Spectral Material Nodes
Spectral's material nodes let a graph read probe lighting, adjust bake-only subsurface color, opt out of GTAO, or process scene color separately from fog. They serve different purposes; you do not need to add all of them to a material.
Node reference
| Node | Purpose | Where to use it |
|---|---|---|
| Spectral Sampler | Read RGB probe lighting at the current pixel. | Surface materials that need explicit probe sampling, such as a custom Unlit material. |
| Spectral Subsurface Boost | Adjust subsurface color for baking while preserving its runtime value. | Supported two-sided foliage or subsurface surface materials. |
| GTAO Disable | Stop Spectral GTAO from darkening this material. | A surface material that should opt out of the effect. |
| Spectral Remove Fog | Remove the fog contribution from supplied scene color before custom processing. | A Post Process material at Scene Color Before DOF. |
| Spectral Reapply Fog | Restore fog after processing the underlying scene. | The matching Post Process graph, after Remove Fog and your operation. |
Relevant engine nodes explains LightmassReplace, material parameters, supporting math nodes, and SceneTexture: PostProcessInput0, with examples of how to use them alongside Spectral.
Adding a node
Open a material in the Material Editor, right-click an empty part of the graph, and search for the exact node name. Current nodes are grouped under Spectral. GTAO Disable is its displayed name, without a Spectral prefix.
Select the node to view any properties in Details. A pin is a graph connection; a property is edited on the selected node. Each page identifies both, including nodes with no adjustable properties.
Apply and save the material after editing. A material recompile updates runtime graph behavior, but it does not rebuild saved lighting. The Subsurface Boost node specifically needs a rebake when its bake-side value changes.
Spectral's normal lighting integration does not require a Spectral Sampler node in every material. Start with the ordinary lit path. Adding sampled lighting to a surface that already receives it can count that lighting twice.
Before testing a graph
Enable the required shader hooks, let materials finish compiling, and use a level with the relevant feature enabled. Probe sampling needs valid baked coverage; GTAO exclusion needs GTAO enabled to show a difference; fog composition needs the supported fog integration and correct post-process stage.
Check platform support too. Adding a material node does not bypass a feature's rendering restrictions.