envSky

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The Env Sky texture is an environment map that generates images of a planetary atmosphere as seen from the surface of a planet.

Sky attributes let you control the composition of the atmosphere and the cloud layer. If no floor is specified, the environment below the horizon is a vertical mirror reflection of the environment above the horizon. If you specify a floor, you can set it to a color or use a texture map.

If a floor is specified and the camera point-of-view drops below that floor, then the sky will turn red as a warning.

You can use the Env Sky texture as a reflection map, by connecting its Out Color attribute to the Reflected Color attribute of an specular shader, such as Blinn or PhongE. You can also use the Env Sky texture as a background, by connecting it to an image plane. For best results, scale the sky so it is in proportion to the half-height of the image plane.

Aside from the attributes listed here, Env Sky inherits additional attributes from TextureEnv.

In the table below, important attributes have their names listed in bold in the description column.

Related nodes

layeredTexture, envCube, envSphere, envBall, envChrome, bump3d, uvChooser, bump2d, texture2d, ramp, file, cloth, water, stencil, checker, fractal, bulge, grid, mountain, texture3d, projection, cloud, granite, crater, leather, stucco, brownian, solidFractal, marble, wood, rock, snow, defaultTextureList, place2dTexture, place3dTexture

Attributes (53)

The following quick index only shows top-level attributes (too many attributes to show them all): airDensity, altitude, azimuth, blur, cloudBrightness (3), cloudSamples, cloudTexture, density, dustDensity, elevation, floorAltitude, floorColor (3), floorSamples, haloBrightness (3), haloSize, hasFloor, pointCamera (3), power, refPointCamera (3), size, skyBrightness (3), skyRadius, skySamples, skyThickness, sunBrightness (3), sunsetBrightness (3), threshold, totalBrightness, useTexture

