#version 420 core

#include <constants.glsl>

#define LIGHTING_TYPE (LIGHTING_TYPE_TRANSMISSION | LIGHTING_TYPE_REFLECTION)

#define LIGHTING_REFLECTION_KIND LIGHTING_REFLECTION_KIND_SPECULAR

#if (FLUID_MODE == FLUID_MODE_LOW)
#define LIGHTING_TRANSPORT_MODE LIGHTING_TRANSPORT_MODE_IMPORTANCE
#elif (FLUID_MODE >= FLUID_MODE_MEDIUM)
#define LIGHTING_TRANSPORT_MODE LIGHTING_TRANSPORT_MODE_RADIANCE
#endif

#define LIGHTING_DISTRIBUTION_SCHEME LIGHTING_DISTRIBUTION_SCHEME_MICROFACET

#define LIGHTING_DISTRIBUTION LIGHTING_DISTRIBUTION_BECKMANN

#define HAS_SHADOW_MAPS

// https://www.shadertoy.com/view/XdsyWf

#include <globals.glsl>
#include <random.glsl>

layout(location = 0) in vec3 f_pos;
layout(location = 1) flat in uint f_pos_norm;
layout(location = 2) in vec2 f_vel;
// in vec3 f_col;
// in float f_light;
// in vec3 light_pos[2];

//struct ShadowLocals {
//  mat4 shadowMatrices;
//    mat4 texture_mat;
//};
//
//layout (std140)
//uniform u_light_shadows {
//    ShadowLocals shadowMats[/*MAX_LAYER_FACES*/192];
//};

layout(std140, set = 2, binding = 0)
uniform u_locals {
    vec4 model_mat0;
    vec4 model_mat1;
    vec4 model_mat2;
    vec4 model_mat3;
    ivec4 atlas_offs;
    float load_time;
};

layout(location = 0) out vec4 tgt_color;
layout(location = 1) out uvec4 tgt_mat;

#include <cloud.glsl>
#include <light.glsl>
#include <lod.glsl>

void wave_dx(vec4 posx, vec4 posy, vec2 dir, float speed, float frequency, float timeshift, out vec4 wave, out vec4 dx) {
    vec4 x = vec4(
        dot(dir, vec2(posx.x, posy.x)),
        dot(dir, vec2(posx.y, posy.y)),
        dot(dir, vec2(posx.z, posy.z)),
        dot(dir, vec2(posx.w, posy.w))
    ) * frequency + timeshift * speed;
    wave = sin(x) + 0.5;
    wave *= wave;
    dx = -wave * cos(x);
}

// Based loosely on https://www.shadertoy.com/view/MdXyzX.
// Modified to allow calculating the wave function 4 times at once using different positions (used for intepolation
// for moving water). The general idea is to sample the wave function at different positions, where those positions
// depend on increments of the velocity, and then interpolate between those velocities to get a smooth water velocity.
vec4 wave_height(vec4 posx, vec4 posy) {
    float iter = 0.0;
    float phase = 4.0;
    float weight = 1.5;
    vec4 w = vec4(0.0);
    float ws = 0.0;
    const float speed_per_iter = 0.1;
    #if (FLUID_MODE == FLUID_MODE_HIGH)
        float speed = 1.0;
        posx *= 0.2;
        posy *= 0.2;
        const float drag_factor = 0.035;
        const int iters = 21;
        const float scale = 15.0;
    #else
        float speed = 2.0;
        posx *= 0.3;
        posy *= 0.3;
        const float drag_factor = 0.04;
        const int iters = 11;
        const float scale = 3.0;
    #endif
    const float iter_shift = (3.14159 * 2.0) / 7.3;

