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/misc/sg_path.hxx>
38 #include <simgear/props/props.hxx>
42 #include <osg/ref_ptr>
43 #include <osg/MatrixTransform>
47 #include <simgear/ephemeris/ephemeris.hxx>
48 #include <simgear/math/SGMath.hxx>
50 #include <simgear/scene/sky/cloud.hxx>
51 #include <simgear/scene/sky/dome.hxx>
52 #include <simgear/scene/sky/moon.hxx>
53 #include <simgear/scene/sky/oursun.hxx>
54 #include <simgear/scene/sky/stars.hxx>
69 SGVec3f adj_sky_color;
72 double sun_angle, moon_angle;
76 * A class to model a realistic (time/date/position) based sky.
80 * The SGSky class models a blended sky dome, a haloed sun, a textured
81 * moon with phase that properly matches the date, stars and planets,
82 * and cloud layers. SGSky is designed to be dropped into existing
83 * plib based applications and depends heavily on plib's scene graph
84 * library, ssg. The sky implements various time of day lighting
85 * effects, it plays well with fog and visibility effects, and
86 * implements scudded cloud fly-through effects. Additionally, you can
87 * wire in the output of the SGEphemeris class to accurately position
88 * all the objects in the sky.
93 * Once you have created an instance of SGSky you must call the
94 * build() method. Building the sky requires several textures. So,
95 * you must specify the path/directory where these textures reside
96 * before building the sky. You do this first by calling the
97 * texture_path() method.
99 * The arguments you pass to the build() method allow you to specify
100 * the horizontal and vertical radiuses of the sky dome, the size of
101 * your sun sphere and moon sphere, a number of planets, and a
102 * multitude of stars. For the planets and stars you pass in an array
103 * of right ascensions, declinations, and magnitudes.
107 * Cloud layers can be added, changed, or removed individually. To add
108 * a cloud layer use the add_cloud_layer() method. The arguments
109 * allow you to specify base height above sea level, layer thickness,
110 * a transition zone for entering/leaving the cloud layer, the size of
111 * the cloud object, and the type of cloud texture. All distances are
112 * in meters. There are additional forms of this method that allow you
113 * to specify your own ssgSimpleState or texture name for drawing the
118 * As the sun circles the globe, you can call the repaint() method to
119 * recolor the sky objects to simulate sunrise and sunset effects,
120 * visibility, and other lighting changes. The arguments allow you to
121 * specify a base sky color (for the top of the dome), a fog color
122 * (for the horizon), the sun angle with the horizon (for
123 * sunrise/sunset effects), the moon angle (so we can make it more
124 * yellow at the horizon), and new star and planet data so that we can
125 * optionally change the magnitude of these (for day / night
128 * Positioning Sky Objects
130 * As time progresses and as you move across the surface of the earth,
131 * the apparent position of the objects and the various lighting
132 * effects can change. the reposition() method allows you to specify
133 * the positions of all the sky objects as well as your view position.
134 * The arguments allow you to specify your view position in world
135 * Cartesian coordinates, the zero elevation position in world
136 * Cartesian coordinates (your longitude, your latitude, sea level),
137 * the ``up'' vector in world Cartesian coordinates, current
138 * longitude, latitude, and altitude. A ``spin'' angle can be
139 * specified for orienting the sky with the sun position so sunset and
140 * sunrise effects look correct. You must specify GMT side real time,
141 * the sun right ascension, sun declination, and sun distance from
142 * view point (to keep it inside your view volume.) You also must
143 * specify moon right ascension, moon declination, and moon distance
148 * The sky is designed to be rendered in three stages. The first stage
149 * renders the parts that form your back drop - the sky dome, the
150 * stars and planets, the sun, and the moon. These should be rendered
151 * before the rest of your scene by calling the preDraw() method. The
152 * second stage renders the clouds that are above the viewer. This stage
153 * is done before translucent objects in the main scene are drawn. It
154 * is seperated from the preDraw routine to enable to implement a
155 * multi passes technique and is located in the drawUpperClouds() method.
156 * The third stage renders the clouds that are below the viewer an which
157 * are likely to be translucent (depending on type) and should be drawn
158 * after your scene has been rendered. Use the drawLowerClouds() method
159 * to draw the second stage of the sky.
161 * A typical application might do the following:
163 * <li> thesky->preDraw( my_altitude );
164 * <li> thesky->drawUpperClouds();
165 * <li> ssgCullAndDraw ( myscene ) ;
166 * <li> thesky->drawLowerClouds();
168 * The current altitude in meters is passed to the preDraw() method
169 * so the clouds layers can be rendered correction from most distant
174 * Visibility and fog is important for correctly rendering the
175 * sky. You can inform SGSky of the current visibility by calling the
176 * set_visibility() method.
