Infection Falloff

Summary

The Infection Falloff operator creates dynamic, simulation-based falloff patterns by propagating values across geometry using infection-style spreading algorithms. Starting from seed points or regions, the infection spreads to neighboring points based on proximity or connectivity, creating organic growth patterns.

This operator supports both radius-based and connectivity-based infection methods, with control over infection rate, dissipation, resistance, and reinfection behavior. Distance-weighted spreading creates natural falloff gradients, while the simulation can be played, stepped, or controlled manually for precise timing.

Seed selection can be defined through spatial fields (sphere, box), specific POP inputs, or existing attributes, with optional transition ranges for smooth seed boundaries. The result can be combined with existing falloff attributes, previewed with color ramps, and optionally enhanced with procedural noise.

Parameters

Page: Infection

Group Group – If there are input groups, specifying a group name in this field will cause this POPX to act only upon the group specified.
Infect By Infectby – – Method used to determine how infection spreads between points.
Radius radius
Connectivity connectivity
Distribution Distribution – – Distribution method for radius-based infection.
Default default
Unique unique
Closest closest
Search Radius Searchradius – Maximum distance for finding neighboring points to infect (radius mode only).
Max Connections Maxconnections – Maximum number of connections each point can have for infection spreading.
Infection Rate Infectionrate – Speed at which infection values spread from infected to uninfected points.
Distance Weighted Spread Distanceweightedspread – Enable distance-based falloff for infection spreading, creating smoother gradients.
Weight Amount Weightamount – Strength of distance-based weighting (when Distance Weighted Spread is enabled).
Dissipation Rate Dissipationrate – Rate at which infection values decrease over time, creating decay effects.
Enable Reinfection Enablereinfection – Allow previously infected points to be reinfected after dissipation (requires Dissipation Rate > 0).
Threshold Threshold – Minimum infection value required before a point can be reinfected (requires reinfection enabled).
Resistance Resistance – Resistance to infection spreading, slowing down the infection process.
Initialize Initializepulse – Reset the infection simulation to initial state.
Start Startpulse – Start the infection simulation from current state.
Play Play – Continuously run the infection simulation.
Step Steppulse – Advance the infection simulation by one step.

Page: Seed

Display Seed Selection Displayseedselection – Visualize the seed selection region for infection starting points.
Enable Dynamic Seed Enabledynamicseed – Allow seed points to change dynamically during simulation.
Threshold Seedthreshold – Minimum value required for seed selection.
Specification POP Specpop – Specify a POP network to use as seed points for infection.
Center Center – Center position of the seed selection region.
Radius Rad – Size of the seed selection region in each axis.
Transition Range Transitionrange – Distance over which seed values transition from 1 to 0 at the region boundary.
Transition Align Transitionalign – Alignment of the transition zone (inward, centered, or outward).
Transition Type Transitiontype – – Curve type for seed region transition falloff.
Linear linear
Smooth Step smoothstep
Ease In Ease Out easeinout
Use Seed Attribute Useseedattribute – Use an existing point attribute to define seed values instead of spatial selection.
Seed Attribute Seedattribute – Name of the attribute to use for seed values (when Use Seed Attribute is enabled).
Output Seed Attribute Outputseedattribute – Write the seed selection values to an output attribute.

Page: Falloff

Combine Operation Combineop – – Mathematical operation for combining infection falloff with existing falloff attributes.
Add add
Substract sub
Multiply mult
Divide div
Screen screen
Overlay overlay
Maximum max
Minimum min
Set set
Combine Falloff Attribute Combineattributescope – Name of the falloff attribute to combine with (when Combine Operation is not Set).
Swap Operation Order Swaporder – Reverse the order of operands in the combination operation.
Combine Strength Combinestrength – Blend amount between original and combined falloff values.
Output Falloff Attribute Outputfalloffattribute – Name of the attribute to write the final falloff values to.
Preview Falloff Previewfalloff – When enabled, visualizes falloff values using a color ramp.
Falloff Ramp Fallofframp – – Color ramp preset used for visualizing falloff values when Preview Falloff is enabled.
Heatmap heatmap
Blackbody blackbody
Infrared infrared
Custom custom
Open Custum Ramp Opencustumramp – Opens the custom color ramp editor for defining a custom falloff visualization gradient.
Reset Custom Ramp Resetcustomramp – Resets the custom color ramp to its default state.

