Unity中UnityCG.cginc中常用的函数(详解)

摄像机方向

WorldSpaceViewDir

输入一个模型空间中的顶点坐标 ==》输出（世界空间）从这个点到摄像机的观察方向；

// 内部实现也是用UnityWorldSpaceViewDir
// Computes world space view direction, from object space position
// *Legacy* Please use UnityWorldSpaceViewDir instead
inline float3 WorldSpaceViewDir( in float4 localPos )
{
    float3 worldPos = mul(unity_ObjectToWorld, localPos).xyz;
    return UnityWorldSpaceViewDir(worldPos);
}

UnityWorldSpaceViewDir

输入一个模型空间中的顶点坐标 ==》输出（世界空间）从这个点到摄像机的观察方向；

// Computes world space view direction, from object space position
inline float3 UnityWorldSpaceViewDir( in float3 worldPos )
{
    return _WorldSpaceCameraPos.xyz - worldPos;
}

ObjSpaceViewDir

模型空间中的顶点坐标 ==》模型空间从这个点到摄像机的观察方向；

// Computes object space view direction
inline float3 ObjSpaceViewDir( in float4 v )
{
    float3 objSpaceCameraPos = mul(unity_WorldToObject, float4(_WorldSpaceCameraPos.xyz, 1)).xyz;
    return objSpaceCameraPos - v.xyz;
}

光源方向

WorldSpaceLightDir

模型空间中的顶点坐标 ==》世界空间中从这个点到光源的方向

// Computes world space light direction, from object space position
// *Legacy* Please use UnityWorldSpaceLightDir instead
inline float3 WorldSpaceLightDir( in float4 localPos )
{
    float3 worldPos = mul(unity_ObjectToWorld, localPos).xyz;
    return UnityWorldSpaceLightDir(worldPos);
}

UnityWorldSpaceLightDir

(ForwardBase Only,not normalized)世界空间中的顶点坐标 ==》世界空间中从这个点到光源的方向

// Computes world space light direction, from world space position
inline float3 UnityWorldSpaceLightDir( in float3 worldPos )
{
    #ifndef USING_LIGHT_MULTI_COMPILE
        return _WorldSpaceLightPos0.xyz - worldPos * _WorldSpaceLightPos0.w;
    #else
        #ifndef USING_DIRECTIONAL_LIGHT
        return _WorldSpaceLightPos0.xyz - worldPos;
        #else
        return _WorldSpaceLightPos0.xyz;
        #endif
    #endif
}

ObjSpaceLightDir

(ForwardBase Only,not normalized)模型空间中的顶点坐标 ==》模型空间中从这个点到光源的方向；

// Computes object space light direction
inline float3 ObjSpaceLightDir( in float4 v )
{
    float3 objSpaceLightPos = mul(unity_WorldToObject, _WorldSpaceLightPos0).xyz;
    #ifndef USING_LIGHT_MULTI_COMPILE
        return objSpaceLightPos.xyz - v.xyz * _WorldSpaceLightPos0.w;
    #else
        #ifndef USING_DIRECTIONAL_LIGHT
        return objSpaceLightPos.xyz - v.xyz;
        #else
        return objSpaceLightPos.xyz;
        #endif
    #endif
}

方向转换

UnityObjectToWorldNormal

法线方向矢量 模型空间==》世界空间

// Transforms normal from object to world space
inline float3 UnityObjectToWorldNormal( in float3 norm )
{
#ifdef UNITY_ASSUME_UNIFORM_SCALING
    return UnityObjectToWorldDir(norm);
#else
    // mul(IT_M, norm) => mul(norm, I_M) => {dot(norm, I_M.col0), dot(norm, I_M.col1), dot(norm, I_M.col2)}
    return normalize(mul(norm, (float3x3)unity_WorldToObject));
#endif
}

UnityObjectToWorldDir

方向矢量 模型空间==》世界空间

// Transforms direction from object to world space
inline float3 UnityObjectToWorldDir( in float3 dir )
{
    return normalize(mul((float3x3)unity_ObjectToWorld, dir));
}

UnityWorldToObjectDir

方向矢量 世界空间==》模型空间

// Transforms direction from world to object space
inline float3 UnityWorldToObjectDir( in float3 dir )
{
    return normalize(mul((float3x3)unity_WorldToObject, dir));
}

TANGENT_SPACE_ROTATION

模型空间==》切线空间 ``` // Declares 3x3 matrix ‘rotation’, filled with tangent space basis #define TANGENT_SPACE_ROTATION \ float3 binormal = cross( normalize(v.normal), normalize(v.tangent.xyz) ) * v.tangent.w; \ float3x3 rotation = float3x3( v.tangent.xyz, binormal, v.normal )

## 顶点计算
### TRANSFORM_TEX
> 缩放和偏移2D纹理的UV，对纹理坐标进行变换，对应材质面板的Tiling和Offset调节项

// Transforms 2D UV by scale/bias property #define TRANSFORM_TEX(tex,name) (tex.xy * name##_ST.xy + name##_ST.zw)

### UnpackNormal

// Unpack normal as DXT5nm (1, y, 1, x) or BC5 (x, y, 0, 1) // Note neutral texture like “bump” is (0, 0, 1, 1) to work with both plain RGB normal and DXT5nm/BC5 fixed3 UnpackNormalmapRGorAG(fixed4 packednormal) { // This do the trick packednormal.x *= packednormal.w;

fixed3 normal;
normal.xy = packednormal.xy * 2 - 1;
normal.z = sqrt(1 - saturate(dot(normal.xy, normal.xy)));
return normal; } inline fixed3 UnpackNormal(fixed4 packednormal) { #if defined(UNITY_NO_DXT5nm)
return packednormal.xyz * 2 - 1; #else
return UnpackNormalmapRGorAG(packednormal); #endif } ```

clip

	// Alpha test
	clip (texColor.a - _Cutoff);
	// Equal to 
    // if ((texColor.a - _Cutoff) < 0.0) {
    // 	    discard;
    // }

Data结构在UnityCG.cginc

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