The CloudLayerNode is a SkyNode that renders a distant layer of clouds. CloudLayerNode are rendered by the SkyRenderer. The clouds are alpha-blended over the background. (The renderer does not draw the background sky, only clouds.)

Clouds are defined by a CloudMap, which provides a cloud texture. The cloud texture stores the transmittance of the sky (see Texture for more information). It is possible to use user-defined textures (see UserDefinedCloudMap), or dynamically generate clouds at runtime (see LayeredCloudMap).

The clouds are projected into the sky. The property SkyCurvature can be used to blend between a paraboloid projection (SkyCurvature = 1) or a planar projection (SkyCurvature = 0). A paraboloid projection makes optimal use of the texture resolution. Therefore, high values like 0.9, should be used for SkyCurvature. If a true paraboloid projection is used (SkyCurvature = 1), then the texture fills the whole sky without any tiling. If the SkyCurvature is less than 1, then the texture does not cover the whole sky and tiling (texture wrapping) is used to fill the sky. If the cloud texture is not a seamlessly tiling texture, then TextureMatrix must be used to change the scale of the texture and hide the seams.

The clouds are lit by SunLight and AmbientLight. A forward scattering effect is visible in the SunDirection. ForwardScatterExponent, ForwardScatterScale and ForwardScatterOffset define the range and strength of this effect. The clouds are also lit in other directions and NumberOfSamples/ SampleDistance define the quality of the lighting effect.

Clouds can be faded out to disappear near the horizon. HorizonFade defines the height where clouds start to fade out.

Cloning: When a CloudLayerNode is cloned the CloudMap is copied by reference (shallow copy). The original and the cloned node will reference the same CloudMap instance.

Reference