SilverLining: SilverLining::AtmosphericConditions Class Reference

Public Member Functions

# SilverLining::AtmosphericConditions Class Reference

A class to set the current simulation conditions for the sky. More...

`#include <AtmosphericConditions.h>`

Inherits SilverLining::MemObject.

Collaboration diagram for SilverLining::AtmosphericConditions:
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List of all members.

## Public Member Functions
| AtmosphericConditions ()
| Default constructor.
virtual | ~AtmosphericConditions ()
| Destructor.
void SILVERLINING_API | SetLocation (const Location &location)
| Sets the simulated geographic location.
const Location &SILVERLINING_API | GetLocation () const
| Gets the current simulated location.
void SILVERLINING_API | SetTime (const LocalTime &time)
| Sets the simulated time of day in local time.
const LocalTime &SILVERLINING_API | GetTime ()
| Retrieves the currently simulated time of day.
int SILVERLINING_API | SetWind (const WindVolume &windVolume)
| Sets a volume of wind for moving clouds.
bool SILVERLINING_API | RemoveWindVolume (int windVolumeHandle)
| Removes a specific wind volume from the simulation.
void SILVERLINING_API | ClearWindVolumes ()
| Clears all wind volumes previously set via SetWind.
void SILVERLINING_API | GetWind (double &velocity, double &heading, double altitude) const
| Retrieves the simulated wind at a given altitude.
void SILVERLINING_API | ApplyWind (double dt)
| Apply wind to cloud layers for given time step.
const | SL_MAP (int, WindVolume)&SILVERLINING_API GetWindVolumes() const
| Get a vector of all wind volumes being simulated.
int SILVERLINING_API | AddCloudLayer (CloudLayer *layer)
| Adds a cloud layer to the simulated atmospheric conditions.
bool SILVERLINING_API | RemoveCloudLayer (int layerHandle)
| Removes a previously added cloud deck from the scene.
void SILVERLINING_API | RemoveAllCloudLayers ()
| Removes all cloud layers from the scene.
bool SILVERLINING_API | GetCloudLayer (int layerHandle, CloudLayer **layer)
| Obtain a pointer to a CloudLayer object.
| SL_MAP (int, CloudLayer *)&SILVERLINING_API GetCloudLayers()
| Obtain the stl map of CloudLayer objects.
void SILVERLINING_API | SetTurbidity (double pTurbidity)
| Sets the "turbidity" of the simulated atmosphere.
double SILVERLINING_API | GetTurbidity () const
| Get the simulated atmospheric turbidity.
void SILVERLINING_API | SetVisibility (double range)
| Sets the simulated visibility in meters; this will affect the appearance of clouds in the distance.
double SILVERLINING_API | GetVisibility () const
| Retrieves the currently simulated visibility, in meters.
void SILVERLINING_API | SetFog (double density, double r, double g, double b)
| Explicitly sets exponential fog color and density, if you need to match an existing scene.
void SILVERLINING_API | ClearFog ()
| Clears explicitly set fog from SetFog(), and reverts the fog to simulating the visibility specified in SetVisibility() instead.
void SILVERLINING_API | GetFog (bool &fogIsSet, double &density, double &r, double &g, double &b)
| Retrieves the explicit fog (if any) set by SetFog().
void SILVERLINING_API | SetLightPollution (double Wm2)
| Sets the simulated amount of nighttime light pollution, in watts per square meter.
double SILVERLINING_API | GetLightPollution () const
| Retrieves the currently simulated light pollution, in watts per square meter.
void SILVERLINING_API | SetPrecipitation (int precipitationType, double precipitationRate, double nearClip=-1, double farClip=-1)
| Simulates global precipitation of a specified type.
void SILVERLINING_API | SetPrecipitationWind (double windX, double windZ)
| Sets a precipitation specific wind vector which is additive to any global wind set at the AtmosphericConditions level.
void SILVERLINING_API | GetPrecipitationWind (double &windX, double &windZ) const
| Retrieves the precipitation specific wind vector.
void SILVERLINING_API | EnableTimePassage (bool enabled, long relightFrequencyMS)
| By default, SilverLining will "freeze" time at the time specified by AtmosphericConditions::SetTime().
void SILVERLINING_API | SetMillisecondTimer (const MillisecondTimer *timer)
| By default, SilverLining will simulate the motion of clouds in the wind and the motion of astronomical objects (when EnableTimePassage() is active) by calling the system's millisecond timer.
const MillisecondTimer *SILVERLINING_API | GetMillisecondTimer () const
| Retrieves the MillisecondTimer previously set by SetMillisecondTimer(), or the default timer if SetMillisecondTimer() is unset or set to NULL.
bool SILVERLINING_API | Serialize (std::ostream &stream)
| Flattens this object and everything in it to a stream buffer.
bool SILVERLINING_API | Unserialize (const Atmosphere *atm, std::istream &stream)
| Restores this object from the stream created using Serialize().

