//     _________      __        __     ___       __     __________      ________        ______        __           
//    /  _____  \    |  |      |  |   |   \     |  |   |   _____  \    |__    __|      /  __  \      |  |          
//   /  /     \__\   |  |      |  |   |    \    |  |   |  |     \  \      |  |        /  /  \  \     |  |          
//  |  |             |  |      |  |   |  |  \   |  |   |  |      |  |     |  |       /  /    \  \    |  |          
//   \  \______      |  |      |  |   |  |\  \  |  |   |  |      |  |     |  |      |  |______|  |   |  |          
//    \______  \     |  |      |  |   |  | \  \ |  |   |  |      |  |     |  |      |   ______   |   |  |          
//           \  \    |  |      |  |   |  |  \  \|  |   |  |      |  |     |  |      |  |      |  |   |  |          
//  ___       |  |   |  |      |  |   |  |   \  |  |   |  |      |  |     |  |      |  |      |  |   |  |          
//  \  \_____/  /     \  \____/  /    |  |    \    |   |  |_____/  /    __|  |__    |  |      |  |   |  |_________ 
//   \_________/       \________/     |__|     \___|   |__________/    |________|   |__|      |__|   |____________|
//
//  General Public License v3.0. Copyright (C) 2026 GamesofDev.
//  https://github.com/GamesofDev/Sundial-Lite
//  https://www.gnu.org/licenses/gpl-3.0.en.html
//
//  Lighting that need to be calculated in visibility bitmask; Write current solid depth for GI accumulation
//

#extension GL_ARB_gpu_shader5 : enable

layout(location = 0) out vec4 texBuffer3;
layout(location = 1) out uint texBuffer6;

in vec2 texcoord;

uniform vec3 viewShadowDirection;

#define PCSS
#define PCSS_SAMPLES 9 // [2 3 4 5 6 7 8 9 10 12 14 16 18 20 25 30 36]
#define SCREEN_SPACE_SHADOW_SAMPLES 12 // [4 5 6 7 8 9 10 12 14 16 18 20 25 30 35 40 45 50]
#define SCREEN_SPACE_SHADOW

const float shadowDistance = 120.0; // [80.0 120.0 160.0 200.0 240.0 280.0 320.0 360.0 400.0 480.0 560.0 640.0]

#include "/settings/CloudSettings.glsl"
#include "/settings/GlobalSettings.glsl"
#include "/libs/Uniform.glsl"
#include "/libs/Common.glsl"
#include "/libs/Atmosphere.glsl"
#include "/libs/Cloud.glsl"
#include "/libs/GbufferData.glsl"
#include "/libs/Shadow.glsl"

#ifdef SHADOW_AND_SKY
    vec3 shadowSpaceSurfaceOffset(vec3 worldOffsetDir) {
        vec3 offset = mat3(shadowModelViewProj0, shadowModelViewProj1, shadowModelViewProj2) * worldOffsetDir;
        offset *= inversesqrt(max(dot(offset.xy, offset.xy), dot(offset, offset) * 0.09)) * 400.0 / shadowDistance / realShadowMapResolution;
        offset.z *= 0.1;
        return offset;
    }

    void percentageCloserSoftShadow(
        vec3 worldPos, vec3 worldGeoNormal, float NdotL, float viewLength, float smoothness,
        float porosity, float skyLight, vec2 noise, inout vec3 shadow, inout vec3 subsurfaceScattering
    ) {
        subsurfaceScattering *= clamp(SUBSERFACE_SCATTERING_STRENTGH * 1e+10, 0.0, 1.0);
        if (weatherStrength < 0.999) {
            vec3 sssShadowCoord = worldPosToShadowCoordNoDistort(worldPos);
            float normalOffsetLen = (viewLength * 2e-3 + 2e-2) * (1.0 + sqrt(1.0 - NdotL));
            vec3 normalOffset = mat3(shadowModelViewProj0, shadowModelViewProj1, shadowModelViewProj2) * (worldGeoNormal * normalOffsetLen * 4096.0 / realShadowMapResolution);
            normalOffset.z *= 0.1;