Page: Noise

Apply Noise Applynoise – Add procedural noise to the infection falloff values.
Combine Operation Combineopnoise – – How to combine noise with infection falloff values.
Add add
Multiply mult
Type Type – – Noise algorithm type (Perlin, Simplex, etc.).
Perlin 2D (GPU) perlin2d
Perlin 3D (GPU) perlin3d
Perlin 4D (GPU) perlin4d
Simplex 2D (GPU) simplex2d
Simplex 3D (GPU) simplex3d
Simplex 4D (GPU) simplex4d
Seed Seed – Random seed for noise generation.
Period Period – Frequency of the noise pattern.
Harmonics Harmon – Number of octaves for fractal noise detail.
Harmonic Spread Spread – Frequency multiplier between octaves.
Harmonic Gain Gain – Amplitude multiplier for each successive octave.
Amplitude Amp – Overall strength of the noise effect.
Exponent Exp – Power curve applied to noise values.
Offset Offset – Constant value added to noise output.
Transform Order Xordnoise – – Order of scale, rotate, and translate transformations for noise space.
Scale Rotate Translate srt
Scale Translate Rotate str
Rotate Scale Translate rst
Rotate Translate Scale rts
Translate Scale Rotate tsr
Translate Rotate Scale trs
Rotate Order Rordnoise – – Rotation axis order for noise space transformation.
Rx Ry Rz xyz
Rx Rz Ry xzy
Ry Rx Rz yxz
Ry Rz Rx yzx
Rz Rx Ry zxy
Rz Ry Rx zyx
Translate Tnoise – Translation offset for noise sampling coordinates.
Rotate Rnoise – Rotation of noise sampling space in degrees.
Scale Snoise – Scale factor for noise sampling coordinates.
Pivot Pnoise – Pivot point for noise space transformations.
Translate 4D T4dnoise – Translation in the 4th dimension for 4D noise types.

Page: Remap

Clamp Clamp – When enabled, constrains falloff values to the 0-1 range.
Fit Fit – Enables remapping of falloff values from an input range to an output range.
Auto Input Min Max Auto – Automatically determines input range from actual min/max falloff values.
Input Min Inputmin – Minimum value of the input range for remapping.
Input Max Inputmax – Maximum value of the input range for remapping.
Output Min Outputmin – Minimum value of the output range for remapping.
Output Max Outputmax – Maximum value of the output range for remapping.
Invert Invert – Reverses the falloff values (1 - value).
Enable Remap Ramp Enableremapramp – Applies a custom curve to remap falloff values non-linearly.
Open Remap Ramp Remapramp – Opens the ramp editor for defining the custom remapping curve.
Reset Remap Ramp Resetremapramp – Resets the remapping curve to a linear ramp.
Ramp TOP Ramptop – External TOP containing a custom remap curve texture.

Page: Common

Bypass Bypass – Pass through the first input to the output unchanged.
Free Extra GPU Memory Freeextragpumem – Free memory that has accumulated when output memory has grown and shrunk.
Render Primitives Renderprimitives – Toggles rendering of POPX Geometry or shows it as point instances only.
SRT / RST Srtrst – Sets the transform order when using POPX Geometry as built-in TouchDesigner instances.

Inputs

Input 0 – POP – POPX Geometry or regular geometry to apply falloff to
Input 1 (Optional) – Seed POP – Seed points geometry for infection starting points

Outputs

Output 0 – POP – Geometry with falloff attribute applied