    for(int i = 0; i < iters; i ++) {
        vec2 p = vec2(sin(iter), cos(iter));
        vec4 wave, dx;
        wave_dx(posx, posy, p, speed, phase, tick.x, wave, dx);
        posx += p.x * dx * weight * drag_factor;
        posy += p.y * dx * weight * drag_factor;
        w += wave * weight;
        iter += iter_shift * 1.5;
        ws += weight;
        weight = mix(weight, 0.0, 0.2);
        phase *= 1.2;
        speed += speed_per_iter;
    }
    return w / ws * scale;
}

float wave_height_vel(vec2 pos) {
    vec4 heights = wave_height(
        pos.x - tick.x * floor(f_vel.x) - vec2(0.0, tick.x).xyxy,
        pos.y - tick.x * floor(f_vel.y) - vec2(0.0, tick.x).xxyy
    );
    return mix(
        mix(heights.x, heights.y, fract(f_vel.x + 1.0)),
        mix(heights.z, heights.w, fract(f_vel.x + 1.0)),
        fract(f_vel.y + 1.0)
    );
}

void main() {
    #ifdef EXPERIMENTAL_BAREMINIMUM
        tgt_color = vec4(simple_lighting(f_pos.xyz, MU_SCATTER, 1.0), 0.5);
        return;
    #endif

    // First 3 normals are negative, next 3 are positive
    vec3 normals[6] = vec3[](vec3(-1,0,0), vec3(1,0,0), vec3(0,-1,0), vec3(0,1,0), vec3(0,0,-1), vec3(0,0,1));

    // TODO: last 3 bits in v_pos_norm should be a number between 0 and 5, rather than 0-2 and a direction.
    uint norm_axis = (f_pos_norm >> 30) & 0x3u;
    // Increase array access by 3 to access positive values
    uint norm_dir = ((f_pos_norm >> 29) & 0x1u) * 3u;
    // Use an array to avoid conditional branching
    // Temporarily assume all water faces up (this is incorrect but looks better)
    vec3 surf_norm = normals[norm_axis + norm_dir];
    vec3 f_norm = vec3(0, 0, 1);//surf_norm;
    vec3 cam_to_frag = normalize(f_pos - cam_pos.xyz);

    // vec4 light_pos[2];
//#if (SHADOW_MODE == SHADOW_MODE_MAP)
//    // for (uint i = 0u; i < light_shadow_count.z; ++i) {
//    //     light_pos[i] = /*vec3(*/shadowMats[i].texture_mat * vec4(f_pos, 1.0)/*)*/;
//    // }
//    vec4 sun_pos = /*vec3(*/shadowMats[0].texture_mat * vec4(f_pos, 1.0)/*)*/;
//#elif (SHADOW_MODE == SHADOW_MODE_CHEAP || SHADOW_MODE == SHADOW_MODE_NONE)
//    vec4 sun_pos = vec4(0.0);
//#endif

    // vec4 vert_pos4 = view_mat * vec4(f_pos, 1.0);
    // vec3 view_dir = normalize(-vec3(vert_pos4)/* / vert_pos4.w*/);
    vec3 view_dir = -cam_to_frag;
    float frag_dist = length(f_pos - cam_pos.xyz);

    vec3 b_norm;
    if (f_norm.z > 0.0) {
        b_norm = vec3(1, 0, 0);
    } else if (f_norm.x > 0.0) {
        b_norm = vec3(0, 1, 0);
    } else {
        b_norm = vec3(0, 0, 1);
    }
    vec3 c_norm = cross(f_norm, b_norm);

    vec3 wave_pos = mod(f_pos + focus_off.xyz, vec3(3000.0)) - (f_pos.z + focus_off.z) * 0.2;
    float wave_sample_dist = 0.1;
    float wave00 = wave_height_vel(wave_pos.xy);
    float wave10 = wave_height_vel(wave_pos.xy + vec2(wave_sample_dist, 0));
    float wave01 = wave_height_vel(wave_pos.xy + vec2(0, wave_sample_dist));

