Albedo Alpha from Rim for Marmoset Toolbag 4

fresnel.frag

#include "data/shader/mat/state.frag"

uniform float uOpacity;   //name "Opacity"  default 1.0   min 0.0  max 2.0
uniform float uExponent;  //name "Exponent"  default 1.0   min 0.0  max 4.0

void RimOpacity( inout FragmentState s )
{
	#ifdef Emissive
		Emissive(s);
	#endif
	float rim = dot(s.vertexEye, s.normal);
	rim = pow(rim, uExponent);
	s.albedo.a = saturate(1.0 - rim) * uOpacity;
}

#ifdef Emissive
	#undef Emissive
#endif
#define Emissive RimOpacity