CALCULATING SYSTEM FOR INTERNAL POINT OF ARBITRARY POLYGON

摘要

PURPOSE:To derive an internal point of an arbitrary polygon by calculating an address to be read out from a refresh memory, from each apex of a polygon by a CPU, reading out a data by a graph display part, and calculating the internal point. CONSTITUTION:A graph display control part 4 draws a contour of a polygon by a line kind designated to designated color memories R, G and B 5, by an instruction from a CPU 2. Subsequently, on a memory W 8, a copy of a contour of the polygon is drawn by a full line. The CPU 2 derives a Y coordinate of one or plural lines being unequal to any apex, from a range of the minimum and maximum values in the Y direction of each apex of the polygon. Subsequently, the total number of straight lines in which the (y) coordinate crosses a straight line for constituting analogously the polygon is derived. Next, the maximum and minimum values in the X direction of each apex are derived, and in its range, a data on the corresponding memory W 8 is read out in accordance with the (y) coordinate, and the total number which becomes '0' '1' is derived. Subsequently, that which is equal in the total number of straight lines for crossing the straight line of the previous polygon constitution, and the total number which becomes '0' '1' on the memory W 8 is derived, and an address which becomes '0' z '1' first, and becomes '1' '0' subsequently becomes an internal point.