3 * Provides a class to model a realistic (time/date/position) based sky.
6 // Written by Curtis Olson, started December 1997.
7 // SSG-ified by Curtis Olson, February 2000.
9 // Copyright (C) 1997-2000 Curtis L. Olson - http://www.flightgear.org/~curt
11 // This library is free software; you can redistribute it and/or
12 // modify it under the terms of the GNU Library General Public
13 // License as published by the Free Software Foundation; either
14 // version 2 of the License, or (at your option) any later version.
16 // This library is distributed in the hope that it will be useful,
17 // but WITHOUT ANY WARRANTY; without even the implied warranty of
18 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
19 // Library General Public License for more details.
21 // You should have received a copy of the GNU General Public License
22 // along with this program; if not, write to the Free Software
23 // Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
33 # error This library requires C++
36 #include <simgear/compiler.h>
37 #include <simgear/math/sg_random.h>
38 #include <simgear/misc/sg_path.hxx>
39 #include <simgear/props/props.hxx>
43 #include <osg/ref_ptr>
44 #include <osg/MatrixTransform>
48 #include <simgear/ephemeris/ephemeris.hxx>
49 #include <simgear/math/SGMath.hxx>
51 #include <simgear/scene/sky/cloud.hxx>
52 #include <simgear/scene/sky/dome.hxx>
53 #include <simgear/scene/sky/moon.hxx>
54 #include <simgear/scene/sky/oursun.hxx>
55 #include <simgear/scene/sky/stars.hxx>
58 class SGReaderWriterOptions;
74 SGVec3f adj_sky_color;
77 double sun_angle, moon_angle;
81 * A class to model a realistic (time/date/position) based sky.
85 * The SGSky class models a blended sky dome, a haloed sun, a textured
86 * moon with phase that properly matches the date, stars and planets,
87 * and cloud layers. SGSky is designed to be dropped into existing
88 * plib based applications and depends heavily on plib's scene graph
89 * library, ssg. The sky implements various time of day lighting
90 * effects, it plays well with fog and visibility effects, and
91 * implements scudded cloud fly-through effects. Additionally, you can
92 * wire in the output of the SGEphemeris class to accurately position
93 * all the objects in the sky.
98 * Once you have created an instance of SGSky you must call the
99 * build() method. Building the sky requires several textures. So,
100 * you must specify the path/directory where these textures reside
101 * before building the sky. You do this first by calling the
102 * texture_path() method.
104 * The arguments you pass to the build() method allow you to specify
105 * the horizontal and vertical radiuses of the sky dome, the size of
106 * your sun sphere and moon sphere, a number of planets, and a
107 * multitude of stars. For the planets and stars you pass in an array
108 * of right ascensions, declinations, and magnitudes.
112 * Cloud layers can be added, changed, or removed individually. To add
113 * a cloud layer use the add_cloud_layer() method. The arguments
114 * allow you to specify base height above sea level, layer thickness,
115 * a transition zone for entering/leaving the cloud layer, the size of
116 * the cloud object, and the type of cloud texture. All distances are
117 * in meters. There are additional forms of this method that allow you
118 * to specify your own ssgSimpleState or texture name for drawing the
123 * As the sun circles the globe, you can call the repaint() method to
124 * recolor the sky objects to simulate sunrise and sunset effects,
125 * visibility, and other lighting changes. The arguments allow you to
126 * specify a base sky color (for the top of the dome), a fog color
127 * (for the horizon), the sun angle with the horizon (for
128 * sunrise/sunset effects), the moon angle (so we can make it more
129 * yellow at the horizon), and new star and planet data so that we can
130 * optionally change the magnitude of these (for day / night
133 * Positioning Sky Objects
135 * As time progresses and as you move across the surface of the earth,
136 * the apparent position of the objects and the various lighting
137 * effects can change. the reposition() method allows you to specify
138 * the positions of all the sky objects as well as your view position.
139 * The arguments allow you to specify your view position in world
140 * Cartesian coordinates, the zero elevation position in world
141 * Cartesian coordinates (your longitude, your latitude, sea level),
142 * the ``up'' vector in world Cartesian coordinates, current
143 * longitude, latitude, and altitude. A ``spin'' angle can be
144 * specified for orienting the sky with the sun position so sunset and
145 * sunrise effects look correct. You must specify GMT side real time,
146 * the sun right ascension, sun declination, and sun distance from
147 * view point (to keep it inside your view volume.) You also must
148 * specify moon right ascension, moon declination, and moon distance
153 * The sky is designed to be rendered in three stages. The first stage
154 * renders the parts that form your back drop - the sky dome, the
155 * stars and planets, the sun, and the moon. These should be rendered
156 * before the rest of your scene by calling the preDraw() method. The
157 * second stage renders the clouds that are above the viewer. This stage
158 * is done before translucent objects in the main scene are drawn. It
159 * is seperated from the preDraw routine to enable to implement a
160 * multi passes technique and is located in the drawUpperClouds() method.
