public override void UpdateBoundingBox()
{
Shape.GetBoundingBox(ref worldTransform, out boundingBox);
//Include the thickness of the terrain.
Vector3 thicknessOffset = Vector3.Normalize(worldTransform.LinearTransform.Down) * thickness;
if (thicknessOffset.X < 0)
boundingBox.Min.X += thicknessOffset.X;
else
boundingBox.Max.X += thicknessOffset.X;
if (thicknessOffset.Y < 0)
boundingBox.Min.Y += thicknessOffset.Y;
else
boundingBox.Max.Y += thicknessOffset.Y;
if (thicknessOffset.Z < 0)
boundingBox.Min.Z += thicknessOffset.Z;
else
boundingBox.Max.Z += thicknessOffset.Z;
}