Move Along Curve

v1.3.0

Modifiers

Summary

The Move Along Curve attaches instances to a curve and animates them along the path using Line Strip POP. It works in two phases similar to Move Along Mesh: first, attaches instances to the curve based on proximity, distribution, or attributes; second, moves instances along the path either procedurally or through a solver.

There are several presets available to set up your instances to move as a group or to distribute themselves evenly along the path. The operator includes options for wrapping from the end of the path to the start, enabling easy looping motion.

The Attach step allows you to attach instances based on their proximity to the curve or based on an even distribution. You can even attach to multiple curves per-instance via a point attribute. The Offset controls determine how much of the original distance between each instance's starting position and the attachment position is maintained.

The Animation step allows procedurally moving instances along the curve based on the Goal parameter, or pushing the instances per timestep in a solver.

Parameters

GroupGroup

If there are input groups, specifying a group name in this field will cause this POPX to act only upon the group specified.

Curve to Attach ToCurve

Reference to a POP for the curve to attach instances to when no second input is connected.

Display CurveDisplaycurve

Visualizes the curve in the viewport.

Display ColorDisplaycolor

Color for curve visualization when Display Curve is enabled.

Display ColorDisplaycolorrDisplay ColorDisplaycolorgDisplay ColorDisplaycolorb

ModeMode

Switches between Simple mode (procedural animation) and Solver mode (per-timestep solver).

SimplesimpleSolversolver

InitializeInitializepulse

Resets the simulation state to initial conditions.

StartStartpulse

Begins the simulation from the current state.

PlayPlay

Toggles simulation playback on or off when in Solver mode.

StepSteppulse

Advances the simulation by one frame when in Solver mode.

Lock to CurveLocktocurve

Locks the initial attachment positions so they don't need to be recalculated every frame, improving performance.

Reattach to CurveReattachtocurve

Recomputes attachment points for all instances.

Curve Select ModeCurveselectmode

Determines how to select which curve primitive to attach to.

Primitive IndexprimUse NearestnearestDistributedist

Primitive IndexPrimindex

Specifies which primitive index to attach to when Curve Select Mode is set to Primitive Index.

Attach MethodAttachmethod

Determines how instances are attached to the selected curve: Nearest Point, Distribute evenly, or use an Attribute.

Nearest PointnearestDistributedistAttributeattr

Search DistanceSearchdistance

Maximum distance for finding nearest attachment points when using Nearest Point attach method.

Attach AttributeAttachattr

Specifies which attribute to use for determining attachment positions when Attach Method is set to Attribute.

Snap Centroid to Curve StartSnaptocentroid

Moves the centroid of all instances to the start of the curve before attaching.

Do Orient SnapDoorientsnap

Applies orientation alignment when snapping centroid to curve start.

Normal AxisNormalaxis

Defines the normal axis for orientation snapping.

Normal AxisNormalaxisxNormal AxisNormalaxisyNormal AxisNormalaxisz

Up AxisUpaxis

Defines the up axis for orientation snapping.

Up AxisUpaxisxUp AxisUpaxisyUp AxisUpaxisz

Maintain OffsetMaintainoffset

Blend amount for maintaining the original offset distance from the curve.

Open Offset Ramp EditorOpenoffsetrampeditor

Opens the internal offset ramp editor for customizing offset behavior along the curve.

Reset Offset RampResetoffsetramp

Resets the offset ramp to default values.

Custom Offset TOPCustomoffsettop

Reference to an external TOP for offset control. When specified, overrides the internal ramp editor.

Maintain Orient OffsetMaintainorientoffset

Blend amount between the original orientation and the curve orientation.

Open Orient Offset Ramp EditorOpenorientoffsetrampeditor

Opens the internal orientation offset ramp editor.

Reset Orient Offset RampResetorientoffsetramp

Resets the orientation offset ramp to default values.

Custom Orient TOPCustomorienttop

Reference to an external TOP for orientation offset. When specified, overrides the internal ramp editor.

Visualize OffsetVisualizeoffset

Displays lines showing the offset between instances and their attachment points.

Fetch Offsets LinesFetchoffsetslines

Creates a select POP with the selected offsets lines of the instances for visualization.

Reorient Input CurveReorientinputcurve

Enables reorientation of the input curve for better tangent and normal calculation.

Invert TangentInverttangent

Reverses the tangent direction of the curve by 180 degrees.

Custom First TangentCustomfirsttangent

Enables specification of a custom tangent vector at the start of the curve.

