Question

我想在Unity中动态绘制2D道路线段。我知道线段的4个边缘点和贝塞尔曲线所需的控制点。这使我可以轻松绘制道路段的外部形状，在此示例中，获得的结果是形成道路形状的2条终点线和2条曲线。

要绘制贝塞尔曲线，我使用的是：https://github.com/dbrizov/NaughtyBezierCurves

目标是用一些纹理填充路段。如何创建与道路形状相同的某种平面或网格？

我的第一个想法是沿着两条曲线并创建平面，也许是曲线的每1/100长度，然后向其添加纹理。但是使用这种方法，我不知道如何旋转平面或如何防止空间或重叠。也许有人对此问题有一个更简单的解决方案。

Answer 1

我拍了DShook's answer from a related question并更改了几行以使其变为两条任意样条线：

using UnityEngine;

[ExecuteInEditMode]
[RequireComponent(typeof(MeshFilter), typeof(MeshRenderer), typeof(BezierSpline))]
public class SplineMesh : MonoBehaviour {

  [Range(1, 20)]
  public int sampleFrequency = 5;

  BezierSpline[] splines;

  Mesh mesh;

  private void Awake () {
    splines = GetComponents<BezierSpline>();
    mesh = GetComponent<Mesh>();
  }

  private Vector3[] vertices;

  public void GenerateMesh(){
    vertices = new Vector3[(sampleFrequency + 1) * 2];

    //iterate over our samples adding two vertices for each one
    for(int s = 0, i = 0; s <= sampleFrequency; s++, i += 2){
      float interval = s / (float)sampleFrequency;

      //get point along spline, and translate to local coords from world
      var point1 = transform.InverseTransformPoint(splines[0].GetPoint(interval));
      var point2 = transform.InverseTransformPoint(splines[1].GetPoint(interval));

      vertices[i] = point1;
      vertices[i + 1] = point2;
    }

    GetComponent<MeshFilter>().mesh = mesh = new Mesh();
    mesh.name = "Spline Mesh";

    mesh.vertices = vertices;

    //now figure out our triangles
    int [] triangles = new int[sampleFrequency * 6];
    for(int s = 0, ti = 0, vi = 0; s < sampleFrequency; s++, ti += 6, vi += 2){
      //first tri
      triangles[ti] = vi;
      triangles[ti + 1] = vi + 3;
      triangles[ti + 2] = vi + 1;
      //second matching tri
      triangles[ti + 3] = vi;
      triangles[ti + 4] = vi + 2;
      triangles[ti + 5] = vi + 3;
    }

    mesh.triangles = triangles;
    mesh.RecalculateNormals();

    Debug.Log("Generated Spline Mesh");
  }


}

您将要确保要渲染的着色器没有背面剔除，即没有Cull Off。

此代码在许多情况下都可以工作，但是从理论上讲可能会导致自身重叠。对于样条线的相对位置没有任何保证，我能想到的唯一解决方法是在sampleFrequency循环的每个步骤中为大于或等于该样条线的每个样条线尝试不同的intervals之前的一对intervals，直到找到一对消除（或最小化）该对将增加的重叠的对。

就设置uv而言，您可以这样设置uv：

    private Vector3[] vertices;
    private Vector2[] uvs;

    // ...

      vertices[i] = point1;
      vertices[i + 1] = point2;

      uvs[i] = new Vector2(0f, sample);
      uvs[i+1] = new Vector2(1f, sample);

    // ...

    mesh.triangles = triangles;
    mesh.RecalculateNormals();
    mesh.uv = uvs;

带有纹理的贝塞尔曲线之间的填充区域

1 个答案: