Expand fill of convex polygon - Unity (C#)

ExpandConvexHull.cs

// this is an adaptation to Unity of the algorithm described 
//. in https://stackoverflow.com/questions/3749678/expand-fill-of-convex-polygon/3897471
using UnityEngine;
using System.Linq;
using System.Collections.Generic;

static class ConvexHull
{
    public static Vector2[] ExpandConvexHull(Vector2[] poly, float distance)
    {
        var expanded = new List<Vector2>();
        var isCw = PolyIsCw(poly);

        for (var i = 0; i < poly.Length; ++i)
        {
            // get this point (pt1), the point before it
            // (pt0) and the point that follows it (pt2)
            var pt0 = poly[(i > 0) ? i - 1 : poly.Length - 1];
            var pt1 = poly[i];
            var pt2 = poly[(i < poly.Length - 1) ? i + 1 : 0];

            // find the line vectors of the lines going
            // into the current point
            var v01 = pt1 - pt0;
            var v12 = pt2 - pt1;

            // find the normals of the two lines, multiplied
            // to the distance that polygon should inflate
            var rot01 = isCw ? Rot90CCW(v01) : Rot90CW(v01);
            var rot12 = isCw ? Rot90CCW(v12) : Rot90CW(v12);
            var d01 = rot01.normalized * distance;
            var d12 = rot12.normalized * distance;

            // use the normals to find two points on the
            // lines parallel to the polygon lines
            var ptx0 = pt0 + d01;
            var ptx10 = pt1 + d01;
            var ptx12 = pt1 + d12;
            var ptx2 = pt2 + d12;

            // find the intersection of the two lines, and
            // add it to the expanded polygon
            expanded.Add(Intersect(ptx0, ptx10, ptx12, ptx2));
        }
        return expanded.ToArray();
    }
    private static Vector2 Intersect(Vector2 line1A, Vector2 line1B, Vector2 line2A, Vector2 line2B)
    {
        var a1 = line1B.x - line1A.x;
        var b1 = line2A.x - line2B.x;
        var c1 = line2A.x - line1A.x;

        var a2 = line1B.y - line1A.y;
        var b2 = line2A.y - line2B.y;
        var c2 = line2A.y - line1A.y;

        var t = (b1 * c2 - b2 * c1) / (a2 * b1 - a1 * b2);

        return new Vector2(
            x: line1A.x + t * (line1B.x - line1A.x),
            y: line1A.y + t * (line1B.y - line1A.y)
        );
    }

    private static Vector2 Rot90CW(Vector2 v)
    {
        return new Vector2(x: v.y, y: -v.x);
    }

    private static Vector2 Rot90CCW(Vector2 v)
    {
        return new Vector2(x: -v.y, y: v.x);
    }

    private static bool PolyIsCw(Vector2[] p)
    {
        return Vector2.Dot(
            Rot90CW(p[1] - p[0]),
            p[2] - p[1]
        ) >= 0;
    }
}