178 * When transitioning through clouds, it is nice to pull in the fog as
179 * you get close to the cloud layer to hide the fact that the clouds
180 * are drawn as a flat polygon. As you get nearer to the cloud layer
181 * it is also nice to temporarily pull in the visibility to simulate
182 * the effects of flying in and out of the puffy edge of the
183 * cloud. These effects can all be accomplished by calling the
184 * modify_vis() method. The arguments allow you to specify your
185 * current altitude (which is then compared to the altitudes of the
186 * various cloud layers.) You can also specify a time factor which
187 * should be the length in seconds since the last time you called
188 * modify_vis(). The time_factor value allows the puffy cloud effect
189 * to be calculated correctly.
191 * The modify_vis() method alters the SGSky's internal idea of
192 * visibility, so you should subsequently call get_visibility() to get
193 * the actual modified visibility. You should then make the
194 * appropriate glFog() calls to setup fog properly for your scene.
198 * Once an instance of SGSky has been successfully initialized, there
199 * are a couple accessor methods you can use such as get_num_layers()
200 * to return the number of cloud layers, get_cloud_layer(i) to return
201 * cloud layer number i, get_visibility() to return the actual
202 * visibility as modified by the sky/cloud model.
209 typedef std::vector<SGSharedPtr<SGCloudLayer> > layer_list_type;
210 typedef layer_list_type::iterator layer_list_iterator;
211 typedef layer_list_type::const_iterator layer_list_const_iterator;
213 // components of the sky
214 SGSharedPtr<SGSkyDome> dome;
215 SGSharedPtr<SGSun> oursun;
216 SGSharedPtr<SGMoon> moon;
217 SGSharedPtr<SGStars> planets;
218 SGSharedPtr<SGStars> stars;
219 layer_list_type cloud_layers;
221 osg::ref_ptr<osg::Group> pre_root, cloud_root;
222 osg::ref_ptr<osg::Switch> pre_selector;
223 osg::ref_ptr<osg::Group> pre_transform;
225 osg::ref_ptr<osg::MatrixTransform> _ephTransform;
231 float effective_visibility;
236 // near cloud visibility state variables
238 double puff_length; // in seconds
239 double puff_progression; // in seconds
240 double ramp_up; // in seconds
241 double ramp_down; // in seconds
244 bool clouds_3d_enabled;
247 double clouds_3d_density;
258 * Initialize the sky and connect the components to the scene
259 * graph at the provided branch. See discussion in detailed class
261 * @param h_radius_m horizontal radius of sky dome
262 * @param v_radius_m vertical radius of sky dome
263 * @param sun_size size of sun
264 * @param moon_size size of moon
265 * @param nplanets number of planets
266 * @param planet_data an array of planet right ascensions, declinations,
268 * @param nstars number of stars
269 * @param star_data an array of star right ascensions, declinations,
272 void build( double h_radius_m, double v_radius_m,
273 double sun_size, double moon_size,
274 const SGEphemeris& eph, SGPropertyNode *property_tree_node );
277 * Repaint the sky components based on current value of sun_angle,
278 * sky, and fog colors. You can also specify new star and planet
279 * data so that we can optionally change the magnitude of these
280 * (for day/night transitions.) See discussion in detailed
283 * Sun and moon angles are specified in degrees relative to local up
284 * <li> 0 degrees = high noon
285 * <li> 90 degrees = sun rise/set
286 * <li> 180 degrees = darkest midnight
287 * @param sky_color the base sky color (for the top of the dome)
288 * @param fog_color the fog color (for the horizon)
289 * @param sun_angle the sun angle with the horizon (for sunrise/sunset
291 * @param moon_angle the moon angle (so we can make it more yellow
293 * @param nplanets number of planets
294 * @param planet_data an array of planet right ascensions, declinations,
296 * @param nstars number of stars
297 * @param star_data an array of star right ascensions, declinations,
300 bool repaint( const SGSkyColor &sc, const SGEphemeris& eph );
303 * Reposition the sky at the specified origin and orientation
305 * lon specifies a rotation about the Z axis
306 * lat specifies a rotation about the new Y axis
307 * spin specifies a rotation about the new Z axis (this allows
308 * additional orientation for the sunrise/set effects and is used
309 * by the skydome and perhaps clouds. See discussion in detailed
311 * @param view_pos specify your view position in world Cartesian
313 * @param zero_elev the zero elevation position in world Cartesian
315 * @param view_up the up vector in world Cartesian coordinates
316 * @param lon current longitude
317 * @param lat current latitude
318 * @param alt current altitude
319 * @param spin an offset angle for orienting the sky effects with the
320 * sun position so sunset and sunrise effects look correct.
