//#define Specular_Reflections // reflections on blocks. REQUIRES A PBR RESOURCEPACK.
#define Screen_Space_Reflections // toggle screenspace reflections. if you want normal performance but still want a bit of shiny, the sun reflection stays on when this is turned off.
#define Sky_reflection // just in case you dont want it i guess
// #define Rough_reflections // turns the roughness GGXVNDF ON. sizable performance impact, and introduces alot of noise.

#define Sun_specular_Strength 3 // increase for more sparkles [1 2 3 4 5 6 7 8 9 10]
#define reflection_quality 30 // adjust the quality of the screenspace reflections. [6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 ]
#define Roughness_Threshold 1.5 // using a curve on the roughness, make the reflections more or less visible on rough surfaces. good for hiding noise on rough materials [1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 3.0 ]

// #define SCREENSHOT_MODE // go render mode and accumulate frames for as long as you want for max image quality.



uniform sampler2D gaux1;
uniform int framemod8;

const vec2[8] offsets = vec2[8](vec2(1./8.,-3./8.),
									vec2(-1.,3.)/8.,
									vec2(5.0,1.)/8.,
									vec2(-3,-5.)/8.,
									vec2(-5.,5.)/8.,
									vec2(-7.,-1.)/8.,
									vec2(3,7.)/8.,
									vec2(7.,-7.)/8.);


// sun specular stuff
float square(float x){
  return x*x;
}
float g(float NdotL, float roughness){
    float alpha = square(max(roughness, 0.02));
    return 2.0 * NdotL / (NdotL + sqrt(square(alpha) + (1.0 - square(alpha)) * square(NdotL)));
}
float gSimple(float dp, float roughness){
  float k = roughness + 1;
  k *= k/8.0;
  return dp / (dp * (1.0-k) + k);
}
vec3 GGX2(vec3 n, vec3 v, vec3 l, float r, vec3 F0) {

  float roughness = r; // when roughness is zero it fucks up
  float alpha = square(roughness) + 1e-5;

  vec3 h = normalize(l + v) ;

  float dotLH = clamp(dot(h,l),0.,1.);
  float dotNH = clamp(dot(h,n),0.,1.);
  float dotNL = clamp(dot(n,l),0.,1.);
  float dotNV = clamp(dot(n,v),0.,1.);
  float dotVH = clamp(dot(h,v),0.,1.);


  float D = alpha / (3.141592653589793*square(square(dotNH) * (alpha - 1.0) + 1.0));
  float G = gSimple(dotNV, roughness) * gSimple(dotNL, roughness);
  vec3 F = F0 + (1. - F0) * exp2((-5.55473*dotVH-6.98316)*dotVH);

  return dotNL * F * (G * D / (4 * dotNV * dotNL + 1e-7));
}


// other shit
float invLinZ (float lindepth){
	return -((2.0*near/lindepth)-far-near)/(far-near);
}
vec3 toClipSpace3(vec3 viewSpacePosition) {
    return projMAD(gbufferProjection, viewSpacePosition) / -viewSpacePosition.z * 0.5 + 0.5;
}
float linZ(float depth) {
    return (2.0 * near) / (far + near - depth * (far - near));
	// l = (2*n)/(f+n-d(f-n))
	// f+n-d(f-n) = 2n/l
	// -d(f-n) = ((2n/l)-f-n)
	// d = -((2n/l)-f-n)/(f-n)

}
// vec3 rayTrace_GI(vec3 dir,vec3 position,float dither, float quality){

//   vec3 clipPosition = toClipSpace3(position);
//   float rayLength = ((position.z + dir.z * far*sqrt(3.)) > -near) ?
//                      (-near -position.z) / dir.z : far*sqrt(3.);
//   vec3 direction = normalize(toClipSpace3(position+dir*rayLength)-clipPosition);  //convert to clip space
//   direction.xy = normalize(direction.xy);

//   //get at which length the ray intersects with the edge of the screen
//   vec3 maxLengths = (step(0.,direction)-clipPosition) / direction;
//   float mult = min(min(maxLengths.x,maxLengths.y),maxLengths.z);

