koobas.hobune.stream
Get / Calculate edges of a 3D object - C #
I need to get all vertices in the edge position of a determinate object 3D (in this case a path).
See the image: 
My question is, how can I get only the edges vertices, like the image?
You can use a convex-hull-algorithm to find the outer edge of a point set. There are a few to pick from, but here's an example of Jarvis march:
using System.Collections;
using System.Collections.Generic;
using System.Linq;
using UnityEngine;
public class FindConvexHull : MonoBehaviour
{
public List<Vector2> points;
public float gizmoSize = 0.1f;
private void OnDrawGizmos()
{
Gizmos.color = Color.white;
foreach(var point in points)
Gizmos.DrawSphere(point, gizmoSize);
var hull = ConvexHull(points);
if(hull != null)
{
Gizmos.color = Color.green;
for (int i = 0; i < hull.Count - 1; i++)
{
Gizmos.DrawLine(hull[i], hull[i+1]);
}
Gizmos.DrawLine(hull[0], hull[hull.Count - 1]);
}
}
private List<Vector2> ConvexHull(List<Vector2> points)
{
List<Vector2> hull = new List<Vector2>();
if(points.Count < 3)
return hull;
int leftMost = 0;
for (int i = 0; i < points.Count; i++)
{
if(points[i].x < points[leftMost].x)
leftMost = i;
}
int pointA = leftMost;
int pointB;
do
{
hull.Add(points[pointA]);
pointB = (pointA + 1) % points.Count;
for (int i = 0; i < points.Count; i++)
{
if(GetTurn(points[pointA], points[i], points[pointB]) == 2)
pointB = i;
}
pointA = pointB;
}
while (pointA != leftMost);
return hull;
}
private float GetTurn(Vector2 a, Vector2 b, Vector2 c)
{
var val = (b.y - a.y) * (c.x - b.x) - (b.x - a.x) * (c.y - b.y);
if (val == 0)
return 0;
if (val > 0)
return 1;
else
return 2;
}
}
