koobas.hobune.stream
Find closest point in triangle to point?
Is there an easy way to find the closest point in triangle to triangle?
Step 1: Get the triangle index and add a plane to the three vertices.
Step 2: Use Vector3.ProjectOnPlane to put a point on the plane.
Step 3: Use cross products with the three vertices and the point.
Step 4: If the point is on a side inside the triangle then bool is true.
This seems to work, but I don't know how to get true if the point is in one triangle or false if none.
using System.Collections;
using System.Collections.Generic;
using UnityEngine;
public class PointOnPlaneInTriangle : MonoBehaviour
{
public bool PointIn;
private Vector3 Point;
private Vector3 CamPos;
public List<Plane> Planes = new List<Plane>();
// Start is called before the first frame update
void Start()
{
}
// Update is called once per frame
void Update()
{
CamPos = Camera.main.transform.position;
Mesh mesh = GetComponent<MeshFilter>().sharedMesh;
var triangles = mesh.triangles;
var vertices = mesh.vertices;
for (int i = 0; i < triangles.Length; i += 3)
{
Vector3 p1 = vertices[triangles[i + 0]];
Vector3 p2 = vertices[triangles[i + 1]];
Vector3 p3 = vertices[triangles[i + 2]];
Vector3 tp1 = transform.TransformPoint(p1);
Vector3 tp2 = transform.TransformPoint(p2);
Vector3 tp3 = transform.TransformPoint(p3);
Planes.Add(new Plane(tp1, tp2, tp3));
for (int e = 0; e < Planes.Count; ++e)
{
Point = Vector3.ProjectOnPlane(CamPos, Planes[e].normal);
}
Vector3 Side1P1 = Vector3.Cross(tp1 - tp2, Point - tp1).normalized;
Vector3 Side1P2 = Vector3.Cross(tp1 - tp2, tp3 - tp1).normalized;
Vector3 Side2P1 = Vector3.Cross(tp2 - tp3, Point - tp2).normalized;
Vector3 Side2P2 = Vector3.Cross(tp2 - tp3, tp1 - tp2).normalized;
Vector3 Side3P1 = Vector3.Cross(tp3 - tp1, Point - tp3).normalized;
Vector3 Side3P2 = Vector3.Cross(tp3 - tp1, tp2 - tp3).normalized;
if (Vector3.Dot(Side1P1, Side1P2) >= 0 && Vector3.Dot(Side2P1, Side2P2) >= 0 && Vector3.Dot(Side3P1, Side3P2) >= 0)
{
PointIn = true;
}
else
{
PointIn = false;
}
Debug.Log(PointIn);
}
}
}
Best Answer
Found this.
using System.Collections;
using System.Collections.Generic;
using UnityEngine;
public class PointOnPlaneInTriangle : MonoBehaviour
{
public bool PointIn;
private Vector3 Point;
private Vector3 CamPos;
public List<Plane> Planes = new List<Plane>();
// Start is called before the first frame update
void Start()
{
}
// Update is called once per frame
void Update()
{
CamPos = Camera.main.transform.position;
Mesh mesh = GetComponent<MeshFilter>().sharedMesh;
int[] triangles = mesh.triangles;
Vector3[] vertices = mesh.vertices;
for (int i = 0; i < triangles.Length; i += 3)
{
Vector3 p1 = vertices[triangles[i + 0]];
Vector3 p2 = vertices[triangles[i + 1]];
Vector3 p3 = vertices[triangles[i + 2]];
Vector3 tp1 = transform.TransformPoint(p1);
Vector3 tp2 = transform.TransformPoint(p2);
Vector3 tp3 = transform.TransformPoint(p3);
Planes.Add(new Plane(tp1, tp2, tp3));
for (int e = 0; e < Planes.Count; ++e)
{
Point = Vector3.ProjectOnPlane(CamPos, Planes[e].normal);
}
//Point in triangle test: blackpawn.com/texts/pointinpoly
// Compute vectors
Vector3 v0 = tp3 - tp1;
Vector3 v1 = tp2 - tp1;
Vector3 v2 = Point - tp1;
// Compute dot products
float dot00 = Vector3.Dot(v0, v0);
float dot01 = Vector3.Dot(v0, v1);
float dot02 = Vector3.Dot(v0, v2);
float dot11 = Vector3.Dot(v1, v1);
float dot12 = Vector3.Dot(v1, v2);
// Compute barycentric coordinates
float invDenom = 1 / (dot00 * dot11 - dot01 * dot01);
float u = (dot11 * dot02 - dot01 * dot12) * invDenom;
float v = (dot00 * dot12 - dot01 * dot02) * invDenom;
// Check if point is in triangle
if (u >= 0 && v >= 0 && u + v < 1)
{
PointIn = true;
}
else
{
PointIn = false;
}
Debug.Log(PointIn);
}
}
}
