| 摘要 |
PROBLEM TO BE SOLVED: To easily display a spot light source expressed with a polygonal cone in three-dimensional computer graphics. SOLUTION: A spot based on the spot light source is expressed as a polygonal cone (such as rectangular cone, for example,) and clipped by the polygonal cone, the inside of that polygonal cone is extracted and the inside part lighted by the spot light source is plotted bright. Besides, the part, which is not lighted by the spot light source, (the outside of the spot) is segmented and that part of plotted dark. The outside of this spot can be segmented while using clipping processing as well. Thus, since inside and outside spaces defined by the spot are respectively plotted bright or dark, the part lighted by the spot light can be plotted bright and the other part can be plotted dark as a result. |
