in diffuse_sun.hlsl 

#ifndef GLASS_MATERIAL
	res.a = diffuseColor.a * MeltFactor.x;
#else
	float specularMax = saturate(max(max(specular.r, specular.g), specular.b));
	if(transparencyFlag == TRANSPARENCY_ADD){
		res.a = saturate(diffuseColor.a + specularMax) * MeltFactor.x * max(SUM_BLEND_SHADOW_COEF_ALPHA, shadow);
		res.a *= 0.20+pow(clamp(1-sunDir.y, 0.1, 1),3)*0.15;
		res.rgb *= max(SUM_BLEND_SHADOW_COEF, shadow);
	}else{
		//float shadowedAlpha = specularMax * lerp(max(BLEND_SHADOW_COEF, shadow), 1.0, BLEND_SHADOW_SPLIT_COEF);
		//res.a = saturate(diffuseColor.a + shadowedAlpha) * MeltFactor.x;
		//res.a = lerp(res.a, res.a * 0.25, smoothstep(0.0, 0.3, -sunDir.y));
		res.a = diffuseColor.a * MeltFactor.x;
		res.rgb *= lerp(max(BLEND_SHADOW_COEF, shadow), 1.0, 1.0 - BLEND_SHADOW_SPLIT_COEF);
	}
#endif

and

//res += calcScratches(input, shadow);