Unity3D实现渐变颜色效果

using System;using System.Collections.Generic;using UnityEngine;using UnityEngine.UI; namespace ExtraFoundation.Components{ [AddComponentMenu("UI/Effects/Gradient")] public class UIGradient : BaseMeshEffect { #region Public Declarations public enum Type {  Vertical,  Horizontal } #endregion  #region Public Properties public Type GradientType = Type.Vertical; [Range(-1f, 1f)] public float Offset = 0f; public Gradient gradient; #endregion  #region Public Methods public override void ModifyMesh(VertexHelper helper) {  if (!IsActive() || helper.currentVertCount == 0)  {  return;  }   vertexList.Clear();  helper.GetUIVertexStream(vertexList);   int nCount = vertexList.Count;  switch (GradientType)  {  case Type.Vertical:   {   float fBottomY = vertexList[0].position.y;   float fTopY = vertexList[0].position.y;   float fYPos = 0f;    for (int i = nCount - 1; i >= 1; --i)   {    fYPos = vertexList[i].position.y;    if (fYPos > fTopY)    fTopY = fYPos;    else if (fYPos < fBottomY)    fBottomY = fYPos;   }    float fUIElementHeight = 1f / (fTopY - fBottomY);   UIVertex v = new UIVertex();    for (int i = 0; i < helper.currentVertCount; i++)   {    helper.PopulateUIVertex(ref v, i);    v.color = gradient.Evaluate((v.position.y - fBottomY) *    fUIElementHeight - Offset);    helper.SetUIVertex(v, i);   }   }   break;  case Type.Horizontal:   {   float fLeftX = vertexList[0].position.x;   float fRightX = vertexList[0].position.x;   float fXPos = 0f;    for (int i = nCount - 1; i >= 1; --i)   {    fXPos = vertexList[i].position.x;    if (fXPos > fRightX)    fRightX = fXPos;    else if (fXPos < fLeftX)    fLeftX = fXPos;   }    float fUIElementWidth = 1f / (fRightX - fLeftX);   UIVertex v = new UIVertex();    for (int i = 0; i < helper.currentVertCount; i++)   {    helper.PopulateUIVertex(ref v, i);    v.color = gradient.Evaluate((v.position.x - fLeftX) *    fUIElementWidth - Offset);    helper.SetUIVertex(v, i);   }    }   break;  default:   break;  } } #endregion  #region Internal Fields private List<UIVertex> vertexList = new List<UIVertex>(); #endregion }}