Long name (short name)	Type	Default	Flags
airDensity (ad)	float	1.0
Air Density controls how light is scattered by the atmosphere, and therefore the "blueness" of the sky. To simulate high-altitude skies (which are black at the zenith, and blue near the horizon), set Air Density to values less than 1.0. To simulate low-altitude skies (which are blue at the zenith, and white near the horizon), set Air Density to values greater than 1.0.
altitude (a)	float	0.2
Altitude controls the apparent altitude of the cloud layer. This does not affect the position of the clouds on the screen. Rather, it affects the fraction of the atmosphere that obscures the clouds near the horizon. Low-altitude clouds disappear into haze much more slowly than high-altitude clouds.
azimuth (az)	angle (double)	145.0deg
Azimuth controls the position of the sun around a vertical axis. Adjust this to move the sun around horizontally without changing its elevation.
blur (b)	float	1.0
Blur controls the size (radius) of the halo around the sun.
cloudBrightness (cb)	float3	0.5, 0.5, 0.5
Cloud Brightness sets the brightness of the ambient scattered light from the atmosphere. This also depends on the current Elevation of the sun.
cloudBrightnessR (cbr) float 0.0 The red component of Cloud Brightness
cloudBrightnessG (cbg) float 0.0 The green component of Cloud Brightness
cloudBrightnessB (cbb) float 0.0 The blue component of Cloud Brightness
cloudSamples (csa)	float	5.0
Cloud Samples controls the number of "samples" that the renderer uses in its calculations of the clouds. You can decrease this value to speed up the environment calculation, but if you do so, you will lose some of the atmospheric effects --- clouds will not fade to mist at the horizon.
cloudTexture (ct)	float	1.0
Cloud Texture lets you assign a layer of clouds to the sky. Map a Cloud texture or other fractal texture to this attribute. Note: if you use this attribute, you must turn on the Use Texture attribute, or you will not see your clouds.
density (d)	float	1.0
Density controls how dense the clouds are. At 0.0, the clouds are non-existent. Increase the value to make the clouds denser. At 5.0, they are heavy rain clouds.
dustDensity (dd)	float	0.0
Dust Density density of the dust in the atmosphere.
elevation (e)	angle (double)	45.0deg
Elevation controls how high the sun is in the sky. An elevation of 0 degrees would put the sun at the horizon, and an elevation of 90 degrees would put it directly overhead.
floorAltitude (fa)	float	-10.0
Floor Altitude controls the position of the floor plane relative to the vertical axis. Increase this to move the floor up, decrease it to move the floor down. Remember to always keep your camera above the floor altitude.
floorColor (fc)	float3	0.4, 0.4, 0.4
Floor Color controls the color of the floor, when Has Floor is turned on. You can, of course, texture map this attribute to get interesting ground effects.
floorColorR (fcr) float 0.0 The red component of Floor Color
floorColorG (fcg) float 0.0 The green component of Floor Color
floorColorB (fcb) float 0.0 The blue component of Floor Color
floorSamples (fsa)	float	1.0
Floor Samples controls the number of "samples" that the renderer uses in its calculations of the floor. You can decrease this value to speed up the environment calculation, but if you do so, you will lose some of the atmospheric effect along the floor (i.e. fading towards the horizon).
haloBrightness (hb)	float3	0.5, 0.5, 0.5
Halo Brightness controls how bright the halo around the sun is. Note: this attribute only affects the brightness of the halo, and not its color.
haloBrightnessR (hbr) float 0.0 The red component of Halo Brightness
haloBrightnessG (hbg) float 0.0 The green component of Halo Brightness
haloBrightnessB (hbb) float 0.0 The blue component of Halo Brightness
haloSize (hs)	float	20.0
Halo Size controls the radius over which direct back-lighting from the sun occurs. This is most noticeable near the edges of thick clouds or anywhere on thin clouds.
hasFloor (hf)	bool	true
Has Floor controls whether there is a floor in the environment. If you turn this off, the environment below the horizon is a mirror reflection of the environment above the horizon.
pointCamera (p)	float3	0.0, 0.0, 0.0
The current sample point that has to be shaded
pointCameraX (px) float 0.0 The x component of the current sample position
pointCameraY (py) float 0.0 The y component of the current sample position
pointCameraZ (pz) float 0.0 The z component of the current sample position
power (po)	float	1.0
Power scales and positions the clouds. If you set Power to 0, you will get clouds that have little or no variation in density within each cloud. As you increase Power, you will see more variation. (Basically, Power acts to modulate the Density attribute.)
refPointCamera (rpc)	float3	0.0, 0.0, 0.0
The current reference sample point that has to be shaded
refPointCameraX (rcx) float 0.0 The x component of the current sample position
refPointCameraY (rcy) float 0.0 The y component of the current sample position
refPointCameraZ (rcz) float 0.0 The z component of the current sample position
size (sz)	float	0.531
Size controls the size (radius) of the disk of the sun.
skyBrightness (sk)	float3	0.5, 0.5, 0.5
Sky Brightness is a color value that is multiplied by the basic sky color. You can use this to brighten or darken or tint the sky.
skyBrightnessR (skr) float 0.0 The red component of Sky Brightness
skyBrightnessG (skg) float 0.0 The green component of Sky Brightness
skyBrightnessB (skb) float 0.0 The blue component of Sky Brightness
skyRadius (sr)	float	50.0
Sky Radius can be thought of as the size of the planet, epressed as a multiple of Sky Thickness. When you increase this, it affects the relative difference in light scattering between light coming from above and light coming from the horizon. The bigger the planet, the more sunlight has to go through as the sun sets. Effectively, increasing this value will result in redder but dimmer sunsets. (You can compensate for dimness by increasing the Sky Brightness)
skySamples (ssa)	float	5.0
Sky Samples controls the number of "samples" that the renderer uses in its calculations above the cloud layer. You can decrease this value to as low as one to speed up the environment calculation. However, decreasing it too much may result in undesirable "flatness" in the image, and loss of detail.
skyThickness (st)	float	1000.0
Sky Thickness controls the thickness of the atmosphere. When this is increased, light has to pass through more air, and is therefore scattered more, showing more color.
sunBrightness (su)	float3	0.5, 0.5, 0.5
Sun Brightness controls how bright the sun is in the environment. Note: this attribute only affects the brightness of the sun, and not its color.
sunBrightnessR (sur) float 0.0 The red component of Sun Brightness
sunBrightnessG (sug) float 0.0 The green component of Sun Brightness
sunBrightnessB (sub) float 0.0 The blue component of Sun Brightness
sunsetBrightness (ss)	float3	1.0, 1.0, 1.0
Sunset Brightness controls the illumination of the clouds when the sun is below the horizon and the clouds are front-lit. This is a very subtle effect and only occurs briefly after sunset.
sunsetBrightnessR (ssr) float 0.0 The red component of Sunset Brightness
sunsetBrightnessG (ssg) float 0.0 The green component of Sunset Brightness
sunsetBrightnessB (ssb) float 0.0 The blue component of Sunset Brightness
threshold (t)	float	0.5
Threshold controls how much of the sky is covered with cloud. At 0.0, the entire sky will be cloudy. As this value increases, you will see more and more of the sky through the cloud layer.
totalBrightness (tb)	float	1.0
Total Brightness controls the overall brightness level of the environment.
useTexture (ut)	bool	false
Use Texture controls whether or not Env Sky pays attention to the Cloud Texture attribute. If you attach a Cloud or other fractal texture node to the Cloud Texture attribute, then you must turn on Use Texture to see the results.