| 摘要 |
PURPOSE:To generate the graphic of truncated pyramid, which is represented with two-dimensional information, through easy operation at low calculation cost, and to displays the figure so that its hidden surfaces are erased. CONSTITUTION:The position of a virtual tip point T when the figure of a frustum of pyramid is assumed from the graphic of the truncated pyramid represented with the two-dimensional coordinate information is found, distances L1, L2,... in two dimensions from the respective sides E1, E2,... on the top surface side of the graphic of the truncated pyramid to the virtual tip point T are found and compared with each other to find the far-near order of the respective sides from the virtual tip point T, and the flanks are selected so that the flanks which are closer to the virtual tip point T are displayed earlier to temporarily determine the display order; and it is discriminated whether or not the selected flank overlaps with an unselected flank and there is a flank closer to the virtual point T within the overlap range than the selected surface and when there is the flank, the display order is changed so that the selected flank is displayed later to determine the final display order, thereby displaying the figure according to the display order. |
