如何反求网格

Question

我正在使用教程https://www.youtube.com/watch?v=73Dc5JTCmKI中的脚本，该脚本显示视图字段。但是我想逆它，所以你看不到白色网格的地方将是白色网格，而不是我现在的，

如何反求网格，这样在哪里是绿色的颜色(没有)将是网格，在哪里是网格，就不会有网格。

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我的剧本：

using UnityEngine;
using System.Collections;
using System.Collections.Generic;

public class FieldOfView : MonoBehaviour {

    public float viewRadius;
    [Range(0,360)]
    public float viewAngle;

    public LayerMask targetMask;
    public LayerMask obstacleMask;

    [HideInInspector]
    public List<Transform> visibleTargets = new List<Transform>();

    public float meshResolution;
    public int edgeResolveIterations;
    public float edgeDstThreshold;

    public float maskCutawayDst = .1f;

    public MeshFilter viewMeshFilter;
    Mesh viewMesh;

    void Start() {
        viewMesh = new Mesh ();
        viewMesh.name = "View Mesh";
        viewMeshFilter.mesh = viewMesh;

        StartCoroutine ("FindTargetsWithDelay", .2f);
    }


    IEnumerator FindTargetsWithDelay(float delay) {
        while (true) {
            yield return new WaitForSeconds (delay);
            FindVisibleTargets ();
        }
    }

    void LateUpdate() {
        DrawFieldOfView ();
    }

    void FindVisibleTargets() {
        visibleTargets.Clear ();
        Collider[] targetsInViewRadius = Physics.OverlapSphere (transform.position, viewRadius, targetMask);

        for (int i = 0; i < targetsInViewRadius.Length; i++) {
            Transform target = targetsInViewRadius [i].transform;
            Vector3 dirToTarget = (target.position - transform.position).normalized;
            if (Vector3.Angle (transform.forward, dirToTarget) < viewAngle / 2) {
                float dstToTarget = Vector3.Distance (transform.position, target.position);
                if (!Physics.Raycast (transform.position, dirToTarget, dstToTarget, obstacleMask)) {
                    visibleTargets.Add (target);
                }
            }
        }
    }

    void DrawFieldOfView() {
        int stepCount = Mathf.RoundToInt(viewAngle * meshResolution);
        float stepAngleSize = viewAngle / stepCount;
        List<Vector3> viewPoints = new List<Vector3> ();
        ViewCastInfo oldViewCast = new ViewCastInfo ();
        for (int i = 0; i <= stepCount; i++) {
            float angle = transform.eulerAngles.y - viewAngle / 2 + stepAngleSize * i;
            ViewCastInfo newViewCast = ViewCast (angle);

            if (i > 0) {
                bool edgeDstThresholdExceeded = Mathf.Abs (oldViewCast.dst - newViewCast.dst) > edgeDstThreshold;
                if (oldViewCast.hit != newViewCast.hit || (oldViewCast.hit && newViewCast.hit && edgeDstThresholdExceeded)) {
                    EdgeInfo edge = FindEdge (oldViewCast, newViewCast);
                    if (edge.pointA != Vector3.zero) {
                        viewPoints.Add (edge.pointA);
                    }
                    if (edge.pointB != Vector3.zero) {
                        viewPoints.Add (edge.pointB);
                    }
                }

            }


            viewPoints.Add (newViewCast.point);
            oldViewCast = newViewCast;
        }

        int vertexCount = viewPoints.Count + 1;
        Vector3[] vertices = new Vector3[vertexCount];
        int[] triangles = new int[(vertexCount-2) * 3];

        vertices [0] = Vector3.zero;
        for (int i = 0; i < vertexCount - 1; i++) {
            vertices [i + 1] = transform.InverseTransformPoint(viewPoints [i]) + Vector3.forward * maskCutawayDst;

            if (i < vertexCount - 2) {
                triangles [i * 3] = 0;
                triangles [i * 3 + 1] = i + 1;
                triangles [i * 3 + 2] = i + 2;
            }
        }

        viewMesh.Clear ();

        viewMesh.vertices = vertices;
        viewMesh.triangles = triangles;
        viewMesh.RecalculateNormals ();
    }


