Function S2Polygon.isNormalized

Return true if every loop of this polygon shares at most one vertex with its parent loop. Every polygon has a unique normalized form. A polygon can be normalized by passing it through S2Builder (with no snapping) in order to reconstruct the polygon from its edges.


					
			bool isNormalized() const;

Generally there is no reason to convert polygons to normalized form. It is mainly useful for testing in order to compare whether two polygons have exactly the same interior, even when they have a different loop structure. For example, a diamond nested within a square (touching at four points) could be represented as a square with a diamond-shaped hole, or as four triangles. Methods such as BoundaryApproxEquals() will report these polygons as being different (because they have different boundaries) even though they contain the same points. However if they are both converted to normalized form (the "four triangles" version) then they can be compared more easily.

Also see ApproxEquals(), which can determine whether two polygons contain approximately the same set of points without any need for normalization.

Authors

ericv@google.com (Eric Veach), madric@gmail.com (Vijay Nayar)

License

Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS-IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.

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