/*========================================================
° TimeOfDay.
° ======================
°
° Category: Sky.
° -----------------------------------------------------
° Description:
° Sky pass.
° -----------------------------------------------------
° Copyright:
° J. Cuellar 2021. MIT License.
° See: LICENSE File.
========================================================*/
shader_type spatial;
render_mode unshaded, depth_draw_never, cull_front, skip_vertex_transform;
// Color correction
uniform vec2 _color_correction_params;
uniform vec4 _ground_color: hint_color;
uniform float _horizon_level;
// uniforms.
uniform vec3 _sun_direction;
uniform vec3 _moon_direction;
uniform float _moon_size;
uniform mat3 _moon_matrix;
uniform mat3 _deep_space_matrix;
// Atmospheric Scattering.
uniform float _atm_darkness;
uniform float _atm_sun_intensity;
uniform vec4 _atm_day_tint: hint_color;
uniform vec4 _atm_horizon_light_tint: hint_color;
uniform vec4 _atm_night_tint: hint_color;
uniform vec3 _atm_level_params;
uniform float _atm_thickness;
// Sun mie phase.
uniform vec4 _atm_sun_mie_tint: hint_color;
uniform float _atm_sun_mie_intensity;
uniform vec4 _atm_moon_mie_tint: hint_color;
uniform float _atm_moon_mie_intensity;
uniform vec3 _atm_beta_ray;
uniform vec3 _atm_beta_mie;
uniform vec3 _atm_sun_partial_mie_phase;
uniform vec3 _atm_moon_partial_mie_phase;
// Sun disk.
uniform vec4 _sun_disk_color: hint_color;
uniform float _sun_disk_intensity;
uniform float _sun_disk_size;
uniform vec4 _moon_color: hint_color;
uniform sampler2D _moon_texture: hint_albedo;
// Background.
uniform sampler2D _background_texture: hint_albedo;
uniform vec4 _background_color: hint_color;
// Stars Field.
uniform vec4 _stars_field_color: hint_color;
uniform sampler2D _stars_field_texture: hint_albedo;
uniform float _stars_scintillation;
uniform float _stars_scintillation_speed;
uniform sampler2D _noise_tex: hint_albedo;
// Clouds.
uniform float _clouds_coverage;
uniform float _clouds_thickness;
uniform float _clouds_absorption;
uniform float _clouds_sky_tint_fade;
uniform float _clouds_intensity;
uniform float _clouds_size;
uniform vec2 _clouds_uv;
uniform float _clouds_offset_speed;
uniform vec2 _clouds_offset;
uniform sampler2D _clouds_texture;
// Inc.
//------------------------------------------------------------------------------
const float kPI = 3.1415927f;
const float kINV_PI = 0.3183098f;
const float kHALF_PI = 1.5707963f;
const float kINV_HALF_PI = 0.6366198f;
const float kQRT_PI = 0.7853982f;
const float kINV_QRT_PI = 1.2732395f;
const float kPI4 = 12.5663706f;
const float kINV_PI4 = 0.0795775f;
const float k3PI16 = 0.1193662f;
const float kTAU = 6.2831853f;
const float kINV_TAU = 0.1591549f;
const float kE = 2.7182818f;
float saturate(float value){
return clamp(value, 0.0, 1.0);
}
vec3 saturateRGB(vec3 value){
return clamp(value.rgb, 0.0, 1.0);
}
// pow3
vec3 contrastLevel(vec3 vec, float level){
return mix(vec, vec * vec * vec, level);
}
vec3 tonemapPhoto(vec3 color, float exposure, float level){
color.rgb *= exposure;
return mix(color.rgb, 1.0 - exp(-color.rgb), level);
}
vec2 equirectUV(vec3 norm){
vec2 ret;
ret.x = (atan(norm.x, norm.z) + kPI) * kINV_TAU;
ret.y = acos(norm.y) * kINV_PI;
return ret;
}
/*
float random(vec2 uv){
float ret = dot(uv, vec2(12.9898, 78.233));
return fract(43758.5453 * sin(ret));
}
*/
float disk(vec3 norm, vec3 coords, lowp float size){
float dist = length(norm - coords);
return 1.0 - step(size, dist);
}
// Atmosphere Inc.
