#version 120
//Volumetric fog rendering
#extension GL_EXT_gpu_shader4 : enable

#define VL_SAMPLES 8 //[4 6 8 10 12 14 16 20 24 30 40 50]
#define Ambient_Mult 1.0 //[0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.75 0.8 0.85 0.9 0.95 1.0 1.5 2.0 3.0 4.0 5.0 6.0 10.0]
#define SEA_LEVEL 70 //[0 10 20 30 40 50 60 70 80 90 100 110 120 130 150 170 190]	//The volumetric light uses an altitude-based fog density, this is where fog density is the highest, adjust this value according to your world.
#define ATMOSPHERIC_DENSITY 1.0 //[0.0 0.5 1.0 1.5 2.0 2.5 3.0 4.0 5.0 7.5 10.0 12.5 15.0 20.]
#define fog_mieg1 0.40 //[0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.75 0.8 0.85 0.9 0.95 1.0]
#define fog_mieg2 0.10 //[0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.75 0.8 0.85 0.9 0.95 1.0]
#define fog_coefficientRayleighR 5.8 //[0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5 8.0 8.5 9.0 9.5 10.0]
#define fog_coefficientRayleighG 1.35 //[0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5 8.0 8.5 9.0 9.5 10.0]
#define fog_coefficientRayleighB 3.31 //[0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5 8.0 8.5 9.0 9.5 10.0]

#define fog_coefficientMieR 3.0 //[0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5 8.0 8.5 9.0 9.5 10.0]
#define fog_coefficientMieG 3.0 //[0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5 8.0 8.5 9.0 9.5 10.0]
#define fog_coefficientMieB 3.0 //[0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5 8.0 8.5 9.0 9.5 10.0]

#define Underwater_Fog_Density 1.0 //[0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.75 0.8 0.85 0.9 0.95 1.0 1.5 2.0 3.0 4.0]

flat varying vec4 lightCol;
flat varying vec3 ambientUp;
flat varying vec3 ambientLeft;
flat varying vec3 ambientRight;
flat varying vec3 ambientB;
flat varying vec3 ambientF;
flat varying vec3 ambientDown;
flat varying float tempOffsets;
flat varying float fogAmount;
flat varying float VFAmount;
uniform sampler2D noisetex;
uniform sampler2D depthtex0;


uniform sampler2D colortex2;
uniform sampler2D colortex3;
// uniform sampler2D colortex4;

uniform vec3 sunVec;
uniform float far;
uniform int frameCounter;
uniform float rainStrength;
uniform float sunElevation;
uniform ivec2 eyeBrightnessSmooth;
uniform float frameTimeCounter;
uniform int isEyeInWater;
uniform vec2 texelSize;


uniform float isWastes;
uniform float isWarpedForest;
uniform float isCrimsonForest;
uniform float isSoulValley;
uniform float isBasaltDelta;


#include "lib/waterOptions.glsl"
#include "lib/color_transforms.glsl"
#include "lib/color_dither.glsl"
#include "lib/projections.glsl"
#include "lib/sky_gradient.glsl"
#include "lib/volumetricClouds.glsl"
#define fsign(a)  (clamp((a)*1e35,0.,1.)*2.-1.)

float interleaved_gradientNoise(){
	return fract(52.9829189*fract(0.06711056*gl_FragCoord.x + 0.00583715*gl_FragCoord.y)+tempOffsets);
}

float densityAtPosFog(in vec3 pos){
	pos /= 18.;
	pos.xz *= 0.5;

	vec3 p = floor(pos);
	vec3 f = fract(pos);

	f = (f*f) * (3.-2.*f);
	vec2 uv =  p.xz + f.xz + p.y * vec2(0.0,193.0);
	vec2 coord =  uv / 512.0;
	vec2 xy = texture2D(noisetex, coord).yx;
	return mix(xy.r,xy.g, f.y);
}


float cloudVol(in vec3 pos){

	vec3 samplePos = pos*vec3(1.0,1./24.,1.0) ;
	vec3 samplePos2 = pos*vec3(1.0,1./48.,1.0) + vec3(frameTimeCounter,0,frameTimeCounter);

	float fog_shape = 1-densityAtPosFog(samplePos * 16.0   );
	float fog_eroded = densityAtPosFog(	samplePos2 * 255.0 );

	return max(	(fog_shape*2.0 - fog_eroded*0.2) - 1.5, 0.0) * 255*255 ;
}
float phaseRayleigh(float cosTheta) {
	const vec2 mul_add = vec2(0.1, 0.28) /acos(-1.0);
	return cosTheta * mul_add.x + mul_add.y; // optimized version from [Elek09], divided by 4 pi for energy conservation
}
mat2x3 getVolumetricRays(float dither,vec3 fragpos, vec3 fragpos_ALT) {