            vec3 basicShadowCoordNoDistort = sssShadowCoord + normalOffset;
            sssShadowCoord = distortShadowCoord(sssShadowCoord - normalOffset);
            float clipLengthInv = inversesqrt(dot(basicShadowCoordNoDistort.xy, basicShadowCoordNoDistort.xy));
            float distortFactor = clipLengthInv * log(distortionStrength / clipLengthInv + 1.0) / log(distortionStrength + 1.0);
            vec3 basicShadowCoord = basicShadowCoordNoDistort;
            basicShadowCoord.st = basicShadowCoord.st * 0.25 * distortFactor + 0.75;

            float normalFactor = clamp(pow(NdotL, pow2(1.0 - smoothness * 0.3)), 0.0, 1.0);
            NdotL = abs(dot(worldGeoNormal, shadowDirection));
            NdotL = NdotL + (1.0 - NdotL) * clamp(porosity * 255.0 / 191.0 - 64.0 / 191.0, 0.0, 1.0);

            vec3 offsetDirection1 = cross(worldGeoNormal, shadowDirection);
            vec3 offsetDirection2 = cross(worldGeoNormal, offsetDirection1);
            offsetDirection1 = shadowSpaceSurfaceOffset(offsetDirection1);
            offsetDirection2 = shadowSpaceSurfaceOffset(offsetDirection2);
            basicShadowCoordNoDistort.z -= 2e-5;

            float avgOcclusionDepth = 0.0;
            float depthSum = 0.0;
            float depthSampleRadius = (0.5 + noise.y) * 2.0;
            float offsetX = -depthSampleRadius;
            for (int i = -1; i <= 1; i++) {
                float offsetY = -depthSampleRadius;
                for (int j = -1; j <= 1; j++) {
                    vec3 sampleCoord = distortShadowCoord(basicShadowCoordNoDistort + offsetX * offsetDirection1 + offsetY * offsetDirection2);
                    float sampleDepth = textureLod(shadowtex1, sampleCoord.st, 0.0).r;
                    depthSum += sampleDepth;
                    avgOcclusionDepth += clamp(sampleCoord.z - sampleDepth, 0.0, 1.0);
                    offsetY += depthSampleRadius;
                }
                offsetX += depthSampleRadius;
            }
            if (depthSum < 8.9999 && all(lessThan(abs(basicShadowCoord - vec3(vec2(0.75), 0.5)), vec3(vec2(0.249), 0.5)))) {
                float filterRadius = min(avgOcclusionDepth * 80.0 / 9.0, 4.0) + 0.02 * shadowDistance / distortFactor;

                vec3 waterShadowCoord = basicShadowCoord - vec3(0.0, 0.5, 0.0);
                float lightFactor = 1.0;
                #ifdef LIGHT_LEAKING_FIX
                    lightFactor = clamp(skyLight * 10.0 + isEyeInWater, 0.0, 1.0);
                #endif
                vec3 caustic = waterCaustic(waterShadowCoord, worldPos, shadowDirection) * lightFactor;
                shadow *= caustic;
                subsurfaceScattering *= caustic;

                const mat2 rotation = mat2(cos(2.39996323), sin(2.39996323), -sin(2.39996323), cos(2.39996323));
                noise.x *= PI * 2.0;
                vec2 sampleAngle = vec2(cos(noise.x), sin(noise.x)) * filterRadius;
                float sampleRadius = noise.y * 1.0 / PCSS_SAMPLES + 1e-6;
                bool needSubsurfaceScattering = porosity > 64.5 / 255.0;

