Unity3D仿星露谷物语开发11之添加Scenary Fader

1、目标

当角色移动到草/树的后面时，因为草/树层级优先级大于等于角色，导致角色无法全部展示。

如下图所示，草遮挡了一半的角色，而树则遮挡了全部的角色。

我们希望当角色走到草/树的后面时，草/树能够改变透明度（不再是1），从而在Game界面可以看到角色。

2、创建Fader脚本

该程序执行物体淡出 / 淡入的操作。

淡出时：会在指定时间内减少alpha值到某个值

淡入时：会在指定时间内增加alpha值到1。

当玩家与物体碰撞(Trigger)后会执行淡出操作，当玩家离开物体后会执行淡入操作。

（1）Settings中配置参数值

在Assets -> Scripts -> Misc -> Settings.cs中新增代码如下：

// Obscuring Item Fader
public const float fadeInSeconds = 0.25f;
public const float fadeOutSeconds = 0.35f;
public const float targetAlpha = 0.45f;

目前Settings.cs的完整代码如下：

using UnityEngine;

public static class Settings
{
    // Obscuring Item Fader
    public const float fadeInSeconds = 0.25f;
    public const float fadeOutSeconds = 0.35f;
    public const float targetAlpha = 0.45f;

    // Player Movement
    public const float runningSpeed = 5.333f;
    public const float walkingSpeed = 2.666f;

    // Player Animation Parameters
    public static int xInput;
    public static int yInput;
    public static int isWalking;
    public static int isRunning;
    public static int toolEffect;
    public static int isUsingToolRight;
    public static int isUsingToolLeft;
    public static int isUsingToolUp;
    public static int isUsingToolDown;
    public static int isLiftingToolRight;
    public static int isLiftingToolLeft;
    public static int isLiftingToolUp;
    public static int isLiftingToolDown;
    public static int isSwingingToolRight;
    public static int isSwingingToolLeft;
    public static int isSwingingToolUp;
    public static int isSwingingToolDown;
    public static int isPickingRight;
    public static int isPickingLeft;
    public static int isPickingUp;
    public static int isPickingDown;

    // Shared Animation Parameters
    public static int idleUp;
    public static int idleDown;
    public static int idleLeft;
    public static int idleRight;


    // static constructor
    static Settings()
    {
        xInput = Animator.StringToHash("xInput");
        yInput = Animator.StringToHash("yInput");
        isWalking = Animator.StringToHash("isWalking");
        isRunning = Animator.StringToHash("isRunning");
        toolEffect = Animator.StringToHash("toolEffect");
        isUsingToolRight = Animator.StringToHash("isUsingToolRight");
        isUsingToolLeft = Animator.StringToHash("isUsingToolLeft");
        isUsingToolUp = Animator.StringToHash("isUsingToolUp");
        isUsingToolDown = Animator.StringToHash("isUsingToolDown");
        isLiftingToolRight = Animator.StringToHash("isLiftingToolRight");
        isLiftingToolLeft = Animator.StringToHash("isLiftingToolLeft");
        isLiftingToolUp = Animator.StringToHash("isLiftingToolUp");
        isLiftingToolDown = Animator.StringToHash("isLiftingToolDown");
        isSwingingToolRight = Animator.StringToHash("isSwingingToolRight");
        isSwingingToolLeft = Animator.StringToHash("isSwingingToolLeft");
        isSwingingToolUp = Animator.StringToHash("isSwingingToolUp");
        isSwingingToolDown = Animator.StringToHash("isSwingingToolDown");
        isPickingRight = Animator.StringToHash("isPickingRight");
        isPickingLeft = Animator.StringToHash("isPickingLeft");
        isPickingUp = Animator.StringToHash("isPickingUp");
        isPickingDown = Animator.StringToHash("isPickingDown");
        idleUp = Animator.StringToHash("idleUp");
        idleDown = Animator.StringToHash("idleDown");
        idleLeft = Animator.StringToHash("idleLeft");
        idleRight = Animator.StringToHash("idleRight");
    }

