pTangentForce

pTangentForce accepts an existing particle stream and changes its motion. It does not create particles, draw an image or replace pEmitter/pRender; the minimal diagnostic graph is pEmitter → pTangentForce → pRender.

The documented behavior is more specific than a generic sideways push: the force is applied perpendicular to the vector between the Tangent Force center and the affected particle. With suitable incoming motion, trajectories bend around the center and can produce orbit-like motion.

X/Y/Z Offset are the coordinates of the Tangent Force center in 3D. They are not a transform of the rendered image and are not the center of the selected Region. Moving Offset relocates the reference point used to calculate the tangential direction.

X/Y/Z Strength independently control tangential-force contribution along each axis. This is not one scalar Strength control: leave two axes at zero to prove the contribution of a single component before combining them.

The captured Resolve baseline shows X Strength 0, Y Strength 0 and Z Strength 0.1. That is useful as an interface reference, not a universal artistic preset; the useful magnitude depends on emitter speed, scene scale, duration and other forces.

The force accumulates changes in particle velocity over time, so judge it across a frame range. A still frame cannot show curvature, velocity accumulation or particles crossing different age/spatial gates.

Random Seed and Reseed provide reproducible randomness where the common particle logic uses it. Keep the seed fixed while comparing Strength or Offset so a different random pattern does not hide the causal change.

Time Lock belongs to common random/time behavior and is not a simulation freeze. It does not replace pRender Pre-Roll, Restart or Sub-Frame Calculation Accuracy.

Conditions Probability is evaluated for each eligible particle on every frame. A value such as 0.6 does not create one permanent 60-percent subset for the whole lifespan; the same particle gets another chance on the next frame.

Age Start/End is a normalized 0–1 portion of particle lifespan, not timeline frame numbers. It can keep launch motion unchanged and enable tangential steering only later in life.

Set Mode and Set 1–32 filter particle Sets that were assigned upstream. pTangentForce does not assign Sets; generators and set-changing particle tools such as pEmitter, pImageEmitter, pChangeStyle and pSpawn do that earlier in the stream.

Region is a separate spatial gate. It defines where pTangentForce is allowed to act but does not define the Tangent Force center. The field Offset and Region geometry can intentionally be placed at different locations.

Region Mode supports Ignore region, intersecting, inside, not intersecting, not inside, entering and leaving relationships. Keep Ignore region for the first baseline so spatial gating cannot hide the force itself.

All, Bezier, Cube, Line, Rectangle and Sphere are built-in Regions and require no extra cable. Bitmap and Mesh are the exceptions: choosing either creates a dynamic Region input.

Bitmap Region uses a 2D image/channel as a spatial gate. It is not an Effect Mask for the rendered RGBA result and it is not the primary Particles input. Verify the actual channel/alpha separately from particle motion.

Mesh Region accepts 3D mesh geometry and can use surface/volume interpretation, winding controls and ObjectID filtering. It is a geometry gate; it does not turn pTangentForce into a renderer or change the particle output type.

For complex motion, prove pTangentForce by itself first, then add pDirectionalForce, pTurbulence, pFriction, pAvoid or pVortex one node at a time. Otherwise similar trajectory changes are difficult to attribute to one force.

pTangentForce is especially useful for controlled sideways/orbit-like bending around a 3D center without the radial attraction/repulsion of pPointForce. It is not a collision solver; use particle collision tools for actual contact behavior and treat tangent force as a steering field.

The output remains Particles. pRender later converts the stream to a visible 2D image or a 3D particle output; ordinary image-processing nodes do not belong in the particle chain before that boundary.