Unity Direction : UnityCG.cginc

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// Computes world space light direction
inline float3 WorldSpaceLightDir( in float4 v )
{
float3 worldPos = mul(_Object2World, v).xyz;
#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
}

// Computes object space light direction
inline float3 ObjSpaceLightDir( in float4 v )
{
float3 objSpaceLightPos = mul(_World2Object, _WorldSpaceLightPos0).xyz;
#ifndef USING_LIGHT_MULTI_COMPILE
  return objSpaceLightPos.xyz - v.xyz * _WorldSpaceLightPos0.w;
#else
  #ifndef USING_DIRECTIONAL_LIGHT
  return objSpaceLightPos.xyz * unity_Scale.w - v.xyz;
  #else
  return objSpaceLightPos.xyz;
  #endif
#endif
}

// Computes world space view direction
inline float3 WorldSpaceViewDir( in float4 v )
{
return _WorldSpaceCameraPos.xyz - mul(_Object2World, v).xyz;
}

// Computes object space view direction
inline float3 ObjSpaceViewDir( in float4 v )
{
float3 objSpaceCameraPos = mul(_World2Object, float4(_WorldSpaceCameraPos.xyz, 1)).xyz * unity_Scale.w;
return objSpaceCameraPos - v.xyz;
}