fteqw/engine/shaders/vulkan/sys/fog.h

#ifdef FRAGMENT_SHADER
	#define w_fogcolour		w_fogcolours.rgb
	#define w_fogalpha		w_fogcolours.a

	vec3 fog3(in vec3 regularcolour)
	{
		if (!FOG)
			return regularcolour;
		float z = w_fogdensity * gl_FragCoord.z / gl_FragCoord.w;
		z = max(0.0,z-w_fogdepthbias);
		if (cvar_r_fog_exp2)
			z *= z;
		float fac = exp2(-(z * 1.442695));
		fac = (1.0-w_fogalpha) + (clamp(fac, 0.0, 1.0)*w_fogalpha);
		return mix(w_fogcolour, regularcolour, fac);
	}
	vec3 fog3additive(in vec3 regularcolour)
	{
		if (!FOG)
			return regularcolour;
		float z = w_fogdensity * gl_FragCoord.z / gl_FragCoord.w;
		z = max(0.0,z-w_fogdepthbias);
		if (cvar_r_fog_exp2)
			z *= z;
		float fac = exp2(-(z * 1.442695));
		fac = (1.0-w_fogalpha) + (clamp(fac, 0.0, 1.0)*w_fogalpha);
		return regularcolour * fac;
	}
	vec4 fog4(in vec4 regularcolour)
	{
		if (!FOG)
			return regularcolour;
		return vec4(fog3(regularcolour.rgb), 1.0) * regularcolour.a;
	}
	vec4 fog4additive(in vec4 regularcolour)
	{
		if (!FOG)
			return regularcolour;
		float z = w_fogdensity * gl_FragCoord.z / gl_FragCoord.w;
		z = max(0.0,z-w_fogdepthbias);
		if (cvar_r_fog_exp2)
			z *= z;
		float fac = exp2(-(z * 1.442695));
		fac = (1.0-w_fogalpha) + (clamp(fac, 0.0, 1.0)*w_fogalpha);
		return regularcolour * vec4(fac, fac, fac, 1.0);
	}
	vec4 fog4blend(in vec4 regularcolour)
	{
		if (!FOG)
			return regularcolour;
		float z = w_fogdensity * gl_FragCoord.z / gl_FragCoord.w;
		z = max(0.0,z-w_fogdepthbias);
		if (cvar_r_fog_exp2)
			z *= z;
		float fac = exp2(-(z * 1.442695));
		fac = (1.0-w_fogalpha) + (clamp(fac, 0.0, 1.0)*w_fogalpha);
		return regularcolour * vec4(1.0, 1.0, 1.0, fac);
	}
#endif