161 * The third stage renders the clouds that are below the viewer an which
162 * are likely to be translucent (depending on type) and should be drawn
163 * after your scene has been rendered. Use the drawLowerClouds() method
164 * to draw the second stage of the sky.
166 * A typical application might do the following:
168 * <li> thesky->preDraw( my_altitude );
169 * <li> thesky->drawUpperClouds();
170 * <li> ssgCullAndDraw ( myscene ) ;
171 * <li> thesky->drawLowerClouds();
173 * The current altitude in meters is passed to the preDraw() method
174 * so the clouds layers can be rendered correction from most distant
179 * Visibility and fog is important for correctly rendering the
180 * sky. You can inform SGSky of the current visibility by calling the
181 * set_visibility() method.
183 * When transitioning through clouds, it is nice to pull in the fog as
184 * you get close to the cloud layer to hide the fact that the clouds
185 * are drawn as a flat polygon. As you get nearer to the cloud layer
186 * it is also nice to temporarily pull in the visibility to simulate
187 * the effects of flying in and out of the puffy edge of the
188 * cloud. These effects can all be accomplished by calling the
189 * modify_vis() method. The arguments allow you to specify your
190 * current altitude (which is then compared to the altitudes of the
191 * various cloud layers.) You can also specify a time factor which
192 * should be the length in seconds since the last time you called
193 * modify_vis(). The time_factor value allows the puffy cloud effect
194 * to be calculated correctly.
196 * The modify_vis() method alters the SGSky's internal idea of
197 * visibility, so you should subsequently call get_visibility() to get
198 * the actual modified visibility. You should then make the
199 * appropriate glFog() calls to setup fog properly for your scene.
203 * Once an instance of SGSky has been successfully initialized, there
204 * are a couple accessor methods you can use such as get_num_layers()
205 * to return the number of cloud layers, get_cloud_layer(i) to return
206 * cloud layer number i, get_visibility() to return the actual
207 * visibility as modified by the sky/cloud model.
214 typedef std::vector<SGSharedPtr<SGCloudLayer> > layer_list_type;
215 typedef layer_list_type::iterator layer_list_iterator;
216 typedef layer_list_type::const_iterator layer_list_const_iterator;
218 // components of the sky
219 SGSharedPtr<SGSkyDome> dome;
220 SGSharedPtr<SGSun> oursun;
221 SGSharedPtr<SGMoon> moon;
222 SGSharedPtr<SGStars> planets;
223 SGSharedPtr<SGStars> stars;
224 layer_list_type cloud_layers;
226 osg::ref_ptr<osg::Group> pre_root, cloud_root;
227 osg::ref_ptr<osg::Switch> pre_selector;
228 osg::ref_ptr<osg::Group> pre_transform;
230 osg::ref_ptr<osg::MatrixTransform> _ephTransform;
236 float effective_visibility;
237 float minimum_sky_visibility;
241 // near cloud visibility state variables
243 double puff_length; // in seconds
244 double puff_progression; // in seconds
245 double ramp_up; // in seconds
246 double ramp_down; // in seconds
249 bool clouds_3d_enabled;
252 double clouds_3d_density;
266 * Initialize the sky and connect the components to the scene
267 * graph at the provided branch. See discussion in detailed class
269 * @param h_radius_m horizontal radius of sky dome
270 * @param v_radius_m vertical radius of sky dome
271 * @param sun_size size of sun
272 * @param moon_size size of moon
273 * @param nplanets number of planets
274 * @param planet_data an array of planet right ascensions, declinations,
276 * @param nstars number of stars
277 * @param star_data an array of star right ascensions, declinations,
280 void build( double h_radius_m, double v_radius_m,
281 double sun_size, double moon_size,
282 const SGEphemeris& eph, SGPropertyNode *property_tree_node,
283 simgear::SGReaderWriterOptions* options);
286 * Repaint the sky components based on current value of sun_angle,
287 * sky, and fog colors. You can also specify new star and planet
288 * data so that we can optionally change the magnitude of these
289 * (for day/night transitions.) See discussion in detailed
292 * Sun and moon angles are specified in degrees relative to local up
293 * <li> 0 degrees = high noon
294 * <li> 90 degrees = sun rise/set
295 * <li> 180 degrees = darkest midnight
296 * @param sky_color the base sky color (for the top of the dome)
297 * @param fog_color the fog color (for the horizon)
298 * @param sun_angle the sun angle with the horizon (for sunrise/sunset
300 * @param moon_angle the moon angle (so we can make it more yellow
302 * @param nplanets number of planets
303 * @param planet_data an array of planet right ascensions, declinations,
305 * @param nstars number of stars
306 * @param star_data an array of star right ascensions, declinations,
309 bool repaint( const SGSkyColor &sc, const SGEphemeris& eph );
312 * Reposition the sky at the specified origin and orientation
314 * lon specifies a rotation about the Z axis
315 * lat specifies a rotation about the new Y axis
316 * spin specifies a rotation about the new Z axis (this allows
317 * additional orientation for the sunrise/set effects and is used
318 * by the skydome and perhaps clouds. See discussion in detailed
320 * @param view_pos specify your view position in world Cartesian
322 * @param zero_elev the zero elevation position in world Cartesian
324 * @param view_up the up vector in world Cartesian coordinates
325 * @param lon current longitude
326 * @param lat current latitude
327 * @param alt current altitude
328 * @param spin an offset angle for orienting the sky effects with the
329 * sun position so sunset and sunrise effects look correct.
