UnpackNormal()函數在UnityCG.cginc中,它是對法線紋理的採樣結果的一個反映射操作,其對應的法線紋理需要設置爲Normal map的格式,才能使用該函數,如下是函數的原型:
// 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
}