如何查找点位于线或面内

Question

I found a point is located inside a Circle using following method.

• Distance between a point and circle center <= circle radius means the point is inside circle.

But I need to find

• The point is located in a line
• The point is located in a polygon

Normally polyline has array of coordinates,if i check with all points in-between points will miss while calculating.

Update:

I used github.com/sromku/polygon-contains-point to find the point is located in a polygon. But it is 2D normal plane. But I need to find a point inside a Polygon calculation on spheroid.How to do this?

Answer 1

q2: search for "point in polygon strategies", from graphic gems.
Point in Polygon also works if the coordinates are longitude (x), latitude (y). At least the algo that count for line crossings, which mostly are the one implemented. Of course if the polygn crosses the datum limit (by ship or plane) or is located at the polar region, then this does not work with the simple apporach.

q1: point line: in school you learned that (abs(normal distance to line) < epsilon) but what you need is distance to line segment . (not line which has infinity length).

For this task you have to transfrom to cartestioan coordinates first.