321 * @param gst GMT side real time
322 * @param sun_ra the sun's current right ascension
323 * @param sun_dec the sun's current declination
324 * @param sun_dist the sun's distance from the current view point
325 * (to keep it inside your view volume.)
326 * @param moon_ra the moon's current right ascension
327 * @param moon_dec the moon's current declination
328 * @param moon_dist the moon's distance from the current view point.
330 bool reposition( const SGSkyState &st, const SGEphemeris& eph, double dt = 0.0 );
333 * Modify the given visibility based on cloud layers, thickness,
334 * transition range, and simulated "puffs". See discussion in detailed
336 * @param alt current altitude
337 * @param time_factor amount of time since modify_vis() last called so
338 * we can scale effect rates properly despite variable frame rates.
340 void modify_vis( float alt, float time_factor );
342 osg::Node* getPreRoot() { return pre_root.get(); }
343 osg::Node* getCloudRoot() { return cloud_root.get(); }
346 * Specify the texture path (optional, defaults to current directory)
347 * @param path base path to texture locations
349 void texture_path( const string& path );
351 /** Enable drawing of the sky. */
352 inline void enable() {
353 pre_selector->setValue(0, 1);
357 * Disable drawing of the sky in the scene graph. The leaf node is still
358 * there, how ever it won't be traversed on by ssgCullandRender()
360 inline void disable() {
361 pre_selector->setValue(0, 0);
365 * Get the current sun color
367 inline SGVec4f get_sun_color() { return oursun->get_color(); }
370 * Get the current scene color
372 inline SGVec4f get_scene_color() { return oursun->get_scene_color(); }
377 * Transfer pointer ownership to this object.
379 * @param layer The new cloud layer to add.
381 void add_cloud_layer (SGCloudLayer * layer);
385 * Get a cloud layer (const).
387 * Pointer ownership remains with this object.
389 * @param i The index of the cloud layer, zero-based.
390 * @return A const pointer to the cloud layer.
392 const SGCloudLayer * get_cloud_layer (int i) const;
396 * Get a cloud layer (non-const).
398 * Pointer ownership remains with this object.
400 * @param i The index of the cloud layer, zero-based.
401 * @return A non-const pointer to the cloud layer.
403 SGCloudLayer * get_cloud_layer (int i);
407 * Return the number of cloud layers currently available.
409 * @return The cloud layer count.
411 int get_cloud_layer_count () const;
414 /** @return current effective visibility */
415 inline float get_visibility() const { return effective_visibility; }
417 /** Set desired clear air visibility.
418 * @param v visibility in meters
420 inline void set_visibility( float v ) {
421 effective_visibility = visibility = (v <= 25.0) ? 25.0 : v;
424 /** Get 3D cloud density */
425 virtual double get_3dCloudDensity() const;
427 /** Set 3D cloud density
428 * @param density 3D cloud density
430 virtual void set_3dCloudDensity(double density);
432 /** Get 3D cloud visibility range*/
433 virtual float get_3dCloudVisRange() const;
435 /** Set 3D cloud visibility range
436 * @param density 3D cloud visibility range
438 virtual void set_3dCloudVisRange(float vis);
440 /** Get 3D cloud impostor distance*/
441 virtual float get_3dCloudImpostorDistance() const;
443 /** Set 3D cloud impostor distance
444 * @param density 3D cloud impostor distance
446 virtual void set_3dCloudImpostorDistance(float vis);
448 /** Get 3D cloud LoD1 Range*/
449 virtual float get_3dCloudLoD1Range() const;
451 /** Set 3D cloud LoD1 Range
452 * @param vis LoD1 Range
454 virtual void set_3dCloudLoD1Range(float vis);
456 /** Get 3D cloud LoD2 Range*/
457 virtual float get_3dCloudLoD2Range() const;
459 /** Set 3D cloud LoD2 Range
460 * @param vis LoD2 Range
462 virtual void set_3dCloudLoD2Range(float vis);
464 /** Get 3D cloud impostor usage */
465 virtual bool get_3dCloudUseImpostors() const;
467 /** Set 3D cloud impostor usage
468 * @param wrap whether use impostors for 3D clouds
470 virtual void set_3dCloudUseImpostors(bool imp);
472 /** Get 3D cloud wrapping */
473 virtual bool get_3dCloudWrap() const;
475 /** Set 3D cloud wrapping
476 * @param wrap whether to wrap 3D clouds
478 virtual void set_3dCloudWrap(bool wrap);
484 #endif // _SG_SKY_HXX