On the converse proposition of Desargues with projective geometry

At first,with the theory of projective geometry,by means of projecting straight line onto infinite distance and introducing the projection of two intersecting lines onto two parallel lines as well as arbitrary quadrangle onto parallelogram,the converse proposition of Desargues within the plane area is proved.Then an auxiliary threepoint shape is made up by using the method of projective geometry.Finally the result of testifying the converse proposition of Desargues within the space is obtained.