reentrant polygon
Học thuậtThân thiện
Definition
Noun: A reentrant polygon is a polygon that has at least one interior angle greater than 180 degrees. This causes the polygon's boundary to "cave inwards" or form a concavity at that vertex. It is also commonly called a concave polygon.
Usage
The term is used in geometry, computer graphics, and computational geometry to describe and classify shapes based on their angles and the nature of their boundaries. * Identifying a reentrant polygon is crucial for certain rendering algorithms in computer graphics. * The star shape is a classic example of a reentrant polygon.
Advanced Usage
- Reentrant Angle: The specific interior angle within the polygon that is greater than 180 degrees, creating the indentation.
- The algorithm checks for the presence of any reentrant angle to classify the polygon.
Variants and Related Words
- Concave Polygon: The more common synonym for a reentrant polygon.
- Reentrant: (Adjective) Describing the angle or the polygon itself.
- Simple Polygon: A polygon whose sides do not intersect. Both convex and reentrant polygons can be simple polygons.
- Complex Polygon: A polygon whose sides intersect, which is a different concept from a reentrant polygon.
Synonyms
- Concave polygon
- Non-convex polygon (in a broad sense)
Antonyms
- Convex polygon (a polygon where all interior angles are less than or equal to 180 degrees)
Noun
- a polygon with one or more reentrant angles