使用Cull命令

  • Cull Back|Front|Off,不渲染背面|前面|关闭

透明度测试的双面渲染

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// Upgrade NOTE: replaced '_Object2World' with 'unity_ObjectToWorld'
// Upgrade NOTE: replaced 'mul(UNITY_MATRIX_MVP,*)' with 'UnityObjectToClipPos(*)'

Shader "Unity Shaders Book/Chapter 8/Alpha Test With Both Side" {
Properties {
_Color ("Color Tint", Color) = (1, 1, 1, 1)
_MainTex ("Main Tex", 2D) = "white" {}
_Cutoff ("Alpha Cutoff", Range(0, 1)) = 0.5
}
SubShader {
Tags {"Queue"="AlphaTest" "IgnoreProjector"="True" "RenderType"="TransparentCutout"}

Pass {
Tags { "LightMode"="ForwardBase" }

// Turn off culling
Cull Off

CGPROGRAM

#pragma vertex vert
#pragma fragment frag

#include "Lighting.cginc"

fixed4 _Color;
sampler2D _MainTex;
float4 _MainTex_ST;
fixed _Cutoff;

struct a2v {
float4 vertex : POSITION;
float3 normal : NORMAL;
float4 texcoord : TEXCOORD0;
};

struct v2f {
float4 pos : SV_POSITION;
float3 worldNormal : TEXCOORD0;
float3 worldPos : TEXCOORD1;
float2 uv : TEXCOORD2;
};

v2f vert(a2v v) {
v2f o;
o.pos = UnityObjectToClipPos(v.vertex);

o.worldNormal = UnityObjectToWorldNormal(v.normal);

o.worldPos = mul(unity_ObjectToWorld, v.vertex).xyz;

o.uv = TRANSFORM_TEX(v.texcoord, _MainTex);

return o;
}

fixed4 frag(v2f i) : SV_Target {
fixed3 worldNormal = normalize(i.worldNormal);
fixed3 worldLightDir = normalize(UnityWorldSpaceLightDir(i.worldPos));

fixed4 texColor = tex2D(_MainTex, i.uv);

clip (texColor.a - _Cutoff);

fixed3 albedo = texColor.rgb * _Color.rgb;

fixed3 ambient = UNITY_LIGHTMODEL_AMBIENT.xyz * albedo;

fixed3 diffuse = _LightColor0.rgb * albedo * max(0, dot(worldNormal, worldLightDir));

return fixed4(ambient + diffuse, 1.0);
}

ENDCG
}
}
FallBack "Transparent/Cutout/VertexLit"
}

透明度混和的双面渲染

写了两个Pass,用来渲染前面和后面,由于关闭了ZWrite,所以无法正确渲染前后面,所以需要分两个pass渲染,先后再前,确保遮挡。

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// Upgrade NOTE: replaced '_Object2World' with 'unity_ObjectToWorld'
// Upgrade NOTE: replaced 'mul(UNITY_MATRIX_MVP,*)' with 'UnityObjectToClipPos(*)'

Shader "Unity Shaders Book/Chapter 8/Alpha Blend With Both Side" {
Properties {
_Color ("Color Tint", Color) = (1, 1, 1, 1)
_MainTex ("Main Tex", 2D) = "white" {}
_AlphaScale ("Alpha Scale", Range(0, 1)) = 1
}
SubShader {
Tags {"Queue"="Transparent" "IgnoreProjector"="True" "RenderType"="Transparent"}

Pass {
Tags { "LightMode"="ForwardBase" }

// First pass renders only back faces 只渲染后面
Cull Front

ZWrite Off
Blend SrcAlpha OneMinusSrcAlpha

CGPROGRAM

#pragma vertex vert
#pragma fragment frag

#include "Lighting.cginc"

fixed4 _Color;
sampler2D _MainTex;
float4 _MainTex_ST;
fixed _AlphaScale;

struct a2v {
float4 vertex : POSITION;
float3 normal : NORMAL;
float4 texcoord : TEXCOORD0;
};

struct v2f {
float4 pos : SV_POSITION;
float3 worldNormal : TEXCOORD0;
float3 worldPos : TEXCOORD1;
float2 uv : TEXCOORD2;
};

v2f vert(a2v v) {
v2f o;
o.pos = UnityObjectToClipPos(v.vertex);

o.worldNormal = UnityObjectToWorldNormal(v.normal);

o.worldPos = mul(unity_ObjectToWorld, v.vertex).xyz;

o.uv = TRANSFORM_TEX(v.texcoord, _MainTex);

return o;
}

fixed4 frag(v2f i) : SV_Target {
fixed3 worldNormal = normalize(i.worldNormal);
fixed3 worldLightDir = normalize(UnityWorldSpaceLightDir(i.worldPos));

fixed4 texColor = tex2D(_MainTex, i.uv);

fixed3 albedo = texColor.rgb * _Color.rgb;

fixed3 ambient = UNITY_LIGHTMODEL_AMBIENT.xyz * albedo;

fixed3 diffuse = _LightColor0.rgb * albedo * max(0, dot(worldNormal, worldLightDir));

return fixed4(ambient + diffuse, texColor.a * _AlphaScale);
}

ENDCG
}

Pass {
Tags { "LightMode"="ForwardBase" }

// Second pass renders only front faces 只渲染前面
Cull Back

ZWrite Off
Blend SrcAlpha OneMinusSrcAlpha

CGPROGRAM

#pragma vertex vert
#pragma fragment frag

#include "Lighting.cginc"

fixed4 _Color;
sampler2D _MainTex;
float4 _MainTex_ST;
fixed _AlphaScale;

struct a2v {
float4 vertex : POSITION;
float3 normal : NORMAL;
float4 texcoord : TEXCOORD0;
};

struct v2f {
float4 pos : SV_POSITION;
float3 worldNormal : TEXCOORD0;
float3 worldPos : TEXCOORD1;
float2 uv : TEXCOORD2;
};

v2f vert(a2v v) {
v2f o;
o.pos = UnityObjectToClipPos(v.vertex);

o.worldNormal = UnityObjectToWorldNormal(v.normal);

o.worldPos = mul(unity_ObjectToWorld, v.vertex).xyz;

o.uv = TRANSFORM_TEX(v.texcoord, _MainTex);

return o;
}

fixed4 frag(v2f i) : SV_Target {
fixed3 worldNormal = normalize(i.worldNormal);
fixed3 worldLightDir = normalize(UnityWorldSpaceLightDir(i.worldPos));

fixed4 texColor = tex2D(_MainTex, i.uv);

fixed3 albedo = texColor.rgb * _Color.rgb;

fixed3 ambient = UNITY_LIGHTMODEL_AMBIENT.xyz * albedo;

fixed3 diffuse = _LightColor0.rgb * albedo * max(0, dot(worldNormal, worldLightDir));

return fixed4(ambient + diffuse, texColor.a * _AlphaScale);
}

ENDCG
}
}
FallBack "Transparent/VertexLit"
}