| 摘要 |
PURPOSE:To speedily and easily display cross sections based on a variety of cut faces by deciding which is larger, a value Z at the point of a calculated cut face and a value Z at the point of a drawn cut face and deciding whether or not the cut face is drawn on a pixel basis. CONSTITUTION:A straight line interpolator obtains data on facing ridgelines of a figure to be drawn, and simultaneously obtains the value Z of each cut face. Based on the data on a pair of ridgelines and a pair of values Z of each cut face, line segment drawing circuits obtain data on drawn line segments. The data on the drawn line segments obtained from the line segment drawing circuits 113, 123-1n3 and the data on drawn line segments obtained from the line segment drawing circuit 113 are supplied to a comparator, which supplies a signal showing whether or not two types of data meet cutting conditions to an XNOR gate. It supplies a flag 1 to an AND gate only it they meet the conditions. Only if the flag 1 is outputted from the AND gate, picture elements based on coordinate data outputted from the line segment drawing circuits are displayed. |