//------------------------------------------------------------------------------
const float RAYLEIGH_ZENITH_LENGTH = 8.4e3;
const float MIE_ZENITH_LENGTH = 1.25e3;
float rayleighPhase(float mu){
return k3PI16 * (1.0 + mu * mu);
}
float miePhase(float mu, vec3 partial){
return kPI4 * (partial.x) * (pow(partial.y - partial.z * mu, -1.5));
}
// Simplifield for more performance.
void simpleOpticalDepth(float y, out float sr, out float sm){
y = max(0.03, y + 0.03) + _atm_level_params.y;
y = 1.0 / (y * _atm_level_params.x);
sr = y * RAYLEIGH_ZENITH_LENGTH;
sm = y * MIE_ZENITH_LENGTH;
}
// Paper based.
void opticalDepth(float y, out float sr, out float sm){
y = max(0.0, y);
y = saturate(y * _atm_level_params.x);
float zenith = acos(y);
zenith = cos(zenith) + 0.15 * pow(93.885 - ((zenith * 180.0) / kPI), -1.253);
zenith = 1.0 / (zenith + _atm_level_params.y);
sr = zenith * RAYLEIGH_ZENITH_LENGTH;
sm = zenith * MIE_ZENITH_LENGTH;
}
vec3 atmosphericScattering(float sr, float sm, vec2 mu, vec3 mult){
vec3 betaMie = _atm_beta_mie;
vec3 betaRay = _atm_beta_ray * _atm_thickness;
vec3 extcFactor = saturateRGB(exp(-(betaRay * sr + betaMie * sm)));
float extcFF = mix(saturate(_atm_thickness * 0.5), 1.0, mult.x);
vec3 finalExtcFactor = mix(1.0 - extcFactor, (1.0 - extcFactor) * extcFactor, extcFF);
float rayleighPhase = rayleighPhase(mu.x);
vec3 BRT = betaRay * rayleighPhase;
vec3 BMT = betaMie * miePhase(mu.x, _atm_sun_partial_mie_phase);
BMT *= _atm_sun_mie_intensity * _atm_sun_mie_tint.rgb;
vec3 BRMT = (BRT + BMT) / (betaRay + betaMie);
vec3 scatter = _atm_sun_intensity * (BRMT * finalExtcFactor) * _atm_day_tint.rgb * mult.y;
scatter = mix(scatter, scatter * (1.0 - extcFactor), _atm_darkness);
vec3 lcol = mix(_atm_day_tint.rgb, _atm_horizon_light_tint.rgb, mult.x);
vec3 nscatter = (1.0 - extcFactor) * _atm_night_tint.rgb;
nscatter += miePhase(mu.y, _atm_moon_partial_mie_phase) *
_atm_moon_mie_tint.rgb * _atm_moon_mie_intensity * 0.005;
return (scatter * lcol) + nscatter;
}
// Clouds.
//------------------------------------------------------------------------------
float noiseClouds(vec2 coords, vec2 offset){
float a = textureLod(_clouds_texture, coords.xy * _clouds_uv + offset.x, 0.0).r;
float b = textureLod(_clouds_texture, coords.xy * _clouds_uv + offset.y, 0.0).r;
return ((a + b) * 0.5);
}
float cloudsDensity(vec2 p, vec2 offset){
float d = noiseClouds(p, offset);
float c = 1.0 - _clouds_coverage;
d = d - c;
//d += d;
return saturate(d);
}
vec4 renderClouds(vec3 pos, float tm){
pos.xy = pos.xz / pos.y;
pos *= _clouds_size;
vec2 wind = _clouds_offset.xy * (tm * _clouds_offset_speed);
float density = cloudsDensity(pos.xy, wind);
float sh = saturate(exp(-_clouds_absorption * density));
float a = saturate(density * _clouds_thickness);
return vec4(vec3(density*sh) * _clouds_intensity, a);
}
// Varyings.
