I am implementing triangle removal of a mesh by using ray cast. It removes the triangles from the moves that the ray cast is hitting it, but the problem is when I am trying to remove the triangles, it removes the back part of the mesh not the front, and only when I am hitting with ray cast from inside of the mesh. I am not sure what can be the problem, any help and guidance will be really appreciated. I have attached the picture.
In the imaged uploaded, the scene view is flipped down and the game view shows the object that cast ray is in middle:
Following is my implementation:
using System.Linq;
using UnityEngine;
using UnityEngine.UI;
using UnityEngine.SceneManagement;
using System.Collections.Generic;
using System.Numerics;
using Vector2 = UnityEngine.Vector2;
using Vector3 = UnityEngine.Vector3;
using Vector4 = UnityEngine.Vector4;
public class RemoveTriangle : MonoBehaviour
{
[Header("Game Object")][Tooltip("The game object that will be removed its triangles")]
public GameObject spherePrefab;
// Better to reference those already in the Inspector
[Header("Mesh Files to Load")]
[SerializeField][Tooltip("Drag and drop the mesh files you want to load")] private MeshFilter meshFilter;
[SerializeField][Tooltip("Drag and drop the mesh files you want to load")] private MeshRenderer meshRenderer;
[SerializeField][Tooltip("Drag and drop the mesh files you want to load")] private MeshCollider meshCollider;
//[SerializeField] [Range(1.0f, 3.0f)] public float raycastSize = 1.0f;
[Header("Origin and Target objects")]
[Tooltip("Drag and drop the origin and target objects")]public Transform SelectOrigin;
[Tooltip("Drag and drop the origin and target objects")]public MeshFilter SelectTarget;
[Header("Raycast Distance")][Tooltip("The distance of the raycast")]
[SerializeField][Range(0.1f,20.0f)]public float MaxDistance = 10f;
private Mesh mesh;
private void Awake()
{
MeshProperties();
}
private void Update()
{
DeleteTriangle();
}
void MeshProperties()
{// Get the mesh from the mesh filter
if (!meshFilter) meshFilter = GetComponent<MeshFilter>();
if (!meshRenderer) meshRenderer = GetComponent<MeshRenderer>();
if (!meshCollider) meshCollider = GetComponent<MeshCollider>();
mesh = meshFilter.mesh;
}// MeshProperties
void DeleteTriangle()
{//raycast from mouse position
if (Input.GetKey(KeyCode.C))
{//raycast from mouse position
Ray ray = new Ray(SelectOrigin.position, SelectOrigin.forward);
RaycastHit hit;
if (Physics.Raycast(ray, out hit, MaxDistance))
{//if raycast hits a triangle
Debug.DrawRay(SelectOrigin.position,
SelectTarget.transform.position - SelectOrigin.position,
Color.red);
Debug.Log("Triangle Removed at: " + hit.point + "/" + hit.triangleIndex + "/" + hit.normal);
//cube.transform.position = hit.point;
// Get current vertices, triangles, uvs,tangents and normals of the mesh
Vector3[] vertices = mesh.vertices;
Vector2[] uv = mesh.uv;
Vector4[] tangents = mesh.tangents;
Vector3[] normals = mesh.normals;
int[] triangles = mesh.triangles;
// Get the vert indices for this triangle
int vertIndex_1 = triangles[hit.triangleIndex * 3 + 0];
int vertIndex_2 = triangles[hit.triangleIndex * 3 + 1];
int vertIndex_3 = triangles[hit.triangleIndex * 3 + 2];
// Get the vertices for this triangle
var vert_1 = vertices[vertIndex_1];
var vert_2 = vertices[vertIndex_2];
var vert_3 = vertices[vertIndex_3];
// Get the uv for this triangle
var uv_1 = uv[vertIndex_1];
var uv_2 = uv[vertIndex_2];
var uv_3 = uv[vertIndex_3];
