来源：/threads/draw-circles-or-primitives-on-the-new-ui-canvas.272488/
效果：
代码：
using UnityEngine;using UnityEngine.UI;public class DrawSquald : MaskableGraphic{[SerializeField]Texture m_Texture;[Range(0, 1)][SerializeField]private float fillAmount;public float FillAmount{get { return fillAmount; }set{fillAmount = value;// This detects a change and sets the vertices dirty so it gets updated //这会检测到一个更改，并将顶点设置为脏，以便它被更新SetVerticesDirty();}}//是否填充public bool fill = true;//圆弧厚度public int thickness = 5;//分段[Range(0, 360)]public int segments = 360;public override Texture mainTexture{get{return m_Texture == null ? s_WhiteTexture : m_Texture;}}/// <summary>/// Texture to be used./// </summary>public Texture texture{get { return m_Texture; }set{if (m_Texture == value)return;m_Texture = value;SetVerticesDirty();SetMaterialDirty();}}// Using arrays is a bit more efficient 使用数组更有效率UIVertex[] uiVertices = new UIVertex[4];Vector2[] uvs = new Vector2[4];Vector2[] pos = new Vector2[4];protected override void Start(){uvs[0] = new Vector2(0, 1);uvs[1] = new Vector2(1, 1);uvs[2] = new Vector2(1, 0);uvs[3] = new Vector2(0, 0);}protected override void OnPopulateMesh(VertexHelper vh){float outer = -rectTransform.pivot.x * rectTransform.rect.width;float inner = -rectTransform.pivot.x * rectTransform.rect.width + thickness;float degrees = 360f / segments;int fa = (int)((segments + 1) * this.fillAmount);// Updated to new vertexhelpervh.Clear();// Changed initial values so the first polygon is correct when circle isn't filledfloat x = outer * Mathf.Cos(0);float y = outer * Mathf.Sin(0);Vector2 prevX = new Vector2(x, y);// Changed initial values so the first polygon is correct when circle isn't filledx = inner * Mathf.Cos(0);y = inner * Mathf.Sin(0);Vector2 prevY = new Vector2(x, y);for (int i = 0; i < fa - 1; i++){// Changed so there isn't a stray polygon at the beginning of the arc//改变了，所以在圆弧的开头没有一个杂散多边形float rad = Mathf.Deg2Rad * ((i + 1) * degrees);float c = Mathf.Cos(rad);float s = Mathf.Sin(rad);pos[0] = prevX;pos[1] = new Vector2(outer * c, outer * s);if (fill){pos[2] = Vector2.zero;pos[3] = Vector2.zero;}else{pos[2] = new Vector2(inner * c, inner * s);pos[3] = prevY;}// Set values for uiVerticesfor (int j = 0; j < 4; j++){uiVertices[j].color = color;uiVertices[j].position = pos[j];uiVertices[j].uv0 = uvs[j];}// Get the current vertex countint vCount = vh.currentVertCount;// If filled, we only need to create one trianglevh.AddVert(uiVertices[0]);vh.AddVert(uiVertices[1]);vh.AddVert(uiVertices[2]);// Create triangle from added verticesvh.AddTriangle(vCount, vCount + 2, vCount + 1);// If not filled we need to add the 4th vertex and another triangleif (!fill){vh.AddVert(uiVertices[3]);vh.AddTriangle(vCount, vCount + 3, vCount + 2);}prevX = pos[1];prevY = pos[2];}}}
使用：
使用就很简单了，附加到一个空的GameObject上面，由于是UI组件，因此需要放在Canvas下面。具体参数的功能可以参照效果图。
版本要求5.2及以上....最低版本具体是5.2还是5.3给忘了...
