}