}

（2）淡入淡出效果的脚本

在Scripts下新建Item的目录。

并在其下创建ObscuringItemFader.cs脚本。

using System.Collections;
using UnityEngine;

[RequireComponent(typeof(SpriteRenderer))]
public class ObscuringItemFader : MonoBehaviour
{
    private SpriteRenderer spriteRenderer;

    // Start is called before the first frame update
    private void Awake()
    {
        spriteRenderer = gameObject.GetComponent<SpriteRenderer>();
    }

    public void FadeOut()
    {
        StartCoroutine(FadeOutRoutine());
    }

    public void FadeIn() 
    {
        StartCoroutine(FadeInRoutine());
    }

    private IEnumerator FadeInRoutine()
    {
        float currentAlpha = spriteRenderer.color.a;
        float distance = 1f - Settings.targetAlpha;

        while (1f - currentAlpha > 0.01f)
        {
            currentAlpha = currentAlpha + distance / Settings.fadeInSeconds * Time.deltaTime;
            spriteRenderer.color = new Color(1f, 1f, 1f, currentAlpha);
            yield return null;
        }

        spriteRenderer.color = new Color(1f, 1f, 1f, 1f);
    }

    private IEnumerator FadeOutRoutine()
    {
        float currentAlpha = spriteRenderer.color.a;
        float distance = currentAlpha - Settings.targetAlpha;

        while(currentAlpha - Settings.targetAlpha > 0.01f)
        {
            currentAlpha = currentAlpha - distance / Settings.fadeOutSeconds * Time.deltaTime;
            spriteRenderer.color = new Color(1f, 1f, 1f, currentAlpha);
            yield return null;
        }

        spriteRenderer.color = new Color(1f, 1f, 1f, Settings.targetAlpha);
    }
}

该脚本需要附加到与角色发生碰撞后需要模糊处理的物体上。

[RequireComponent(typeof(SpriteRenderer))]：该脚本使用的前提是当前对象有SpriteRenderer组件
distance / Settings.fadeOutSeconds * Time.deltaTime：每一帧的变动值。
SpriteRenderer的Color：默认的Color为(1f,1f,1f,1f）

yield return null：当使用yield return null时，协程会在下一帧继续执行。这意味着协程将暂停一帧，然后在下一帧继续执行。使用yield return null可以在每一帧之间进行操作，比如更新游戏对象的位置、旋转或者其他计算。

（3）触发淡入淡出的脚本

在Scripts -> Item目录下创建TriggerObscuringItemFader脚本。

using UnityEngine;

public class TriggerObscuringItemFader : MonoBehaviour
{

    private void OnTriggerEnter2D(Collider2D collision)
    {
        // Get the gameobject we have collided with, and then get all the Obscuring Item Fader components on it and its children - and then trigger the fade out
        ObscuringItemFader[] obscuringItemFaders = collision.gameObject.GetComponentsInChildren<ObscuringItemFader>();   

        if(obscuringItemFaders.Length > 0)
        {
            for(int i = 0; i < obscuringItemFaders.Length; i++)
            {
                obscuringItemFaders[i].FadeOut();
            }
        }
    }

    private void OnTriggerExit2D(Collider2D collision)
    {
        // Get the gameobject we have collided with, and then get all the Obscuring Item Fader components on it and its children - and then trigger the fade in
        ObscuringItemFader[] obscuringItemFaders = collision.gameObject.GetComponentsInChildren<ObscuringItemFader>();

        if (obscuringItemFaders.Length > 0)
        {
            for (int i = 0; i < obscuringItemFaders.Length; i++)
            {
                obscuringItemFaders[i].FadeIn();
            }
        }
    }

}

collision.gameObject 是碰撞中的另一个游戏对象。

GetComponentsInChildren<Type>() 是一个用于获取游戏对象及其所有子对象的组件的函数。