    // Possibility of div by zero when slope = 0,
    // however this only results in no water surface appearing
    // and is not likely to occur (could not find any occurrences)
    float slope = abs((wave00 - wave10) * (wave00 - wave01)) + 0.001;

    vec3 nmap = vec3(
        -(wave10 - wave00) / wave_sample_dist,
        -(wave01 - wave00) / wave_sample_dist,
        wave_sample_dist / slope
    );

    #if (CLOUD_MODE != CLOUD_MODE_NONE)
        if (rain_density > 0 && surf_norm.z > 0.5) {
            vec3 drop_density = vec3(2, 2, 2);
            vec3 drop_pos = wave_pos + vec3(0, 0, -time_of_day.x * 0.025);
            vec2 cell2d = floor(drop_pos.xy * drop_density.xy);
            drop_pos.z += noise_2d(cell2d * 13.1) * 10;
            drop_pos.z *= 0.5 + hash_fast(uvec3(cell2d, 0));
            vec3 cell = vec3(cell2d, floor(drop_pos.z * drop_density.z));

            if (fract(hash(fract(vec4(cell, 0) * 0.01))) < rain_density * rain_occlusion_at(f_pos.xyz) * 50.0) {
                vec3 off = vec3(hash_fast(uvec3(cell * 13)), hash_fast(uvec3(cell * 5)), 0);
                vec3 near_cell = (cell + 0.5 + (off - 0.5) * 0.5) / drop_density;

                float dist = length((drop_pos - near_cell) / vec3(1, 1, 2));
                float drop_rad = 0.125;
                nmap.xy += (drop_pos - near_cell).xy
                    * max(1.0 - abs(dist - drop_rad) * 50, 0)
                    * 2500
                    * sign(dist - drop_rad)
                    * max(drop_pos.z - near_cell.z, 0);
            }
        }
    #endif

    nmap = mix(f_norm, normalize(nmap), min(1.0 / pow(frag_dist, 0.75), 1));

    //float suppress_waves = max(dot(), 0);
    vec3 norm = normalize(f_norm * nmap.z + b_norm * nmap.x + c_norm * nmap.y);
    //norm = f_norm;

    vec3 water_color = (1.0 - MU_WATER) * MU_SCATTER;
#if (SHADOW_MODE == SHADOW_MODE_CHEAP || SHADOW_MODE == SHADOW_MODE_MAP || FLUID_MODE >= FLUID_MODE_MEDIUM)
    float f_alt = alt_at(f_pos.xy);
#elif (SHADOW_MODE == SHADOW_MODE_NONE || FLUID_MODE == FLUID_MODE_LOW)
    float f_alt = f_pos.z;
#endif

    float fluid_alt = mix(f_pos.z, f_alt, f_norm.z == 0);
    const float alpha = 0.255/*/ / 4.0*//* / 4.0 / sqrt(2.0)*/;
    const float n2 = 1.3325;
    const float R_s2s0 = pow((1.0 - n2) / (1.0 + n2), 2);
    const float R_s1s0 = pow((1.3325 - n2) / (1.3325 + n2), 2);
    const float R_s2s1 = pow((1.0 - 1.3325) / (1.0 + 1.3325), 2);
    const float R_s1s2 = pow((1.3325 - 1.0) / (1.3325 + 1.0), 2);
    float R_s = (f_pos.z < fluid_alt) ? mix(R_s2s1 * R_s1s0, R_s1s0, medium.x) : mix(R_s2s0, R_s1s2 * R_s2s0, medium.x);