//Get the Normals for this triangle
var normal_1 = mesh.normals[vertIndex_1];
var normal_2 = mesh.normals[vertIndex_2];
var normal_3 = mesh.normals[vertIndex_3];
//Get Tangents for this triangle
Vector4 tangent_1 = mesh.tangents[vertIndex_1];
Vector4 tangent_2 = mesh.tangents[vertIndex_2];
Vector4 tangent_3 = mesh.tangents[vertIndex_3];
// Get the positions for the vertices
var vertPos_1 = vertices[vertIndex_1];
var vertPos_2 = vertices[vertIndex_2];
var vertPos_3 = vertices[vertIndex_3];
// Get the center of the triangle
var center = (vertPos_1 + vertPos_2 + vertPos_3) / 3;
// Now for all three vertices we first check if any other triangle if using it
// by simply count how often the indices are used in the triangles list
var verticesOccur_1 = 0;
var verticesOccur_2 = 0;
var verticesOccur_3 = 0;
for (var i = 0; i < triangles.Length; i++)
{
if (triangles[i] == vertIndex_1)
verticesOccur_1++;
if (triangles[i] == vertIndex_2)
verticesOccur_2++;
if (triangles[i] == vertIndex_3)
verticesOccur_3++;
}//end for
// Remove the vertices
if (verticesOccur_1 == 1)
vertices[vertIndex_1] = Vector3.zero;
if (verticesOccur_2 == 1)
vertices[vertIndex_2] = Vector3.zero;
if (verticesOccur_3 == 1)
vertices[vertIndex_3] = Vector3.zero;
// Remove the uv
if (verticesOccur_1 == 1)
uv[vertIndex_1] = Vector2.zero;
if (verticesOccur_2 == 1)
uv[vertIndex_2] = Vector2.zero;
if (verticesOccur_3 == 1)
uv[vertIndex_3] = Vector2.zero;
// Remove the normals
if (verticesOccur_1 == 1)
mesh.normals[vertIndex_1] = Vector3.zero;
if (verticesOccur_2 == 1)
mesh.normals[vertIndex_2] = Vector3.zero;
if (verticesOccur_3 == 1)
mesh.normals[vertIndex_3] = Vector3.zero;
// Remove the tangents
if (verticesOccur_1 == 1)
mesh.tangents[vertIndex_1] = Vector4.zero;
if (verticesOccur_2 == 1)
mesh.tangents[vertIndex_2] = Vector4.zero;
if (verticesOccur_3 == 1)
mesh.tangents[vertIndex_3] = Vector4.zero;
//fix the triangles
//for (var i = 0; i < triangles.Length; i++)
//{
//if (triangles[i] == vertIndex_1) triangles[i] = 0;
// (triangles[i] == vertIndex_2) triangles[i] = 0;
//if (triangles[i] == vertIndex_3) triangles[i] = 0;
//}]
// Find the intersecting triangles by checking if the ray intersects with their vertices
//var intersectingTriangles = new List<int>();
/* for (var i = 0; i < triangles.Length; i += 3)
{
var triangleVertIndex_1 = triangles[i + 0];
var triangleVertIndex_2 = triangles[i + 1];
var triangleVertIndex_3 = triangles[i + 2];
var triangleVertPos_1 = vertices[triangleVertIndex_1];
var triangleVertPos_2 = vertices[triangleVertIndex_2];
var triangleVertPos_3 = vertices[triangleVertIndex_3];
}*/
// Remove the triangles and update the mesh
triangles[hit.triangleIndex * 3] = 0;
triangles[hit.triangleIndex * 3 + 1] = 0;
triangles[hit.triangleIndex * 3 + 2] = 0;
//update the mesh with the new vertices, uv, normals and tangents
mesh.vertices = vertices;
mesh.uv = uv;
mesh.tangents = tangents;
mesh.normals = normals;
//update the tirangles
mesh.triangles = triangles;
// Recalculate the normals
mesh.RecalculateNormals();
// Recalculate the tangents
mesh.RecalculateTangents();
// Recalculate the bounds
mesh.RecalculateBounds();
}//end of if
else
{
Debug.Log("No Triangle to remove" + hit.point);
}//end of if hit.triangleIndex
}//end of remove triangle
}//end of class
}//end of class
I tried to change the setting of mesh, but it did not give me a good result. I feel like there is a problem with the mesh, but I cannot understand what the problem is.
