Unity3D 自定义UI组件画圆、圆弧、扇形

来源：https://forum.unity3d.com/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 vertexhelper        vh.Clear();                 // Changed initial values so the first polygon is correct when circle isn't filled        float 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 filled        x = 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 uiVertices            for (int j = 0; j < 4; j++)            {                uiVertices[j].color = color;                uiVertices[j].position = pos[j];                uiVertices[j].uv0 = uvs[j];            }            // Get the current vertex count            int vCount = vh.currentVertCount;            // If filled, we only need to create one triangle            vh.AddVert(uiVertices[0]);            vh.AddVert(uiVertices[1]);            vh.AddVert(uiVertices[2]);            // Create triangle from added vertices            vh.AddTriangle(vCount, vCount + 2, vCount + 1);            // If not filled we need to add the 4th vertex and another triangle            if (!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...