Multistage clipping method
First Claim
1. A method for performing clipping in a graphic workstation by a multistage technique, wherein said method operates on geometric data in said workstation, said data having size characteristics, said method comprising the steps of:
- establishing a first clipping region larger than a desired field of view;
defining a virtual viewport which is a mapping transformation of said first clipping region, said virtual viewport being defined for accurately clipping geometric primitives; and
selecting said first clipping region based on said size characteristics of the data being processed.
0 Assignments
0 Petitions
Accused Products
Abstract
A method for clipping two and three dimensional graphic primitives for use in a computer graphics workstation. During the first clipping stage, the system removes all graphic primitives which lie outside an arbitrary clipping volume or window that is an enlargement of the desired viewing volume or window. This clipping volume (window) is then projected and mapped onto a virtual viewport which is larger than the real viewport. After this mapping occurs, rendering effects (such as line styles, line width, pattern fill, hatch fill, etc.) are applied to the primitive. A subsequent stage of clipping is then applied to clip the virtual viewport to the real viewport which is the user'"'"'s visible area. Use of the clipping volume (window) during the first stage of clipping makes it simpler to transform geometric primitives which are partially visible to the viewer, and gives visible primitives a richer set of invariant geometric properties so that their rendering effects may be more easily and correctly carried out.
-
Citations
15 Claims
-
1. A method for performing clipping in a graphic workstation by a multistage technique, wherein said method operates on geometric data in said workstation, said data having size characteristics, said method comprising the steps of:
-
establishing a first clipping region larger than a desired field of view; defining a virtual viewport which is a mapping transformation of said first clipping region, said virtual viewport being defined for accurately clipping geometric primitives; and selecting said first clipping region based on said size characteristics of the data being processed. - View Dependent Claims (2, 3, 4)
-
-
5. A method for generating pixel data for image display in a graphic display system including the steps of:
-
generating geometric data in a world coordinate space; selecting a data subset containing geometric data to be displayed, whereby that part of the data outside a first clipping region is eliminated; mapping said selected data subset to a virtual viewport; eliminating that part of the virtual viewport outside a real viewport; and generating pixel data for the image to be displayed. - View Dependent Claims (6, 7, 8, 9)
-
-
10. A method for generating data for image display from a graphics primitive in a graphics display system, comprising the steps of:
-
transforming said graphics primitive from a first to a second coordinate space; clipping said transformed graphics primitive against a first clipping region; mapping said clipped graphics primitive from said first clipping region to a virtual viewport; generating pixels from said mapped graphics primitive; and clipping those pixels generated from said mapped graphics primitive that are outside a real viewport. - View Dependent Claims (11, 12, 13, 14, 15)
-
Specification