source/effects/sky.cpp

   1 #include <msp/geometry/hypersphere.h>
   2 #include <msp/geometry/ray.h>
   3 #include "directionallight.h"
   4 #include "error.h"
   5 #include "mesh.h"
   6 #include "renderer.h"
   7 #include "resources.h"
   8 #include "texture2d.h"
   9 #include "sky.h"
  10
  11 using namespace std;
  12
  13 namespace Msp {
  14 namespace GL {
  15
  16 Sky::Sky(Renderable &r, DirectionalLight &s):
  17         Effect(r),
  18         sun(s),
  19         transmittance_lookup(128, 64, (COLOR_ATTACHMENT,RGB16F)),
  20         transmittance_shprog(Resources::get_global().get<Program>("_sky_transmittance.glsl.shader")),
  21         transmittance_lookup_dirty(true),
  22         distant(256, 128, (COLOR_ATTACHMENT,RGB16F)),
  23         distant_shprog(Resources::get_global().get<Program>("_sky_distant.glsl.shader")),
  24         fullscreen_mesh(Resources::get_global().get<Mesh>("_fullscreen_quad.mesh")),
  25         backdrop_shprog(Resources::get_global().get<Program>("_sky_backdrop.glsl.shader")),
  26         sampler(Resources::get_global().get<Sampler>("_linear_clamp.samp")),
  27         wrap_sampler(Resources::get_global().get<Sampler>("_linear_clamp_v.samp")),
  28         rendered(false)
  29 {
  30         shdata.uniform("n_steps", 50);
  31
  32         set_planet(Planet::earth());
  33         set_view_height(5.0f);
  34 }
  35
  36 void Sky::set_planet(const Planet &p)
  37 {
  38         planet = p;
  39         shdata.uniform("events.rayleigh_scatter", planet.rayleigh_scatter.r, planet.rayleigh_scatter.g, planet.rayleigh_scatter.b);
  40         shdata.uniform("events.mie_scatter", planet.mie_scatter.r, planet.mie_scatter.g, planet.mie_scatter.b);
  41         shdata.uniform("events.mie_absorb", planet.mie_absorb.r, planet.mie_absorb.g, planet.mie_absorb.b);
  42         shdata.uniform("events.ozone_absorb", planet.ozone_absorb.r, planet.ozone_absorb.g, planet.ozone_absorb.b);
  43         shdata.uniform("rayleigh_density_decay", planet.rayleigh_density_decay);
  44         shdata.uniform("mie_density_decay", planet.mie_density_decay);
  45         shdata.uniform("ozone_band_center", planet.ozone_band_center);
  46         shdata.uniform("ozone_band_extent", planet.ozone_band_extent);
  47         shdata.uniform("atmosphere_thickness", planet.atmosphere_thickness);
  48         shdata.uniform("planet_radius", planet.planet_radius);
  49         shdata.uniform("ground_albedo", planet.ground_albedo.r, planet.ground_albedo.g, planet.ground_albedo.b);
  50 }
  51
  52 void Sky::set_view_height(float h)
  53 {
  54         view_height = h;
  55         shdata.uniform("view_height", h);
  56 }
  57
  58 Color Sky::get_transmittance(const Vector3 &look_dir)
  59 {
  60         Vector3 pos(0.0f, 0.0f, view_height);
  61         Vector3 planet_center(0.0f, 0.0f, -planet.planet_radius);
  62
  63         Geometry::Ray<float, 3> ray(pos-planet_center, look_dir);
  64         Geometry::HyperSphere<float, 3> surface(planet.planet_radius);
  65         Geometry::SurfacePoint<float, 3> intersection;
  66         if(surface.get_intersections(ray, &intersection, 1))
  67                 return Color(0.0f);
  68
  69         Geometry::HyperSphere<float, 3> space(planet.planet_radius+planet.atmosphere_thickness);
  70         if(!space.get_intersections(ray, &intersection, 1))
  71                 return Color(1.0f);
  72
  73         float step_size = intersection.distance/50;
  74
  75         Color path_extinction(0.0f);
  76         for(unsigned i=0; i<50; ++i)
  77         {
  78                 Vector3 from_center = pos-planet_center;
  79                 float height = from_center.norm()-planet.planet_radius;
  80
  81                 Color rayleigh_scatter = planet.rayleigh_scatter*exp(height/planet.rayleigh_density_decay);
  82                 Color mie_scatter = planet.mie_scatter*exp(height/planet.mie_density_decay);
  83                 Color mie_absorb = planet.mie_absorb*exp(height/planet.mie_density_decay);
  84                 Color ozone_absorb = planet.ozone_absorb*max(1.0f-abs(height-planet.ozone_band_center)/planet.ozone_band_extent, 0.0f);
  85
  86                 path_extinction = path_extinction+(rayleigh_scatter+mie_scatter+mie_absorb+ozone_absorb)*step_size;