    // Water is transparent so both normals are valid.
    vec3 cam_norm = faceforward(norm, norm, cam_to_frag);
    vec3 reflect_ray_dir = reflect(cam_to_frag/*-view_dir*/, norm);
    vec3 refract_ray_dir = refract(cam_to_frag/*-view_dir*/, norm, 1.0 / n2);
    vec3 sun_view_dir = view_dir;///*sign(cam_pos.z - fluid_alt) * view_dir;*/cam_pos.z <= fluid_alt ? -view_dir : view_dir;
    // vec3 sun_view_dir = cam_pos.z <= fluid_alt ? -view_dir : view_dir;
    /* vec4 reflect_ray_dir4 = view_mat * vec4(reflect_ray_dir, 1.0);
    reflect_ray_dir = normalize(vec3(reflect_ray_dir4) / reflect_ray_dir4.w); */
    // vec3 cam_to_frag = normalize(f_pos - cam_pos.xyz);
    // Squared to account for prior saturation.
    float f_light = 1.0;// pow(f_light, 1.5);
    vec3 ray_dir;
    if (medium.x == MEDIUM_WATER) {
        ray_dir = refract(cam_to_frag, -norm, 1.33);
    } else {
        // Ensure the ray doesn't accidentally point underwater
        // TODO: Make this more efficient?
        ray_dir = normalize(max(reflect_ray_dir, vec3(-1.0, -1.0, 0.0)));
    }
    // /*const */vec3 water_color = srgb_to_linear(vec3(0.2, 0.5, 1.0));
    // /*const */vec3 water_color = srgb_to_linear(vec3(0.8, 0.9, 1.0));
    // NOTE: Linear RGB, attenuation coefficients for water at roughly R, G, B wavelengths.
    // See https://en.wikipedia.org/wiki/Electromagnetic_absorption_by_water
    // /*const */vec3 water_attenuation = MU_WATER;// vec3(0.8, 0.05, 0.01);
    // /*const */vec3 water_color = vec3(0.2, 0.95, 0.99);

    /* vec3 sun_dir = get_sun_dir(time_of_day.x);
    vec3 moon_dir = get_moon_dir(time_of_day.x); */
#if (SHADOW_MODE == SHADOW_MODE_CHEAP || SHADOW_MODE == SHADOW_MODE_MAP)
    vec4 f_shadow = textureBicubic(t_horizon, s_horizon, pos_to_tex(f_pos.xy));
    float sun_shade_frac = horizon_at2(f_shadow, f_alt, f_pos, sun_dir);
#elif (SHADOW_MODE == SHADOW_MODE_NONE)
    float sun_shade_frac = 1.0;//horizon_at2(f_shadow, f_alt, f_pos, sun_dir);
#endif
    float moon_shade_frac = 1.0;// horizon_at2(f_shadow, f_alt, f_pos, moon_dir);
    // float sun_shade_frac = horizon_at(/*f_shadow, f_pos.z, */f_pos, sun_dir);
    // float moon_shade_frac = horizon_at(/*f_shadow, f_pos.z, */f_pos, moon_dir);
    // float shade_frac = /*1.0;*/sun_shade_frac + moon_shade_frac;

    vec3 reflect_color;
    #if (REFLECTION_MODE >= REFLECTION_MODE_MEDIUM)
        // This is now done in the post-process cloud shader
        /* reflect_color = get_sky_color(ray_dir, time_of_day.x, f_pos, vec3(-100000), 0.125, true, 1.0, true, sun_shade_frac); */
        /* reflect_color = get_cloud_color(reflect_color, ray_dir, f_pos.xyz, time_of_day.x, 100000.0, 0.1); */
        reflect_color = vec3(0);
    #else
        reflect_color = get_sky_color(ray_dir, time_of_day.x, f_pos, vec3(-100000), 0.125, true, 1.0, true, sun_shade_frac);
    #endif
    // Sort of non-physical, but we try to balance the reflection intensity with the direct light from the sun,
    // resulting in decent reflection of the ambient environment even after the sun has gone down.
    reflect_color *= f_light * (sun_shade_frac * 0.75 + 0.25);

    // Prevent the sky affecting light when underground
    float not_underground = clamp((f_pos.z - f_alt) / 32.0 + 1.0, 0.0, 1.0);
    reflect_color *= not_underground;

