Volume Sample Float


The Volume Sample Float shader will sample a volume channel of the new volume API. It should be plugged into one of the components of the standard_volume shader if you need to further edit the result of the reading of a channel, for instance to color correct it, etc.

For more information on volume workflows refer to the Volume page.

Both the 'Volume Sample Float' and 'Volume Sample RGB' shaders share the same Sampling controls, the only difference being the type of the output, RGB or float. 

These parameters are not texturable due to performance reasons.

 

Volume Sample Float Attributes

Channel
When not empty, this channel will be used to sample the scattering values for the volume instead of the Scattering parameter.

Position Offset

An object space offset to apply to the volume sampling position when using named channels to fetch the volume data. This is useful to displace the volume data.

You will need to connect a noise texture to the position offset to see any result.

Interpolation

The voxel interpolation to use when sampling the volume data using named channels.

Volume Type

Interpret the volume data as fog (density) or SDF (signed distance function). In SDF mode, the inside is converted to a constant density of 1.

Signed Distance Function

Offset

Offset the SDF values by this distance, allowing to dilate or erode the SDF boundary shape.


Blend

The distance over which to smooth out the edges of the SDF. 


Invert

By default, positive distances represent space outside of the boundary while negative distances mean inside. This parameter lets you invert this convention.

 

Remap Attributes

These are useful parameters to remap the float sampled values to an arbitrary range. The operations are applied in the same order as the parameters. 

Input Min / Max

The range of input values that will be mapped internally to [0, 1]. The internal values are not clamped.

Input Min

Input Max

Contrast

Scale values around the Contrast Pivot.

Contrast Pivot

The origin of the contrast scaling.

(Contrast 1.5)

Bias

Push or pull values by altering the slope at the beginning of the range. Bias values below 0.5 decrease the slope and lower values overall.  Above 0.5, the slope is higher, and the value grow's more quickly. A value of 0.5 has no effect.

Gain

Increase or decrease the slope of the mid range values. Gain values below 0.5 increase the contrast whereas values above 0.5 flatten the mid range values. A value of 0.5 has no effect.

Output Min / Max

The range to remap the internal values to on output. No clamping is done by default, see Clamp Min / Max.

Output Min

Output Max

Clamp Min / Max

When enabled, the output values will be clamped at Output Min and/or Output Max.

 

 

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