## Detailed Description

A class to set the current simulation conditions for the sky.

This class allows you to specify the simulated time, location, wind, visibility, haze, and cloud cover for your scene. You do so by instantiating your own AtmosphericConditions object, configuring it by calling its methods, and then passing it into your Atmosphere object via Atmosphere::SetConditions().

To make changes to the AtmosphericConditions after it has been passed into Atmosphere::SetConditions(), call Atmosphere::GetConditions() and call methods on the AtmosphericConditions reference that it returns. Atmosphere::SetConditions() copies your AtmosphericConditions into the Atmosphere class, so changes made to the AtmosphericConditions used to initialize the Atmosphere will have no effect.

## Constructor & Destructor Documentation

SilverLining::AtmosphericConditions::AtmosphericConditions | ( |  | ) |

Default constructor.

Creates an AtmosphericConditions object with default settings.

virtual SilverLining::AtmosphericConditions::~AtmosphericConditions | ( |  | ) | `[virtual]`

Destructor.

Destroys all members, but does not destroy the CloudLayer objects passed into AddCloudLayer().

## Member Function Documentation

int SILVERLINING_API SilverLining::AtmosphericConditions::AddCloudLayer | ( | CloudLayer * | layer | ) |

Adds a cloud layer to the simulated atmospheric conditions.

Cloud layers are created via the CloudLayerFactory::Create() method, and won't become part of your scene until they are added to a AtmosphericConditions class that is then passed into Atmosphere::SetConditions(). The CloudLayer object will be destroyed along with this AtmosphericConditions class; there's no need to keep this object around for cleanup.

Parameters:

  | layer | A CloudLayer created via CloudLayerFactory::Create(). This CloudLayer should be configured and seeded (see CloudLayer::SeedClouds()) prior to being passed in.

Returns:
  An integer handle to the cloud layer that may be used in calls to RemoveCloudLayer() and GetCloudLayer().

void SILVERLINING_API SilverLining::AtmosphericConditions::ApplyWind | ( | double | dt | ) |

Apply wind to cloud layers for given time step.

This is called by the Atmosphere class; you do not need to call this directly!

Parameters:

  | dt | Length of time to simulate wind over, in seconds.

void SILVERLINING_API SilverLining::AtmosphericConditions::ClearFog | ( |  | ) |

Clears explicitly set fog from SetFog(), and reverts the fog to simulating the visibility specified in SetVisibility() instead.

void SILVERLINING_API SilverLining::AtmosphericConditions::ClearWindVolumes | ( |  | ) |

Clears all wind volumes previously set via SetWind.

void SILVERLINING_API SilverLining::AtmosphericConditions::EnableTimePassage | ( | bool | enabled,
|  | long | relightFrequencyMS |
| ) |  |  |

By default, SilverLining will "freeze" time at the time specified by AtmosphericConditions::SetTime().

If you want to simulate the passage of time, call EnableTimePassage with the enabled parameter set to true.

Relighting the clouds is a relatively expensive operation, so for real time applications you probably won't want to relight the clouds every frame. The relightFrequencyMS parameter allows you to specify the interval, in milliseconds, between cloud relighting passes. The sky will continue to update in real time, along with the position of the sun, moon, and stars, between these intervals. If you have specified your own MillisecondTimer with SetMillisecondTimer(), the interval will be computed based on its concept of time.

If the enabled parameter is false (the default,) or the relightFrequencyMS parameter is set to -1, cloud relighting will only happen in response to calls to AtmosphericConditions::SetTime().

