public class MeshDrawRing : MonoBehaviour
{
public Material mat;
public Transform go;
public float radius = 6; //外半径
public float innerRadius = 3; //内半径
public int segments = 60; //分割数
public int angleDegree = 360; //扇形或扇面的角度
private void Start()
{
transform.eulerAngles = Vector3.left * 90;
}
private void Update()
{
DrawRing(radius, innerRadius, segments, angleDegree, go.position);
}
/// <summary>
/// 画圆环
/// </summary>
/// <param name="radius">圆半径</param>
/// <param name="innerRadius">内圆半径</param>
/// <param name="segments">圆的分割数</param>
/// <param name="angleDegree">圆覆盖的角度</param>
/// <param name="centerCircle">圆心坐标</param>
void DrawRing(float radius, float innerRadius, int segments, int angleDegree, Vector3 centerCircle)
{
gameObject.AddComponent<MeshFilter>();
gameObject.AddComponent<MeshRenderer>();
gameObject.GetComponent<MeshRenderer>().material = mat;
//顶点
Vector3[] vertices = new Vector3[segments * 2];
angleDegree = Mathf.Clamp(angleDegree, 0, 360);
float deltaAngle = Mathf.Deg2Rad * angleDegree / segments;
float currentAngle = 0;
for (int i = 0; i < vertices.Length; i += 2)
{
float cosA = Mathf.Cos(currentAngle);
float sinA = Mathf.Sin(currentAngle);
vertices[i] = new Vector3(cosA * innerRadius + centerCircle.x, sinA * innerRadius + centerCircle.y, 0);
vertices[i + 1] = new Vector3(cosA * radius + centerCircle.x, sinA * radius + centerCircle.y, 0);
currentAngle += deltaAngle;
}
//三角形
int[] triangles = new int[segments * 6];
for (int i = 0, j = 0; i < segments * 6; i += 6, j += 2)
{
triangles[i] = j;
triangles[i + 1] = (j + 1) % vertices.Length;
triangles[i + 2] = (j + 3) % vertices.Length;
triangles[i + 3] = j;
triangles[i + 4] = (j + 3) % vertices.Length;
triangles[i + 5] = (j + 2) % vertices.Length;
}
//uv:
Vector2[] uvs = new Vector2[vertices.Length];
for (int i = 0; i < vertices.Length; i++)
{
uvs[i] = new Vector2(vertices[i].x / radius / 2 + 0.5f, vertices[i].z / radius / 2 + 0.5f);
}
Mesh mesh = GetComponent<MeshFilter>().mesh;
mesh.Clear();
mesh.vertices = vertices;
mesh.triangles = triangles;
mesh.uv = uvs;
}
}