                float sssRadius = (0.25 + 0.25 / filterRadius) * distortFactor;
                float transparentShadow = 1e-6;
                vec3 transparentShadowColor = vec3(0.0);
                float opticalDepth = 0.0;
                float solidShadow = 0.0;
                for (int i = 0; i < PCSS_SAMPLES; i++) {
                    vec2 sampleRotation = sampleRadius * inversesqrt(sampleRadius) * sampleAngle;
                    vec3 sampleOffset = sampleRotation.x * offsetDirection1 + sampleRotation.y * offsetDirection2;
                    vec3 sampleShadowCoord = distortShadowCoord(basicShadowCoordNoDistort + sampleOffset);
                    if (normalFactor > 1e-5) {
                        float sampleSolidShadow = textureLod(shadowtex0, sampleShadowCoord, 0.0);
                        solidShadow += sampleSolidShadow;
                    }

                    if (needSubsurfaceScattering) {
                        vec3 sssSampleCoord = sssShadowCoord + vec3(sampleOffset.st * sssRadius, 0.0);
                        float shadowDepth = textureLod(shadowtex1, sssSampleCoord.st, 0.0).r;
                        opticalDepth += clamp(sssSampleCoord.z - shadowDepth + 1e-4, 0.0, 1.0);
                    }

                    sampleAngle = rotation * sampleAngle;
                    sampleRadius += 1.0 / PCSS_SAMPLES;
                    #ifdef TRANSPARENT_SHADOW
                        sampleShadowCoord.x -= 0.5;
                        float sampleTransparentShadow = textureLod(shadowtex0, sampleShadowCoord, 0.0);
                        if (sampleTransparentShadow < 1.0) {
                            sampleTransparentShadow = 1.0 - sampleTransparentShadow;
                            vec3 sampleTransparentColor = textureLod(shadowcolor0, sampleShadowCoord.st, 0.0).rgb;
                            transparentShadow += sampleTransparentShadow;
                            transparentShadowColor += sampleTransparentColor * sampleTransparentShadow;
                        }
                    #endif
                }
                #ifdef TRANSPARENT_SHADOW
                    transparentShadowColor /= transparentShadow;
                    transparentShadow /= PCSS_SAMPLES;
                    transparentShadowColor *= transparentShadowColor;
                    transparentShadowColor = mix(vec3(1.0), transparentShadowColor, vec3(transparentShadow));
                    shadow *= transparentShadowColor;
                    subsurfaceScattering *= transparentShadowColor;
                #endif

                solidShadow *= normalFactor / PCSS_SAMPLES;
                if (needSubsurfaceScattering && SUBSERFACE_SCATTERING_STRENTGH > 0.0) {
                    const float absorptionScale = SUBSERFACE_SCATTERING_STRENTGH / (191.0);
                    float absorptionBeta = -4e+3 * 0.5 * 1.44269502 / max(porosity * absorptionScale * 255.0 - absorptionScale * 64.0, 1e-5) * opticalDepth / PCSS_SAMPLES;
                    subsurfaceScattering *= exp2(absorptionBeta) * (1.0 - solidShadow) * NdotL;
                }
                shadow *= solidShadow;
            }
            else {
                skyLight = smoothstep(0.8, 0.9, skyLight);
                shadow *= skyLight * normalFactor;
                subsurfaceScattering *= skyLight * (1.0 - normalFactor) * NdotL * step(64.5 / 255.0, porosity);
            }
        }
    }

    float screenSpaceShadow(vec3 viewPos, float NdotL, float viewLength, float porosity, vec2 noise, float handOffset) {
        vec4 originProjPos = vec4(vec3(gbufferProjection[0].x, gbufferProjection[1].y, gbufferProjection[2].z) * viewPos, -viewPos.z);
        originProjPos.z += gbufferProjection[3].z;
        originProjPos.xy += gbufferProjection[2].xy * viewPos.z;
        #ifdef TAA
            originProjPos.xy += taaOffset * originProjPos.w;
        #endif
        float projScale = 0.5 / originProjPos.w;
        vec4 originCoord = vec4(originProjPos.xyz * projScale + 0.5, 0.0);

