[Some boundary points return false] contains - Polygon

[hossainruetcse]

Some points on boundary line or on polygon vertices return false in contains- Polygon.
For example ,
polygon- (0,0), (5, 0), (5, 5 ) , (0, 5) returns false for point (0,0)

[Wulfheart]

I'm doubting this is repository is actively monitored by maintainers.

However the following code results in this output:

package main

import (
	"fmt"

	geo "github.com/kellydunn/golang-geo"
)

func main() {
	poly := []*geo.Point{
		geo.NewPoint(0, 0), geo.NewPoint(0, 1), geo.NewPoint(1, 1), geo.NewPoint(1, 0),
	}
	gon := geo.NewPolygon(poly)
	fmt.Println("x:0\ty:0\t", "Expecting: true\t", "Got:", gon.Contains(geo.NewPoint(0, 0)))
	fmt.Println("x:0.5\ty:0\t", "Expecting: true\t", "Got:", gon.Contains(geo.NewPoint(0.5, 0)))
	fmt.Println("x:0.5\ty:0.7\t", "Expecting: true\t", "Got:", gon.Contains(geo.NewPoint(0.5, 0.7)))
	fmt.Println("x:2\ty:8\t", "Expecting: false\t", "Got:", gon.Contains(geo.NewPoint(2, 8)))

}

Output:

x:0     y:0      Expecting: true         Got: false
x:0.5   y:0      Expecting: true         Got: true
x:0.5   y:0.7    Expecting: true         Got: true
x:2     y:8      Expecting: false        Got: false

Does anyone have an idea how this could be fixed? Which algorithm is used? Raycasting or Gauß-Jordan or ...?

I made little repo to just run and go.

[kellydunn]

👋 howdy!

I'm doubting this is repository is actively monitored by maintainers.

yes life keeps me busy and I haven't had time to maintain this as much as I would like, but! I welcome any PRs if you'd like to contribute upstream!

It's been a while since I've looked at the Polygon code, but I believe it's historically used Raycasting: https://github.com/kellydunn/golang-geo/blob/master/polygon.go#L65

[Wulfheart]

I didn't change anything on the raycasting algorithm but #71 should be a viable workaround.