Point In Polygon Tester
Even-odd ray-casting test of whether a point lies inside a simple polygon given as parallel vertex coordinate lists, with exact boundary detection.
Description
Determine whether a planar point lies inside, outside, or exactly on a polygon boundary.
Point in Polygon Tester determine whether a planar point lies inside, outside, or exactly on a polygon boundary.
Use this for hit testing, simple geofencing on projected coordinates, region classification, and validating interactive geometry.
When to use Point in Polygon Tester
Use this for hit testing, simple geofencing on projected coordinates, region classification, and validating interactive geometry.
How it works
An even-odd horizontal ray test determines interior membership, while a segment collinearity check reports boundary points. Boundary counts as inside.
Interpreting the result
Keep the input units, direction conventions, encoding, and ordering rules visible when reusing the result. Preserve the full returned value for downstream calculations and round only for presentation.
Assumptions and limitations
Vertices must describe a simple polygon in order. Self-intersections, floating-point near-boundary cases, spherical geography, holes, and longitude wraparound need specialized handling.