Unity 利用Mesh在Unity中绘制扇形图片
直接上脚本，挂空物体上就行：
using UnityEngine;
using System.Collections;
using System.Collections.Generic;
[RequireComponent(typeof(MeshRenderer), typeof(MeshFilter))]
public class TestProgressBar : MonoBehaviour
{
public float radius = 2;
[Range(0,360)]//把角度限制在0-360
public float startAngleDegree = 0;
[Range(0,360)]//把角度限制在0-360
public float angleDegree = 100;
public int angleDegreePrecision = 1000;
public int radiusPrecision = 1000;
//与之前的代码相比, 已经不需要分割的三角形数了
private MeshFilter meshFilter;
private SectorMeshCreator creator = new SectorMeshCreator();
[ExecuteInEditMode]
private void Awake()
{
meshFilter = GetComponent
}
private void Update()
{
meshFilter.mesh = creator.CreateMesh(radius, startAngleDegree, angleDegree, angleDegreePrecision, radiusPrecision);
}
//在Scene界面画辅助线
void OnDrawGizmos()
{
Gizmos.color = Color.gray;
DrawMesh();
}
//在Scene界面画辅助线
void OnDrawGizmosSelected()
{
Gizmos.color = Color.green;
DrawMesh();
}
private void DrawMesh()
{
Mesh mesh = creator.CreateMesh(radius, startAngleDegree, angleDegree, angleDegreePrecision, radiusPrecision);
int[] tris = mesh.triangles;
for (int i = 0; i < tris.Length; i += 3)
{
Gizmos.DrawLine(convert2World(mesh.vertices[tris[i]]), convert2World(mesh.vertices[tris[i + 1]]));
Gizmos.DrawLine(convert2World(mesh.vertices[tris[i]]), convert2World(mesh.vertices[tris[i + 2]]));
Gizmos.DrawLine(convert2World(mesh.vertices[tris[i + 1]]), convert2World(mesh.vertices[tris[i + 2]]));
}
}
private Vector3 convert2World(Vector3 src)
{
return transform.TransformPoint(src);
}
private class SectorMeshCreator
{
private float radius;
private float startAngleDegree;
private float angleDegree;
private Mesh cacheMesh;
///
/// 创建一个扇形Mesh
///
/// 扇形半径
/// 扇形开始角度
/// 扇形角度
/// 扇形角度精度（在满足精度范围内，认为是同个角度）
///
///
/// 扇形半价精度（在满足半价精度范围内，被认为是同个半价）。
/// 比如：半价精度为1000，则：1.001和1.002不被认为是同个半径。因为放大1000倍之后不相等。
/// 如果半价精度设置为100，则1.001和1.002可认为是相等的。
///
///
///
public Mesh CreateMesh(float radius, float startAngleDegree, float angleDegree, int angleDegreePrecision, int radiusPrecision)
{
if (checkDiff(radius, startAngleDegree, angleDegree, angleDegreePrecision, radiusPrecision))
{//参数有改变才需要重新画mesh
Mesh newMesh = Create(radius, startAngleDegree, angleDegree);
if (newMesh != null)
{
cacheMesh = newMesh;
this.radius = radius;
this.startAngleDegree = startAngleDegree;
this.angleDegree = angleDegree;
}
}
return cacheMesh;
}
private Vector3 CalcPoint(float angle)
{//这个函数计算了非特殊角度射线在正方形上的点
angle = angle % 360;
if (angle == 0) {
return new Vector3 (1, 0, 0);
} else if (angle == 180) {
return new Vector3(-1,0,0);
}
//这里分别对应这个射线处于上图哪个三角形中, 分别计算
if (angle <= 45 || angle > 315) {
return new Vector3(1,Mathf.Tan(Mathf.Deg2Rad*angle), 0);
} else if (angle <= 135) {
return new Vector3(1/Mathf.Tan(Mathf.Deg2Rad*angle), 1, 0);
} else if (angle <= 225) {
return new Vector3(-1, -Mathf.Tan(Mathf.Deg2Rad*angle), 0);
} else {
return new Vector3(-1/Mathf.Tan(Mathf.Deg2Rad*angle), -1, 0);
}
}
private Mesh Create(float radius, float startAngleDegree, float angleDegree)
{
if (startAngleDegree == 360) {
startAngleDegree = 0;
}
Mesh mesh = new Mesh();
List
calcVertices.Add (Vector3.zero);//第一个点是圆心点
calcVertices.Add (CalcPoint (startAngleDegree));//第二个点是起始角度对应的点
float [] specialAngle = new float[]{45, 135, 225, 315};//上图正方形4个顶点对应的角度和点
Vector3 [] specialPoint = new Vector3[] {new Vector3(1,1,0),
new Vector3(-1,1,0),
new Vector3(-1,-1,0),
new Vector3(1,-1,0)};
//计算正方形四个点是不是在要画的扇形范围内, 如果是, 则是要画出来的顶点
for (int i = 0; i < specialAngle.Length; ++i) {
if(startAngleDegree < specialAngle[i] && specialAngle[i] - startAngleDegree < angleDegree)
{
calcVertices.Add(specialPoint[i]);
}
}
//这里为什么要第二个for循环? 扇形的角度+起始角度就可能超过360, 所以要计算到720
for (int i = 0; i < specialAngle.Length; ++i) {
if(startAngleDegree < specialAngle[i]+360 && specialAngle[i]+360 - startAngleDegree < angleDegree)
{
calcVertices.Add(specialPoint[i]);
}
}
calcVertices.Add (CalcPoint (startAngleDegree + angleDegree));
Vector3[] vertices = new Vector3[calcVertices.Count];
//uv是网格上的点对应到纹理上的某个位置的像素, 纹理是一张图片, 所以是二维
Vector2[] uvs = new Vector2[vertices.Length];
for (int i = 0; i < vertices.Length; ++i) {
//之前是按半径为单位长度1计算的顶点, 实际顶点是要算上实际半径
vertices[i] = calcVertices[i]*radius;
//纹理的半径就是0.5, 圆心在0.5f, 0.5f的位置
uvs[i] = new Vector2(calcVertices[i].x*0.5f+0.5f,calcVertices[i].y*0.5f+0.5f);
}
int[] triangles = new int[(vertices.Length-2)*3];
for (int i = 0, vi = 1; i < triangles.Length; i += 3, vi++)
{//每个三角形都是由圆心点+两个相邻弧度上的点构成的
triangles[i] = 0;
triangles[i + 2] = vi;
triangles[i + 1] = vi + 1;
}
mesh.vertices = vertices;
mesh.triangles = triangles;
mesh.uv = uvs;
return mesh;
}
private bool checkDiff(float radius, float startAngleDegree, float angleDegree, int angleDegreePrecision, int radiusPrecision)
{
return (int)(startAngleDegree - this.startAngleDegree) != 0 || (int)((angleDegree - this.angleDegree) * angleDegreePrecision) != 0 ||
(int)((radius - this.radius) * radiusPrecision) != 0;
}
}
}