| 摘要 |
PURPOSE:To plot the thick line of a correct circular arc at high speed by dividing the circular arc into closed area parts capable of being represented by two straight lines and two monotonously decreasing curves, and painting out every closed area part by one line unit successively from an upper part to a lower part. CONSTITUTION:In the processing of a first partial arc ABCD, since the point of the maximum Y-coordinate is A, digital differentiation (DDA) generation is executed by making the circular arc AB a left-hand side and a segment AD a right-hand side. The initial value of Y is Y-coordinate of A. An interval between the point x1 on the circular arc of the left-hand side and the point x2 on the segment of the right-hand side is plotted in a horizontal line. This operation is continued until Y-coordinate generated by this DDA generation becomes the value of the point of the larger Y- coordinate between the point B and D. After the processing up to the point D is finished by the DDA generation, the DDA generation of the right-hand side is changed to the circular arc DC. After the DDA generation is executed up to the point B similarly to the above-mentioned operation, this time, the DDA generation of the left-hand side is changed to the segment BC. As for the partial arc ADFH and the partial arc EFHG too, plotting in the partial arc can be executed through the similar operation. |
