Unity中用Shader实现镜子效果_mirror shaders

做项目的时候要用到镜子，折腾了一下午，发现做镜子还是蛮快的，总结了一下网上的教程，大致有这么几种做法：

1、使用反射探针（Reflection Probe）

2、使用Render Texture

3、使用Shader着色器，我发现这种方法步骤比较少，而且重复使用起来也方便

下面就介绍一下这个方法，以及期间我踩过的坑；官方的教程在这里：MirrorReflection4

（我之所以说比较简单，是因为Shader方法可以用网上现成的代码，基本不用改

话不多说进入正题：

首先利用Shader做镜子，需要两段代码，一个是.shader着色器代码，另一个是C#脚本代码

着色器代码如下：

Mirror.shader

Shader "FX/MirrorReflection"
{
	Properties
	{
		_MainTex ("Base (RGB)", 2D) = "white" {}
		[HideInInspector] _ReflectionTex ("", 2D) = "white" {}
	}
	SubShader
	{
		Tags { "RenderType"="Opaque" }
		LOD 100
 
		Pass {
			CGPROGRAM
			#pragma vertex vert
			#pragma fragment frag
			#include "UnityCG.cginc"
			struct v2f
			{
				float2 uv : TEXCOORD0;
				float4 refl : TEXCOORD1;
				float4 pos : SV_POSITION;
			};
			float4 _MainTex_ST;
			v2f vert(float4 pos : POSITION, float2 uv : TEXCOORD0)
			{
				v2f o;
				o.pos = mul (UNITY_MATRIX_MVP, pos);
				o.uv = TRANSFORM_TEX(uv, _MainTex);
				o.refl = ComputeScreenPos (o.pos);
				return o;
			}
			sampler2D _MainTex;
			sampler2D _ReflectionTex;
			fixed4 frag(v2f i) : SV_Target
			{
				fixed4 tex = tex2D(_MainTex, i.uv);
				fixed4 refl = tex2Dproj(_ReflectionTex, UNITY_PROJ_COORD(i.refl));
				return tex * refl;
			}
			ENDCG
	    }
	}
}

C#脚本代码如下：

MirrorReflection.cs

using UnityEngine;
using System.Collections;
 
// This is in fact just the Water script from Pro Standard Assets,
// just with refraction stuff removed.
 
[ExecuteInEditMode] // Make mirror live-update even when not in play mode
public class MirrorReflection : MonoBehaviour
{
	public bool m_DisablePixelLights = true;
	public int m_TextureSize = 256;
	public float m_ClipPlaneOffset = 0.07f;
 
	public LayerMask m_ReflectLayers = -1;
 
	private Hashtable m_ReflectionCameras = new Hashtable(); // Camera -> Camera table
 
	private RenderTexture m_ReflectionTexture = null;
	private int m_OldReflectionTextureSize = 0;
 
	private static bool s_InsideRendering = false;
 
	// This is called when it's known that the object will be rendered by some
	// camera. We render reflections and do other updates here.
	// Because the script executes in edit mode, reflections for the scene view
	// camera will just work!
	public void OnWillRenderObject()
	{
		var rend = GetComponent<Renderer>();
		if (!enabled || !rend || !rend.sharedMaterial || !rend.enabled)
			return;