| 摘要 |
PURPOSE:To calculate very easily the position of a point to be depicted in depicting an optional curve on a picture space by providing a grating point position change means deciding whether or not the value of the grating point is changed. CONSTITUTION:When the most significant bit of a residual register 72 goes to ''1'' as the result of addition of an increment DELTAx of a coordinate xn to a residual difference Rx, it means that a change takes place to a grating point in x direction. When the most significant bit of an increment register 71 is ''0'' in this case, since one grating point is moved positively, an adder circuit 76 increments the grating point xn transmitted from a grating point pointer 75 by 1 to store a new grating point (Xn+1) to the grating point pointer 75. On the other hand, when the most significant bit of the increment register 71 goes to ''1'', since it means that the grating point is moved negatively, a subtraction circuit 77 subtracts one from the grating point Xn transmitted from the grating pointer 75 to store a new grating point (Xn-1) to the grating point pointer 75. |
