类崩坏三NPR渲染分析（一）
使用MatCap实现空之律者的翅膀效果
什么是MatCap
Material Capture(材质捕获)，通常被简称为MatCap，在Zbrush、Sculptris、Mudbox等3D软件中有比较多的使用。
MatCap Shader的基本思路是，使用某特定材质球的贴图，作为当前材质的视图空间环境贴图（view-space environment map），来实现具有均匀表面着色的反射材质物体的显示。考虑到物体的所有法线的投影的范围在x(-1,1),y(-1,1),构成了一个圆形，所以MatCap 贴图中存储光照信息的区域是一个圆形。
基于MatCap思想的Shader，可以无需提供任何光照，只需提供一张或多张合适的MatCap贴图作为光照结果的“指导”即可。
实现组成
1.首先我们需要实现的描边效果
2.在描边的基础上我们加上MatCap效果来模拟PBR
3.在此基础之上再加上扭曲效果、菲涅尔反射和高光
描边效果
我们采用的是法线外扩的方法来实现描边效果
加了蓝色的描边效果
SubShader {
Tags {
"RenderType"="Opaque"
}
Pass {
Name "Outline"
Tags {
}
Cull Front
CGPROGRAM
#pragma vertex vert
#pragma fragment frag
#include "UnityCG.cginc"
#pragma fragmentoption ARB_precision_hint_fastest
#pragma multi_compile_shadowcaster
#pragma multi_compile_fog
#pragma only_renderers d3d9 d3d11 glcore gles
#pragma target 3.0
uniform float _LineWidth;
uniform float4 _LineColor;
struct VertexInput {
float4 vertex : POSITION;
float3 normal : NORMAL;
};
struct VertexOutput {
float4 pos : SV_POSITION;
UNITY_FOG_COORDS(0)
};
VertexOutput vert (VertexInput v) {
VertexOutput o = (VertexOutput)0;
o.pos = UnityObjectToClipPos( float4(v.vertex.xyz + v.normal*_LineWidth,1) );
UNITY_TRANSFER_FOG(o,o.pos);
return o;
}
float4 frag(VertexOutput i, float facing : VFACE) : COLOR {
float isFrontFace = ( facing >= 0 ? 1 : 0 );
float faceSign = ( facing >= 0 ? 1 : -1 );
return fixed4(_LineColor.rgb,0);
}
ENDCG
}
MatCap Shader
Pass {
Name "FORWARD"
Tags {
"LightMode"="ForwardBase"
}
Cull Off
CGPROGRAM
#pragma vertex vert
#pragma fragment frag
#define UNITY_PASS_FORWARDBASE
#include "UnityCG.cginc"
#pragma multi_compile_fwdbase_fullshadows
#pragma multi_compile_fog
#pragma only_renderers d3d9 d3d11 glcore gles
#pragma target 3.0
uniform sampler2D _MainTex; uniform float4 _MainTex_ST;
uniform float _FresnelPower;
uniform float4 _FresnelColor;
uniform float4 _MainColor;
uniform sampler2D _MatCap; uniform float4 _MatCap_ST;
uniform sampler2D _BumpMap; uniform float4 _BumpMap_ST;
struct VertexInput {
float4 vertex : POSITION;
float3 normal : NORMAL;
float4 tangent : TANGENT;
float2 texcoord0 : TEXCOORD0;
};
struct VertexOutput {
float4 pos : SV_POSITION;
float2 uv0 : TEXCOORD0;
float4 posWorld : TEXCOORD1;
float3 normalDir : TEXCOORD2;
float3 tangentDir : TEXCOORD3;
float3 bitangentDir : TEXCOORD4;
UNITY_FOG_COORDS(4)
};
VertexOutput vert (VertexInput v) {
VertexOutput o = (VertexOutput)0;
o.uv0 = v.texcoord0;
o.normalDir = UnityObjectToWorldNormal(v.normal);
o.pos = UnityObjectToClipPos( v.vertex );
o.tangentDir = normalize( mul( unity_ObjectToWorld, float4( v.tangent.xyz, 0.0 ) ).xyz );
o.bitangentDir = normalize(cross(o.normalDir, o.tangentDir) * v.tangent.w);
o.posWorld = mul(unity_ObjectToWorld, v.vertex);
UNITY_TRANSFER_FOG(o,o.pos);
return o;
}
float4 frag(VertexOutput i, float facing : VFACE) : COLOR {
float isFrontFace = ( facing >= 0 ? 1 : 0 );
float faceSign = ( facing >= 0 ? 1 : -1 );
