public bool Intersects(XMVector origin, XMVector direction, out float distance)
{
Debug.Assert(Internal.XMVector3IsUnit(direction), "Reviewed");
// Load the box.
XMVector v_center = this.center;
XMVector v_extents = this.extents;
// Adjust ray origin to be relative to center of the box.
XMVector t_origin = v_center - origin;
// Compute the dot product againt each axis of the box.
// Since the axii are (1,0,0), (0,1,0), (0,0,1) no computation is necessary.
XMVector axisDotOrigin = t_origin;
XMVector axisDotDirection = direction;
// if (fabs(AxisDotDirection) <= Epsilon) the ray is nearly parallel to the slab.
XMVector isParallel = XMVector.LessOrEqual(axisDotDirection.Abs(), CollisionGlobalConstants.RayEpsilon);
// Test against all three axii simultaneously.
XMVector inverseAxisDotDirection = axisDotDirection.Reciprocal();
XMVector t1 = (axisDotOrigin - v_extents) * inverseAxisDotDirection;
XMVector t2 = (axisDotOrigin + v_extents) * inverseAxisDotDirection;
// Compute the max of min(t1,t2) and the min of max(t1,t2) ensuring we don't
// use the results from any directions parallel to the slab.
XMVector t_min = XMVector.Select(XMVector.Min(t1, t2), CollisionGlobalConstants.FltMin, isParallel);
XMVector t_max = XMVector.Select(XMVector.Max(t1, t2), CollisionGlobalConstants.FltMax, isParallel);
// t_min.x = maximum( t_min.x, t_min.y, t_min.z );
// t_max.x = minimum( t_max.x, t_max.y, t_max.z );
t_min = XMVector.Max(t_min, XMVector.SplatY(t_min)); // x = max(x,y)
t_min = XMVector.Max(t_min, XMVector.SplatZ(t_min)); // x = max(max(x,y),z)
t_max = XMVector.Min(t_max, XMVector.SplatY(t_max)); // x = min(x,y)
t_max = XMVector.Min(t_max, XMVector.SplatZ(t_max)); // x = min(min(x,y),z)
// if ( t_min > t_max ) return false;
XMVector noIntersection = XMVector.Greater(XMVector.SplatX(t_min), XMVector.SplatX(t_max));
// if ( t_max < 0.0f ) return false;
noIntersection = XMVector.OrInt(noIntersection, XMVector.Less(XMVector.SplatX(t_max), XMGlobalConstants.Zero));
// if (IsParallel && (-Extents > AxisDotOrigin || Extents < AxisDotOrigin)) return false;
XMVector parallelOverlap = axisDotOrigin.InBounds(v_extents);
noIntersection = XMVector.OrInt(noIntersection, XMVector.AndComplementInt(isParallel, parallelOverlap));
if (!Internal.XMVector3AnyTrue(noIntersection))
{
// Store the x-component to *pDist
t_min.StoreFloat(out distance);
return(true);
}
distance = 0.0f;
return(false);
}
public bool Intersects(XMVector v0, XMVector v1, XMVector v2)
{
// Load the sphere.
XMVector v_center = this.center;
XMVector v_radius = XMVector.Replicate(this.radius);
// Compute the plane of the triangle (has to be normalized).
XMVector n = XMVector3.Normalize(XMVector3.Cross(v1 - v0, v2 - v0));
// Assert that the triangle is not degenerate.
Debug.Assert(!XMVector3.Equal(n, XMGlobalConstants.Zero), "Reviewed");
// Find the nearest feature on the triangle to the sphere.
XMVector dist = XMVector3.Dot(v_center - v0, n);
// If the center of the sphere is farther from the plane of the triangle than
// the radius of the sphere, then there cannot be an intersection.
XMVector noIntersection = XMVector.Less(dist, -v_radius);
noIntersection = XMVector.OrInt(noIntersection, XMVector.Greater(dist, v_radius));
// Project the center of the sphere onto the plane of the triangle.
XMVector point = v_center - (n * dist);
// Is it inside all the edges? If so we intersect because the distance
// to the plane is less than the radius.
XMVector intersection = Internal.PointOnPlaneInsideTriangle(point, v0, v1, v2);
// Find the nearest point on each edge.
XMVector radiusSq = v_radius * v_radius;
// Edge 0,1
point = Internal.PointOnLineSegmentNearestPoint(v0, v1, v_center);
// If the distance to the center of the sphere to the point is less than
// the radius of the sphere then it must intersect.
intersection = XMVector.OrInt(intersection, XMVector.LessOrEqual(XMVector3.LengthSquare(v_center - point), radiusSq));
// Edge 1,2
point = Internal.PointOnLineSegmentNearestPoint(v1, v2, v_center);
// If the distance to the center of the sphere to the point is less than
// the radius of the sphere then it must intersect.
intersection = XMVector.OrInt(intersection, XMVector.LessOrEqual(XMVector3.LengthSquare(v_center - point), radiusSq));
// Edge 2,0
point = Internal.PointOnLineSegmentNearestPoint(v2, v0, v_center);
// If the distance to the center of the sphere to the point is less than
// the radius of the sphere then it must intersect.
intersection = XMVector.OrInt(intersection, XMVector.LessOrEqual(XMVector3.LengthSquare(v_center - point), radiusSq));
return(XMVector4.EqualInt(XMVector.AndComplementInt(intersection, noIntersection), XMVector.TrueInt));
}
