In trueSKY, the sky is modified in two ways: through sky keyframes and the sky layer. Keyframe properties will dictate the look of the sky at a given point in time - with interpolation used to derive properties at times between keyframes – whereas layer properties will be active throughout a sequence. Both can be modified via the sequencer or through the Blueprint system.
|Sea Level Deg. C||For infra-red rendering.||-273.0 to 1000|
|Zenith||Colour of the Zenith (Sky above you). See Sky Colours||RGB|
|Horizon||Colour of the Horizon (Sky around you). See Sky Colours||RGB|
|Loop||If the sky should loop the first day. The loop can be seen on the timeline, indicated by a yellow bracket above the Sky Layer.||Bool|
|Sky Multiplier||Multiplier to scale the brightness of the Sky.||1 to 100|
|Planet Radius||Radius of the planet in meters.||100 to 100000|
|Atmosphere Thickness||Thickness of the Atmosphere in Km.||10 to 1000|
|Ozone||Ozone level of the atmosphere.||0 to 0.2|
|Emissivity||Emissivity of the Atmosphere.||0 to 1|
|Rayleigh Coefficient||Rayleigh scattering coefficients at standard sea level density, xyz = RGB. Can be calculated based on wavelength with Auto Button.||0 to 10000|
|Atmospherics Amortization||How to spread the cost of rendering atmospherics over frames. Similar to Cloud Amortization||1 to 8|
|Automatic Sun Position||Whether to calculate sun position from date and time.||Bool|
|Light Wavelength (R,G,B)||Wavelength of the light from the sun.||0 to 1000|
|Irradiance||Irradiance of the Sun, in Watts/m2/nm. XYZ=RGB.||0 to 50|
|Diameter||Size of sun’s radius in degrees||0.0 to 3600.0|
|Link Keyframe time and daytime||See Link Keyframe Time||Bool|
|Time Zone||Time Zone based on Greenwich Mean Time (GMT).||Between -12.0 and 12.0|
|Start Date||For calculating start position of sun/moon. Where 01/01/2000 = 0 , -1 = 31/12/1999, 01/01/2016 = 5844(format DD:MM:YYYY).||-100000 to 100000|
|Sun Multiplier||Multiplier to scale the brightness of sunlight in the scene.||From 1 to 10|
|Max Sun Radiance||Maximum Sun radiance produced.||0 to 1000000.0|
|Adjust Sun Radiance||If enabled, adjusting the Sun radiance will cause the sun to automatically scale to keep spectral irradiance the same.||Bool|
The moon has a customisable texture, so you can use it to make some interesting effects!
|Automatic Moon Position||Whether to calculate moon position from date and time.||Bool|
|Albedo||The proportion of the incident light that is reflected by a surface.||0.0 to 1.0|
|Diameter||Size of moon’s radius in degrees||0.0 to 3600.0|
|Colour||Colour of the moon. Uses a colour wheel, can also input HTML Colour Code.||RGB|
|Moon texture||Texture to use for the moon. trueSKY has a moon texture by default||.png|
|Moon Multiplier||Brightness multiplier for the moon||0.0 to 10.0|
|Max Magnitude||Maximum Magnitude of stars.||0.0 to 9.0|
|Brightness||Star Brightness.||1.0 to 10000.0|
|Minimum Pixel Size||Minimum size of each star.||1.0 to 10000.0|
|Background||Brightness multiplier for background texture.||0.000001 to 0.001|
|Find Constellation||Out for Repairs||Out for Repairs|
|Cosmic Background Texture||Texture to appear for the night sky. Default is an image of the Milky way||.png|
|Minimum Star Pixel Size||Minimum pixel size of stars in the sky. If set to 0 they are drawn as point, otherwise as quads. Does not affect the Sun.||0 to|
A keyframe’s haze value determines how much Mie-scattered haze (i.e. mist or fog) is present. Haze is considered to have a density that falls-off exponentially with altitude, so the HazeScaleHeightKm property determines the scaling height for this exponential. TheHazeBaseHeightKm is also used. Below this height, full haze is applied.
|Visibility||Visibility controls haze/fog, represents visibility at sea level.||0.1 to 10000|
|Haze/fog||Amount of haze/mist.||0.00001 to 1000.0.|
|Haze Base||Base altitude above which haze decreases in density.||-2.0 to 20.0.|
|Haze Scale||Vertical scale over which haze reduces with altitude.||0.1 to 10.0.|
|Eccentricity||Anisotropy of Mie scattering.||0.0 to 1.0.|
|Ground Fog||Strength of ground fog.||0.0 to 10.0.|
|Fog Ceiling||Fog Ceiling in Km.||0 to 10.|
|Mie Coefficients||Mie scattering coefficients. XYZ = RGB||0 to 50|
The SkyKeyframer has two modes of operation. By switching LinkKeyframeTimeAndDaytimeon or off, you can choose whether the keyframes have a daytime value which is independent of time, or whether these two numbers are the same.
Here we enable this link by calling SetLinkKeyframeTimeAndDaytime, then verify that daytime and time are now the same:
If they are not linked, then while daytime is defined as above, the keyframe’s time value is arbitrary - it could represent the real time in seconds, or some other scale. Furthermore, while the keyframes will be sorted so that they are in ascending order of time, daytime will have no such restriction. You could have a midday keyframe, followed by sunset, followed by midday again. Here, we set all the keyframes to be at daytime=0.25 (6am):
You could also disable automaticSunPosition, in which case daytime will have no effect on sun position.
The unlinked time mode is particularly suitable to situations where you will use the Simul API to change conditions on the fly. At any given time, two keyframes are being used for rendering, and the next one along will be partially updated. So the properties of the fourth keyframe can be changed without having any need for recalculations.
simul::sky::SkyKeyframe *k=environment->skyKeyframer->GetNextModifiableKeyframe(); k->haze=20.f;
This works just as well with linked as with unlinked times.
You can manually set the colour of the horizon or the upper sky(Zenith) using the Sky Keyframes. Enable Store as Colours and then set your colours manually. This is a great way to create unique, alien landscapes.
Make sure to apply the colour to all your keyframes if you want it to be throughout the whole day cycle, or set different colours for different times, and watch as the Sky blends as time progresses.