public ContainmentType Contains(BoundingSphere sh)
{
XMVector sphereCenter = sh.Center;
XMVector sphereRadius = XMVector.Replicate(sh.Radius);
XMVector boxCenter = this.center;
XMVector boxExtents = this.extents;
XMVector boxMin = boxCenter - boxExtents;
XMVector boxMax = boxCenter + boxExtents;
//// Find the distance to the nearest point on the box.
//// for each i in (x, y, z)
//// if (SphereCenter(i) < BoxMin(i)) d2 += (SphereCenter(i) - BoxMin(i)) ^ 2
//// else if (SphereCenter(i) > BoxMax(i)) d2 += (SphereCenter(i) - BoxMax(i)) ^ 2
XMVector d = XMGlobalConstants.Zero;
// Compute d for each dimension.
XMVector lessThanMin = XMVector.Less(sphereCenter, boxMin);
XMVector greaterThanMax = XMVector.Greater(sphereCenter, boxMax);
XMVector minDelta = sphereCenter - boxMin;
XMVector maxDelta = sphereCenter - boxMax;
// Choose value for each dimension based on the comparison.
d = XMVector.Select(d, minDelta, lessThanMin);
d = XMVector.Select(d, maxDelta, greaterThanMax);
// Use a dot-product to square them and sum them together.
XMVector d2 = XMVector3.Dot(d, d);
if (XMVector3.Greater(d2, XMVector.Multiply(sphereRadius, sphereRadius)))
{
return(ContainmentType.Disjoint);
}
XMVector insideAll = XMVector.LessOrEqual(boxMin + sphereRadius, sphereCenter);
insideAll = XMVector.AndInt(insideAll, XMVector.LessOrEqual(sphereCenter, boxMax - sphereRadius));
insideAll = XMVector.AndInt(insideAll, XMVector.Greater(boxMax - boxMin, sphereRadius));
return(XMVector3.EqualInt(insideAll, XMVector.TrueInt) ? ContainmentType.Contains : ContainmentType.Intersects);
}
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));
}
