Photon Shader Node Reference

Node descriptions 2.2.2

Photon nodes bring runtime particle streams, camera data, scene textures, and coordinate conversions into the graph.

Photon nodes bridge the generic graph compiler to particle instances, scene buffers, and full-screen passes.

Particle Graph Inputs

Node	Outputs	Graph/stage behavior
Particle Data	position, color, litColor, light, uv, normal	Particle and function graphs; usable in both stages
Additional Data	selected scalar or vec3 channel	Read in vertex, auto-varying to fragment; unsupported = zero
Custom Data	selected vec4 stream	Read in vertex, auto-varying; preview = zero
Viewport	viewport size and screen information	Screen-dependent calculations
Depth Fade	intersection fade	Fragment; needs scene depth
Dynamic Light	light (vec3)	Fragment only; zero in previews and while dynamic lights are off
World to Screen UV	screen UV from world position	Coordinate conversion
Screen to World	reconstructed world position	Fragment; needs depth/camera matrices

Particle Data.position is camera-relative world position after interpolation. color is the authored/runtime particle color, before lighting. litColor is color × the light map, sampled the way blocks sample it (filtered between levels). Since 2.2.8 light is the light map at the particle, fetched the way vanilla particles fetch it: color × light is exactly a vanilla particle's lighting. Trail UV normally uses the length axis instead of sprite-frame semantics.

On a Particle Emitter, Additional and Custom Data also work without GPU instancing since 2.2.8. Trails, beams and AraTrail need instancing for them; see Additional GPU Data.

Dynamic Light

Since 2.2.8

Dynamic Light (group Photon Scene) returns the light Photon's dynamic lights cast on this fragment, as light (vec3). It takes an optional world-space normal (leave it unconnected for billboards) and a wrap from 0 to 1. It is fragment-only and works in particle and function graphs. For ports, saturation and a typical setup, see Dynamic Light Node.

Additional Data Channels

The node dropdown is generated from PhotonGpuChannels, so it stays aligned with the runtime registry. Selecting a channel also marks that stream as required; Photon uploads it without requiring the inspector toggle. See Additional GPU Data for meanings and emitter support.

Fullscreen Graph Nodes

Node	Purpose
Fullscreen Position	Fullscreen vertex position and UV basis
Fullscreen Output	Final processed color/alpha
Texel Size	1 / renderTargetSize for neighbor samples
Scene Color/Texture input	Current graph input or named Render Graph texture
Scene Depth	Depth-based blur, outline, and reconstruction

Fullscreen-only nodes cannot be placed in a particle Shader Graph. Likewise, Particle Data has no meaning in a Fullscreen Graph.

Screen-Space Accuracy

• UV origin and depth conventions are handled by Photon nodes; avoid hard-coded flips.
• Sample neighboring pixels with Texel Size, not a fixed 1/1920 value.
• Depth is nonlinear unless a node explicitly exposes linearized depth.
• Under Iris, scene/depth availability depends on the active pipeline. Test graceful output when a buffer is absent.

TIP

Select a node and open its description panel before wiring it. Since 2.2.2, Photon nodes describe ports, stage constraints, channel types, and GLSL equivalents inside the editor.