光照模型中法线纹理的使用
其实就是让法线纹理中的法线替代了原模型的顶点法线
切线空间中计算
将世界空间转换到切线空间
其实一直有一个疑问,就是既然是法线纹理了,必定至少需要(r,g,b)三个值,为什么还需要在另算Z方向上的值,为什么不直接存储呢?难道是值少了一个值,是为了做压缩?
再回来看的时候发现确实只需要存XY,因为Z的方向是固定的,最后可以通过X,Y,算出来,(X,Y,Z)是单位向量
Shader "Unlit/NormalMapping_WorldToTangent"
{
Properties
{
_Color("Color",Color)=(1.0,1.0,1.0,1.0)
_MainTex("Main Tex",2D)="white"{}
_BumpTex("Bump Tex",2D)="Bump"{}
_Specular("Specular",Color)=(1.0,1.0,1.0,1.0)
_Gloss("Gloss",Range(30.0,100.0))=30.0
_BumpScale("Bump Scale",float)=1.0
}
SubShader
{
Pass
{
Tags{"LightModel"="ForwardBase"}
CGPROGRAM
#include "Lighting.cginc"
#include "UnityCG.cginc"
#pragma vertex vert
#pragma fragment frag
fixed4 _Color;
sampler2D _MainTex;
float4 _MainTex_ST;
sampler2D _BumpTex;
float4 _BumpTex_ST;
fixed4 _Specular;
float _Gloss;
float _BumpScale;
struct a2v
{
float4 vertex:POSITION;
float3 normal:NORMAL;
float4 tangent:TANGENT;
float4 texcoord:TEXCOORD0;
};
struct v2f
{
float4 pos:SV_POSITION;
float3 tangentViewDir:TEXCOORD0;
float3 tangentLightDir:TEXCOORD1;
float4 uv: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 * _BumpTex_ST.xy + _BumpTex_ST.zw;
float3 worldNormal = UnityObjectToWorldNormal(v.normal);
float3 worldTangent = UnityObjectToWorldDir(v.tangent.xyz);
float3 binormal = cross(worldNormal,worldTangent) * v.tangent.w;
float3x3 rotation = float3x3(worldTangent,binormal,worldNormal);
o.tangentLightDir = mul(rotation,WorldSpaceLightDir(v.vertex));
o.tangentViewDir = mul(rotation,WorldSpaceViewDir(v.vertex));
return o;
}
fixed4 frag(v2f i):SV_TARGET
{
float3 tangentViewDir = normalize(i.tangentViewDir);
float3 tangentLightDir = normalize(i.tangentLightDir);
///采样法线纹理
fixed4 packedNormal = tex2D(_BumpTex,i.uv.zw);
float3 tangentNormal = UnpackNormal(packedNormal);
tangentNormal.xy *= _BumpScale;
tangentNormal.z = sqrt(1-saturate(dot(tangentNormal.xy,tangentNormal.xy)));
fixed3 albedo = tex2D(_MainTex,i.uv.xy).rgb * _Color.rgb;
fixed3 ambient = UNITY_LIGHTMODEL_AMBIENT.xyz * albedo;
fixed3 diffuse = _LightColor0.rgb * albedo * saturate(dot(tangentNormal,tangentLightDir));
fixed3 halfNormal = normalize(tangentLightDir+tangentViewDir);
fixed3 specular = _LightColor0.rgb * _Specular * pow(saturate(dot(tangentNormal,halfNormal)),_Gloss);
return fixed4(ambient+diffuse+specular,1.0);
}
ENDCG
}
}
Fallback "Specular"
}
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