Clouds will move with respect to the simulated wind irregardless of calling this method.

Parameters:

  | enabled | True if you want to simulate the passage of time between calls to SetTime(); false if the simulated time should remain static.
  | relightFrequencyMS | The interval, in milliseconds, between cloud relighting passes. Set to -1 to prevent cloud relighting outside of calls to SetTime().

bool SILVERLINING_API SilverLining::AtmosphericConditions::GetCloudLayer | ( | int | layerHandle,
|  | CloudLayer ** | layer |
| ) |  |  |

Obtain a pointer to a CloudLayer object.

Given a cloud layer handle, obtain its underlying CloudLayer object.

Parameters:

  | layerHandle | The integer handle to a cloud layer previously returned by AddCloudLayer().
  | layer | A pointer to a pointer to receive the CloudLayer object pointer requested.

Returns:
  false if the layerHandle does not specify a CloudLayer being managed by this class.

void SILVERLINING_API SilverLining::AtmosphericConditions::GetFog | ( | bool & | fogIsSet,
|  | double & | density,
|  | double & | r,
|  | double & | g,
|  | double & | b |
| ) |  |  |

Retrieves the explicit fog (if any) set by SetFog().

Parameters:

  | fogIsSet | Returns true if SetFog has been called and ClearFog has not, meaning we are using fog with an explicitly defined application setting instead of simulating visibility.
  | density | The exponential fog density term set in SetFog()
  | r | The red component of the fog color specified in SetFog(). Ranges from 0-1.
  | g | The green component of the fog color specified in SetFog(). Ranges from 0-1.
  | b | The blue component of the fog color specified in SetFog(). Ranges from 0-1.

double SILVERLINING_API SilverLining::AtmosphericConditions::GetLightPollution | ( |  | ) | const`[inline]`

Retrieves the currently simulated light pollution, in watts per square meter.

const Location& SILVERLINING_API SilverLining::AtmosphericConditions::GetLocation | ( |  | ) | const

Gets the current simulated location.

Returns:
  A const reference to a Location object that may be queried for the current simulated geographic position.

const MillisecondTimer* SILVERLINING_API SilverLining::AtmosphericConditions::GetMillisecondTimer | ( |  | ) | const`[inline]`

Retrieves the MillisecondTimer previously set by SetMillisecondTimer(), or the default timer if SetMillisecondTimer() is unset or set to NULL.

void SILVERLINING_API SilverLining::AtmosphericConditions::GetPrecipitationWind | ( | double & | windX,
|  | double & | windZ |
| ) |  |  | const`[inline]`

Retrieves the precipitation specific wind vector.

See also:
  SetWind()

const LocalTime& SILVERLINING_API SilverLining::AtmosphericConditions::GetTime | ( |  | ) |

Retrieves the currently simulated time of day.

Use this to obtain the local time, time zone, and daylight savings time observance being simulated.

This will also reflect the passage of time simulated by activating EnableTimePassage(). As such, it may differ from what was originally passed into SetTime() if time passage is activated.

Returns:
  A const reference to a LocalTime object, which may be queried for the local time, time zone, and DST information being simulated.

double SILVERLINING_API SilverLining::AtmosphericConditions::GetTurbidity | ( |  | ) | const`[inline]`

Get the simulated atmospheric turbidity.

See SetTurbidity() for an explanation of turbidity values.

double SILVERLINING_API SilverLining::AtmosphericConditions::GetVisibility | ( |  | ) | const`[inline]`

Retrieves the currently simulated visibility, in meters.

void SILVERLINING_API SilverLining::AtmosphericConditions::GetWind | ( | double & | velocity,
|  | double & | heading,
|  | double | altitude |
| ) |  |  | const

Retrieves the simulated wind at a given altitude.

Parameters:

  | velocity | Receives the simulated wind velocity in meters per second
  | heading | Receives the simulated wind direction in degrees from North
  | altitude | The altitude, in meters, for which you want wind information.

void SILVERLINING_API SilverLining::AtmosphericConditions::RemoveAllCloudLayers | ( |  | ) |

Removes all cloud layers from the scene.

