使用 GrabPass 来实现玻璃的效果
Shader "Unlit/GlassShader"
{
Properties
{
_MainTex ("Main Tex", 2D) = "white" {
}
_BumpMap ("Normal Tex", 2D) = "bump" {
}
_Cubemap ("Environment Cubemap", Cube) = "_Skybox" {
}
_Distortion ("Distortion", Range(0,100)) = 10
_RefractAmount ("Refract Amount", Range(0, 1)) = 1
}
SubShader
{
Tags {
"Queue" = "Transparent" "RenderType" = "Opaque" }
GrabPass {
"_RefractionTex" }
Pass
{
CGPROGRAM
#pragma vertex vert
#pragma fragment frag
#include <UnityCG.cginc>
struct a2v
{
float4 vertex : POSITION;
float3 normal : NORMAL;
float4 tangent : TANGENT;
float4 texcoord : TEXCOORD0;
};
struct v2f
{
float4 pos : SV_POSITION;
float4 scrPos : TEXCOORD0;
float4 uv : TEXCOORD1;
float4 TtoW0 : TEXCOORD2;
float4 TtoW1 : TEXCOORD3;
float4 TtoW2 : TEXCOORD4;
};
sampler2D _MainTex;
float4 _MainTex_ST;
sampler2D _BumpMap;
float4 _BumpMap_ST;
samplerCUBE _Cubemap;
float _Distortion;
fixed _RefractAmount;
sampler2D _RefractionTex;
float4 _RefractionTex_TexelSize;
v2f vert(a2v v)
{
v2f o;
o.pos = UnityObjectToClipPos(v.vertex.xyz);
o.scrPos = ComputeGrabScreenPos(o.pos);
o.uv.xy = TRANSFORM_TEX(v.texcoord, _MainTex);
o.uv.zw = TRANSFORM_TEX(v.texcoord, _BumpMap);
float3 worldPos = mul(unity_ObjectToWorld, v.vertex).xyz;
float3 worldNormal = UnityObjectToWorldNormal(v.normal);
float3 worldTangent = UnityObjectToWorldDir(v.tangent.xyz);
float3 worldBinormal = cross(worldNormal, worldTangent) * v.tangent.w;
o.TtoW0 = float4(worldTangent.x, worldBinormal.x, worldNormal.x, worldPos.x);
o.TtoW1 = float4(worldTangent.y, worldBinormal.y, worldNormal.y, worldPos.y);
o.TtoW2 = float4(worldTangent.z, worldBinormal.z, worldNormal.z, worldPos.z);
return o;
}
fixed4 frag(v2f i) : SV_Target
{
float3 worldPos = float3(i.TtoW0.w, i.TtoW1.w, i.TtoW2.w);
fixed3 viewDir = UnityWorldSpaceViewDir(worldPos);
fixed3 bump = UnpackNormal(tex2D(_BumpMap, i.uv.zw));
float2 offset = bump.xy * _Distortion * _RefractionTex_TexelSize.xy;
i.scrPos.xy = offset * i.scrPos.z + i.scrPos.xy;
fixed3 refrColor = tex2D(_RefractionTex, i.scrPos.xy / i.scrPos.w).rgb;
bump = normalize(half3(dot(i.TtoW0.xyz, bump), dot(i.TtoW1.xyz, bump), dot(i.TtoW2.xyz, bump)));
fixed3 reflDir = reflect(-viewDir, bump);
fixed4 texColor = tex2D(_MainTex, i.uv.xy);
fixed3 reflColor = texCUBE(_Cubemap, reflDir) * texColor.rgb;
fixed3 finalColor = reflColor * (1 - _RefractAmount) + refrColor * _RefractAmount;
return fixed4(finalColor, 1);
}
ENDCG
}
}
FallBack "Diffuse"
}