1.在切线空间下计算
struct Attributes
{
float4 positionOS : POSITION;
float3 normal:NORMAL;
float4 tangent : TANGENT;
float4 texcoord : TEXCOORD0;
};
使用TANGENT语义来定义切线变量，需要注意的是，类型为 float4，因为需要使用tangent.w来确定在切线空间中副切线的方向性.
struct Varyings
{
float4 positionCS : SV_POSITION;
float4 uv : TEXCOORD0;
float3 lightDir: TEXCOORD1;
float3 viewDir : TEXCOORD2;
};
注意uv变量，定义为float4类型，xy存储_MainTex的纹理坐标，zw存储_BumpMap的纹理坐标.
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 {
Tags {
"RenderType"="Opaque"
"RenderPipeline"="UniversalPipeline"
}
Pass {
HLSLPROGRAM
#pragma vertex vert
#pragma fragment frag
#include "Packages/com.unity.render-pipelines.universal/ShaderLibrary/Core.hlsl"
#include "Packages/com.unity.render-pipelines.universal/ShaderLibrary/Lighting.hlsl"
#include "Packages/com.unity.render-pipelines.universal/ShaderLibrary/Input.hlsl"
CBUFFER_START(UnityPerMaterial)
half4 _Color;
sampler2D _MainTex;
float4 _MainTex_ST;
sampler2D _BumpMap;
float4 _BumpMap_ST;
float _BumpScale;
half4 _Specular;
float _Gloss;
CBUFFER_END
struct Attributes
{
float4 positionOS : POSITION;
float3 normal:NORMAL;
float4 tangent : TANGENT;
float4 texcoord : TEXCOORD0;
};
struct Varyings
{
float4 positionCS : SV_POSITION;
float4 uv : TEXCOORD0;
float3 lightDir: TEXCOORD1;
float3 viewDir : TEXCOORD2;
};
// Unity doesn't support the 'inverse' function in native shader
// so we write one by our own
// Note: this function is just a demonstration, not too confident on the math or the speed
// Reference: http://answers.unity3d.com/questions/218333/shader-inversefloat4x4-function.html
float4x4 inverse(float4x4 input)
{
#define minor(a,b,c) determinant(float3x3(input.a, input.b, input.c))
float4x4 cofactors = float4x4(
minor(_22_23_24, _32_33_34, _42_43_44),
-minor(_21_23_24, _31_33_34, _41_43_44),
minor(_21_22_24, _31_32_34, _41_42_44),
-minor(_21_22_23, _31_32_33, _41_42_43),
-minor(_12_13_14, _32_33_34, _42_43_44),
minor(_11_13_14, _31_33_34, _41_43_44),
-minor(_11_12_14, _31_32_34, _41_42_44),
minor(_11_12_13, _31_32_33, _41_42_43),
minor(_12_13_14, _22_23_24, _42_43_44),
-minor(_11_13_14, _21_23_24, _41_43_44),
minor(_11_12_14, _21_22_24, _41_42_44),
-minor(_11_12_13, _21_22_23, _41_42_43),
-minor(_12_13_14, _22_23_24, _32_33_34),
minor(_11_13_14, _21_23_24, _31_33_34),
-minor(_11_12_14, _21_22_24, _31_32_34),
minor(_11_12_13, _21_22_23, _31_32_33)
);
#undef minor
return transpose(cofactors) / determinant(input);
}
Varyings vert(Attributes input)
{
Varyings output;
output.positionCS = mul(UNITY_MATRIX_MVP, input.positionOS);
//也可以使用 TransformObjectToHClip 方法
//output.positionCS = TransformObjectToHClip(input.positionOS.xyz);
output.uv.xy = input.texcoord.xy * _MainTex_ST.xy + _MainTex_ST.zw;
output.uv.zw = input.texcoord.xy * _BumpMap_ST.xy + _BumpMap_ST.zw;
// 或者调用内置函数
//output.uv.xy = TRANSFORM_TEX(input.texcoord, _MainTex);
//output.uv.zw = TRANSFORM_TEX(input.texcoord, _BumpMap);
///
/// Note that the code below can handle both uniform and non-uniform scales
///
// Construct a matrix that transforms a point/vector from tangent space to world space
float3 worldNormal = TransformObjectToWorldNormal(input.normal);
float3 worldTangent = TransformObjectToWorldDir(input.tangent.xyz);
float3 worldBinormal = cross(worldNormal, worldTangent) * input.tangent.w;
/*
float4x4 tangentToWorld = float4x4(worldTangent.x, worldBinormal.x, worldNormal.x, 0.0,
worldTangent.y, worldBinormal.y, worldNormal.y, 0.0,
worldTangent.z, worldBinormal.z, worldNormal.z, 0.0,
0.0, 0.0, 0.0, 1.0);
// The matrix that transforms from world space to tangent space is inverse of tangentToWorld
float3x3 worldToTangent = inverse(tangentToWorld);
*/
//wToT = the inverse of tToW = the transpose of tToW as long as tToW is an orthogonal matrix.
float3x3 worldToTangent = float3x3(worldTangent, worldBinormal, worldNormal);
// Transform the light and view dir from world space to tangent space
float3 positionWS = TransformObjectToWorld(input.positionOS);
float3 worldLightPos = TransformObjectToWorld(_MainLightPosition.xyz);
float3 worldLightDir = worldLightPos - positionWS;
//Light mainLight = GetMainLight();
//float3 worldLightDir = mainLight.direction;
float3 worldSpaceViewDir = _WorldSpaceCameraPos.xyz - positionWS;
output.lightDir = mul(worldToTangent, worldLightDir);
output.viewDir = mul(worldToTangent, worldSpaceViewDir);
///
/// Note that the code below can only handle uniform scales, not including non-uniform scales
///
// Compute the binormal
// 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
// float3x3 rotation = float3x3(v.tangent.xyz, binormal, v.normal);
// Or just use the built-in macro
// TANGENT_SPACE_ROTATION;
//
// // Transform the light direction from object space to tangent space
// o.lightDir = mul(rotation, normalize(ObjSpaceLightDir(v.vertex))).xyz;
// // Transform the view direction from object space to tangent space
// o.viewDir = mul(rotation, normalize(ObjSpaceViewDir(v.vertex))).xyz;
return output;
}
half4 frag(Varyings input): SV_Target
{
float3 tangentLightDir = normalize(input.lightDir);
float3 tangentViewDir = normalize(input.viewDir);
// Get the texel in the normal map
float4 packedNormal = tex2D(_BumpMap, input.uv.zw);
float3 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.z = sqrt(1.0 - saturate(dot(tangentNormal.xy, tangentNormal.xy)));
float3 albedo = tex2D(_MainTex, input.uv).rgb * _Color.rgb;
float3 ambient = UNITY_LIGHTMODEL_AMBIENT.xyz * albedo;
float3 diffuse = _MainLightColor.rgb * albedo * max(0, dot(tangentNormal, tangentLightDir));
float3 halfDir = normalize(tangentLightDir + tangentViewDir);
float3 specular = _MainLightColor.rgb * _Specular.rgb *
pow(max(0, dot(tangentNormal, halfDir)), _Gloss);
return float4(ambient + diffuse + specular, 1.0);
}
ENDHLSL
}
}
}