Unity3D仿星露谷物语开发17之空库存栏UI

1、目标

将库存栏放在游戏界面中，一般情况下角色居中展示时库存栏在底部，当角色位于界面下方时库存栏展示在顶部避免遮挡。

2、CanvasGroup组件

用于集中控制UI元素的透明度、交互性和射线投射行为。CanvasGroup的Alpha属性允许渐变效果，Interactable决定元素是否可交互，BlocksRaycasts影响图形射线检测，而IgnoreParentGroups选项则控制是否忽略父对象的CanvasGroup设置。这些特性在创建互动游戏场景时尤为有用。

3、Aspect Ratio Fitter组件

Aspect Ratio Fitter 组件的核心作用是按照给定的宽高比调整 UI 元素的尺寸。它可以根据宽度调整高度，也可以根据高度调整宽度，从而确保 UI 元素的宽高比始终固定，不会因为外部布局的变化而拉伸或压缩。

它有以下几种模式：

None：不做任何宽高比调整，元素保持原始尺寸。
Width Controls Height：根据宽度来调整高度，确保元素的宽高比保持不变。
Height Controls Width：根据高度来调整宽度，以确保比例正确。
Fit In Parent：在父容器内缩放元素，保持宽高比不变，同时确保元素的大小适合父容器。
Envelope Parent：让元素包裹住父容器，保持比例，同时元素可能会超过父容器的边界。

这个属性用于设置 UI 元素的目标宽高比。通常，宽高比是通过 宽度 / 高度 的形式表示。例如，如果想保持 16:9 的比例，则需要将 Aspect Ratio 设置为 16 / 9。

4、创建UI

在Hierarchy -> PersistentScene中创建空对象命名为UI。

在UI下创建Canvas命名为MainGameUICanvas。Canvas是UI组件的容器。相关属性设置如下：

在MainGameUICanvas下创建空物体命名为UICanvasGroup，添加两个组件Canvas Group和Aspect Ratio Fitter。

在UICanvasGroup下创建空物体命名为UIInventoryBar。

添加Image组件，并设置下列属性。

对于位置信息，按Shift + Alt键选中中间底部，此时Pos X/Y/Z均为0，修改Pos Y为2.5。

（Shift -> Shift + Alt键）

效果如下：

5、编写脚本

在Assets -> Scripts下新增UI目录，同时新增UIInventory子目录，在此目录下新增UIInventorybar.cs脚本。

（1）优化Player类

首先，我们需要根据角色的位置判断bar到底是处于底部还是顶部，所以Player类需要对外提供坐标信息，而且是相对屏幕的坐标。

修改Player.cs如下：

private Camera mainCamera;mainCamera = Camera.main;public Vector3 GetPlayerViewportPosition()
{// Vector3 viewport position for player (0,0) viewport bottom left, (1,1) viewport top rightreturn mainCamera.WorldToViewportPoint(gameObject.transform.position);
}

