Sunsky Texture

Texture Plugin for LightWave 3D

Sunsky

Texture plugin for LightWave3D 8.0 & 9.0+
coded by Denis Pontonnier.
x64 compile by Marvin Landis.
UB compiles by Michael Wolf.

-A Sunsky procedural texture for Texture Environment.

-Getting the rotation angles of the selected Light it simulates a daylight sky, angles are evaluated in world coordinates.

-The Lightwave "Sun Spot" motion modifier can be applied to the light for accurate sun position/rotation
with date/time for a given location (keep default 1 km or more as distance).

-Like Skylight texture, it is based on 'A Practical Analytic Model for Daylight'
from A. J. Preetham, Peter Shirley and Brian Smits.

-Unlike the simplified Renderman shader, it gets zxY colors from the original sampling method and
lets the users choose between 6 color systems to convert to current rgb values, and choose different
ways to apply exponential exposure to get viewable colors.

-Brightness, Constrast, Hue, Saturation and Gamma are available in Correction tab.

-An attenuated Sun color is evaluated mixing :

Rayleigh scattering,
Aerosol (water + dust) attenuation,
Attenuation due to ozone absorption,
Attenuation due to mixed gases absorption,
Attenuation due to water vapor absorption,

to map a disk on the sky texture,
the sun color is normalized at 100% intensity, but it can be set to higher value for texture.

-Sunsky includes a Suncolor channel modifier plugin for sending and applying the color and intensity
to the R, G and B Color envelope of the sun light.
The Sky Amount is for mixing the solar color with the color of the brightest area of the sky with same correction
than the texture. Since the Sun color is normalized, it is a saturated value, decrease it around 0.5 to get a color
like after exposure.
Intensity channel is also a mix between the the Sun Intensity after HSV exposure and the amount of the brightest
sky value after conversion, exposure and correction,
it is scaled by the sun intensity parameter set in the texture plugin and the
Value parameter in the modifier.

-With "(Inv) Exp. Exposure" set to zero exposure is skipped (x32 version), with full colors and radiosity enabled,
final render need to be re-exposed or tonemapped with a proper gamma (e.g. DP Filter Tonemap and Exposure node).

Thanks to Paolo Zambrini for suggesting and testing,
and Grzegorz Tanski and Michael Wolf for help.

Download (Win32)         Sunsky_x32.zip
  (Updated 07/07/09)
Download (Win64)         Sunsky_x64.zip
  (Updated 07/07/09)
Download (Mac UB)       Sunsky_UB.zip
  (Updated 09/01/09)