Unity中实现UI渐变

Posted 2022-04-28 Hello Bug.

一：效果演示

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二：使用

TopColor：顶部颜色
BottomColor：底部颜色

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三：代码实现

using System.Collections.Generic;
using UnityEngine;
using UnityEngine.UI;

[DisallowMultipleComponent]
[AddComponentMenu("LFramework/UI/Effects/Gradient", 1)]
public class Gradient : BaseMeshEffect

    //顶部颜色
    [SerializeField]
    Color32 m_TopColor = Color.white;
    public Color32 TopColor
    
        get
        
            return m_TopColor;
        
        set
        
            m_TopColor = value;
            graphic.SetVerticesDirty();
        
    

    //底部颜色
    [SerializeField]
    Color32 m_BottomColor = Color.black;
    public Color32 BottomColor
    
        get
        
            return m_BottomColor;
        
        set
        
            m_BottomColor = value;
            graphic.SetVerticesDirty();
        
    

    //顶点缓存
    List<UIVertex> vertexCache = new List<UIVertex>();

    public override void ModifyMesh(VertexHelper vh)
    
        if (!IsActive())
        
            return;
        

        vh.GetUIVertexStream(vertexCache);

        ApplyGradient(vertexCache);

        vh.Clear();
        vh.AddUIVertexTriangleStream(vertexCache);
        vertexCache.Clear();
    

    void ApplyGradient(List<UIVertex> vertexCache)
    
        if (vertexCache.Count == 0)
        
            return;
        

        float topY = vertexCache[0].position.y;
        float bottomY = vertexCache[0].position.y;
        foreach (var vertex in vertexCache)
        
            if (vertex.position.y > topY)
            
                topY = vertex.position.y;
            
            else if (vertex.position.y < bottomY)
            
                bottomY = vertex.position.y;
            
        

        float centerY = (topY + bottomY) / 2;
        int vertexCount = vertexCache.Count;
        for (int i = 0; i < vertexCount; i++)
        
            UIVertex veretx = vertexCache[i];
            if (veretx.position.y < centerY)
            
                veretx.color = m_BottomColor;
            
            else
            
                veretx.color = m_TopColor;
            
            vertexCache[i] = veretx;
        
    

    //int vertexCount = vertexCache.Count;
    //for (int i = 0; i < vertexCount; i++)
    //
    //    UIVertex veretx = vertexCache[i];
    //    if (i % 6 == 0 || i % 6 == 1 || i % 6 == 5)
    //    
    //        veretx.color = m_TopColor;
    //    
    //    else
    //    
    //        veretx.color = m_BottomColor;
    //    
    //    vertexCache[i] = veretx;
    //