        vec4 projDirection = vec4(vec3(gbufferProjection[0].x, gbufferProjection[1].y, gbufferProjection[2].z) * viewShadowDirection, -viewShadowDirection.z);
        projDirection.xy += gbufferProjection[2].xy * viewShadowDirection.z;
        float traceLength = projIntersectionScreenEdge(originProjPos, projDirection);
        vec4 targetProjPos = originProjPos + projDirection * traceLength;
        float targetProjScale = 0.5 / targetProjPos.w;
        vec4 targetCoord = vec4(targetProjPos.xyz * targetProjScale + 0.5, 0.0);

        #ifdef LOD
            projDirection.z = projDirection.z / gbufferProjection[2].z * projLod()[2].z;
            float originProjDepthLod = viewPos.z * projLod()[2].z + projLod()[3].z;
            originCoord.w = originProjDepthLod * projScale + 0.5;
            targetCoord.w = (originProjDepthLod + projDirection.z * traceLength) * targetProjScale + 0.5;
        #endif

        vec4 stepSize = targetCoord - originCoord;
        stepSize *= inversesqrt(dot(stepSize.xy, stepSize.xy));
        originCoord += stepSize * max(texelSize.x, texelSize.y) * 1.5;

        float shadow = 1.0;
        float stepScale = 1.0;
        float porosityScale = (1.0 - clamp(porosity - 0.25, 0.0, 1.0));
        stepSize *= 0.003 * 12.0 / SCREEN_SPACE_SHADOW_SAMPLES;

        targetCoord = originCoord + stepSize * SCREEN_SPACE_SHADOW_SAMPLES;
        vec3 targetViewPos = screenToViewPos(targetCoord.xy, targetCoord.z);
        #ifdef LOD
            if (targetCoord.z >= 1.0) {
                targetViewPos = screenToViewPosLod(targetCoord.xy, targetCoord.w);
            }
        #endif
        const float absorptionScale = SUBSERFACE_SCATTERING_STRENTGH / (191.0);
        vec3 viewPosDiff = targetViewPos - viewPos;
        float absorptionBeta = -0.5 / (max(porosity * absorptionScale * 255.0 - absorptionScale * 64.0, 1e-5) * inversesqrt(dot(viewPosDiff, viewPosDiff)));
        float absorption = exp2(absorptionBeta * porosityScale * 0.5) * step(0.25, porosity) * (1.0 - clamp(NdotL * 10.0, 0.0, 1.0) * porosityScale) + 1.0;
        float shadowWeight = clamp(1.0 - abs(NdotL) * 10.0, 0.0, 1.0) * clamp(1.0 - 1.1 / viewLength / shadowDistance, 0.0, 1.0);

        vec4 sampleCoord = originCoord + noise.x * stepSize;
        sampleCoord.zw -= 2e-7;

        float maximumThickness = 0.0005 * viewLength + 0.03 * handOffset;
        float maximumThicknessLod = 0.5 * viewLength;
        sampleCoord.zw -= vec2(maximumThickness, maximumThicknessLod);

