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 );
   7
   8 const float SUN_ANGLE       = 0.0001;
   9 const float PI              = 3.14159265358979323846264;
  10
  11 //struct world_info
  12 //{
  13 //   float time,
  14 //         time_of_day,
  15 //         day_phase,
  16 //         sunset_phase;
  17 //
  18 //   vec3 sun_dir;
  19 //};
  20
  21 vec3 rand33(vec3 p3)
  22 {
  23         p3 = fract(p3 * vec3(.1031, .1030, .0973));
  24    p3 += dot(p3, p3.yxz+33.33);
  25    return fract((p3.xxy + p3.yxx)*p3.zyx);
  26 }
  27
  28 float stars( vec3 rd, float rr, float size ){
  29    vec3 co = rd * rr;
  30
  31    float a = atan(co.y, length(co.xz)) + 4.0 * PI;
  32
  33    float spaces = 1.0 / rr;
  34    size = (rr * 0.0015) * fwidth(a) * 1000.0 * size;
  35    a -= mod(a, spaces) - spaces * 0.5;
  36
  37    float count = floor(sqrt(pow(rr, 2.0) * (1.0 - pow(sin(a), 2.0))) * 3.0);
  38
  39    float plane = atan(co.z, co.x) + 4.0 * PI;
  40    plane = plane - mod(plane, PI / count);
  41
  42    vec2 delta = rand33(vec3(plane, a, 0.0)).xy;
  43
  44    float level = sin(a + spaces * (delta.y - 0.5) * (1.0 - size)) * rr;
  45    float ydist = sqrt(rr * rr - level * level);
  46    float angle = plane + (PI * (delta.x * (1.0-size) + size * 0.5) / count);
  47    vec3 center = vec3(cos(angle) * ydist, level, sin(angle) * ydist);
  48    float star = smoothstep(size, 0.0, distance(center, co));
  49    return star;
  50 }
  51
  52 float luminance( vec3 v )
  53 {
  54    return dot( v, vec3(0.2126, 0.7152, 0.0722) );
  55 }
  56
  57 vec3 clearskies_ambient( vec3 dir )
  58 {
  59    float sun_azimuth  = g_sunset_phase * (dot( dir.xz, g_sun_dir.xz )*0.4+0.6);
  60    float sky_gradient = dir.y;
  61
  62    /* Blend phase colours */
  63    vec3 ambient  = g_daysky_colour.rgb   * (g_day_phase-g_sunset_phase*0.1);
  64         ambient += g_sunset_colour.rgb   * (1.0-dir.y*0.5)*sun_azimuth;
  65         ambient += g_nightsky_colour.rgb * (1.0-g_day_phase);
  66
  67    /* Add gradient */
  68         ambient -= sky_gradient * luminance(ambient);
  69
  70    return ambient;
  71 }
  72
  73 vec3 clearskies_sky( vec3 ray_dir )
  74 {
  75    ray_dir.y = abs( ray_dir.y );
  76    vec3 sky_colour  = clearskies_ambient( ray_dir );
  77
  78    /* Sun */
  79    float sun_theta  = dot( ray_dir, g_sun_dir.xyz );
  80    float sun_size   = max( 0.0, sun_theta * 0.5 + 0.5 + SUN_ANGLE );
  81    float sun_shape  = pow( sun_size, 2000.0 );
  82          sun_shape += sun_size * max(g_sun_dir.y,0.0) * 0.5;
  83
  84    vec3 sun_colour  = mix( vec3(1.0), g_sunset_colour.rgb, g_sunset_phase*0.5 );
  85         sun_colour *= sun_shape;
  86
  87
  88    float star = 0.0;
  89    float star_blend = 10.0*max(0.0,(1.0-g_day_phase*2.0));
  90
  91    if( star_blend > 0.001 ){
  92       for( float j = 1.0; j <= 4.1; j += 1.0 ){
  93          float m = mix(0.6, 0.9, smoothstep(1.0, 2.0, j));
  94          star += stars( ray_dir, 1.94 * pow( 1.64, j ), m ) * (1.0/pow(4.0, j));
  95       }
  96    }
  97
  98    vec3 composite   = sky_colour + sun_colour + star*star_blend;
  99    return composite;
 100 }
 101
 102 vec3 clearskies_lighting( vec3 normal, float shadow, vec3 halfview )
 103 {
 104    float fresnel = 1.0 - abs(dot(normal,halfview));
 105
 106    vec3  reflect_colour = mix( g_daysky_colour.rgb, g_sunset_colour.rgb,
 107                                g_sunset_phase );
 108
 109    vec3  sky_reflection = 0.5 * fresnel * reflect_colour;
 110    vec3  light_sun      = max( CLEARSKIES_LIGHT_DOT_MIN,
 111                                dot(normal,g_sun_dir.xyz)*0.75+0.25
 112                            ) * g_sun_colour.rgb * g_day_phase;
 113
 114    float scaled_shadow = max( shadow, 1.0 - max(g_sun_dir.y,0.0) );
 115    vec3 ambient = mix( g_ambient_colour.rgb, g_sunset_ambient.rgb,
 116                        g_sunset_phase );
 117
 118    return ambient + (light_sun + sky_reflection) * shadow;
 119 }