    // DirectionalLight sun_info = get_sun_info(sun_dir, sun_shade_frac, light_pos);
    DirectionalLight sun_info = get_sun_info(sun_dir, sun_shade_frac, /*sun_pos*/f_pos);
    DirectionalLight moon_info = get_moon_info(moon_dir, moon_shade_frac/*, light_pos*/);

    // Hack to determine water depth: color goes down with distance through water, so
    // we assume water color absorption from this point a to some other point b is the distance
    // along the the ray from a to b where it intersects with the surface plane; if it doesn't,
    // then the whole segment from a to b is considered underwater.
    // TODO: Consider doing for point lights.
    // vec3 cam_surface_dir = faceforward(vec3(0.0, 0.0, 1.0), cam_to_frag, vec3(0.0, 0.0, 1.0));

    // vec3 water_intersection_surface_camera = vec3(cam_pos);
    // bool _water_intersects_surface_camera = IntersectRayPlane(f_pos, view_dir, vec3(0.0, 0.0, /*f_alt*/f_pos.z + f_light), cam_surface_dir, water_intersection_surface_camera);
    // // Should work because we set it up so that if IntersectRayPlane returns false for camera, its default intersection point is cam_pos.
    // float water_depth_to_camera = length(water_intersection_surface_camera - f_pos);

    // vec3 water_intersection_surface_light = f_pos;
    // bool _light_intersects_surface_water = IntersectRayPlane(f_pos, sun_dir.z <= 0.0 ? sun_dir : moon_dir, vec3(0.0, 0.0, /*f_alt*/f_pos.z + f_light), vec3(0.0, 0.0, 1.0), water_intersection_surface_light);
    // // Should work because we set it up so that if IntersectRayPlane returns false for light, its default intersection point is f_pos--
    // // i.e. if a light ray can't hit the water, it shouldn't contribute to coloring at all.
    // float water_depth_to_light = length(water_intersection_surface_light - f_pos);

    // // For ambient color, we just take the distance to the surface out of laziness.
    // float water_depth_to_vertical = max(/*f_alt - f_pos.z*/f_light, 0.0);

    // // Color goes down with distance...
    // // See https://en.wikipedia.org/wiki/Beer%E2%80%93Lambert_law.
    // vec3 water_color_direct = exp(-MU_WATER);//exp(-MU_WATER);//vec3(1.0);
    // vec3 water_color_direct = exp(-water_attenuation * (water_depth_to_light + water_depth_to_camera));
    // vec3 water_color_ambient = exp(-water_attenuation * (water_depth_to_vertical + water_depth_to_camera));
    vec3 mu = MU_WATER;
    // NOTE: Default intersection point is camera position, meaning if we fail to intersect we assume the whole camera is in water.
    vec3 cam_attenuation = compute_attenuation_point(f_pos, -view_dir, mu, fluid_alt, cam_pos.xyz);
    //reflect_color *= cam_attenuation;
    // float water_depth_to_vertical = max(/*f_alt - f_pos.z*/f_light, 0.0);
    // For ambient color, we just take the distance to the surface out of laziness.
    // See https://en.wikipedia.org/wiki/Beer%E2%80%93Lambert_law.
    // float water_depth_to_vertical = max(fluid_alt - cam_pos.z/*f_light*/, 0.0);
    // vec3 ambient_attenuation = exp(-mu * water_depth_to_vertical);