        for (int i = 0; i < SCREEN_SPACE_SHADOW_SAMPLES; i++) {
            if (any(greaterThan(abs(sampleCoord.xy - 0.5), vec2(0.5))) || shadow < 0.01) {
                break;
            }
            float sampleDepth = uintBitsToFloat(texelFetch(colortex6, ivec2(sampleCoord.st * screenSize), 0).r);
            bool hit;
            #ifdef LOD
                if (sampleDepth < 0.0) {
                    hit = abs(sampleCoord.w + sampleDepth) < maximumThicknessLod && sampleDepth > -1.0;
                }
                else
            #endif
            {
                sampleDepth -= handOffset;
                hit = abs(sampleCoord.z - sampleDepth) < maximumThickness && sampleDepth < 1.0;
                if (hit) {
                    vec2 sampleTexelCoord = sampleCoord.xy * screenSize + 0.5;
                    vec2 sampleTexel = floor(sampleTexelCoord);
                    vec4 sh = uintBitsToFloat(textureGather(colortex6, sampleTexel * texelSize, 0));
                    sh -= handOffset;
                    vec2 fpc = sampleTexelCoord - sampleTexel;
                    vec2 x = mix(sh.wx, sh.zy, vec2(fpc.x));
                    float sampleDepth = mix(x.x, x.y, fpc.y);
                    hit = abs(sampleCoord.z - sampleDepth) < maximumThickness;
                }
            }
            shadow *= clamp(absorption - float(hit), 0.0, 1.0);
            sampleCoord += stepSize;
        }

        return clamp(mix(shadow, 1.0, shadowWeight), 0.0, 1.0);
    }

    vec3 renderSun(vec3 rayDir, vec3 lightDir, vec3 sunLight) {
        //http://www.physics.hmc.edu/faculty/esin/a101/limbdarkening.pdf
        float cosAngle = clamp(dot(rayDir, lightDir), 0.0, 1.0);
        const vec3 u = vec3(1.0, 1.0, 1.0);
        const vec3 a = vec3(0.397, 0.503, 0.652);
        float theta = acos(cosAngle);
        float centerToEdge = (theta / sunRadius);

        vec3 sun = vec3(0.0);
        if (theta < sunRadius) {
            vec3 light = sunLight;
            float mu = 1.0 - centerToEdge * centerToEdge;
            vec3 factor = vec3(1.0) - u * (vec3(1.0) - pow(vec3(mu), a * 0.5));

            sun = light * factor;
        }
        return sun;
    }
#endif

void main() {
    ivec2 texel = ivec2(gl_FragCoord.st);
    GbufferData gbufferData = getGbufferData(texel, texcoord);
    vec3 viewPos;
    vec3 viewPosNoPOM;
    float depthWithParallax = uintBitsToFloat(texelFetch(colortex6, texel, 0).x);
    #ifdef LOD
        if (gbufferData.depth == 1.0) {
            gbufferData.depth = getLodDepthSolidDeferred(texcoord);
            viewPos = screenToViewPosLod(texcoord, gbufferData.depth - 1e-7);
            viewPosNoPOM = viewPos;
            gbufferData.depth = -gbufferData.depth;
        } else
    #endif
    {
        float handDepth = gbufferData.depth / MC_HAND_DEPTH - 0.5 / MC_HAND_DEPTH + 0.5;
        if (gbufferData.materialID == MAT_HAND && abs(handDepth - 0.5) < 0.5) {
            gbufferData.depth = handDepth;
        }
        float depthWithHand = gbufferData.depth - 1e-7;
        vec3 viewDirection = vec3(texcoord * 2.0 - 1.0, gbufferProjectionInverse[3].z);
        #ifdef TAA
            viewDirection.xy -= taaOffset;
        #endif
        viewDirection.xy = vec2(gbufferProjectionInverse[0].x, gbufferProjectionInverse[1].y) * viewDirection.xy + gbufferProjectionInverse[3].xy;
        depthWithHand = depthWithHand * 2.0 - 1.0;
        viewPosNoPOM = viewDirection / (gbufferProjectionInverse[2].w * depthWithHand + gbufferProjectionInverse[3].w);
        depthWithHand = depthWithParallax - float(depthWithParallax > 1.0);
        viewPos = viewDirection / (gbufferProjectionInverse[2].w * (depthWithHand * 2.0 - 1.0) + gbufferProjectionInverse[3].w);
    }
    float blendedFrames = gbufferData.albedo.w * 255.0;
    texBuffer6 = packF8D24(blendedFrames, gbufferData.depth);
    if (texel.y < 1 && texel.x < 4) {
        texBuffer6 = floatBitsToUint(depthWithParallax);
    }
    vec3 worldPos = mat3(gbufferModelViewInverse) * viewPosNoPOM;

