shader入門要旨:1枚のテクスチャ法線マップマテリアル(接線空間)(ノート11)
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基本的な考え方は、パッチシェーダでテクスチャサンプリングにより接線空間の法線を得てから、接線空間の視点方向、光照射方向などと計算することです.
// Upgrade NOTE: replaced 'mul(UNITY_MATRIX_MVP,*)' with 'UnityObjectToClipPos(*)'
Shader "Unity Shaders Book/Chapter 7/Normal Map In Tangent Space" {
Properties {
_Color ("Color Tint", Color) = (1, 1, 1, 1)
_MainTex ("Main Tex", 2D) = "white" {}
_BumpMap ("Normal Map", 2D) = "bump" {}
_BumpScale ("Bump Scale", Float) = 1.0
_Specular ("Specular", Color) = (1, 1, 1, 1)
_Gloss ("Gloss", Range(8.0, 256)) = 20
}
SubShader {
Pass {
Tags { "LightMode"="ForwardBase" }
CGPROGRAM
#pragma vertex vert
#pragma fragment frag
#include "Lighting.cginc"
fixed4 _Color;
sampler2D _MainTex;
float4 _MainTex_ST;
sampler2D _BumpMap;
float4 _BumpMap_ST;
float _BumpScale;
fixed4 _Specular;
float _Gloss;
struct a2v {
float4 vertex : POSITION;
float3 normal : NORMAL;
float4 tangent : TANGENT;
float4 texcoord : TEXCOORD0;
};
struct v2f {
float4 pos : SV_POSITION;
float4 uv : TEXCOORD0;
float3 lightDir: TEXCOORD1;
float3 viewDir : TEXCOORD2;
};
v2f vert(a2v v) {
v2f o;
o.pos = UnityObjectToClipPos(v.vertex);
o.uv.xy = v.texcoord.xy * _MainTex_ST.xy + _MainTex_ST.zw;
o.uv.zw = v.texcoord.xy * _BumpMap_ST.xy + _BumpMap_ST.zw;
// Compute the binormal
// , v.tangent.w ,w
//float3 binormal = cross( normalize(v.normal), normalize(v.tangent.xyz) ) * v.tangent.w;
// Construct a matrix which transform vectors from object space to tangent space
// rotation
//float3x3 rotation = float3x3(v.tangent.xyz, binormal, v.normal);
// Or just use the built-in macro (UnityCG.cginc)
TANGENT_SPACE_ROTATION;
// Transform the light direction from object space to tangent space
//
o.lightDir = mul(rotation, ObjSpaceLighDir(v.vertex)).xyz;
// Transform the view direction from object space to tangent space
//
o.viewDir = mul(rotation, ObjSpaceViewDir(v.vertex)).xyz;
return o;
}
fixed4 frag(v2f i) : SV_Target {
fixed3 tangentLightDir = normalize(i.lightDir);
fixed3 tangentViewDir = normalize(i.viewDir);
// Get the texel in the normal map
fixed4 packedNormal = tex2D(_BumpMap, i.uv.zw);
fixed3 tangentNormal;
// If the texture is not marked as "Normal map"
//tangentNormal.xy = (packedNormal.xy * 2 - 1) * _BumpScale;
//tangentNormal.z = sqrt(1.0 - saturate(dot(tangentNormal.xy, tangentNormal.xy)));
// Or mark the texture as "Normal map", and use the built-in funciton
tangentNormal = UnpackNormal(packedNormal);
//
tangentNormal.xy *= _BumpScale;
// tangentNormal
//
// tangentNormal.xy = (packedNormal.xy * 2 - 1);
tangentNormal.z = sqrt(1.0 - saturate(dot(tangentNormal.xy, tangentNormal.xy)));
//
fixed3 albedo = tex2D(_MainTex, i.uv).rgb * _Color.rgb;
fixed3 ambient = UNITY_LIGHTMODEL_AMBIENT.xyz * albedo;
fixed3 diffuse = _LightColor0.rgb * albedo * max(0, dot(tangentNormal, tangentLightDir));
fixed3 halfDir = normalize(tangentLightDir + tangentViewDir);
fixed3 specular = _LightColor0.rgb * _Specular.rgb * pow(max(0, dot(tangentNormal, halfDir)), _Gloss);
return fixed4(ambient + diffuse + specular, 1.0);
}
ENDCG
}
}
FallBack "Specular"
}