//   vec3 stepv = direction * mult / quality*vec3(RENDER_SCALE,1.0);

// 	vec3 spos = clipPosition*vec3(RENDER_SCALE,1.0) ;

// 	float minZ = spos.z+stepv.z;
// 	float maxZ = spos.z+stepv.z;

// 	spos.xy += TAA_Offset*texelSize*0.5/RENDER_SCALE;
//   spos += stepv*dither ;

// 	for(int i = 0; i < int(quality); i++){
// 		float sp = sqrt(texelFetch2D(colortex4,ivec2(spos.xy/texelSize/4),0).w/65000.0);
// 		float currZ = linZ(spos.z);
// 		if( sp < currZ) {
// 			float dist = abs(sp-currZ)/currZ;
// 			if (dist <= 0.05) return vec3(spos.xy, invLinZ(sp))/vec3(RENDER_SCALE,1.0);
// 		}
// 		spos += stepv ;
// 	}
//   return vec3(1.1);
// }
vec3 rayTrace_GI(vec3 dir,vec3 position,float dither, float quality){

	vec3 clipPosition = toClipSpace3(position);
	float rayLength = ((position.z + dir.z * far*sqrt(3.)) > -near) ?
	                   (-near -position.z) / dir.z : far*sqrt(3.);
	vec3 direction = normalize(toClipSpace3(position+dir*rayLength)-clipPosition);  //convert to clip space
	direction.xy = normalize(direction.xy);

	//get at which length the ray intersects with the edge of the screen
	vec3 maxLengths = (step(0.,direction)-clipPosition) / direction;
	float mult = maxLengths.y;

	vec3 stepv = direction * mult / quality*vec3(RENDER_SCALE,1.0) * dither;
	vec3 spos = clipPosition*vec3(RENDER_SCALE,1.0) ;

	spos.xy += TAA_Offset*texelSize*0.5/RENDER_SCALE;

	float biasdist =  clamp(position.z*position.z/50.0,1,2); // shrink sample size as distance increases

	for(int i = 0; i < int(quality); i++){
		spos += stepv;
		float sp = sqrt(texelFetch2D(colortex4,ivec2(spos.xy/texelSize/4),0).w/65000.0);
		float currZ = linZ(spos.z);

		if( sp < currZ) {
			float dist = abs(sp-currZ)/currZ;
			if (abs(dist) < biasdist*0.05) return vec3(spos.xy, invLinZ(sp))/vec3(RENDER_SCALE,1.0);
		}
		spos += stepv;
	}
  return vec3(1.1);
}

void frisvad(in vec3 n, out vec3 f, out vec3 r){
    if(n.z < -0.9) {
        f = vec3(0.,-1,0);
        r = vec3(-1, 0, 0);
    } else {
    	float a = 1./(1.+n.z);
    	float b = -n.x*n.y*a;
    	f = vec3(1. - n.x*n.x*a, b, -n.x) ;
    	r = vec3(b, 1. - n.y*n.y*a , -n.y);
    }
}
mat3 CoordBase(vec3 n){
	vec3 x,y;
    frisvad(n,x,y);
    return mat3(x,y,n);
}
float unpackRoughness(float x){
  float r = 1.0 - x;
  return clamp(r*r,0,1);
}
vec2 R2_samples_spec(int n){
	vec2 alpha = vec2(0.75487765, 0.56984026);
	return fract(alpha * n);
}

