void GetSamplingOrigin(ref BoundingBox entityBoundingBox, out Vector3 xSpacing, out Vector3 zSpacing, out float perColumnArea, out Vector3 origin)
{
//Compute spacing and increment informaiton.
float widthIncrement = (entityBoundingBox.Max.X - entityBoundingBox.Min.X) / samplePointsPerDimension;
float lengthIncrement = (entityBoundingBox.Max.Z - entityBoundingBox.Min.Z) / samplePointsPerDimension;
xSpacing = new Vector3(widthIncrement, 0, 0);
zSpacing = new Vector3(0, 0, lengthIncrement);
Vector3.Transform(ref xSpacing, ref surfaceTransform.Orientation, out xSpacing);
Vector3.Transform(ref zSpacing, ref surfaceTransform.Orientation, out zSpacing);
perColumnArea = widthIncrement * lengthIncrement;
//Compute the origin.
Vector3 minimum;
RigidTransform.Transform(ref entityBoundingBox.Min, ref surfaceTransform, out minimum);
//Matrix3X3.TransformTranspose(ref entityBoundingBox.Min, ref surfaceOrientationTranspose, out minimum);
Vector3 offset;
Vector3.Multiply(ref xSpacing, .5f, out offset);
Vector3.Add(ref minimum, ref offset, out origin);
Vector3.Multiply(ref zSpacing, .5f, out offset);
Vector3.Add(ref origin, ref offset, out origin);
//TODO: Could adjust the grid origin such that a ray always hits the deepest point.
//The below code is a prototype of the idea, but has bugs.
//var convexInfo = collidable as ConvexCollisionInformation;
//if (convexInfo != null)
//{
// Vector3 dir;
// Vector3.Negate(ref upVector, out dir);
// Vector3 extremePoint;
// convexInfo.Shape.GetExtremePoint(dir, ref convexInfo.worldTransform, out extremePoint);
// //Use extreme point to snap to grid.
// Vector3.Subtract(ref extremePoint, ref origin, out offset);
// float offsetX, offsetZ;
// Vector3.Dot(ref offset, ref right, out offsetX);
// Vector3.Dot(ref offset, ref backward, out offsetZ);
// offsetX %= widthIncrement;
// offsetZ %= lengthIncrement;
// if (offsetX > .5f * widthIncrement)
// {
// Vector3.Multiply(ref right, 1 - offsetX, out offset);
// }
// else
// {
// Vector3.Multiply(ref right, -offsetX, out offset);
// }
// if (offsetZ > .5f * lengthIncrement)
// {
// Vector3 temp;
// Vector3.Multiply(ref right, 1 - offsetZ, out temp);
// Vector3.Add(ref temp, ref offset, out offset);
// }
// else
// {
// Vector3 temp;
// Vector3.Multiply(ref right, -offsetZ, out temp);
// Vector3.Add(ref temp, ref offset, out offset);
// }
// Vector3.Add(ref origin, ref offset, out origin);
//}
}
