Component:LUT Material: Difference between revisions

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Added further detail to LUT construction and usage. Still need to add examples and images.
m ProbablePrime moved page LUT Material (Component) to Component:LUT Material: Creating component Namespace
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Revision as of 06:30, 20 January 2024


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Component image 
LUT Material component as seen in the Scene Inspector


An LUT or Lookup Table is a way of mapping input values to output values via sampling a 3D Texture. This 3D table of values allows for any arbitrary function to be applied to an input.

Fields

Fields
Name Type Description
persistent Bool Determines whether or not this item will be saved to the server.
UpdateOrder Int Controls the order in which this component is updated.
Enabled Bool Controls whether or not this component is enabled.
HighPriorityIntegration Bool
Rect Rect
RectClip Bool
ColorMask ColorMask The color channels to affect
StencilComparison StencilComparison
StencilOperation StencilOperation
StencilID Byte
StencilWriteMask Byte
StencilReadMask Byte
RenderQueue Int
_shader IAssetProvider<Shader>
LUT IAssetProvider<Texture3D> The 3D texture to use as a lookup table
SecondaryLUT IAssetProvider<Texture3D> A secondary 3D texture to use to lerp between
Lerp Float Allows blending from the first LUT (0) or the secondary LUT (1)
BlendMode BlendMode
Sidedness Sidedness
ZWrite ZWrite
ZTest ZTest

Usage

An LUT is commonly constructed via 2D slices of a 3D Texture. These slices represent XY planes of incremental Z coordinates ranging from 0 to 1. This can either be packed into a single 2D image, or imported as multiple 2D images in a folder where each slice is alphabetically organized.

Currently the maximum packed 2D image that the importer detects as a valid LUT is 1024x32. In this orientation there are 32 total cells arranged as 32x32 pixel sub images. A 1:1 mapping LUT which simply maps its inputs directly to the same value on its outputs is shown below which demonstrates the coordinate system:

Linear LUT
Linear LUT
  • The Red channel increases constantly from 0 to 1 from left to right within each cell and repeats.
Linear LUT Red Channel
Linear LUT Red channel
  • The Green channel linearly increases from the top to bottom.
Linear LUT Green Channel
Linear LUT Green channel
  • The Blue channel increases step wise within each cell itself, the first cell being all 0, and the last cell is all 1.
Linear LUT Blue Channel
Linear LUT Blue channel


The mapping function of an LUT takes an input RGB value and then samples the 3D Texture at that corresponding coordinate to find the output RGB value, using the 3D Texture's Filter Mode and Wrap Mode to resolve how intermediate values work.


Examples

Related Components