| 摘要 |
PURPOSE:To obtain efficiently on-points with respect to a curve constituted of two-dimensional basis splines by dividing two-dimensional basis splines in a protrusive polygon having hit points in its interior into kinked lines and by obtaining the kinked line nearest to the hit point. CONSTITUTION:A coordinate series of apexes of a figure, for instance, a maximum protrusive polygon consisting of Pi, Pi+1, Pi+2 and Pi+3 is decided. In this case the maximum protrusive polygon turns out to be triangles Pi, Pi+1 and Pi+3. Base areas Q1, Q2, Q3 and Q4 are added to respective sides of the protrusive polygon. Whether or not a hit point H exists in the protrusive polygon area and the band areas Q1, Q2, Q3 and Q4 is investigated. Apex coordinates and the number where the hit point considerably exists are stored. Kinked line coordinates with respect to the stored number can be obtained. The coordinates nearest to the hit point with respect to the kinked line can be obtained. The on-calculation is carried out by an on-point calculating means existing in a figure editing part in terms of CAD system 1. |