330 * @param gst GMT side real time
331 * @param sun_ra the sun's current right ascension
332 * @param sun_dec the sun's current declination
333 * @param sun_dist the sun's distance from the current view point
334 * (to keep it inside your view volume.)
335 * @param moon_ra the moon's current right ascension
336 * @param moon_dec the moon's current declination
337 * @param moon_dist the moon's distance from the current view point.
339 bool reposition( const SGSkyState &st, const SGEphemeris& eph, double dt = 0.0 );
342 * Modify the given visibility based on cloud layers, thickness,
343 * transition range, and simulated "puffs". See discussion in detailed
345 * @param alt current altitude
346 * @param time_factor amount of time since modify_vis() last called so
347 * we can scale effect rates properly despite variable frame rates.
349 void modify_vis( float alt, float time_factor );
351 osg::Node* getPreRoot() { return pre_root.get(); }
352 osg::Node* getCloudRoot() { return cloud_root.get(); }
355 * Specify the texture path (optional, defaults to current directory)
356 * @param path base path to texture locations
358 void texture_path( const string& path );
360 /** Enable drawing of the sky. */
361 inline void enable() {
362 pre_selector->setValue(0, 1);
366 * Disable drawing of the sky in the scene graph. The leaf node is still
367 * there, how ever it won't be traversed on by ssgCullandRender()
369 inline void disable() {
370 pre_selector->setValue(0, 0);
374 * Get the current sun color
376 inline SGVec4f get_sun_color() { return oursun->get_color(); }
379 * Get the current scene color
381 inline SGVec4f get_scene_color() { return oursun->get_scene_color(); }
386 * Transfer pointer ownership to this object.
388 * @param layer The new cloud layer to add.
390 void add_cloud_layer (SGCloudLayer * layer);
394 * Get a cloud layer (const).
396 * Pointer ownership remains with this object.
398 * @param i The index of the cloud layer, zero-based.
399 * @return A const pointer to the cloud layer.
401 const SGCloudLayer * get_cloud_layer (int i) const;
405 * Get a cloud layer (non-const).
407 * Pointer ownership remains with this object.
409 * @param i The index of the cloud layer, zero-based.
410 * @return A non-const pointer to the cloud layer.
412 SGCloudLayer * get_cloud_layer (int i);
416 * Return the number of cloud layers currently available.
418 * @return The cloud layer count.
420 int get_cloud_layer_count () const;
423 /** @return current effective visibility */
424 inline float get_visibility() const { return effective_visibility; }
426 /** Set desired clear air visibility.
427 * @param v visibility in meters
429 inline void set_visibility( float v ) {
430 effective_visibility = visibility = (v <= 25.0) ? 25.0 : v;
433 /** Get 3D cloud density */
434 double get_3dCloudDensity() const;
436 /** Set 3D cloud density
437 * @param density 3D cloud density
439 void set_3dCloudDensity(double density);
441 /** Get 3D cloud visibility range*/
442 float get_3dCloudVisRange() const;
444 /** Set 3D cloud visibility range
445 * @param density 3D cloud visibility range
447 void set_3dCloudVisRange(float vis);
449 /** Get 3D cloud impostor distance*/
450 float get_3dCloudImpostorDistance() const;
452 /** Set 3D cloud impostor distance
453 * @param density 3D cloud impostor distance
455 void set_3dCloudImpostorDistance(float vis);
457 /** Get 3D cloud LoD1 Range*/
458 float get_3dCloudLoD1Range() const;
460 /** Set 3D cloud LoD1 Range
461 * @param vis LoD1 Range
463 void set_3dCloudLoD1Range(float vis);
465 /** Get 3D cloud LoD2 Range*/
466 float get_3dCloudLoD2Range() const;
468 /** Set 3D cloud LoD2 Range
469 * @param vis LoD2 Range
471 void set_3dCloudLoD2Range(float vis);
473 /** Get 3D cloud impostor usage */
474 bool get_3dCloudUseImpostors() const;
476 /** Set 3D cloud impostor usage
477 * @param wrap whether use impostors for 3D clouds
479 void set_3dCloudUseImpostors(bool imp);
481 /** Get 3D cloud wrapping */
482 bool get_3dCloudWrap() const;
484 /** Set 3D cloud wrapping
485 * @param wrap whether to wrap 3D clouds
487 void set_3dCloudWrap(bool wrap);
490 /** Get minimum sky visibility */
491 float get_minimum_sky_visibility() const;
493 /** Set minimum sky visibility */
494 void set_minimum_sky_visibility( float value );
496 #endif // _SG_SKY_HXX