The volume_sample_RGB shader will sample a volume channel of the new volume API. It should be connected to one of the components of the volume_standard shader if you need to further edit the result of the reading of a channel, for instance to color correct it, etc. 

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.

A tutorial that demonstrates this shader can be found here.

 

Sampling

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.

 

Color Correction

Similarly, Volume Sample RGB has a set of parameters to alter the output color regrouped in the Color Correction tab. The operations are applied in the same order as the parameters.

Gamma

Apply a gamma correction to the color.

Hue Shift

Rotate the color hue, a value of 1 means a full rotation.

Saturation

Scale the saturation by this factor.

Contrast

Scale values around the contrast_pivot.

Contrast Pivot

The origin of the contrast scaling. The default is 0.18, the average perceptual mid-gray.

(Contrast 3)

Exposure

Multiply the color using a photo f-stop scale, where an increment of 1 doubles the luminosity.

Multiply

Multiply the color by this factor.

Add

Add this value to the color.

 

 

  • No labels