i.normalDir = normalize(i.normalDir);
i.normalDir *= faceSign;
float3 viewDirection = normalize(_WorldSpaceCameraPos.xyz - i.posWorld.xyz);
float3 normalDirection = i.normalDir;
float4 _MainTex_var = tex2D(_MainTex,TRANSFORM_TEX(i.uv0, _MainTex));
float3x3 tangentTransform = float3x3( i.tangentDir, i.bitangentDir, i.normalDir);
float4 _BumpMap_var = tex2D(_BumpMap,TRANSFORM_TEX(i.uv0, _BumpMap));
float3 normalLocal = _BumpMap_var.rgb;
float3 normalDir = normalize(mul(normalLocal, tangentTransform )); // Perturbed normals
float2 _MatCaprg = (mul( UNITY_MATRIX_V, float4(normalDir,0) ).xyz.rgb*0.5+0.5).rg;
float4 _MatCap_var = tex2D(_MatCap,TRANSFORM_TEX(_MatCaprg, _MatCap));
float3 finalColor = ((_MainColor.rgb*_MainTex_var.rgb)+(pow(1.0-max(0,dot(normalDirection, viewDirection)),_FresnelPower)*_FresnelColor.rgb));
finalColor = finalColor + _MatCap_var * _MainColor;
fixed4 finalRGBA = fixed4(finalColor,1);
UNITY_APPLY_FOG(i.fogCoord, finalRGBA);
return finalRGBA;
}
ENDCG
}
完整代码
Shader "LightWings" {
Properties {
_LineWidth ("LineWidth", Range(0, 0.1)) = 0
[HDR]_LineColor ("LineColor", Color) = (0.0895329,0.2127204,1,1)
_MainTex ("MainTex", 2D) = "white" {}
[HDR]_MainColor ("MainColor", Color) = (0.007352948,0.4660244,1,1)
_FresnelPower ("FresnelPower", Range(0.1, 10)) = 1.201405
[HDR]_FresnelColor ("FresnelColor", Color) = (0.6617647,0.944016,1,1)
_MatCap ("MatCap", 2D) = "white" {}
_BumpMap ("BumpMap", 2D) = "white" {}
}
SubShader {
Tags {
"RenderType"="Opaque"
}
Pass {
Name "Outline"
Tags {
}
Cull Front
CGPROGRAM
#pragma vertex vert
#pragma fragment frag
#include "UnityCG.cginc"
#pragma fragmentoption ARB_precision_hint_fastest
#pragma multi_compile_shadowcaster
#pragma multi_compile_fog
#pragma only_renderers d3d9 d3d11 glcore gles
#pragma target 3.0
uniform float _LineWidth;
uniform float4 _LineColor;
struct VertexInput {
float4 vertex : POSITION;
float3 normal : NORMAL;
};
struct VertexOutput {
float4 pos : SV_POSITION;
UNITY_FOG_COORDS(0)
};
VertexOutput vert (VertexInput v) {
VertexOutput o = (VertexOutput)0;
o.pos = UnityObjectToClipPos( float4(v.vertex.xyz + v.normal*_LineWidth,1) );
UNITY_TRANSFER_FOG(o,o.pos);
return o;
}
float4 frag(VertexOutput i, float facing : VFACE) : COLOR {
float isFrontFace = ( facing >= 0 ? 1 : 0 );
float faceSign = ( facing >= 0 ? 1 : -1 );
return fixed4(_LineColor.rgb,0);
}
ENDCG
}
Pass {
Name "FORWARD"
Tags {
"LightMode"="ForwardBase"
}
Cull Off
CGPROGRAM
#pragma vertex vert
#pragma fragment frag
#define UNITY_PASS_FORWARDBASE
#include "UnityCG.cginc"
#pragma multi_compile_fwdbase_fullshadows
#pragma multi_compile_fog
#pragma only_renderers d3d9 d3d11 glcore gles
#pragma target 3.0
uniform sampler2D _MainTex; uniform float4 _MainTex_ST;
uniform float _FresnelPower;
uniform float4 _FresnelColor;
uniform float4 _MainColor;
uniform sampler2D _MatCap; uniform float4 _MatCap_ST;
