public Ray Transfer(Vector3d objectPos, Vector3d lensPos)
{
Debug.Assert(Math.Abs(lensPos.Z) < epsilon);
if (!IsPointWithinLens(lensPos))
{
return(null);
}
Vector4d transformedPos = Vector4d.Transform(
(new Vector4d(objectPos) + Vector4d.UnitW),
GetTransferMatrix(objectPos.Z));
if (Math.Abs(transformedPos.W) > epsilon)
{
Vector4d.Divide(ref transformedPos, transformedPos.W, out transformedPos);
}
Vector3d outputDirection = transformedPos.Xyz;
if (Math.Abs(transformedPos.W) > epsilon)
{
outputDirection -= lensPos;
}
if (Math.Abs(objectPos.Z) <= FocalLength)
{
// the image of the incoming ray origin was in the same
// half-plane as the origin itself
outputDirection = -outputDirection;
}
return(new Ray(lensPos, outputDirection));
}