// MinecraftPT — Translucent_FS
// Composites translucent geometry (water, glass, particles) on top of solid.

#include "/Lib/Settings.glsl"
#include "/Lib/Utilities.glsl"
#include "/Lib/BasicFunctions/LightingConstants.glsl"
#include "/Lib/GbufferData.glsl"
#include "/Lib/BasicFunctions/Sunlight_Shadow.glsl"
#include "/Lib/BasicFunctions/Blocklight.glsl"
#include "/Lib/PathTracing/Tracer/SampleIRC.glsl"
#include "/Lib/PathTracing/Tracer/ShadowTracing.glsl"

uniform sampler2D colortex12; // combined HDR solid scene
uniform sampler2D colortex4;  // translucent albedo
uniform sampler2D colortex5;  // translucent normal

layout(location = 0) out vec4 colorOut;

void main(){
	ivec2 texelCoord = ivec2(gl_FragCoord.xy);

	float depth = texelFetch(depthtex0, texelCoord, 0).r;
	if (depth >= 1.0){
		colorOut = texelFetch(colortex12, texelCoord, 0);
		return;
	}

	// Check if there is translucent data
	vec4 gbuffer5 = texelFetch(colortex5, texelCoord, 0);
	float matID = gbuffer5.a * 255.0;

	if (matID < 0.5){
		colorOut = texelFetch(colortex12, texelCoord, 0);
		return;
	}

	bool isSmooth;
	GbufferData gbuffer = GetGbufferDataTranslucent(texelCoord, isSmooth);

	vec4 viewPos = gbufferProjectionInverse * vec4(vec2(texelCoord) / screenSize * 2.0 - 1.0, depth * 2.0 - 1.0, 1.0);
	viewPos.xyz /= viewPos.w;
	vec3 worldPos = gbufferModelViewInverse[3].xyz + viewPos.xyz;

	vec3 solidColor = texelFetch(colortex12, texelCoord, 0).rgb;

	// Water: blend with refraction
	vec3 color = solidColor;

	if (matID == MATID_WATER){
		vec3 waterColor = gbuffer.albedo;
		float alpha = gbuffer.albedoAlpha;

		// Fresnel
		vec3 viewDir = normalize(-viewPos.xyz);
		float NdotV = max(dot(gbuffer.worldNormal, viewDir), 0.0);
		float fresnel = 0.02 + 0.98 * pow(1.0 - NdotV, 5.0);

		// Light contribution (sun + sky) on water
		vec3 sunLight = GetSunlight(viewPos.xyz, worldPos, gbuffer.vertexNormal, gbuffer.worldNormal, gbuffer.lightmap.x);
		vec3 waterLight = waterColor * (sunLight + Blocklight(gbuffer.lightmap) * 0.5);

		// Water tint / depth color
		vec3 deepColor = waterColor * 0.3;

		color = mix(solidColor, waterLight + deepColor, fresnel * 0.8 + 0.2);

	}else if (matID == MATID_STAINEDGLASS){
		vec3 glassColor = gbuffer.albedo;
		float alpha = gbuffer.albedoAlpha;

		vec3 viewDir = normalize(-viewPos.xyz);
		float NdotV = max(dot(gbuffer.worldNormal, viewDir), 0.0);
		float fresnel = 0.04 + 0.96 * pow(1.0 - NdotV, 5.0);

		color = mix(solidColor, solidColor * glassColor, fresnel);
		color += glassColor * 0.1;

	}else{
		// Particles etc — additively blend
		color = solidColor + gbuffer.albedo * gbuffer.albedoAlpha * 0.5;
	}

	colorOut = vec4(color, 1.0);
}