    EdgeInfo FindEdge(ViewCastInfo minViewCast, ViewCastInfo maxViewCast) {
        float minAngle = minViewCast.angle;
        float maxAngle = maxViewCast.angle;
        Vector3 minPoint = Vector3.zero;
        Vector3 maxPoint = Vector3.zero;

        for (int i = 0; i < edgeResolveIterations; i++) {
            float angle = (minAngle + maxAngle) / 2;
            ViewCastInfo newViewCast = ViewCast (angle);

            bool edgeDstThresholdExceeded = Mathf.Abs (minViewCast.dst - newViewCast.dst) > edgeDstThreshold;
            if (newViewCast.hit == minViewCast.hit && !edgeDstThresholdExceeded) {
                minAngle = angle;
                minPoint = newViewCast.point;
            } else {
                maxAngle = angle;
                maxPoint = newViewCast.point;
            }
        }

        return new EdgeInfo (minPoint, maxPoint);
    }


    ViewCastInfo ViewCast(float globalAngle) {
        Vector3 dir = DirFromAngle (globalAngle, true);
        RaycastHit hit;

        if (Physics.Raycast (transform.position, dir, out hit, viewRadius, obstacleMask)) {
            return new ViewCastInfo (true, hit.point, hit.distance, globalAngle);
        } else {
            return new ViewCastInfo (false, transform.position + dir * viewRadius, viewRadius, globalAngle);
        }
    }

    public Vector3 DirFromAngle(float angleInDegrees, bool angleIsGlobal) {
        if (!angleIsGlobal) {
            angleInDegrees += transform.eulerAngles.y;
        }
        return new Vector3(Mathf.Sin(angleInDegrees * Mathf.Deg2Rad),0,Mathf.Cos(angleInDegrees * Mathf.Deg2Rad));
    }

    public struct ViewCastInfo {
        public bool hit;
        public Vector3 point;
        public float dst;
        public float angle;

        public ViewCastInfo(bool _hit, Vector3 _point, float _dst, float _angle) {
            hit = _hit;
            point = _point;
            dst = _dst;
            angle = _angle;
        }
    }

    public struct EdgeInfo {
        public Vector3 pointA;
        public Vector3 pointB;

        public EdgeInfo(Vector3 _pointA, Vector3 _pointB) {
            pointA = _pointA;
            pointB = _pointB;
        }
    }

}

我知道我必须改变一些三角形，但我不知道如何设置它们。

    vertices [0] = Vector3.zero;
for (int i = 0; i < vertexCount - 1; i++) {
    vertices [i + 1] = transform.InverseTransformPoint(viewPoints [i]) + Vector3.forward * maskCutawayDst;

    if (i < vertexCount - 2) {
        triangles [i * 3] = 0;
        triangles [i * 3 + 1] = i + 1;
        triangles [i * 3 + 2] = i + 2;
    }
}

viewMesh.Clear ();

viewMesh.vertices = vertices;
viewMesh.triangles = triangles;
viewMesh.RecalculateNormals ();

对不起，我不知道如何更好地解释它。

编辑，所以我仍然有一些问题。你的解决方案对我没用。首先，没有"circleRadius"，所以我使用viewRadius代替它。其次，它给我的论点始终超出范围。我的代码稍微变了一点，下面是它的外观：

        int vertexCount = viewPoints.Count + 1;
    var vertices = new Vector3[vertexCount];
    var triangles = new int[(vertexCount - 2) * 3];

    vertices[0] = Vector3.zero;
    for (int i = 0; i < vertexCount - 1; i++)
    {
        vertices[i + 1] = transform.InverseTransformPoint(viewPoints[i]);

        if (i < vertexCount - 2)
        {
            triangles[i * 3] = 0;
            triangles[i * 3 + 1] = i + 1;
            triangles[i * 3 + 2] = i + 2;
        }
    }

