unity实现玻璃效果

一、使用Cubemap，做一个假反射



shader代码如下:

Shader "Custom/glassShader" {
Properties {
_MainColor("Main Color",Color)=(1,1,1,1)
_MainTex ("Base (RGB)", 2D) = "white" {}
_Cube("Cube",CUBE)=""{}
}
SubShader {
Tags {"RenderType"="Opaque"}
LOD 200

//cull off

CGPROGRAM
#pragma surface surf Lambert alpha

fixed4 _MainColor;
sampler2D _MainTex;
samplerCUBE _Cube;

struct Input {
float2 uv_MainTex;
float3 worldRefl;
};

void surf (Input IN, inout SurfaceOutput o) {
half4 c = tex2D (_MainTex, IN.uv_MainTex);
o.Albedo = c.rgb*_MainColor.rgb;
o.Emission=texCUBE(_Cube,IN.worldRefl).rgb;
o.Alpha = c.a*_MainColor.a;
}
ENDCG
}

FallBack "Diffuse"
}

二、使用GrabPass，抓取屏幕纹理,实现实时反射

shader代码如下:

Shader "Unlit/GrabGlass"
{
Properties
{
_Color("Main Color",Color)=(1,1,1,1)
_MainTex ("Texture", 2D) = "white" {}
}
SubShader
{

Tags {"Queue"="Transparent" "RenderType"="Opaque" }//Opaque
LOD 100

//绘制半透明物体 关闭深度缓存
ZWrite Off
//透明混合
Blend SrcAlpha OneMinusSrcAlpha

//如果没有命名,则可以用_GrabTexture来读取,不过开销很大,应用到特殊效果时才去应用
GrabPass
{
"_GrabTex"
}

Pass
{
CGPROGRAM
#pragma vertex vert
#pragma fragment frag
// make fog work
#pragma multi_compile_fog

#include "UnityCG.cginc"

struct appdata
{
float4 vertex : POSITION;
float2 uv : TEXCOORD0;
};

struct v2f
{
float2 uv : TEXCOORD0;
UNITY_FOG_COORDS(1)
float4 vertex : SV_POSITION;
};

sampler2D _MainTex;
float4 _MainTex_ST;
fixed4 _Color;
sampler2D _GrabTex;

v2f vert (appdata v)
{
v2f o;
o.vertex = mul(UNITY_MATRIX_MVP, v.vertex);
o.uv = TRANSFORM_TEX(v.uv, _MainTex);
UNITY_TRANSFER_FOG(o,o.vertex);
return o;
}

fixed4 frag (v2f i) : SV_Target
{
// sample the texture
fixed4 col = tex2D(_MainTex, i.uv)*_Color;

// apply fog
UNITY_APPLY_FOG(i.fogCoord, col);
//调整一下uv
float2 uv=i.uv;
uv.x=1-uv.x;
return col*tex2D(_GrabTex,uv);
}
ENDCG
}
}
}

效果如下:



三、使用摄像机实现实时反射

因为GrabPass,相对来说消耗较大,只建议用于一些特殊效果，于是这里就借助辅助摄像机，来实现实时反射效果，当然这需要多写一个脚本，同时需要在辅助摄像机中屏蔽玻璃本身

shader代码如下:

Shader "Unlit/CameraGlass"
{
Properties
{
_MainTex ("Texture", 2D) = "white" {}
}
SubShader
{
Tags { "RenderType"="Opaque" }
LOD 100

Pass
{
CGPROGRAM
#pragma vertex vert
#pragma fragment frag
// make fog work
#pragma multi_compile_fog

#include "UnityCG.cginc"

struct appdata
{
float4 vertex : POSITION;
float2 uv : TEXCOORD0;
};

struct v2f
{
float2 uv : TEXCOORD0;
UNITY_FOG_COORDS(1)
float4 vertex : SV_POSITION;
};

sampler2D _MainTex;
float4 _MainTex_ST;

v2f vert (appdata v)
{
v2f o;
o.vertex = mul(UNITY_MATRIX_MVP, v.vertex);
o.uv = TRANSFORM_TEX(v.uv, _MainTex);
UNITY_TRANSFER_FOG(o,o.vertex);
return o;
}

fixed4 frag (v2f i) : SV_Target
{
// sample the texture  需要调整一下uv
fixed4 col = tex2D(_MainTex, 1-i.uv);
// apply fog
UNITY_APPLY_FOG(i.fogCoord, col);
return col;
}
ENDCG
}
}
}

脚本代码如下:

using UnityEngine;
using System.Collections;

public class RenderGlassTexture : MonoBehaviour {

/// <summary>
/// 辅助摄像机
/// 原理:就是将辅助摄像机所看到的内容渲染到玻璃物体上,所以就实现了实时反射的镜面效果
/// 因为玻璃也是场景中的物体,所以辅助摄像机也会看见他
/// 所以最好能将玻璃物体单独放在一个层级中,让辅助摄像机不去渲染他
/// </summary>
public Camera cam;
private RenderTexture renderTex;
/// <summary>
/// 玻璃shader
/// </summary>
public Shader glassShader;
/// <summary>
/// 玻璃材质
/// </summary>
private Material m_GlassMaterial;
protected Material GlassMaterial
{
get
{
if (m_GlassMaterial == null)
{
m_GlassMaterial = new Material(glassShader);
}
return m_GlassMaterial;
}
}

// Use this for initialization
void Start () {
renderTex = new RenderTexture(Screen.width, Screen.height, 16);
cam.targetTexture = renderTex;
}

//在摄像机开始裁剪场景之前调用
void OnPreCull()
{
GlassMaterial.SetTexture("_MainTex", renderTex);
}

//在相机完成场景渲染后调用
void OnPostRender()
{
GlassMaterial.SetTexture("_MainTex", null);
}
}

效果如下: