实现透明效果的方法有两种：透明度测试和透明度混合
透明度测试
透明度测试实现的效果只有不透明和完全透明两种效果，不需要关闭深度写入。只要小于阈值就舍弃、
Shader "Unity Shaders Book/Chapter 8/Alpha Test" {
Properties {
_Color ("Color Tint", Color) = (1, 1, 1, 1)
_MainTex ("Main Tex", 2D) = "white" {
}
_Cutoff ("Alpha Cutoff", Range(0, 1)) = 0.5
}
SubShader {
//IgnoreProjector:使这个shader不受投影器的影响
//RenderType:将这个shader归入提前定义的组
Tags {
"Queue"="AlphaTest" "IgnoreProjector"="True" "RenderType"="TransparentCutout"}
Pass {
Tags {
"LightMode"="ForwardBase" }
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);
// Alpha test
clip (texColor.a - _Cutoff);
// Equal to
// if ((texColor.a - _Cutoff) < 0.0) {
// discard;
// }
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"
}
透明度混合
使用当前片元的透明度作为和混合因子和颜色缓冲中的颜色值混合，需要关闭深度写入。
Shader "Unity Shaders Book/Chapter 8/Alpha Blend" {
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" }
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"
}
开启深度写入的半透明
增加一个pass，只开启深度写入，不输出颜色值
Shader "Unity Shaders Book/Chapter 8/Alpha Blending With ZWrite" {
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"}
// Extra pass that renders to depth buffer only
Pass {
ZWrite On
//ColorMask RGBA0,0代表不输出颜色值
ColorMask 0
}
Pass {
Tags {
"LightMode"="ForwardBase" }
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"
}
常见的混合类型
双面渲染
透明度测试的双面渲染
Cull Back(剔除背面) | Front（正面） | Off（关闭，即双面渲染）
透明度混合的双面渲染
分成三个Pass：背面——正面——混合（因为Pass顺序执行，所以先渲染背面）
只需要在前两个Pass中cull front 和cull back即可
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"
}