public bool Intersects(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);
return(XMVector3.LessOrEqual(d2, XMVector.Multiply(sphereRadius, sphereRadius)));
}
public ContainmentType Contains(XMVector point)
{
XMVector v_center = this.center;
XMVector v_radius = XMVector.Replicate(this.radius);
XMVector distanceSquared = XMVector3.LengthSquare(point - v_center);
XMVector radiusSquared = XMVector.Multiply(v_radius, v_radius);
return(XMVector3.LessOrEqual(distanceSquared, radiusSquared) ? ContainmentType.Contains : ContainmentType.Disjoint);
}
public static BoundingBox CreateFromSphere(BoundingSphere sh)
{
XMVector sp_Center = sh.Center;
XMVector sh_Radius = XMVector.Replicate(sh.Radius);
XMVector min = XMVector.Subtract(sp_Center, sh_Radius);
XMVector max = XMVector.Add(sp_Center, sh_Radius);
Debug.Assert(XMVector3.LessOrEqual(min, max), "Reviewed");
return(new BoundingBox((min + max) * 0.5f, (max - min) * 0.5f));
}
public static BoundingBox CreateMerged(BoundingBox b1, BoundingBox b2)
{
XMVector b1_Center = b1.center;
XMVector b1_Extents = b1.extents;
XMVector b2_Center = b2.center;
XMVector b2_Extents = b2.extents;
XMVector min = XMVector.Subtract(b1_Center, b1_Extents);
min = XMVector.Min(min, XMVector.Subtract(b2_Center, b2_Extents));
XMVector max = XMVector.Add(b1_Center, b1_Extents);
max = XMVector.Max(max, XMVector.Add(b2_Center, b2_Extents));
Debug.Assert(XMVector3.LessOrEqual(min, max), "Reviewed");
return(new BoundingBox((min + max) * 0.5f, (max - min) * 0.5f));
}
public bool Intersects(BoundingSphere sh)
{
// Load A.
XMVector v_centerA = this.center;
XMVector v_radiusA = XMVector.Replicate(this.radius);
// Load B.
XMVector v_centerB = sh.center;
XMVector v_radiusB = XMVector.Replicate(sh.radius);
// Distance squared between centers.
XMVector delta = v_centerB - v_centerA;
XMVector distanceSquared = XMVector3.LengthSquare(delta);
// Sum of the radii squared.
XMVector radiusSquared = XMVector.Add(v_radiusA, v_radiusB);
radiusSquared = XMVector.Multiply(radiusSquared, radiusSquared);
return(XMVector3.LessOrEqual(distanceSquared, radiusSquared));
}
public static bool Intersects(XMVector origin, XMVector direction, XMVector v0, XMVector v1, XMVector v2, out float uCoordinate, out float vCoordinate, out float distance)
{
Debug.Assert(Internal.XMVector3IsUnit(direction), "Reviewed");
XMVector zero = XMGlobalConstants.Zero;
XMVector e1 = v1 - v0;
XMVector e2 = v2 - v0;
// p = Direction ^ e2;
XMVector p = XMVector3.Cross(direction, e2);
// det = e1 * p;
XMVector det = XMVector3.Dot(e1, p);
XMVector u, v, t;
if (XMVector3.GreaterOrEqual(det, CollisionGlobalConstants.RayEpsilon))
{
// Determinate is positive (front side of the triangle).
XMVector s = origin - v0;
// u = s * p;
u = XMVector3.Dot(s, p);
XMVector noIntersection = XMVector.Less(u, zero);
noIntersection = XMVector.OrInt(noIntersection, XMVector.Greater(u, det));
// q = s ^ e1;
XMVector q = XMVector3.Cross(s, e1);
// v = Direction * q;
v = XMVector3.Dot(direction, q);
noIntersection = XMVector.OrInt(noIntersection, XMVector.Less(v, zero));
noIntersection = XMVector.OrInt(noIntersection, XMVector.Greater(u + v, det));
// t = e2 * q;
t = XMVector3.Dot(e2, q);
noIntersection = XMVector.OrInt(noIntersection, XMVector.Less(t, zero));
if (XMVector4.EqualInt(noIntersection, XMVector.TrueInt))
{
uCoordinate = 0.0f;
vCoordinate = 0.0f;
distance = 0.0f;
return(false);
}
}
else if (XMVector3.LessOrEqual(det, CollisionGlobalConstants.RayNegEpsilon))
{
// Determinate is negative (back side of the triangle).
XMVector s = origin - v0;
// u = s * p;
u = XMVector3.Dot(s, p);
XMVector noIntersection = XMVector.Greater(u, zero);
noIntersection = XMVector.OrInt(noIntersection, XMVector.Less(u, det));
// q = s ^ e1;
XMVector q = XMVector3.Cross(s, e1);
// v = Direction * q;
v = XMVector3.Dot(direction, q);
noIntersection = XMVector.OrInt(noIntersection, XMVector.Greater(v, zero));
noIntersection = XMVector.OrInt(noIntersection, XMVector.Less(u + v, det));
// t = e2 * q;
t = XMVector3.Dot(e2, q);
noIntersection = XMVector.OrInt(noIntersection, XMVector.Greater(t, zero));
if (XMVector4.EqualInt(noIntersection, XMVector.TrueInt))
{
uCoordinate = 0.0f;
vCoordinate = 0.0f;
distance = 0.0f;
return(false);
}
}
else
{
// Parallel ray.
uCoordinate = 0.0f;
vCoordinate = 0.0f;
distance = 0.0f;
return(false);
}
// (u / det) and (v / dev) are the barycentric coordinates of the intersection.
u = XMVector.Divide(u, det);
v = XMVector.Divide(v, det);
t = XMVector.Divide(t, det);
// Store the x-component to *pDist
u.StoreFloat(out uCoordinate);
v.StoreFloat(out vCoordinate);
t.StoreFloat(out distance);
return(true);
}
