Sutherland–Hodgman algorithm: Difference between revisions

Revision as of 07:55, 16 January 2017

Revision as of 05:39, 30 March 2017

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This process is repeated iteratively for each clip polygon side, using the output list from one stage as the input list for the next. Once all sides of the clip polygon have been processed, the final generated list of vertices defines a new single polygon that is entirely visible. Note that if the subject polygon was [[concave polygon|concave]] at vertices outside the clipping polygon, the new polygon may have coincident (i.e. overlapping) edges – this is acceptable for rendering, but not for other applications such as computing shadows.

[[image:Sutherland-Hodgman clipping sample.svg|center|frame|All steps offor clipping concave polygon 'W' bywith a 5-sided convex polygon]]

The [[Weiler–Atherton]] algorithm overcomes this by returning a set of divided polygons, but is more complex and computationally more expensive, so Sutherland–Hodgman is used for many rendering applications. Sutherland–Hodgman can also be extended into 3D space by clipping the polygon paths based on the boundaries of planes defined by the viewing space.