Abstract: Correlation of two-dimensional displayed points of an axonometric projection with corresponding three-dimensional points of the projected shapes. A point on a display screen surface is selected and the screen coordinates of the points of the three-dimensional shape are found by converting successive points of the shape to two-dimensional screen equivalents. Comparing the converted coordinates to those of the selected point identifies the shape point corresponding to the selected shape.

Abstract: Macroinstructions for computer-aided design systems can be designed by the user without special language or syntax using the systems' menu-driven instruction set. Macroinstructions can be nested. The designer constructs patterns and the steps are recorded. Parameters can be selectively included in the macroinstructions or can be supplied at the time the macroinstructions are played. The designer can also create geometrics by storing a routine that will automatically draw dependent figures by supplying the dependent parameters to maintain given relationships between the dependent and independent figures according to the parameters supplied for the independent figure.