  87                 pos += look_dir*step_size;
  88         }
  89
  90         return Color(exp(-path_extinction.r), exp(-path_extinction.g), exp(-path_extinction.b));
  91 }
  92
  93 void Sky::setup_frame(Renderer &renderer)
  94 {
  95         if(rendered)
  96                 return;
  97
  98         rendered = true;
  99
 100         shdata.uniform("light_color", sun.get_color());
 101         shdata.uniform("light_dir", -sun.get_direction());
 102         sun.set_transmittance(get_transmittance(-sun.get_direction()));
 103
 104         Renderer::Push push(renderer);
 105
 106         if(transmittance_lookup_dirty)
 107         {
 108                 transmittance_lookup_dirty = false;
 109                 renderer.set_framebuffer(&transmittance_lookup.get_framebuffer());
 110                 renderer.set_shader_program(&transmittance_shprog, &shdata);
 111                 fullscreen_mesh.draw(renderer);
 112         }
 113
 114         renderer.set_framebuffer(&distant.get_framebuffer());
 115         renderer.set_shader_program(&distant_shprog, &shdata);
 116         renderer.set_texture("transmittance_lookup", &transmittance_lookup.get_target_texture(0), &sampler);
 117         fullscreen_mesh.draw(renderer);
 118
 119         renderable.setup_frame(renderer);
 120 }
 121
 122 void Sky::finish_frame()
 123 {
 124         if(rendered)
 125         {
 126                 rendered = false;
 127                 renderable.finish_frame();
 128         }
 129 }
 130
 131 void Sky::render(Renderer &renderer, Tag tag) const
 132 {
 133         renderable.render(renderer, tag);
 134
 135         if(!enabled_methods.count(tag))
 136                 return;
 137
 138         Renderer::Push push(renderer);
 139
 140         renderer.set_shader_program(&backdrop_shprog, &shdata);
 141         renderer.set_texture("distant", &distant.get_target_texture(0), &wrap_sampler);
 142         fullscreen_mesh.draw(renderer);
 143 }
 144
 145 void Sky::set_debug_name(const string &name)
 146 {
 147 #ifdef DEBUG
 148         transmittance_lookup.set_debug_name(name+" [RT:transmittance]");
 149         distant.set_debug_name(name+" [RT:distant]");
 150         shdata.set_debug_name(name+" [UBO]");
 151 #else
 152         (void)name;
 153 #endif
 154 }
 155
 156
 157 Sky::Planet::Planet():
 158         rayleigh_scatter(0.0f),
 159         mie_scatter(0.0f),
 160         mie_absorb(0.0f),
 161         ozone_absorb(0.0f),
 162         rayleigh_density_decay(1e3f),
 163         mie_density_decay(1e3f),
 164         ozone_band_center(1e4f),
 165         ozone_band_extent(1e2f),
 166         atmosphere_thickness(2e4f),
 167         planet_radius(1e6f),
 168         ground_albedo(0.2f)
 169 { }
 170
 171 Sky::Planet Sky::Planet::earth()
 172 {
 173         Planet planet;
 174         planet.rayleigh_scatter = Color(5.802e-6f, 13.558e-6f, 33.1e-6f);
 175         planet.mie_scatter = Color(3.996e-6f, 3.996e-6f, 3.996e-6f);
 176         planet.mie_absorb = Color(4.4e-6f, 4.4e-6f, 4.4e-6f);
 177         planet.ozone_absorb = Color(0.65e-6f, 1.881e-6f, 0.085e-6f);
 178         planet.rayleigh_density_decay = -8e3f;
 179         planet.mie_density_decay = -1.2e3f;
 180         planet.ozone_band_center = 25e3f;
 181         planet.ozone_band_extent = 15e3f;
 182         planet.atmosphere_thickness = 1e5f;
 183         planet.planet_radius = 6.36e6f;
 184         return planet;
 185 }
 186
 187
 188 Sky *Sky::Template::create(const map<string, Renderable *> &renderables) const
 189 {
 190         Renderable *content = get_item(renderables, content_name);
 191         if(!content || !sun)
 192                 throw invalid_operation("Sky::Template::create");
 193         return new Sky(*content, *sun);
 194 }
 195
 196
 197 DataFile::Loader::ActionMap Sky::Template::Loader::shared_actions;
 198
 199 Sky::Template::Loader::Loader(Template &t, Collection &c):
 200         DerivedObjectLoader<Template, Effect::Template::Loader>(t, c)
 201 {
 202         set_actions(shared_actions);
 203 }
 204
 205 void Sky::Template::Loader::init_actions()
 206 {
 207         Effect::Template::Loader::init_actions();
 208         add("sun", &Template::sun);
 209 }
 210
 211 } // namespace GL
 212 } // namespace Msp