    // For ambient reflection, we just take the water

    vec3 k_a = vec3(1.0);
    // Oxygen is light blue.
    vec3 k_d = vec3(1.0);
    vec3 k_s = vec3(0.0);//2.0 * reflect_color;

    vec3 emitted_light, reflected_light;
    // vec3 light, diffuse_light, ambient_light;
    // vec3 light_frac = /*vec3(1.0);*/light_reflection_factor(f_norm/*vec3(0, 0, 1.0)*/, view_dir, vec3(0, 0, -1.0), vec3(1.0), vec3(R_s), alpha);
    // 0 = 100% reflection, 1 = translucent water
    float passthrough = max(dot(cam_norm, -cam_to_frag), 0) * 0.75;

    float max_light = 0.0;
    max_light += get_sun_diffuse2(sun_info, moon_info, cam_norm, /*time_of_day.x*/sun_view_dir, f_pos, mu, cam_attenuation, fluid_alt, k_a/* * (shade_frac * 0.5 + light_frac * 0.5)*/, vec3(k_d), /*vec3(f_light * point_shadow)*//*reflect_color*/k_s, alpha, f_norm, 1.0, emitted_light, reflected_light);
    emitted_light *= not_underground;
    reflected_light *= not_underground;

    // Global illumination when underground (silly)
    emitted_light += (1.0 - not_underground) * 0.05;

    float point_shadow = shadow_at(f_pos, f_norm);
    reflected_light *= point_shadow;
    // Apply cloud layer to sky
    // reflected_light *= /*water_color_direct * */reflect_color * f_light * point_shadow * shade_frac;
    // emitted_light *= /*water_color_direct*//*ambient_attenuation * */f_light * point_shadow * max(shade_frac, MIN_SHADOW);
    // max_light *= f_light * point_shadow * shade_frac;
    // reflected_light *= /*water_color_direct * */reflect_color * f_light * point_shadow;
    // emitted_light *= /*water_color_direct*//*ambient_attenuation * */f_light * point_shadow;
    // max_light *= f_light * point_shadow;

    // vec3 diffuse_light_point = vec3(0.0);
    // max_light += lights_at(f_pos, cam_norm, view_dir, mu, cam_attenuation, fluid_alt, k_a, vec3(1.0), /*vec3(0.0)*/k_s, alpha, emitted_light, diffuse_light_point);

    // vec3 dump_light = vec3(0.0);
    // vec3 specular_light_point = vec3(0.0);
    // lights_at(f_pos, cam_norm, view_dir, mu, cam_attenuation, fluid_alt, vec3(0.0), vec3(0.0), /*vec3(1.0)*/k_s, alpha, dump_light, specular_light_point);
    // diffuse_light_point -= specular_light_point;
    // max_light += lights_at(f_pos, cam_norm, view_dir, mu, cam_attenuation, fluid_alt, k_a, /*k_d*/vec3(0.0), /*vec3(0.0)*/k_s, alpha, emitted_light, /*diffuse_light*/reflected_light);

    max_light += lights_at(f_pos, cam_norm, view_dir, mu, cam_attenuation, fluid_alt, k_a, /*k_d*//*vec3(0.0)*/k_d, /*vec3(0.0)*/k_s, alpha, f_norm, 1.0, emitted_light, /*diffuse_light*/reflected_light);

    //float reflected_light_point = length(reflected_light);///*length*/(diffuse_light_point.r) + f_light * point_shadow;
    // TODO: See if we can be smarter about this using point light distances.
    // reflected_light += k_d * (diffuse_light_point/* + f_light * point_shadow * shade_frac*/) + /*water_color_ambient*/specular_light_point;

    /* vec3 point_light = light_at(f_pos, norm);
    emitted_light += point_light;
    reflected_light += point_light; */

    // get_sun_diffuse(norm, time_of_day.x, light, diffuse_light, ambient_light, 0.0);
    // diffuse_light *= f_light * point_shadow;
    // ambient_light *= f_light * point_shadow;
    // vec3 point_light = light_at(f_pos, norm);
    // light += point_light;
    // diffuse_light += point_light;
    // reflected_light += point_light;
    // vec3 surf_color = srgb_to_linear(vec3(0.2, 0.5, 1.0)) * light * diffuse_light * ambient_light;
    const float REFLECTANCE = 1.0;
    vec3 surf_color = illuminate(max_light, view_dir, water_color * emitted_light/* * log(1.0 - MU_WATER)*/, /*cam_attenuation * *//*water_color * */reflect_color * REFLECTANCE + water_color * reflected_light/* * log(1.0 - MU_WATER)*/);

