ugui源码阅读 - Graphic渲染原理

using UnityEngine;
using UnityEngine.UI;

[RequireComponent(typeof(CanvasRenderer))]
public class TestCanvasRenderer : MonoBehaviour
{
    [SerializeField]
    public Texture m_Texture;
    private VertexHelper m_VertexHelper;

    void Start()
    {
        UpdateRenderer();
    }

    void UpdateRenderer()
    {
        var canvasRenderer = GetComponent<CanvasRenderer>();
        canvasRenderer.Clear();

        var vh = new VertexHelper();

        //设置顶点
        var mesh = new Mesh();
        PopulateMesh(vh);
        vh.FillMesh(mesh);
        canvasRenderer.SetMesh(mesh);

        //设置材质和贴图
        canvasRenderer.materialCount = 1;
        var myMat = Canvas.GetDefaultCanvasMaterial();
        canvasRenderer.SetMaterial(myMat, 0);

        var myTexture = (null == m_Texture) ? Texture2D.whiteTexture : m_Texture;
        canvasRenderer.SetTexture(myTexture);
    }

    void PopulateMesh(VertexHelper vh)
    {
        Color32 vertColor = Color.white;

        float width = 150;
        float height = 100;
        //这边添加一个四边形
        vh.AddVert(new Vector3(0, 0), vertColor, new Vector2(0f, 0f)); //左下
        vh.AddVert(new Vector3(0, height), vertColor, new Vector2(0f, 1f)); //左上
        vh.AddVert(new Vector3(width, height), vertColor, new Vector2(1f, 1f)); //右上
        vh.AddVert(new Vector3(width, 0), vertColor, new Vector2(1f, 0f)); //右下

        //顺时针
        vh.AddTriangle(0, 1, 2);
        vh.AddTriangle(2, 3, 0);
    }

#if UNITY_EDITOR
    protected void OnValidate()
    {
        UpdateRenderer();
    }

#endif

}