public static BoundingSphere CreateFromPoints(XMFloat3[] points)
{
if (points == null)
{
throw new ArgumentNullException("points");
}
if (points.Length == 0)
{
throw new ArgumentOutOfRangeException("points");
}
// Find the points with minimum and maximum x, y, and z
XMVector minX, maxX, minY, maxY, minZ, maxZ;
minX = maxX = minY = maxY = minZ = maxZ = points[0];
for (int i = 1; i < points.Length; i++)
{
XMVector point = points[i];
float px = point.X;
float py = point.Y;
float pz = point.Z;
if (px < minX.X)
{
minX = point;
}
if (px > maxX.X)
{
maxX = point;
}
if (py < minY.Y)
{
minY = point;
}
if (py > maxY.Y)
{
maxY = point;
}
if (pz < minZ.Z)
{
minZ = point;
}
if (pz > maxZ.Z)
{
maxZ = point;
}
}
// Use the min/max pair that are farthest apart to form the initial sphere.
XMVector deltaX = maxX - minX;
XMVector distX = XMVector3.Length(deltaX);
XMVector deltaY = maxY - minY;
XMVector distY = XMVector3.Length(deltaY);
XMVector deltaZ = maxZ - minZ;
XMVector distZ = XMVector3.Length(deltaZ);
XMVector v_center;
XMVector v_radius;
if (XMVector3.Greater(distX, distY))
{
if (XMVector3.Greater(distX, distZ))
{
// Use min/max x.
v_center = XMVector.Lerp(maxX, minX, 0.5f);
v_radius = distX * 0.5f;
}
else
{
// Use min/max z.
v_center = XMVector.Lerp(maxZ, minZ, 0.5f);
v_radius = distZ * 0.5f;
}
}
else
{
//// Y >= X
if (XMVector3.Greater(distY, distZ))
{
// Use min/max y.
v_center = XMVector.Lerp(maxY, minY, 0.5f);
v_radius = distY * 0.5f;
}
else
{
// Use min/max z.
v_center = XMVector.Lerp(maxZ, minZ, 0.5f);
v_radius = distZ * 0.5f;
}
}
// Add any points not inside the sphere.
for (int i = 0; i < points.Length; i++)
{
XMVector point = points[i];
XMVector delta = point - v_center;
XMVector dist = XMVector3.Length(delta);
if (XMVector3.Greater(dist, v_radius))
{
// Adjust sphere to include the new point.
v_radius = (v_radius + dist) * 0.5f;
v_center += (XMVector.Replicate(1.0f) - XMVector.Divide(v_radius, dist)) * delta;
}
}
return(new BoundingSphere(v_center, v_radius.X));
}