    // passthrough = pow(passthrough, 1.0 / (1.0 + water_depth_to_camera));
    /* surf_color = cam_attenuation.g < 0.5 ?
        vec3(1.0, 0.0, 0.0) :
        vec3(0.0, 1.0, 1.0)
    ; */
    // passthrough = passthrough * length(cam_attenuation);

    // vec3 reflect_ray_dir = reflect(cam_to_frag, norm);
    // Hack to prevent the reflection ray dipping below the horizon and creating weird blue spots in the water
    // reflect_ray_dir.z = max(reflect_ray_dir.z, 0.01);

    // vec4 _clouds;
    // vec3 reflect_color = get_sky_color(reflect_ray_dir, time_of_day.x, f_pos, vec3(-100000), 0.25, false, _clouds) * f_light;
    // Tint
    // reflect_color = mix(reflect_color, surf_color, 0.6);

    // vec4 color = mix(vec4(reflect_color * 2.0, 1.0), vec4(surf_color, 1.0 / (1.0 + /*diffuse_light*/(f_light * point_shadow + point_light) * 0.25)), passthrough);
    // vec4 color = mix(vec4(reflect_color * 2.0, 1.0), vec4(surf_color, 1.0 / (1.0 + /*diffuse_light*/(/*f_light * point_shadow*/f_light * point_shadow + reflected_light_point/* + point_light*//*reflected_light*/) * 0.25)), passthrough);
    // vec4 color = mix(vec4(surf_color, 1.0), vec4(surf_color, 0.0), passthrough);
    //vec4 color = vec4(surf_color, 1.0);
    // vec4 color = mix(vec4(reflect_color, 1.0), vec4(surf_color, 1.0 / (1.0 + /*diffuse_light*/(/*f_light * point_shadow*/reflected_light_point/* + point_light*//*reflected_light*/))), passthrough);

    // float log_cam = log(min(cam_attenuation.r, min(cam_attenuation.g, cam_attenuation.b)));
    float min_refl = 0.0;
    float opacity = (1.0 - passthrough) * 0.5 / (1.0 + min_refl);
    if (medium.x != MEDIUM_WATER) {
        min_refl = min(emitted_light.r, min(emitted_light.g, emitted_light.b));
    } else {
        // Hack to make the transparency of the surface fade when underwater to avoid artifacts
        if (dot(refract_ray_dir, cam_to_frag) > 0.0) {
            opacity = 0.99;
        } else {
            opacity = min(sqrt(max(opacity, clamp((f_pos.z - cam_pos.z) * 0.05, 0.0, 1.0))), 0.99);
        }
    }
    vec4 color = vec4(surf_color, opacity);// * (1.0 - /*log(1.0 + cam_attenuation)*//*cam_attenuation*/1.0 / (2.0 - log_cam)));
    // vec4 color = vec4(surf_color, mix(1.0, 1.0 / (1.0 + /*0.25 * *//*diffuse_light*/(/*f_light * point_shadow*/reflected_light_point)), passthrough));
    // vec4 color = vec4(surf_color, mix(1.0, length(cam_attenuation), passthrough));

    /* reflect_color = reflect_color * 0.5 * (diffuse_light + ambient_light);
    // 0 = 100% reflection, 1 = translucent water
    float passthrough = dot(faceforward(f_norm, f_norm, cam_to_frag), -cam_to_frag);

    vec4 color = mix(vec4(reflect_color, 1.0), vec4(vec3(0), 1.0 / (1.0 + diffuse_light * 0.25)), passthrough); */

    tgt_color = color;
    tgt_mat = uvec4(uvec3((norm + 1.0) * 127.0), MAT_FLUID);
}