	//project pixel position into projected shadowmap space
	vec3 wpos = mat3(gbufferModelViewInverse) * fragpos + gbufferModelViewInverse[3].xyz;
	vec3 fragposition = mat3(shadowModelView) * wpos + shadowModelView[3].xyz;
	fragposition = diagonal3(shadowProjection) * fragposition + shadowProjection[3].xyz;


	//project view origin into projected shadowmap space
	vec3 start = toShadowSpaceProjected(vec3(0.));

	//rayvector into projected shadow map space
	//we can use a projected vector because its orthographic projection
	//however we still have to send it to curved shadow map space every step
	vec3 dV = (fragposition-start);
	vec3 dVWorld = (wpos-gbufferModelViewInverse[3].xyz);

	float maxLength = min(length(dVWorld),far*4)/length(dVWorld);
	dV *= maxLength;
	dVWorld *= maxLength;

	//apply dither
	vec3 progress = start.xyz;
	vec3 progressW = gbufferModelViewInverse[3].xyz+cameraPosition;
	vec3 vL = vec3(0.);
	float dL = length(dVWorld);

    vec3 lightSource = normalize(WsunVec);
	vec3 viewspace_sunvec = mat3(gbufferModelView) * lightSource;
	float SdotV = dot(normalize(viewspace_sunvec), normalize(fragpos));

	float mie = phaseg(SdotV,0.8);
	float rayL = phaseRayleigh(SdotV);

	float mu = 1.0;
	vec3 absorbance = vec3(1.0);
	float expFactor = 11.0;

	vec3 fogColor = gl_Fog.color.rgb * 0.5 ;
	vec3 lightning = SunCol ;

	vec3 rC = vec3(fogColor.r*1e-6, fogColor.g*1e-5, fogColor.b*1e-5);
	vec3 mC = vec3(fogColor.r*1e-6, fogColor.g*1e-6,  fogColor.b*1e-6);

	for (int i=0;i<VL_SAMPLES+10;i++) {
		float d = (pow(expFactor, float(i+dither)/float(VL_SAMPLES+10))/expFactor - 1.0/expFactor)/(1-1.0/expFactor);
		float dd = pow(expFactor, float(i+dither)/float(VL_SAMPLES+10)) * log(expFactor) / float(VL_SAMPLES+10)/(expFactor-1.0);
		progressW = gbufferModelViewInverse[3].xyz+cameraPosition + d*dVWorld;

		float densityVol = cloudVol(progressW);
		float density = densityVol*mu*300.;

		float CastLight = 0;
		
		for (int j=0; j < 3; j++){
			vec3 shadowSamplePos =  progressW + WsunVec * (5+j*10 ) ;
			
			float densityVol2 = cloudVol(shadowSamplePos);
			CastLight += densityVol2/255;
		}


		//Just air

		vec2 airCoef = exp(-max(progressW.y-SEA_LEVEL,0.0)/vec2(8.0e3, 1.2e3)*vec2(6.,7.0)) * 24;

		//Pbr for air, yolo mix between mie and rayleigh for water droplets
		vec3 rL = rC*airCoef.x;
		vec3 m = (airCoef.y+density)*mC;

		vec3 DirectLight = lightning * (rayL*rL+m*mie) * exp(CastLight/25) * 1e-5 * mie	;
		vec3 DirectLight2 = lightning * (rayL*rL+m*mie) * exp(CastLight / -25) 	 ;
		
		vec3 AmbientLight =  fogColor * max(1 - exp(dot(m,vec3(1)) * -25 ),0.05)  / 150	;
		


		vec3 vL0 = AmbientLight + clamp( DirectLight+DirectLight2 ,0,255) ;


		// vL += (vL0 - vL0 * exp(-density*mu*dd*dL)) / (density*mu+0.00000001)*absorbance;
		// absorbance *= clamp(exp(-(density)*mu*dd*dL),0.0,1.0);
		
		vL += (vL0 - vL0 * exp(-(rL+m)*dd*dL)) / ((rL+m)+0.00000001)*absorbance;
		absorbance *= clamp(exp(-(rL+m)*dd*dL),0.0,1.0);
		
