Hi @AliceHalley
Let’s see…
Track Particle Position:
Keep both the current and last positions within a Vector parameter.
Update Positions:
Each frame, set the last position equal to the current position, then set the current position according to where the particle lies along the spline.
Calculate Velocity:
Decrease the last position from the current position and divide by the delta time to get velocity:
Velocity =
Current Position−Previous Position
_____________________________________
Δt
Use in Niagara:
Implement this reasoning in Niagara with User Parameters for storing positions and calculating velocity per frame.