| 摘要 |
<p>A method for clip checking three dimensional images for display on a computer display system. The display system includes a computer having a central processing unit(CPU) coupled to a memory and a cathode ray tube (CRT) display. The method of the present invention includes inputting a plurality of points comprising an image to be displayed, wherein each of the points is described by X,Y,Z and W world coordinates. The points are stored in the memory coupled to the CPU. The CPU executes a viewing algorithm which transforms the world coordinates for each point into view reference coordinates. The view reference coordinates have an origin at the viewpoint of the user, with the Z axis pointed outward in the direction of the display screen. Each of the points of the image are described by clipping bits X Right, X Left, Y Top, Y Bottom, Z Back, and Z Front. The view reference coordinate system permits the user to selectively enable/disable clipping quadrants in X,Y,Z and W space. The present invention determines the value of the clipping bits for all of the points (vertices) comprising the image. Using predefined combinational logic, the clipping bits are evaluated and the logic determines if the image is visible, hidden, or if it intersects at least one clipping plane. The method provides an efficient means for determining if a three dimensional image is to be displayed on a computer display system.</p> |