	}
	return mat2x3(vL,absorbance);
}

void waterVolumetrics(inout vec3 inColor, vec3 rayStart, vec3 rayEnd, float estEyeDepth, float estSunDepth, float rayLength, float dither, vec3 waterCoefs, vec3 scatterCoef, vec3 ambient, vec3 lightSource, float VdotL){
		int spCount = 16;

		vec3 start = toShadowSpaceProjected(rayStart);
		vec3 end = toShadowSpaceProjected(rayEnd);
		vec3 dV = (end-start);
		//limit ray length at 32 blocks for performance and reducing integration error
		//you can't see above this anyway
		float maxZ = min(rayLength,32.0)/(1e-8+rayLength);
		dV *= maxZ;
		rayLength *= maxZ;
		float dY = normalize(mat3(gbufferModelViewInverse) * rayEnd).y * rayLength;
		vec3 absorbance = vec3(1.0);
		vec3 vL = vec3(0.0);
		float phase = phaseg(VdotL, Dirt_Mie_Phase);
		float expFactor = 11.0;
		for (int i=0;i<spCount;i++) {
			float d = (pow(expFactor, float(i+dither)/float(spCount))/expFactor - 1.0/expFactor)/(1-1.0/expFactor);		// exponential step position (0-1)
			float dd = pow(expFactor, float(i+dither)/float(spCount)) * log(expFactor) / float(spCount)/(expFactor-1.0);	//step length (derivative)
			vec3 spPos = start.xyz + dV*d;
			vec3 ambientMul = exp(-max(estEyeDepth - dY * d,0.0) * waterCoefs * 1.1);
			vec3 light = (ambientMul*ambient )*scatterCoef;
			vL += (light - light * exp(-waterCoefs * dd * rayLength)) / waterCoefs *absorbance;
			absorbance *= exp(-dd * rayLength * waterCoefs);
		}
		inColor += vL;
}
float blueNoise(){
  return fract(texelFetch2D(noisetex, ivec2(gl_FragCoord.xy)%512, 0).a + 1.0/1.6180339887 * frameCounter);
}
//////////////////////////////VOID MAIN//////////////////////////////
//////////////////////////////VOID MAIN//////////////////////////////
//////////////////////////////VOID MAIN//////////////////////////////
//////////////////////////////VOID MAIN//////////////////////////////
//////////////////////////////VOID MAIN//////////////////////////////

varying vec2 texcoord;
void main() {
/* DRAWBUFFERS:0 */
	if (isEyeInWater == 0){
		vec2 tc = floor(gl_FragCoord.xy)*2.0*texelSize+0.5*texelSize;
		float z = texture2D(depthtex0,tc).x;
		vec3 fragpos = toScreenSpace(vec3(tc,z));
		
  		vec3 fragpos_ALT = toScreenSpace(vec3(texcoord-vec2(0.0)*texelSize*0.5,z));

		float noise = blueNoise();
		mat2x3 vl = getVolumetricRays(noise,fragpos,fragpos_ALT);
		float absorbance = dot(vl[1],vec3(0.22,0.71,0.07));
		gl_FragData[0] = clamp(vec4(vl[0],absorbance),0.000001,65000.);
	}
	else {
		float dirtAmount = Dirt_Amount;
		vec3 waterEpsilon = vec3(Water_Absorb_R, Water_Absorb_G, Water_Absorb_B);
		vec3 dirtEpsilon = vec3(Dirt_Absorb_R, Dirt_Absorb_G, Dirt_Absorb_B);
		vec3 totEpsilon = dirtEpsilon*dirtAmount + waterEpsilon;
		vec3 scatterCoef = dirtAmount * vec3(Dirt_Scatter_R, Dirt_Scatter_G, Dirt_Scatter_B) / pi;
		vec2 tc = floor(gl_FragCoord.xy)*2.0*texelSize+0.5*texelSize;
		float z = texture2D(depthtex0,tc).x;
		vec3 fragpos = toScreenSpace(vec3(tc,z));
		float noise=blueNoise();
		vec3 vl = vec3(0.0);
		float estEyeDepth = clamp((14.0-eyeBrightnessSmooth.y/255.0*16.0)/14.0,0.,1.0);
		estEyeDepth *= estEyeDepth*estEyeDepth*34.0;
		#ifndef lightMapDepthEstimation
			estEyeDepth = max(Water_Top_Layer - cameraPosition.y,0.0);
		#endif
		waterVolumetrics(vl, vec3(0.0), fragpos, estEyeDepth, estEyeDepth, length(fragpos), noise, totEpsilon, scatterCoef, ambientUp*8./150./3.*0.84*2.0/pi, lightCol.rgb*8./150./3.0*(0.91-pow(1.0-sunElevation,5.0)*0.86), dot(normalize(fragpos), normalize(sunVec)));
		gl_FragData[0] = clamp(vec4(vl,1.0),0.000001,65000.);
	}

}