vec3 sampleGGXVNDF(vec3 V_, float roughness, float U1, float U2){
	// stretch view
	vec3 V = normalize(vec3(roughness * V_.x, roughness * V_.y, V_.z));
	// orthonormal basis
	vec3 T1 = (V.z < 0.9999) ? normalize(cross(V, vec3(0,0,1))) : vec3(1,0,0);
	vec3 T2 = cross(T1, V);
	// sample point with polar coordinates (r, phi)
	float a = 1.0 / (1.0 + V.z);
	float r = sqrt(U1*0.25);
	float phi = (U2<a) ? U2/a * 3.141592653589793 : 3.141592653589793 + (U2-a)/(1.0-a) * 3.141592653589793;
	float P1 = r*cos(phi);
	float P2 = r*sin(phi)*((U2<a) ? 1.0 : V.z);
	// compute normal
	vec3 N = P1*T1 + P2*T2 + sqrt(max(0.0, 1.0 - P1*P1 - P2*P2))*V;
	// unstretch
	N = normalize(vec3(roughness*N.x, roughness*N.y, max(0.0, N.z)));
	return N;
}


vec3 rayTraceSpeculars(vec3 dir,vec3 position,float dither, float quality, bool hand){
	vec3 clipPosition = toClipSpace3(position);
	float rayLength = ((position.z + dir.z * far*sqrt(3.)) > -near) ?
	                   (-near -position.z) / dir.z : far*sqrt(3.);
	vec3 direction = normalize(toClipSpace3(position+dir*rayLength)-clipPosition);  //convert to clip space
	direction.xy = normalize(direction.xy);

	//get at which length the ray intersects with the edge of the screen
	vec3 maxLengths = (step(0.,direction)-clipPosition) / direction;
	float mult = min(min(maxLengths.x,maxLengths.y),maxLengths.z);

	vec3 stepv = direction * mult / quality*vec3(RENDER_SCALE,1.0);

	vec3 spos = clipPosition*vec3(RENDER_SCALE,1.0) + stepv*dither;

	float minZ = spos.z+stepv.z;
	float maxZ = spos.z+stepv.z;

	spos.xy += TAA_Offset*texelSize*0.5/RENDER_SCALE;

	float dist = 1.0 + clamp(position.z*position.z/50.0,0,2); // shrink sample size as distance increases
  	for (int i = 0; i <= int(quality); i++) {

		// decode depth buffer
		vec2 testthing = hand ? spos.xy*texelSize : spos.xy/texelSize/4.0; // fix for ssr on hand
		float sp = sqrt(texelFetch2D(gaux1,ivec2(testthing),0).w/65000.0);
		sp = invLinZ(sp);
		
		if(sp <= max(maxZ,minZ) && sp >= min(maxZ,minZ) ) return vec3(spos.xy/RENDER_SCALE,sp);
		spos += stepv;
		
		//small bias
		float biasamount = 0.0002 / dist;
		if(hand) biasamount = 0.01;
		minZ = maxZ-biasamount / ld(spos.z);
		
		maxZ += stepv.z;
  	}
  return vec3(1.1);
}

vec3 mix_vec3(vec3 X, vec3 Y, float A){
	return X * (1.0 - A) + Y * A;
}
float mix_float(float X, float Y, float A){
	return X * (1.0 - A) + Y * A;
}


// pain
void MaterialReflections(
	inout vec3 Output,
	float roughness, 
	vec3 f0,
	vec3 albedo,
    vec3 sunPos,
    vec3 sunCol,
    float diffuse,
    float lightmap,
	vec3 normal,
	vec3 np3,
	vec3 fragpos,
    vec3 noise,
    bool hand
){
	vec3 Reflections_Final = Output;

	float Outdoors = clamp((lightmap-0.6)*5.0, 0.0,1.0);
	// float Outdoors = clamp((lightmap-0.5) * , 0.0,1.0);
	
	roughness = unpackRoughness(roughness);
	f0 = f0.y == 0.0 ? vec3(0.04) : f0;

		// roughness = 0.0;
		// f0 = vec3(0.9);

	mat3 basis = CoordBase(normal);
	vec3 normSpaceView = -np3*basis ;

	// roughness stuff
	#ifdef Rough_reflections
		int seed = (frameCounter%40000);
		vec2  ij = fract(R2_samples_spec(seed) + noise.rg) ;

		vec3 H = sampleGGXVNDF(normSpaceView, roughness, ij.x, ij.y);
		if(hand) H = normalize(vec3(0.0,0.0,1.0));
	#else
		vec3 H = normalize(vec3(0.0,0.0,1.0));
	#endif
	
	vec3 Ln = reflect(-normSpaceView, clamp(H,-1.0,1.0));
	vec3 L = basis * Ln;

