shaders/light_clearskies.glsl

   1 const vec3  DAYSKY_COLOUR   = vec3( 0.37, 0.54, 0.97 );
   2 const vec3  NIGHTSKY_COLOUR = vec3( 0.03, 0.05, 0.20 );
   3 const vec3  SUNSET_COLOUR   = vec3( 1.00, 0.32, 0.01 );
   4 const vec3  AMBIENT_COLOUR  = vec3( 0.13, 0.17, 0.35 );
   5 const vec3  SUNSET_AMBIENT  = vec3( 0.25, 0.17, 0.51 );
   6 const vec3  SUN_COLOUR      = vec3( 1.10, 0.89, 0.35 ) * 1.125;
   7
   8 const float SUN_ANGLE       = 0.0001;
   9 const float TIME_RATE       = 0.025;
  10
  11 const float PI              = 3.14159265;
  12
  13 struct world_info
  14 {
  15    float time,
  16          time_of_day,
  17          day_phase,
  18          sunset_phase;
  19
  20    vec3 sun_dir;
  21 };
  22
  23 float luminance( vec3 v )
  24 {
  25    return dot( v, vec3(0.2126, 0.7152, 0.0722) );
  26 }
  27
  28 vec3 scene_ambient( vec3 dir, const world_info w )
  29 {
  30    float sun_azimuth  = dot( dir.xz, w.sun_dir.xz ) * 0.4 + 0.6;
  31    float sky_gradient = dir.y;
  32
  33    /* Blend phase colours */
  34    vec3 ambient  = DAYSKY_COLOUR   * (w.day_phase-w.sunset_phase*0.1);
  35         ambient += SUNSET_COLOUR   * (1.0-dir.y*0.5) * w.sunset_phase * sun_azimuth;
  36         ambient += NIGHTSKY_COLOUR * (1.0-w.day_phase);
  37
  38    /* Add gradient */
  39         ambient -= sky_gradient * luminance(ambient);
  40
  41    return ambient;
  42 }
  43
  44 vec3 scene_sky( vec3 ray_dir, const world_info w )
  45 {
  46    ray_dir.y = abs( ray_dir.y );
  47    vec3 sky_colour  = scene_ambient( ray_dir, w );
  48
  49    /* Sun */
  50    float sun_theta  = dot( ray_dir, w.sun_dir );
  51    float sun_size   = max( 0.0, sun_theta * 0.5 + 0.5 + SUN_ANGLE );
  52    float sun_shape  = pow( sun_size, 2000.0 );
  53          sun_shape += sun_size * max(w.sun_dir.y,0.0) * 0.5;
  54
  55    vec3 sun_colour  = mix( vec3(1.0), SUNSET_COLOUR, w.sunset_phase*0.5 );
  56         sun_colour *= sun_shape;
  57
  58    vec3 composite   = sky_colour + sun_colour;
  59    return composite;
  60 }
  61
  62 vec3 scene_compute_ambient( vec3 normal, const world_info w )
  63 {
  64    return scene_ambient( (normal * vec3(1.0,-1.0,1.0)) * 0.5 + 0.5, w );
  65 }
  66
  67 vec3 SR_LIGHT( vec3 normal, vec2 dir, vec3 colour )
  68 {
  69    vec3 dir3 = vec3
  70    (
  71       cos(dir.y) * cos(dir.x),
  72                    sin(dir.x),
  73       sin(dir.y) * cos(dir.x)
  74    );
  75
  76    float flight = max( dot( normal, dir3 ) * 0.75 + 0.25, 0.0 );
  77
  78    return flight * colour;
  79 }
  80
  81 vec3 scene_lighting_old( vec3 normal, const world_info w )
  82 {
  83    vec3 SR_COLOUR_SUN  = vec3( 1.36,  1.35, 1.01 );
  84    vec3 SR_COLOUR_FILL = vec3( 0.33,  0.56, 0.64 );
  85    vec3 SR_COLOUR_RIM  = vec3( 0.05,  0.05, 0.23 );
  86
  87    return SR_LIGHT( normal, vec2(  0.63, -0.08 ), SR_COLOUR_SUN ) +
  88           SR_LIGHT( normal, vec2( -2.60, -0.13 ), SR_COLOUR_FILL ) +
  89           SR_LIGHT( normal, vec2(  2.60, -0.84 ), SR_COLOUR_RIM ) ;
  90 }
  91
  92 vec3 scene_lighting( vec3 normal, float shadow, vec3 halfview, const world_info w )
  93 {
  94    float fresnel = 1.0 - abs(dot(normal,halfview));
  95
  96    vec3  sky_reflection = 0.5 * fresnel * mix( DAYSKY_COLOUR, SUNSET_COLOUR, w.sunset_phase );
  97    vec3  light_sun      = max(0.0,dot(normal,w.sun_dir)*0.75+0.25) * SUN_COLOUR
  98                            * w.day_phase;
  99
 100    float scaled_shadow = max( shadow, 1.0 - max(w.sun_dir.y,0.0) );
 101
 102    vec3 ambient = mix( AMBIENT_COLOUR, SUNSET_AMBIENT, w.sunset_phase );
 103
 104    return ambient + (light_sun + sky_reflection) * shadow;
 105
 106
 107
 108
 109
 110
 111    float  sun_theta = dot( normal, w.sun_dir );
 112
 113    float  softness_min = 0.5;
 114    float  softness     = softness_min + w.sunset_phase * (1.0-softness_min);
 115    float  light_min    = 0.0 * w.day_phase;
 116    float  light_direct = light_min + smoothstep( -softness, softness, sun_theta ) * (1.0-light_min);
 117           light_direct *= clamp(w.sun_dir.y * 4.0 + 1.0,0.0,1.0) * shadow;
 118
 119    float  light_bounce  = 0.5 + 0.5 * dot( -normal, w.sun_dir );
 120           light_bounce *= light_bounce * max( w.sun_dir.y, 0.0 );
 121
 122    vec3   light_colour = SUN_COLOUR*w.day_phase + (SUNSET_COLOUR*w.sunset_phase + 0.1);
 123    vec3   dark_colour  = mix( AMBIENT_COLOUR, SUNSET_AMBIENT, w.sunset_phase );
 124
 125    float  spec         = newlight_specular( normal, w.sun_dir, halfview, 2.0 )
 126                             * 0.2 * shadow * w.day_phase;
 127
 128    return mix(dark_colour, light_colour, light_direct) +
 129               spec +
 130               dark_colour * light_bounce;
 131 }
 132
 133 void scene_state( float world_time, out world_info w )
 134 {
 135    w.time         = world_time;
 136    w.time_of_day  = fract( w.time );
 137    w.day_phase    = cos( w.time_of_day * PI * 2.0 )      * 0.5 + 0.5;
 138    w.sunset_phase = cos( w.time_of_day * PI * 4.0 + PI ) * 0.5 + 0.5;
 139    w.sunset_phase = pow( w.sunset_phase, 6.0 );
 140
 141    float a        = w.time_of_day * PI * 2.0;
 142    w.sun_dir      = normalize( vec3( sin( a ), cos( a ), 0.2) );
 143 }
 144