All CloudLayer objects currently contained by this class will be removed and deleted.

bool SILVERLINING_API SilverLining::AtmosphericConditions::RemoveCloudLayer | ( | int | layerHandle | ) |

Removes a previously added cloud deck from the scene.

The specified CloudLayer handle, if found, will be removed from the simulation and its CloudLayer object deleted.

Parameters:

  | layerHandle | The integer handle previously returned from AddCloudLayer().

Returns:
  true if the cloud deck was removed, false if the handle specified was not found.

bool SILVERLINING_API SilverLining::AtmosphericConditions::RemoveWindVolume | ( | int | windVolumeHandle | ) |

Removes a specific wind volume from the simulation.

Parameters:

  | windVolumeHandle | The handle returned from AtmosphericConditions::SetWind().

bool SILVERLINING_API SilverLining::AtmosphericConditions::Serialize | ( | std::ostream & | stream | ) |

Flattens this object and everything in it to a stream buffer.

void SILVERLINING_API SilverLining::AtmosphericConditions::SetFog | ( | double | density,
|  | double | r,
|  | double | g,
|  | double | b |
| ) |  |  |

Explicitly sets exponential fog color and density, if you need to match an existing scene.

If set, this will override the visibility effects from SetVisibility(). Color components are specified in the range 0-1. Density should be 1.0 / simulated visibility. If set, astronomical objects (the sun, moon, and stars) are not drawn, and clouds will be fogged as you specify. This is intended for real, thick fog, as opposed to SetVisibility(), which simulates extinction from atmospheric scattering. When using this, you'll usually want to call DrawSky() with false in the first parameter to suppress drawing the sky box, and just clear your back buffer to the fog color instead.

void SILVERLINING_API SilverLining::AtmosphericConditions::SetLightPollution | ( | double | Wm2 | ) | `[inline]`

Sets the simulated amount of nighttime light pollution, in watts per square meter.

Defaults to zero. A reasonable value would be in the order of 0.01

void SILVERLINING_API SilverLining::AtmosphericConditions::SetLocation | ( | const Location & | location | ) |

Sets the simulated geographic location.

This affects the sun and moon positions relative to the horizon, and thereby also affects the lighting of the scene. Be sure that the location specified is consistent with the time zone specified in the LocalTime passed to SetTime(), or you will experience confusing results.

Parameters:

  | location | A reference to a Location object that embodies the simulated latitude and longitude.

void SILVERLINING_API SilverLining::AtmosphericConditions::SetMillisecondTimer | ( | const MillisecondTimer * | timer | ) |

By default, SilverLining will simulate the motion of clouds in the wind and the motion of astronomical objects (when EnableTimePassage() is active) by calling the system's millisecond timer.

If you want to accelerate, slow, or reverse the passage of time, you may instead provide your own MillisecondTimer implementation, and pass it in here. See the documentation for the MillisecondTimer class for more details.

Parameters:

  | timer | The MillisecondTimer object to use for moving clouds and astronomical objects over time, relative to the LocalTime passed into SetTime(). Pass NULL to restore the default timer.

void SILVERLINING_API SilverLining::AtmosphericConditions::SetPrecipitation | ( | int | precipitationType,
|  | double | precipitationRate,
|  | double | nearClip = `-1`,
|  | double | farClip = `-1` |
| ) |  |  |

Simulates global precipitation of a specified type.

Precipitation effects will display if the type is set to something other than NONE.

Note, you may also set precipitation effects associated with a CloudLayer that only render when the camera is underneath a rain cloud with the similar CloudLayer::SetPrecipitation() method.

For mixed precipitation, you may call SetPrecipitation multiple times with different precipitation types. To clear all precipitation, call SetPrecipitation with a type of CloudLayer::NONE. If you call this method multiple times for the same precipitation type, the intensity specified will overwrite the intensity previously specified for that type.

