Get Final Opacity

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Get Final Opacity[edit]

Get Final Opacity

Provides the "Final Opacity" of the current Render State. The Render State is affected by any shaders which were called before this function is called, among other things.

Final Opacity is the fractional amount by which a surface visually occludes the light from another surface, background. It also affects how much light passes through an object when calculating shadows (if they are enabled). Opacity = 1 - Transparency. Note that Final Opacity may be different from Final Alpha to allow special effects when compositing the rendered image over another background.

In Terragen, alphas and opacities have 3 channels to represent potentially different opacities in the Red, Green and Blue channels of an image. This is necessary to correctly composite media with wavelength-dependent scattering or absorption, such as planetary atmospheres and coloured glass.

Although Final Alpha is defined to include atmosphere contributions if they have been applied, in practice Get Final Alpha will always provide the alpha of the surface prior to atmosphere due to the places where you can use it. Future changes to the renderer may expose contexts where functions can be used after atmosphere.

The Input connection is not used by this node.

A single object or device in the node network which generates or modifies data and may accept input data or create output data or both, depending on its function. Nodes usually have their own settings which control the data they create or how they modify data passing through them. Nodes are connected together in a network to perform work in a network-based user interface. In Terragen 2 nodes are connected together to describe a scene.