所以在这种情况下，我应该把它改为：

        int vertexCount = viewPoints.Count + 1;
    Vector3[] vertices = new Vector3[(vertexCount) * 2];
    int[] triangles = new int[(vertexCount) * 6];

    for (int i = 0; i < (vertexCount - 1) * 2; i += 2)
    {
        vertices[i] = transform.InverseTransformPoint(viewPoints[i]);
        vertices[i + 1] = Vector3.Normalize(viewPoints[i]) * viewRadius;
    }
    for (int i = 0; i < (vertexCount - 3) * 2; i += 1)
    {
        triangles[i * 6 + 0] = i * 4;
        triangles[i * 6 + 1] = i * 4 + 1;
        triangles[i * 6 + 2] = i * 4 + 2;
        triangles[i * 6 + 3] = i * 4 + 1;
        triangles[i * 6 + 4] = i * 4 + 2;
        triangles[i * 6 + 5] = i * 4 + 3;
    }

编辑2

所以我修改了我的代码，这很好，但是当我在播放模式下测试它时，它会给我错误：

ArgumentOutOfRangeException: Argument is out of range.
Parameter name: index
FieldOfViews.DrawFieldOfView () (at Assets/_Game/FieldOfView.cs:111)

它在网上：

vertices[i] = transform.InverseTransformPoint(viewPoints[i]) + Vector3.forward * maskCutawayDst;

当我为测试目的移除这条车道时，它还在以下方面出现了相同的错误：

vertices[i + 1] = Vector3.Normalize(viewPoints[i]) * circleRadius;

我不知道这是否会导致问题，但我的maskCutawayDst是0.1，circleRadius是15。

Answer 1

密码如下：

  int vertexCount = viewPoints.Count + 1;
    Vector3[] vertices = new Vector3[vertexCount];
    int[] triangles = new int[(vertexCount-2) * 3];

    vertices [0] = Vector3.zero;
    for (int i = 0; i < vertexCount - 1; i++) {
        vertices [i + 1] = transform.InverseTransformPoint(viewPoints [i]) + Vector3.forward * maskCutawayDst;

        if (i < vertexCount - 2) {
            triangles [i * 3] = 0;
            triangles [i * 3 + 1] = i + 1;
            triangles [i * 3 + 2] = i + 2;
        }
    }

变到

        int vertexCount = viewPoints.Count + 1;
        Vector3[] vertices = new Vector3[(vertexCount) * 2];
        int[] triangles = new int[(vertexCount) * 6];

        for (int i = 0; i < vertexCount; i++)
        {
            Vector3 vertex = transform.InverseTransformPoint(viewPoints[(i == viewPoints.Count) ? 0 : i]);
            vertices[i * 2] = vertex;
            vertices[i * 2 + 1] = vertex.normalized * viewRadius;
        }
        for (int i = 0; i < (vertexCount); i++)
        {
            int j = (vertexCount - 1 == i) ? 0 : i;
            triangles[i * 6 + 0] = j * 2 + 0;
            triangles[i * 6 + 1] = j * 2 + 1;
            triangles[i * 6 + 2] = j * 2 + 2;
            triangles[i * 6 + 3] = j * 2 + 1;
            triangles[i * 6 + 4] = j * 2 + 3;
            triangles[i * 6 + 5] = j * 2 + 2;
        }

解释：

图1:正在发生的事情的一部分

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第一个程序在红色区域创建了一个三角形。这是在中间和两条相交射线之间(相交的红线)。要“逆”这一点，我们必须将这两条线作为一个四角线连接到一个固定距离的外部点。将向量归一化为有一个单位长度，然后乘以具有所有点的固定距离。这是用代码完成的。

   for (int i = 0; i < vertexCount; i++)
        {
            Vector3 vertex = transform.InverseTransformPoint(viewPoints[(i == viewPoints.Count) ? 0 : i]);
            vertices[i * 2] = vertex;
            vertices[i * 2 + 1] = vertex.normalized * viewRadius;
        }

然后将这些顶点转换成两个三角形(以表示一个四角)。下面的代码。形成了绿色的区域。

for (int i = 0; i < (vertexCount); i++)
{
    int j = (vertexCount - 1 == i) ? 0 : i;
    triangles[i * 6 + 0] = j * 2 + 0;
    triangles[i * 6 + 1] = j * 2 + 1;
    triangles[i * 6 + 2] = j * 2 + 2;
    triangles[i * 6 + 3] = j * 2 + 1;
    triangles[i * 6 + 4] = j * 2 + 3;
    triangles[i * 6 + 5] = j * 2 + 2;
}