uniform sampler2D _BumpMap; uniform float4 _BumpMap_ST;
struct VertexInput {
float4 vertex : POSITION;
float3 normal : NORMAL;
float4 tangent : TANGENT;
float2 texcoord0 : TEXCOORD0;
};
struct VertexOutput {
float4 pos : SV_POSITION;
float2 uv0 : TEXCOORD0;
float4 posWorld : TEXCOORD1;
float3 normalDir : TEXCOORD2;
float3 tangentDir : TEXCOORD3;
float3 bitangentDir : TEXCOORD4;
UNITY_FOG_COORDS(4)
};
VertexOutput vert (VertexInput v) {
VertexOutput o = (VertexOutput)0;
o.uv0 = v.texcoord0;
o.normalDir = UnityObjectToWorldNormal(v.normal);
o.pos = UnityObjectToClipPos( v.vertex );
o.tangentDir = normalize( mul( unity_ObjectToWorld, float4( v.tangent.xyz, 0.0 ) ).xyz );
o.bitangentDir = normalize(cross(o.normalDir, o.tangentDir) * v.tangent.w);
o.posWorld = mul(unity_ObjectToWorld, v.vertex);
UNITY_TRANSFER_FOG(o,o.pos);
return o;
}
float4 frag(VertexOutput i, float facing : VFACE) : COLOR {
float isFrontFace = ( facing >= 0 ? 1 : 0 );
float faceSign = ( facing >= 0 ? 1 : -1 );
i.normalDir = normalize(i.normalDir);
i.normalDir *= faceSign;
float3 viewDirection = normalize(_WorldSpaceCameraPos.xyz - i.posWorld.xyz);
float3 normalDirection = i.normalDir;
float4 _MainTex_var = tex2D(_MainTex,TRANSFORM_TEX(i.uv0, _MainTex));
float3x3 tangentTransform = float3x3( i.tangentDir, i.bitangentDir, i.normalDir);
float4 _BumpMap_var = tex2D(_BumpMap,TRANSFORM_TEX(i.uv0, _BumpMap));
float3 normalLocal = _BumpMap_var.rgb;
float3 normalDir = normalize(mul(normalLocal, tangentTransform )); // Perturbed normals
float2 _MatCaprg = (mul( UNITY_MATRIX_V, float4(normalDir,0) ).xyz.rgb*0.5+0.5).rg;
float4 _MatCap_var = tex2D(_MatCap,TRANSFORM_TEX(_MatCaprg, _MatCap));
float3 finalColor = ((_MainColor.rgb*_MainTex_var.rgb)+(pow(1.0-max(0,dot(normalDirection, viewDirection)),_FresnelPower)*_FresnelColor.rgb));
finalColor = finalColor + _MatCap_var * _MainColor;
fixed4 finalRGBA = fixed4(finalColor,1);
UNITY_APPLY_FOG(i.fogCoord, finalRGBA);
return finalRGBA;
}
ENDCG
}
Pass {
Name "ShadowCaster"
Tags {
"LightMode"="ShadowCaster"
}
Offset 1, 1
Cull Off
CGPROGRAM
#pragma vertex vert
#pragma fragment frag
#define UNITY_PASS_SHADOWCASTER
#include "UnityCG.cginc"
#include "Lighting.cginc"
#pragma fragmentoption ARB_precision_hint_fastest
#pragma multi_compile_shadowcaster
#pragma multi_compile_fog
#pragma only_renderers d3d9 d3d11 glcore gles
#pragma target 3.0
struct VertexInput {
float4 vertex : POSITION;
};
struct VertexOutput {
V2F_SHADOW_CASTER;
};
VertexOutput vert (VertexInput v) {
VertexOutput o = (VertexOutput)0;
o.pos = UnityObjectToClipPos( v.vertex );
TRANSFER_SHADOW_CASTER(o)
return o;
}
float4 frag(VertexOutput i, float facing : VFACE) : COLOR {
float isFrontFace = ( facing >= 0 ? 1 : 0 );
float faceSign = ( facing >= 0 ? 1 : -1 );
SHADOW_CASTER_FRAGMENT(i)
}
ENDCG
}
}
FallBack "Diffuse"
}
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