	// fresnel stuff
	float fresnel = pow(clamp(1.0 + dot(-Ln, H),0.0,1.0),5.0);
	// vec3 F = f0 + (1.0 - f0) * fresnel; 
	
	vec3 F = mix(f0, vec3(1.0), fresnel); 
	vec3 rayContrib = F;

			
	float NdotV = clamp(normalize(dot(np3, normal))*10000.,0.,1.);
    bool hasReflections = (f0.y * (1.0 - roughness * Roughness_Threshold)) > 0.01;

	if (Roughness_Threshold == 1.0){ hasReflections = roughness > -1; NdotV = -1.0;}

	if (!hasReflections || NdotV > 0.0 ) Outdoors = 0.0;
	
	// SSR, Sky, and Sun reflections
	vec4 Reflections = vec4(0.0);
	vec3 SkyReflection = skyCloudsFromTex(L, colortex4).rgb / 150. * 5.;
	vec3 SunReflection = diffuse * GGX2(clamp(normal,-1,1), -np3,  sunPos, roughness, f0) * 8./150./3. * sunCol * Sun_specular_Strength;

	#ifndef Sky_reflection
		SkyReflection = Reflections_Final;
	#endif

	#ifdef Screen_Space_Reflections
		if ( hasReflections	&& NdotV <= 0.0) { // Skip SSR if ray contribution is low
			#ifdef SCREENSHOT_MODE
				float rayQuality = reflection_quality; 
			#else
				float rayQuality = mix_float(reflection_quality,0.0,sqrt(roughness)); // Scale quality with ray contribution
			#endif
			vec3 rtPos = rayTraceSpeculars( mat3(gbufferModelView) * L,fragpos.xyz,  noise.b, rayQuality, hand);
			if (rtPos.z < 1. ){ // Reproject on previous frame
				vec3 previousPosition = mat3(gbufferModelViewInverse) * toScreenSpace(rtPos) + gbufferModelViewInverse[3].xyz + cameraPosition-previousCameraPosition;
				previousPosition = mat3(gbufferPreviousModelView) * previousPosition + gbufferPreviousModelView[3].xyz;
				previousPosition.xy = projMAD(gbufferPreviousProjection, previousPosition).xy / -previousPosition.z * 0.5 + 0.5;
				if (previousPosition.x > 0.0 && previousPosition.y > 0.0 && previousPosition.x < 1.0 && previousPosition.x < 1.0) {
					Reflections.a = 1.0;
					Reflections.rgb = texture2D(colortex5,previousPosition.xy).rgb;
				}
			}
		}
	#endif

	// check if the f0 is within the metal ranges, then tint by albedo if it's true.
	vec3 Metals = f0.y > 229.5/255.0 ? clamp(albedo + fresnel,0.0,1.0) : vec3(1.0);

	Reflections.rgb *= Metals;
	SunReflection *= Metals;
	#ifdef Sky_reflection
		SkyReflection *= Metals;
	#endif
	float lumaRayContrib = luma(rayContrib);
	// darken albedos, and stop darkening where the sky gets occluded indoors
	Reflections_Final *= mix_float(1.0 - (Reflections.a*lumaRayContrib), 1.0 - lumaRayContrib, Outdoors);
	
	// apply all reflections to the lighting
	Reflections_Final += Reflections.rgb * lumaRayContrib;
	Reflections_Final += SkyReflection * lumaRayContrib * (1.0-Reflections.a) * Outdoors ;

	float visibilityFactor = clamp(exp2((pow(roughness,3.0) / f0.y) * -4),0,1);
	#ifdef Rough_reflections
		Output = hand ? mix_vec3(Output,  Reflections_Final, visibilityFactor) : Reflections_Final;
	#else
		Output = mix_vec3(Output,  Reflections_Final, visibilityFactor);
	#endif

	Output += SunReflection ;
}