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前言

仅适用于VRAR项目！
需求：
人物说话时：头旁边出现说话内容，且根据内容长短，以打字效果的方式，进行向下自动扩充，并且UI复用，可以多人物使用。
功能：
1.永远朝向相机
2.打字效果
3.UI不会被模型遮挡
4.切换位置
5.文字自动根据内容扩充
效果：

一、UI搭建

1.创建基节点

创建空物体作为UI的父节点，改名字：UIDialog，因为是3dUI，大小和高度根据自己的情况调节即可

2.创建Canvas

因为是VR项目，所以就用XR创建Canvas：在Hierarchy面板中右击鼠标–>XR–>UICanvas

3.添加永远看向相机代码

using UnityEngine;public class LookatPlayer : MonoBehaviour
{Camera MainCamera;void Awake(){MainCamera = Camera.main;if (MainCamera == null){Debug.LogError("没有找到MainCamera");return;}}void Update(){this.transform.LookAt(MainCamera.transform);// this.transform.forward = Vector3.forward;this.transform.localRotation = Quaternion.Euler(new Vector3(0, this.transform.localRotation.eulerAngles.y, 0));}
}

4.创建UI背景，设置相关操作

1.锚点设置

把Pivot的Y改为：1，即可。作业：扩张时会向下，扩展。

2.添加组件：Vertical Layout Group、Content Size Fitter

Vertical Layout Group：竖向排列 （横向排列：Horizontal Layout Group）
Content Size Fitter：根据子物体内容多少扩展（可根据需求设置：横向或者竖向，如下图）

3.添加文本

我选择添加旧版文本：Text (Legacy)，并没有使用Text (TMP)，原因是后面要做一个UI不被模型遮挡的效果。
但是TextMeshPro - Text (UI)组件效果更好

