Unproject the given window coordinates <code>(winX, winY)</code> by <code>this</code> matrix using the specified viewport.
<p>
This method differs from {@link #unproject(double, double, int[], Vector2d) unproject()}
in that it assumes that <code>this</code> is already the inverse matrix of the original projection matrix.
It exists to avoid recomputing the matrix inverse with every invocation.
@see #unproject(double, double, int[], Vector2d)
@param winX
the x-coordinate in window coordinates (pixels)
@param winY
the y-coordinate in window coordinates (pixels)
@param viewport
the viewport described by <code>[x, y, width, height]</code>
@param dest
will hold the unprojected position
@return dest
Unproject the given window coordinates <code>(winX, winY)</code> by <code>this</code> matrix using the specified viewport. <p> This method differs from {@link #unproject(double, double, int[], Vector2d) unproject()} in that it assumes that <code>this</code> is already the inverse matrix of the original projection matrix. It exists to avoid recomputing the matrix inverse with every invocation.
@see #unproject(double, double, int[], Vector2d)
@param winX the x-coordinate in window coordinates (pixels) @param winY the y-coordinate in window coordinates (pixels) @param viewport the viewport described by <code>[x, y, width, height]</code> @param dest will hold the unprojected position @return dest