一种快速球面窗口三维线的裁剪算法

提出一种快速的球面窗口三维线裁剪方法：排除两端点都在任意坐标半轴方向球切面之外或任意45＆#176;方向球切面之外的线段,并确定至少一端点在球面内的线段与球面窗口的相交关系.对于其它两端点都在球面窗口之外的线段,过球心作决策平面,并相交球面形成决策圆.通过判断线段两端点在决策平面的同侧还是异侧,以及线段与决策平面的交点相对于决策圆的位置关系确定线段是否与球面窗口相交.该方法可以快速排除大部分不与球面窗口相交的线段,加快求交进程,显著提高裁剪效率.

A Fast 3D Line Clipping Algorithm Against Spherical Window

A fast method for three-dimensional line clipping against spherical surface window is presented. The line segment is eliminated when both endpoints are outside the tangent plane of a sphere which normal vector is coordinate axis direction or 45°direction, and the intersection of line segment that at least one end- point is inside spherical window is determined. To other line segments that both endpoints are outside spherical window, the decision circle is formed when sphere intersects with decision plane passing the center. The inter- section is determined by identifying the position of two endpoints relative to the decision plane and the position of the intersection point relative to the decision circle. The new algorithm can quickly discard most of the line segments that are completely outside spherical window, quickly calculate the intersections and improve the clipping efficiency.