public class DrawSector : MonoBehaviour {
public float Radius = 6; // 外半徑
public float innerRadius = 3; // 內半徑
public float angleDegree = 360; // 扇形或扇面角度
public int Segments = 60; // 分割數
public MeshFilter meshFilter;
private void Start() {
meshFilter = GetComponent<MeshFilter>();
}
private void Update() {
meshFilter.mesh = CreateMesh(Radius, innerRadius, angleDegree, Segments);
}
Mesh CreateMesh(float radius, float innerRadius, float angledegree, int segments) {
// vertices(頂點):
int vertices_count = segments * 2 + 2; // 因為vertices(頂點)的個數與triangles(索引三角形個數)必須匹配
Vector3[] vertices = new Vector3[vertices_count];
float angleRad = Mathf.Deg2Rad * angledegree;
float angleCur = angleRad;
float angledelta = angleRad / segments;
for (int i = 0; i < vertices_count; i += 2) {
float cosA = Mathf.Cos(angleCur);
float sinA = Mathf.Sin(angleCur);
vertices[i] = new Vector3(radius * cosA, 0, radius * sinA);
vertices[i + 1] = new Vector3(innerRadius * cosA, 0, innerRadius * sinA);
angleCur -= angledelta;
}
// triangles:
int triangle_count = segments * 6;
int[] triangles = new int[triangle_count];
for (int i = 0, vi = 0; i < triangle_count; i += 6, vi += 2) {
triangles[i] = vi;
triangles[i + 1] = vi + 3;
triangles[i + 2] = vi + 1;
triangles[i + 3] = vi + 2;
triangles[i + 4] = vi + 3;
triangles[i + 5] = vi;
}
// uv:
Vector2[] uvs = new Vector2[vertices_count];
for (int i = 0; i < vertices_count; i++) {
uvs[i] = new Vector2(vertices[i].x / radius / 2 + 0.5f, vertices[i].y / radius / 2 + 0.5f);
}
// 負載屬性於 mesh
Mesh mesh = new Mesh();
mesh.vertices = vertices;
mesh.triangles = triangles;
mesh.uv = uvs;
return mesh;
}
}