二、UI不被模型遮挡

如果UI设置跟随，或者当前位置模型太多，会出现UI被模型挡住，看不全UI面板的内容。
所有Text、Image都需要指定该shader


效果图：

使用Shader修改渲染层级

// Unity built-in shader source. Copyright (c) 2016 Unity Technologies. MIT license (see license.txt)Shader "Custom/UIForground"
{Properties{[PerRendererData] _MainTex ("Sprite Texture", 2D) = "white" {}_Color ("Tint", Color) = (1,1,1,1)_StencilComp ("Stencil Comparison", Float) = 8_Stencil ("Stencil ID", Float) = 0_StencilOp ("Stencil Operation", Float) = 0_StencilWriteMask ("Stencil Write Mask", Float) = 255_StencilReadMask ("Stencil Read Mask", Float) = 255_ColorMask ("Color Mask", Float) = 15[Toggle(UNITY_UI_ALPHACLIP)] _UseUIAlphaClip ("Use Alpha Clip", Float) = 0}SubShader{Tags{"Queue"="Transparent""IgnoreProjector"="True""RenderType"="Transparent""PreviewType"="Plane""CanUseSpriteAtlas"="True"}Stencil{Ref [_Stencil]Comp [_StencilComp]Pass [_StencilOp]ReadMask [_StencilReadMask]WriteMask [_StencilWriteMask]}Cull OffLighting OffZWrite Off//ZTest [unity_GUIZTestMode]ZTest AlwaysBlend One OneMinusSrcAlphaColorMask [_ColorMask]Pass{Name "Default"CGPROGRAM#pragma vertex vert#pragma fragment frag#pragma target 2.0#include "UnityCG.cginc"#include "UnityUI.cginc"#pragma multi_compile_local _ UNITY_UI_CLIP_RECT#pragma multi_compile_local _ UNITY_UI_ALPHACLIPstruct appdata_t{float4 vertex   : POSITION;float4 color    : COLOR;float2 texcoord : TEXCOORD0;UNITY_VERTEX_INPUT_INSTANCE_ID};struct v2f{float4 vertex   : SV_POSITION;fixed4 color    : COLOR;float2 texcoord  : TEXCOORD0;float4 worldPosition : TEXCOORD1;half4  mask : TEXCOORD2;UNITY_VERTEX_OUTPUT_STEREO};sampler2D _MainTex;fixed4 _Color;fixed4 _TextureSampleAdd;float4 _ClipRect;float4 _MainTex_ST;float _UIMaskSoftnessX;float _UIMaskSoftnessY;v2f vert(appdata_t v){v2f OUT;UNITY_SETUP_INSTANCE_ID(v);UNITY_INITIALIZE_VERTEX_OUTPUT_STEREO(OUT);float4 vPosition = UnityObjectToClipPos(v.vertex);OUT.worldPosition = v.vertex;OUT.vertex = vPosition;float2 pixelSize = vPosition.w;pixelSize /= float2(1, 1) * abs(mul((float2x2)UNITY_MATRIX_P, _ScreenParams.xy));float4 clampedRect = clamp(_ClipRect, -2e10, 2e10);float2 maskUV = (v.vertex.xy - clampedRect.xy) / (clampedRect.zw - clampedRect.xy);OUT.texcoord = TRANSFORM_TEX(v.texcoord.xy, _MainTex);OUT.mask = half4(v.vertex.xy * 2 - clampedRect.xy - clampedRect.zw, 0.25 / (0.25 * half2(_UIMaskSoftnessX, _UIMaskSoftnessY) + abs(pixelSize.xy)));OUT.color = v.color * _Color;return OUT;}fixed4 frag(v2f IN) : SV_Target{half4 color = IN.color * (tex2D(_MainTex, IN.texcoord) + _TextureSampleAdd);#ifdef UNITY_UI_CLIP_RECThalf2 m = saturate((_ClipRect.zw - _ClipRect.xy - abs(IN.mask.xy)) * IN.mask.zw);color.a *= m.x * m.y;#endif#ifdef UNITY_UI_ALPHACLIPclip (color.a - 0.001);#endifcolor.rgb *= color.a;return color;}ENDCG}}
}

三、打字效果代码

using System.Collections;
using System.Collections.Generic;
using Twq;
using UnityEngine;
using UnityEngine.UI;
/// <summary>
/// 对话框(3DUI，可换到任意人物头部位置)
/// </summary>
public class UICS_Dialog : SingletonMono<UICS_Dialog>
{public GameObject Mask;float Speed = 10;public  Text textLabel;void Start(){// GetText("作业负责人：进入场景后，弹出界面对任务进行一个介绍，可以视频、文字，点击开始");}/// <summary>/// 获得文字/// </summary>/// <param name="textToType"></param>public void GetText(string text_){StartCoroutine(WriteText(text_));}/// <summary>/// 写出来/// </summary>/// <param name="textToType"></param>/// <returns></returns>IEnumerator WriteText(string text_){float t = 0;//经过的时间int charIndex = 0;//字符串索引值while (charIndex < text_.Length){t += Time.deltaTime * Speed;//简单计时器赋值给tcharIndex = Mathf.FloorToInt(t);//把t转为int类型赋值给charIndexcharIndex = Mathf.Clamp(charIndex, 0, text_.Length);textLabel.text = text_.Substring(0, charIndex);yield return null;}textLabel.text = text_;}/// <summary>/// 设置UI/// </summary>/// <param name="bo">UI显隐开关</param>/// <param name="parentTran">父节点</param>/// <param name="textStr">文字内容</param>public void SetState(bool bo, Transform parentTran, string textStr){this.transform.SetParent(parentTran);//设置父节点this.transform.position = new Vector3(0,1.345f,0);//设置固定高度this.transform.Rotate(new Vector3(0,0,0)); //设置旋转Mask.SetActive(bo);//设置UI显隐if (bo){GetText(textStr);}}}

总结

好记性不如烂笔头！