| 摘要 |
PROBLEM TO BE SOLVED: To make it possible to naturally plot the side face of a three-dimensional(3D) graphic when arbitrarily deforming or moving that graphic in a 2D plotting environ ment, by generating the graphic by two-point perspective projection with which two attention points are placed on a screen and the projection lines of 3D graphic are centralized upon these points. SOLUTION: In addition to an attention point C1 in one-point perspective projections, an attention point C2 is designated at any arbitrary position. On a y-axial side on a reference plane as a surface, a side A1A2 far from the attention point C2 is defined as a reference side, and the projection lines are drawn from both the ends A1 and A2 of that side to the attention point C2. Respective sides in the y-axial direction are plotted and the intersections of these sides and projection lines drawn from both the ends of reference side to the respective attention points are respectively linked. Thus, the 3D graphic plotted by one-point perspective projections is plotted again into the 3D graphic based on two-point perspective projections. Namely, the 3D graphic is plotted in the 2D graphic plotting environment and when deforming that graphic or moving it to any arbitrary position, the graphic is plotted by two-point perspective projections with two fixed points on the screen as the attention points. |