First TangentFirsttangent

Custom tangent vector for the first point of the curve.

First TangentFirsttangentxFirst TangentFirsttangentyFirst TangentFirsttangentz

Twist Curve AmountTwistcurveamount

Amount of twist to apply to the curve orientation in degrees.

Open Twist Curve Ramp EditorOpentwistcurverampeditor

Opens the internal twist ramp editor for modulating twist along the curve.

Reset Twist Curve RampResettwistcurveramp

Resets the twist ramp to default values.

Custom Twist Curve TOPCustomtwistcurvetop

Reference to an external TOP for twist control. When specified, overrides the internal ramp editor.

Twist by AttributeTwistbyattribute

Enables twist control via a point attribute instead of the ramp or TOP.

Twist AttributeTwistattr

Name of the point attribute to use for twist values when Twist by Attribute is enabled.

Resample MethodResamplemethod

Line strip resample method.

NonenoneDivisions per Line StriplinestripDistance between Pointsdist

DivisionsResampledivs

The number of divisions.

Max DistanceResamplemaxdist

Maximum distance between points.

Maximum Number of VerticesMaxverts

Sets the number of vertices to be allocated.

Max Tries for Binary SearchMaxtries

Max number of iterations for binary search when linearly resampling.

Do FalloffDofalloff

Enables falloff-based modulation of animation effects.

Falloff Affects SpeedAffectspeed

Allows falloff values to modulate instance movement speed.

Falloff Affects RotationAffectrot

Allows falloff values to modulate instance rotation alignment.

Falloff AttributeFalloffattr

Specifies which attribute to use for falloff values that modulate animation intensity.

Goal TypeGoaltype

Determines how goal position is calculated: Goal U (parametric) or Arc Length (distance-based).

Goal UgoaluArc Lengtharclen

GoalGoal

Target position along the curve for procedural animation in Simple mode. 0 is the start, 1 is the end of the curve.

SpeedSpeed

Global speed multiplier for instance movement along the curve in Solver mode.

Random SpeedRandomspeed

Amount of random variation applied to each instance's speed.

SeedSeedspeed

Random seed value for speed randomization.

ReverseReverse

Reverses the direction of movement along the curve.

Align to CurveAligntocurve

Aligns instance orientation to follow the curve tangent direction.

WrapWrap

Enables wrapping from the end of the curve back to the start for continuous looping motion.

Output Goal AttributesOutputgoalattrs

Outputs GoalU and CurveIndex attributes.

Twist AmountTwistamount

Additional twist rotation applied during animation in degrees.

Open Twist Ramp EditorOpentwistrampeditor

Opens the internal twist ramp editor for animation twist modulation.

Reset Twist RampResettwistramp

Resets the animation twist ramp to default values.

Custom Twist TOPCustomtwisttop

Reference to an external TOP for animation twist control. When specified, overrides the internal ramp editor.

Scale by GoalScalebygoal

Enables scale modulation based on goal position along the curve.

Remap ScaleRemapscale

Remaps the output scale values from the ramp to this range.

Remap ScaleRemapscalexRemap ScaleRemapscaley

Open Scale Ramp EditorOpenscalerampeditor

Opens the internal scale ramp editor for creating custom scale curves based on goal position.

Reset Scale RampResetscaleramp

Resets the scale ramp to default values.

Custom Scale TOPCustomscaletop

Reference to an external TOP for scale control. When specified, overrides the internal ramp editor.

Accelerate by GoalAcceleratebygoal

Enables acceleration modulation based on goal position along the curve.

Open Acceleration Ramp EditorOpenaccrampeditor

Opens the internal acceleration ramp editor for modulating speed along the curve.

Reset Acceleration RampResetaccramp

Resets the acceleration ramp to default values.

Custom Acceleration TOPCustomacctop

Reference to an external TOP for acceleration control. When specified, overrides the internal ramp editor.

BypassBypass

Pass through the first input to the output unchanged.

Free Extra GPU MemoryFreeextragpumem

Free memory that has accumulated when output memory has grown and shrunk.

Render PrimitivesRenderprimitives

Toggles rendering of POPX Geometry or shows it as point instances only.

Convert to Point PrimitivesConverttoptprim

Converts points to primitive points when Render Primitives is toggled off.

SRT / RSTSrtrst

Sets the transform order when using POPX Geometry as built-in TouchDesigner instances.

Inputs

Input 0POP

POPX/POP Geometry

Input 1POP

Curve to Attach To

Outputs

Output 0POP

POPX_out1