此时Player.cs完整代码如下：

using System.Collections;
using System.Collections.Generic;
using UnityEngine;public class Player : SingletonMonobehaviour<Player>
{private float xInput;private float yInput;private bool isWalking;private bool isRunning;private bool isIdle;private bool isCarrying = false;private ToolEffect toolEffect = ToolEffect.none;private bool isUsingToolRight;private bool isUsingToolLeft;private bool isUsingToolUp;private bool isUsingToolDown;private bool isLiftingToolRight;private bool isLiftingToolLeft;private bool isLiftingToolUp;private bool isLiftingToolDown;private bool isPickingRight;private bool isPickingLeft;private bool isPickingUp;private bool isPickingDown;private bool isSwingToolRight;private bool isSwingToolLeft;private bool isSwingToolUp;private bool isSwingToolDown;private Camera mainCamera;private Rigidbody2D rigidbody2D;private Direction playerDirection;private float movementSpeed;private bool _playerInputIsDisabled = false;public bool PlayerInputIsDisabled { get => _playerInputIsDisabled; set => _playerInputIsDisabled = value; }protected override void Awake(){base.Awake();rigidbody2D = GetComponent<Rigidbody2D>();mainCamera = Camera.main;}private void Update(){#region  Player InputResetAnimationTrigger();PlayerMovementInput();PlayerWalkInput();// Send event to any listeners for player movement inputEventHandler.CallMovementEvent(xInput, yInput, isWalking, isRunning, isIdle, isCarrying, toolEffect,isUsingToolRight, isUsingToolLeft, isUsingToolUp, isUsingToolDown,isLiftingToolRight, isLiftingToolLeft, isLiftingToolUp, isLiftingToolDown,isPickingRight, isPickingLeft, isPickingUp, isPickingDown,isSwingToolRight, isSwingToolLeft, isSwingToolUp, isSwingToolDown,false, false, false, false);#endregion}private void FixedUpdate(){PlayerMovement();}private void PlayerMovement(){Vector2 move = new Vector2(xInput * movementSpeed * Time.deltaTime, yInput * movementSpeed * Time.deltaTime);rigidbody2D.MovePosition(rigidbody2D.position + move);}private void ResetAnimationTrigger(){toolEffect = ToolEffect.none;isUsingToolRight = false;isUsingToolLeft = false;isUsingToolUp = false;isUsingToolDown = false;isLiftingToolRight = false;isLiftingToolLeft = false;isLiftingToolUp = false;isLiftingToolDown = false;isPickingRight = false;isPickingLeft = false;isPickingUp = false;isPickingDown = false;isSwingToolRight = false;isSwingToolLeft = false;isSwingToolUp = false;isSwingToolDown = false;}private void PlayerMovementInput(){xInput = Input.GetAxisRaw("Horizontal");yInput = Input.GetAxisRaw("Vertical");// 斜着移动if (xInput != 0 && yInput != 0) {xInput = xInput * 0.71f;yInput = yInput * 0.71f;}// 在移动if (xInput != 0 || yInput != 0) {isRunning = true;isWalking = false;isIdle = false;movementSpeed = Settings.runningSpeed;// Capture player direction for save gameif (xInput < 0){playerDirection = Direction.left;}else if (xInput > 0){playerDirection = Direction.right;}else if (yInput < 0){playerDirection = Direction.down;}else{playerDirection = Direction.up;}}else if(xInput == 0 && yInput == 0){isRunning = false;isWalking = false;isIdle = true;}}// 按住Shift键移动为walkprivate void PlayerWalkInput(){if(Input.GetKey(KeyCode.LeftShift) || Input.GetKey(KeyCode.RightShift)){isRunning = false;isWalking = true;isIdle = false;movementSpeed = Settings.walkingSpeed;}else{isRunning = true;isWalking = false;isIdle = false;movementSpeed = Settings.runningSpeed;}}public Vector3 GetPlayerViewportPosition(){// Vector3 viewport position for player (0,0) viewport bottom left, (1,1) viewport top rightreturn mainCamera.WorldToViewportPoint(gameObject.transform.position);}
}

（2）编写UIInventorybar类

using System;
using System.Collections;
using System.Collections.Generic;
using UnityEngine;public class UIInventoryBar : MonoBehaviour
{private RectTransform rectTransform;private bool _isInventoryBarPositionBottom = true;public bool IsInventoryBarPositionBottom { get { return _isInventoryBarPositionBottom;} set { _isInventoryBarPositionBottom = value; } }private void Awake(){rectTransform = GetComponent<RectTransform>();}private void Update(){// Switch inventory bar position depending on player positionSwitchInventoryBarPosition();}private void SwitchInventoryBarPosition(){Vector3 playerViewportPosition = Player.Instance.GetPlayerViewportPosition();if (playerViewportPosition.y > 0.3f && IsInventoryBarPositionBottom == false){rectTransform.pivot = new Vector2(0.5f, 0f);rectTransform.anchorMin = new Vector2(0.5f, 0f);rectTransform.anchorMax = new Vector2(0.5f, 0f);rectTransform.anchoredPosition = new Vector2(0f, 2.5f);IsInventoryBarPositionBottom = true;}else if (playerViewportPosition.y <= 0.3f && IsInventoryBarPositionBottom == true) {rectTransform.pivot = new Vector2(0.5f, 1f);rectTransform.anchorMin = new Vector2(0.5f, 1f);rectTransform.anchorMax = new Vector2(0.5f, 1f);rectTransform.anchoredPosition = new Vector2(0f, -2.5f);IsInventoryBarPositionBottom = false;}}
}

以上参数的值对应Rect Transform的值，比如当位于底部时：