Bounding Boxes for Circle and Arcs in 3D
- by David Rutten
Given curves of type Circle and Circular-Arc in 3D space, what is a good way to compute accurate bounding boxes (world axis aligned)?
Edit: found solution for circles, still need help with Arcs.
C# snippet for solving BoundingBoxes for Circles:
public static BoundingBox CircleBBox(Circle circle)
{
Point3d O = circle.Center;
Vector3d N = circle.Normal;
double ax = Angle(N, new Vector3d(1,0,0));
double ay = Angle(N, new Vector3d(0,1,0));
double az = Angle(N, new Vector3d(0,0,1));
Vector3d R = new Vector3d(Math.Sin(ax), Math.Sin(ay), Math.Sin(az));
R *= circle.Radius;
return new BoundingBox(O - R, O + R);
}
private static double Angle(Vector3d A, Vector3d B)
{
double dP = A * B;
if (dP <= -1.0) { return Math.PI; }
if (dP >= +1.0) { return 0.0; }
return Math.Acos(dP);
}