    vec4 finalColor = vec4(vec3(0.0), blendedFrames);
    if (abs(gbufferData.depth) < 1.0) {
        worldPos += gbufferModelViewInverse[3].xyz;
        vec3 worldGeoNormal = normalize(mat3(gbufferModelViewInverse) * gbufferData.geoNormal);

        finalColor.rgb += gbufferData.emissive * PBR_BRIGHTNESS * PI;
        finalColor.rgb *= gbufferData.albedo.rgb;

        #ifdef SHADOW_AND_SKY
            vec3 f0 = vec3(0.04);
            vec3 f82 = vec3(1.0);
            #ifdef LABPBR_F0
                f0 = mix(f0, vec3(gbufferData.metalness), step(0.001, gbufferData.metalness));
                f82 = hardcodedMetal(gbufferData.metalness);
                gbufferData.metalness = step(229.5 / 255.0, gbufferData.metalness);
            #endif
            f0 = mix(f0, gbufferData.albedo.rgb, gbufferData.metalness);
            float viewLength = inversesqrt(dot(viewPos, viewPos));
            vec3 viewDir = viewPos * viewLength;
            float NdotV = clamp(dot(viewDir, -gbufferData.normal), 0.0, 1.0);
            vec3 diffuseAbsorption = (1.0 - gbufferData.metalness) * diffuseAbsorptionWeight(NdotV, gbufferData.smoothness, f0, f82);

            vec3 shadow = sunColor * basicSunlight;
            float NdotL = clamp(dot(gbufferData.normal, viewShadowDirection), 0.0, 1.0);
            vec3 shadowDiffuse = gbufferData.albedo.rgb * diffuseAbsorption;
            vec3 shadowSpecular = sunlightSpecular(viewDir, viewShadowDirection, gbufferData.normal, gbufferData.smoothness * 0.995, NdotL, NdotV, f0, f82) * airAbsorption(11.4 * gbufferData.smoothness);
            vec2 noise = blueNoiseTemporal(texcoord).xy;
            #ifdef SCREEN_SPACE_SHADOW
                shadow *= screenSpaceShadow(viewPos, dot(worldGeoNormal, shadowDirection), viewLength, gbufferData.porosity, noise, float(depthWithParallax > 1.0));
            #endif
            #ifdef CLOUD_SHADOW
                shadow *= cloudShadow(worldPos, shadowDirection);
            #endif
            vec3 subsurfaceScattering = vec3(float(gbufferData.porosity > 64.5 / 255.0)) * shadow * shadowDiffuse;
            shadow *= shadowDiffuse + shadowSpecular;
            float shadowLightFactor = 1.0;
            #ifdef LIGHT_LEAKING_FIX
                shadowLightFactor = clamp(gbufferData.lightmap.y * 10.0 + isEyeInWater, 0.0, 1.0);
            #endif
            #ifdef PCSS
                percentageCloserSoftShadow(
                    worldPos, worldGeoNormal, NdotL, 1.0 / viewLength, gbufferData.smoothness,
                    gbufferData.porosity, gbufferData.lightmap.y, noise, shadow, subsurfaceScattering
                );
            #else
                singleSampleShadow(
                    worldPos, worldGeoNormal, NdotL, gbufferData.smoothness, gbufferData.porosity,
                    gbufferData.lightmap.y, shadow, subsurfaceScattering
                );
            #endif
            shadow += subsurfaceScattering;
            finalColor.rgb += shadow;
        }
        else {
            vec3 worldDir = normalize(worldPos);
            finalColor.rgb = renderSun(worldDir, sunDirection, vec3(300.0)) + gbufferData.albedo.rgb * 2.0;
    #endif
    }

    texBuffer3 = finalColor;
}

/* DRAWBUFFERS:36 */
