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Parameter

Description

Color (bottom)

This allows for gradient coloring of the global fog. This value will be the bottom color of the fog

Color (bottom) multiplier

This value is multiplied by the bottom fog color and specifies the brightness of the top fog color.

Height (bottom)

Specifies a reference height for the vertical fog gradient (in range [-5000..35000], default is 0).
For the fog color this marks the height at which it will reach the specified color at the top.
For the fog density it marks the height at which the vertical density fall off reaches the specified density.

Density (bottom)

Density at the top (in range [0..1], default is 1). Please note that it is possible to set the top density to a higher value than the bottom density.
This will effectively flip the vertical fall off and produce thick fog in the sky and clear views at the bottom. Also note that both top and bottom density can be equal.
In this case you create a fog effect that is entirely depth based only. It is also important to understand that the volumetric fog computations treat a level as a continuous unbound volume.
That means specifying a density > 0 at your given top height doesn't mean that fog will suddenly stop there but instead continues to gradually fall off.
The same is true for the bottom boundary or density values < 1.

Color (top)

This allows for gradient coloring of the global fog. This value will be the top color of the fog.

Color (top) multiplier

This value is multiplied by the top fog color and specifies the brightness of the top fog color.

Height (top)

Specifies a reference height for the vertical fog gradient (in range [-5000..35000], default is 4000).
For the fog color this marks the height at which it will reach the specified color at the top.
For the fog density it marks the height at which the vertical density fall off reaches the specified density.

Density (top)

Density at the top (in range [0..1], default is 1). Please note that it is possible to set the top density to a higher value than the bottom density.
This will effectively flip the vertical fall off and produce thick fog in the sky and clear views at the bottom.
Also note that both top and bottom density can be equal. In this case you create a fog effect that is entirely depth based only.
It is also important to understand that the volumetric fog computations treat a level as a continuous unbound volume.
That means specifying a density > 0 at your given top height doesn't mean that fog will suddenly stop there but instead continues to gradually fall off.
The same is true for the bottom boundary or density values < 1.

Color height offset

Shifts the color of the vertical fog gradient towards the top or bottom (in range [-1..1], default is 0).

Color (radial) & multiplier

Specifies the color of the fog component responsible for producing halos around the sun and in-scattering of sun light.

Radial size

Specifies the size of the radial fog component (in range [0..1], default is 0.75).

Radial lobe

Specifies how much the radial fog component is affected by distance (in range [0..1], default is 0.5).
Small values will make it affect the horizon only while bigger values will make it appear to over glow the scene.


On the left is a Radial Lobe of 0 (note sharp horizon) and on the right is Radial Lobe of 0.3 (note blurred horizon).


Be aware that too high Radial Lobe value will cause the lobe it to project in front of objects. 1 on left, 0 on right.

Final density clamp

Specifies the maximum fog density that is allowed for final blending with the scene (in range [0..1], default is 1).
This allows the sky, horizon and other bright distant objects to punch through even if the fog is dense.
However, care should be taken to not set this value too low as otherwise depth perception is compromised and will result in implausible visuals and seemingly apparent artifacts especially when moving the camera.

Global density

This value specifies the global density of the volumetric fog. Higher values produce denser fog.

Ramp start

The ramp values can be used to control the fog density in relation to the camera.
This value sets the distance from the camera at which the fog will start to be rendered (at 0 density).

Ramp end

This sets the distance from the camera at which the fog will be rendered at its maximum density, set by the Global Density parameter.

Ramp influence

This value determines how much the ramp values effect the rendering of the fog.

Shadow darkening

Specifies how much the fog color computed per pixel (via the settings above) is generally darkened based on the volumetric shadow value computed by the engine per pixel (in range [0..1], default is 0.25).
The factor is applied after a darkened fog color has been calculated using the sun and ambient darkening factor below.

Shadow darkening sun

Specifies how much the radial fog color is influenced individually (in range [0..1], default is 1).

Shadow darkening ambient

Specifies how much the ambient fog color (i.e. height gradient) is influenced individually (in range [0..1], default is 1).

Shadow range

Specifies how far volumetric shadows get traced (in range [0..1], default is 0.1; that is, up until 10% of the level's far clip plane distance).
Please note that the number of samples per view ray do not increase so smaller values will result in more accurate results but shadows won't cast that far.

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