Parameters:

  | precipitationType | The type of precipitation to simulate under this cloud layer - CloudLayer::NONE, CloudLayer::RAIN, CloudLayer::WET_SNOW, CloudLayer::DRY_SNOW, or CloudLayer::SLEET.
  | precipitationRate | The simulated rate of precipitation, in millimeters per hour. Reasonable ranges might be between 1 for light rain or 20 for heavier rain. This value will be clamped to the value specified by rain-max-intensity, snow-max-intensity, or sleet-max-intensity in resources/SilverLining.config, which is 30 by default.
  | nearClip | How close to the camera the closest precipitation particles will be rendered. The near clipping plane will be adjusted to include this distance while the precipitation is being rendererd. Values less than zero will result in the default value being applied.
  | farClip | The farthest distance from the camera that precipitation particles will be rendered. Since there is an upper bound on the number of particles rendered per frame, changing the difference between nearClip and farClip may result in changes to the intensity of the precipitation. By default this difference is 7.5 world units. Values less than zero will result in the default value being applied.

void SILVERLINING_API SilverLining::AtmosphericConditions::SetPrecipitationWind | ( | double | windX,
|  | double | windZ |
| ) |  |  | `[inline]`

Sets a precipitation specific wind vector which is additive to any global wind set at the AtmosphericConditions level.

The vector itself specifies the wind direction and the length of the vector provides the wind velocity.

Parameters:

  | windX | The east vector of the precipitation specific wind, in meters/s.
  | windZ | The south vector of the precipitation specific wind, in meters/s.

See also:
  GetWind()

void SILVERLINING_API SilverLining::AtmosphericConditions::SetTime | ( | const LocalTime & | time | ) |

Sets the simulated time of day in local time.

You must specify if daylight savings time is currently being observed or not. Be sure that the time zone specified is consistent with the simulated Location passed to SetLocation(), or you will experience confusing results.

Parameters:

  | time | A reference to a LocalTime object that embodies the simulated local time, time zone, and daylight savings time observation.

void SILVERLINING_API SilverLining::AtmosphericConditions::SetTurbidity | ( | double | pTurbidity | ) | `[inline]`

Sets the "turbidity" of the simulated atmosphere.

You can think of this as a measure of "haziness." 1.0 would be a perfectly clear day and is the minimum value. Some guidelines for setting this value:

2 = very clear, range 50 km 3 = clear, range 15 km 7 = light haze, range 8 km

Setting turbidity is not an appropriate way to simulate fog; see Atmosphere::SetHaze() for one method, or for dense fog simply clear the backbuffer to the fog color and pass false to Atmosphere::DrawSky() to suppress the sky rendering altogether.

Turbidity just lets you simulate the number of particles in the air. In practice it will vary the color of the sky from a pure light blue to a hazy, darker, yellowish color. Turbidity values below 1.8 or above 20.0 lead to unpredictable results and are clamped.

Parameters:

  | \pTurbidity | The ratio of scattering due to haze to scattering due to molecules.

void SILVERLINING_API SilverLining::AtmosphericConditions::SetVisibility | ( | double | range | ) | `[inline]`

Sets the simulated visibility in meters; this will affect the appearance of clouds in the distance.

Defaults to 30km. This is intended only for light haze, and serves only to blend clouds into the sky in the distance. It does not fog the sky itself. For thicker fog, see AtmosphericConditions::SetFog() and Atmosphere::SetHaze().

int SILVERLINING_API SilverLining::AtmosphericConditions::SetWind | ( | const WindVolume & | windVolume | ) |

Sets a volume of wind for moving clouds.

You may call this multiple times to define different wind velocities and directions at different altitudes. Wind also has some influence on cloud formation and the rendering of virga effects.

Parameters:

  | windVolume | A WindVolume to add to the simulation.

Returns:
  A handle to the wind volume

SilverLining::AtmosphericConditions::SL_MAP | ( | int | ,
|  | CloudLayer * |  |
| ) |  |  | `[inline]`

Obtain the stl map of CloudLayer objects.

An accessor for a reference to the STL map of CloudLayer objects managed by this AtmosphericConditions class. It is not const, and so it may be directly manipulated. Use with care.

const SilverLining::AtmosphericConditions::SL_MAP | ( | int | ,
|  | WindVolume |  |
| ) |  |  | const`[inline]`

Get a vector of all wind volumes being simulated.

Returns:
  A const reference to the STL vector of wind volumes currently being simulated.

The documentation for this class was generated from the following file:

- /home/fkane/sl/trunk/Public Headers/AtmosphericConditions.h