有些项目需要根据设备性能自动修改Quality的设置，如何判断设备性能已经在上一篇中讲过了。这一篇把判断设备性能和设置质量放到一起去，形成静态类工具。
调用方式如下：

using UnityEngine;

public class Test : MonoBehaviour
{

    void Start()
    {
        Debug.Log(DevicePerformanceUtil.GetDevicePerformanceLevel());
        //根据设备配置自动设置质量
        DevicePerformanceUtil.ModifySettingsBasedOnPerformance();
        //手动设置质量
        //DevicePerformanceUtil.SetQualitySettings(QualityLevel.Low);
    }
}

工具脚本：

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

/// <summary>
/// 硬件设备性能适配工具
/// </summary>
public static class DevicePerformanceUtil
{
    /// <summary>
    /// 获取设备性能评级
    /// </summary>
    /// <returns>性能评级</returns>
    public static DevicePerformanceLevel GetDevicePerformanceLevel()
    {
        if (SystemInfo.graphicsDeviceVendorID == 32902)
        {
            //集显
            return DevicePerformanceLevel.Low;
        }
        else //NVIDIA系列显卡（N卡）和AMD系列显卡
        {
            //根据目前硬件配置三个平台设置了不一样的评判标准（仅个人意见）
            //CPU核心数
#if UNITY_EDITOR || UNITY_STANDALONE_WIN
            if (SystemInfo.processorCount <= 2)
#elif UNITY_STANDALONE_OSX || UNITY_IPHONE
            if (SystemInfo.processorCount < 2)
#elif UNITY_ANDROID
            if (SystemInfo.processorCount <= 4)
#endif
            {
                //CPU核心数<=2判定为低端
                return DevicePerformanceLevel.Low;
            }
            else
            {
                //显存
                int graphicsMemorySize = SystemInfo.graphicsMemorySize;
                //内存
                int systemMemorySize = SystemInfo.systemMemorySize;
#if UNITY_EDITOR || UNITY_STANDALONE_WIN
                if (graphicsMemorySize >= 4000 && systemMemorySize >= 8000)
                    return DevicePerformanceLevel.High;
                else if (graphicsMemorySize >= 2000 && systemMemorySize >= 4000)
                    return DevicePerformanceLevel.Mid;
                else
                    return DevicePerformanceLevel.Low;
#elif UNITY_STANDALONE_OSX || UNITY_IPHONE
            if (graphicsMemorySize >= 4000 && systemMemorySize >= 8000)
                    return DevicePerformanceLevel.High;
                else if (graphicsMemorySize >= 2000 && systemMemorySize >= 4000)
                    return DevicePerformanceLevel.Mid;
                else
                    return DevicePerformanceLevel.Low;
#elif UNITY_ANDROID
            if (graphicsMemorySize >= 6000 && systemMemorySize >= 8000)
                    return DevicePerformanceLevel.High;
                else if (graphicsMemorySize >= 2000 && systemMemorySize >= 4000)
                    return DevicePerformanceLevel.Mid;
                else
                    return DevicePerformanceLevel.Low;
#endif
            }
        }
    }

    /// <summary>
    /// 根据手机性能修改项目设置
    /// </summary>
    /// <param name="lowQuality">QualitySettings中对应Low的等级</param>
    /// <param name="midQuality">QualitySettings中对应Mid的等级</param>
    /// <param name="highQuality">QualitySettings中对应High的等级</param>
    public static void ModifySettingsBasedOnPerformance(int lowQuality, int midQuality, int highQuality)
    {
        DevicePerformanceLevel level = GetDevicePerformanceLevel();
        switch (level)
        {
            case DevicePerformanceLevel.Low:
                QualitySettings.SetQualityLevel(lowQuality, true);
                break;
            case DevicePerformanceLevel.Mid:
                QualitySettings.SetQualityLevel(midQuality, true);
                break;
            case DevicePerformanceLevel.High:
                QualitySettings.SetQualityLevel(highQuality, true);
                break;
        }
    }

    /// <summary>
    /// 根据机型配置自动设置质量
    /// </summary>
    public static void ModifySettingsBasedOnPerformance()
    {
        DevicePerformanceLevel level = GetDevicePerformanceLevel();
        switch (level)
        {
            case DevicePerformanceLevel.Low:
                SetQualitySettings(QualityLevel.Low);
                break;
            case DevicePerformanceLevel.Mid:
                SetQualitySettings(QualityLevel.Mid);
                break;
            case DevicePerformanceLevel.High:
                SetQualitySettings(QualityLevel.High);
                break;
        }
    }

    /// <summary>
    /// 根据自身需要调整各级别需要修改的设置，可根据需求修改低中高三种方案某一项具体设置
    /// </summary>
    /// <param name="qualityLevel">质量等级</param>
    public static void SetQualitySettings(QualityLevel qualityLevel)
    {
        switch (qualityLevel)
        {
            case QualityLevel.Low:
                //前向渲染使用的像素灯的最大数量，建议最少为1
                QualitySettings.pixelLightCount = 2;
                //你可以设置使用最大分辨率的纹理或者部分纹理（低分辨率纹理的处理开销低）。选项有 0_完整分辨率，1_1/2分辨率，2_1/4分辨率，3_1/8分辨率
                QualitySettings.masterTextureLimit = 1;
                //设置抗锯齿级别。选项有​​ 0_不开启抗锯齿，2_2倍，4_4倍和8_8倍采样。
                QualitySettings.antiAliasing = 0;
                //是否使用粒子软融合
                QualitySettings.softParticles = false;
                //启用实时反射探针，此设置需要用的时候再打开
                QualitySettings.realtimeReflectionProbes = false;
                //如果启用，公告牌将面向摄像机位置而不是摄像机方向。似乎与地形系统有关，此处没啥必要打开
                QualitySettings.billboardsFaceCameraPosition = false;
                //设置软硬阴影是否打开
                QualitySettings.shadows = ShadowQuality.Disable;
                //设置垂直同步方案，VSyncs数值需要在每帧之间传递，使用0为不等待垂直同步。值必须是0，1或2。
                QualitySettings.vSyncCount = 0;
                break;
            case QualityLevel.Mid:
                QualitySettings.pixelLightCount = 4;
                QualitySettings.antiAliasing = 2;
                QualitySettings.softParticles = false;
                QualitySettings.realtimeReflectionProbes = true;
                QualitySettings.billboardsFaceCameraPosition = true;
                QualitySettings.shadows = ShadowQuality.HardOnly;
                QualitySettings.vSyncCount = 2;
                break;
            case QualityLevel.High:
                QualitySettings.pixelLightCount = 4;
                QualitySettings.antiAliasing = 8;
                QualitySettings.softParticles = true;
                QualitySettings.realtimeReflectionProbes = true;
                QualitySettings.billboardsFaceCameraPosition = true;
                QualitySettings.shadows = ShadowQuality.All;
                QualitySettings.vSyncCount = 2;
                break;
        }
    }
}
public enum DevicePerformanceLevel
{
    Low,
    Mid,
    High
}
public enum QualityLevel
{
    Low,
    Mid,
    High
}