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Jarvis march convex hull unity c# script
/*Please do support www.bitshiftprogrammer.com by joining the facebook page : fb.com/BitshiftProgrammer
Legal Stuff:
This code is free to use no restrictions but attribution would be appreciated.
Any damage caused either partly or completly due to usage of this stuff is not my responsibility*/
using System.Collections;
using System.Collections.Generic;
using UnityEngine;
public class JarvisMarchConvexHull : MonoBehaviour
{
public Transform[] points;
[Range(0.05f,1.5f)]
public float size;
public bool drawIt;
private HashSet<Transform> result;
void Start()
{
result = new HashSet<Transform>();
}
void Update()
{
result = new HashSet<Transform>();
int leftMostIndex = 0;
for (int i = 1; i < points.Length; i++)
{
if (points[leftMostIndex].position.x > points[i].position.x)
leftMostIndex = i;
}
result.Add(points[leftMostIndex]);
List<Transform> collinearPoints = new List<Transform>();
Transform current = points[leftMostIndex];
while (true)
{
Transform nextTarget = points[0];
for (int i = 1; i < points.Length; i++)
{
if (points[i] == current)
continue;
float x1, x2, y1, y2;
x1 = current.position.x - nextTarget.position.x;
x2 = current.position.x - points[i].position.x;
y1 = current.position.y - nextTarget.position.y;
y2 = current.position.y - points[i].position.y;
float val = (y2 * x1) - (y1 * x2);
if (val > 0)
{
nextTarget = points[i];
collinearPoints = new List<Transform>();
}
else if (val == 0)
{
if (Vector2.Distance(current.position, nextTarget.position) < Vector2.Distance(current.position, points[i].position))
{
collinearPoints.Add(nextTarget);
nextTarget = points[i];
}
else
collinearPoints.Add(points[i]);
}
}
foreach (Transform t in collinearPoints)
result.Add(t);
if (nextTarget == points[leftMostIndex])
break;
result.Add(nextTarget);
current = nextTarget;
}
}
void OnDrawGizmos()
{
if (drawIt)
{
if (result != null)
{
List<Transform> outter = new List<Transform>();
foreach (var item in result)
outter.Add(item);
for (int i = 0; i < outter.Count - 1; i++)
Gizmos.DrawLine(outter[i].position, outter[i + 1].position);
Gizmos.DrawLine(outter[0].position, outter[outter.Count - 1].position);
}
for (int i = 0; i < points.Length; i++)
{
Gizmos.color = Color.cyan;
if (result != null)
{
if (result.Contains(points[i]))
Gizmos.color = Color.yellow;
}
Gizmos.DrawSphere(points[i].position, size);
}
}
}
}
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