//------------------------------------------------------------------------------
varying vec4 world_pos;
varying vec4 moon_coords;
varying vec3 deep_space_coords;
varying vec4 angle_mult;
void vertex(){
vec4 vert = vec4(VERTEX, 0.0);
POSITION = PROJECTION_MATRIX * INV_CAMERA_MATRIX * WORLD_MATRIX * vert;
POSITION.z = POSITION.w;
world_pos = WORLD_MATRIX * vert;
moon_coords.xyz = (_moon_matrix * VERTEX) / _moon_size + 0.5;
moon_coords.w = dot(world_pos.xyz, _moon_direction.xyz);
deep_space_coords.xyz = (_deep_space_matrix * VERTEX).xyz;
angle_mult.x = saturate(1.0 - _sun_direction.y);
angle_mult.y = saturate(_sun_direction.y + 0.45);
angle_mult.z = saturate(-_sun_direction.y + 0.30);
angle_mult.w = saturate(-_sun_direction.y + 0.60);
}
void fragment(){
vec3 col = vec3(0.0);
vec3 worldPos = normalize(world_pos).xyz;
vec3 cloudsPos = worldPos;
// Atmosphere.
vec2 mu = vec2(dot(_sun_direction, worldPos), dot(_moon_direction, worldPos));
float sr, sm;
simpleOpticalDepth(worldPos.y + _atm_level_params.z + _horizon_level, sr, sm);
worldPos.y += _horizon_level;
float horizonBlend = saturate((worldPos.y - 0.03) * 3.0);
vec3 scatter = atmosphericScattering(sr, sm, mu.xy, angle_mult.xyz);
col.rgb += scatter.rgb;
// Near Space.
vec3 nearSpace = vec3(0.0);
vec3 sunDisk = disk(worldPos, _sun_direction, _sun_disk_size) *
_sun_disk_color.rgb * scatter.rgb;
sunDisk *= _sun_disk_intensity;
// Moon.
vec4 moon = texture(_moon_texture, vec2(-moon_coords.x+1.0, moon_coords.y));
moon.rgb = contrastLevel(moon.rgb * _moon_color.rgb, _moon_color.a);
moon *= saturate(moon_coords.w);
float moonMask = saturate(1.0 - moon.a);
nearSpace = moon.rgb + (sunDisk.rgb * moonMask);
col.rgb += nearSpace;
vec3 deepSpace = vec3(0.0);
vec2 deepSpaceUV = equirectUV(normalize(deep_space_coords));
// Background.
vec3 deepSpaceBackground = textureLod(_background_texture, deepSpaceUV, 0.0).rgb;
deepSpaceBackground *= _background_color.rgb;
deepSpaceBackground = contrastLevel(deepSpaceBackground, _background_color.a);
deepSpace.rgb += deepSpaceBackground.rgb * moonMask;
// Stars Field.
float starsScintillation = textureLod(_noise_tex, UV + (TIME * _stars_scintillation_speed), 0.0).r;
starsScintillation = mix(1.0, starsScintillation * 1.5, _stars_scintillation);
vec3 starsField = textureLod(_stars_field_texture, deepSpaceUV, 0.0).rgb * _stars_field_color.rgb;
starsField = saturateRGB(mix(starsField.rgb, starsField.rgb * starsScintillation, _stars_scintillation));
//deepSpace.rgb -= saturate(starsField.r*10.0);
deepSpace.rgb += starsField.rgb * moonMask;
deepSpace.rgb *= angle_mult.z;
col.rgb += deepSpace.rgb * horizonBlend;
// Clouds.
vec4 clouds = renderClouds(cloudsPos, TIME);
clouds.a = saturate(clouds.a);
clouds.rgb *= mix(mix(vec3(1.0), _atm_horizon_light_tint.rgb, angle_mult.x),
_atm_night_tint.rgb, angle_mult.w);
clouds.a = mix(0.0, clouds.a, horizonBlend);
col.rgb = mix(col.rgb, clouds.rgb + mix(vec3(0.0), scatter, _clouds_sky_tint_fade), clouds.a);
col.rgb = mix(col.rgb, _ground_color.rgb * scatter, saturate((-worldPos.y - _atm_level_params.z)*100.0));
col.rgb = tonemapPhoto(col.rgb, _color_correction_params.y, _color_correction_params.x);
ALBEDO = col.rgb;
}