Material 在 Unity3d 中通过光线投射确定子网格

Question

我正在尝试将道具随机放置在网格上。网格有 2 个 materials，我只想将道具放在其中一个 materials 上。我目前正在通过光线投射来执行此操作，确定命中点的 material，如果 material 正确，我会在该点放置一个道具。我遇到 material 被错误确定的问题，我不确定为什么。代码如下。使用 UnityEngine；

public class BoundingBoxTry : MonoBehaviour {

// Use this for initialization
public MeshFilter meshFilter;
private Renderer rend;
private Mesh mesh;
private Bounds bnds;
private float nextX, nextZ, maxX, minX, maxZ, minZ;
public GameObject rayOrigin;
public GameObject propPreFab;
private MeshCollider thisCollider;
void Start () {
    thisCollider = GetComponentInChildren<MeshCollider>();
    rend = GetComponentInChildren<Renderer>();
    mesh = GetComponentInChildren<MeshFilter>().sharedMesh;
    bnds = rend.bounds;
}

void Update () {
    nextX = Random.Range(0, bnds.size.x);   
    nextZ = Random.Range(0, bnds.size.z);   
    nextX = nextX-bnds.size.x/2;
    nextZ = nextZ-bnds.size.z/2;
    nextX = bnds.center.x-nextX;
    nextZ = bnds.center.z-nextZ;
    RaycastHit hit = new RaycastHit();
    Vector3 randomCoord = new Vector3(nextX, 0, nextZ);
    rayOrigin.transform.position = new Vector3(nextX, 100, nextZ);
    bool didHit = Physics.Raycast(rayOrigin.transform.position, -new Vector3(0, 1, 0), out hit);
    int vertCounter = 0;

    if(didHit && hit.collider == thisCollider){
        for (int sMC = 0; sMC < mesh.subMeshCount; sMC++)
        {
            int[] subMesh = mesh.GetTriangles(sMC);
            vertCounter = vertCounter + subMesh.Length;             
            if(hit.triangleIndex < vertCounter){
                if(rend.sharedMaterials[sMC] == rayOrigin.GetComponent<Renderer>().sharedMaterial){
                    GameObject prop = Instantiate(propPreFab, hit.point, Quaternion.identity);
                }
                else{
                }
            }
        }
    }
}
}

我还附上了一张图片来展示我所看到的行为。

Answer 1

当然，只要我提出并沉思这个问题，我就能弄明白。 Arman 的 link 也很有帮助。我看到的问题是由于我没有完全理解我从 triangleIndex 调用中获得的数据造成的。调用 triangleIndex 时，您会收到一个顶点索引。要从该顶点命中三角形，您必须将顶点索引乘以 3，然后验证哪个子网格被光线投射命中。

Material 在 Unity3d 中通过光线投射确定子网格

Material determination of submeshes through raycasting in Unity3d

c#

unity3d

raycasting