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YivanLee：专题概述及目录?

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INTRODUCTION：

虽然现在大家都是张口闭口PBR了，对MatCap这种小儿科不怎么看得起，但是制作很多效果的时候，用MatCap依然是一个很不错的解决方案的。

MatCap原理非常简单，我们使用法线在摄像机的方向投射的二维平面进行采样。

可以看到原理非常简单但是很实用。

MAIN CONTENT：

MatCap In Unreal engine 4

MatCap In Unity

Shader "Unlit/S_MaterialCapture"
{
Properties
{
_MatCapTexure ("MaterialCaptureTexture", 2D) = "white" {}
_Normaltexture ("Normaltexture", 2D) = "bump" {}
}
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;
float4 tangent : TANGENT;
float4 normal : NORMAL;
};

struct v2f
{
float2 uv : TEXCOORD0;
float3 tangent : TEXCOORD2;
float3 normal : TEXCOORD3;
float3 binormal : TEXCOORD4;
UNITY_FOG_COORDS(1)
float4 vertex : SV_POSITION;
};

sampler2D _MatCapTexure;
float4 _MatCapTexure_ST;
sampler2D _Normaltexture;
float4 _Normaltexture_ST;

v2f vert (appdata v)
{
v2f o;
o.vertex = UnityObjectToClipPos(v.vertex);
o.uv = TRANSFORM_TEX(v.uv, _MatCapTexure);
o.tangent = UnityObjectToWorldDir(v.tangent);
o.normal = UnityObjectToWorldDir(v.normal);
o.binormal = cross(v.tangent, v.normal);
UNITY_TRANSFER_FOG(o,o.vertex);
return o;
}

fixed4 frag (v2f i) : SV_Target
{
half4 finalcolor = half4(1, 1, 1, 1);

// sample the texture
float3 texnorm = UnpackNormal(tex2D(_Normaltexture, i.uv));
float3x3 transmatrix = float3x3(i.tangent, i.binormal, i.normal);

float3 texnorm_ws = normalize(mul(texnorm, transmatrix));
float3 texnorm_vs = mul(UNITY_MATRIX_V, texnorm_ws);

float3 vv = float3(0, 0, 1);
float3 rv = vv - (dot(vv, texnorm_vs) * -2 * texnorm_vs);
float2 matcapuv = rv.xy / (sqrt((rv.x * rv.x) + (rv.y * rv.y) + (rv.z + 1) * (rv.z + 1)) * 0.75) + 0.5;

fixed4 MatCapColor = tex2D(_MatCapTexure, matcapuv);

finalcolor.rgb = MatCapColor;

// apply fog
UNITY_APPLY_FOG(i.fogCoord, finalcolor);
return finalcolor;
}
ENDCG
}
}
}

SUMMARY AND OUTLOOK：

Enjoy it！

NEXT：

Todo...

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