Particle size by speed not working

I need help with particles. I am just starting out with particles and i put a size by speed module for sparks to get longer in the direction they travel. But the size by speed doesnt work. If i put a number into Y, the particles dont change size in any direction and if i put a number into X, they change size in both axes making it basically a uniform scale. I watched the unreal tutorials on sparks and put numbers into both max scale and speed scale in the Y. Also, when I tested to see if it would work with gpu sprites, the particles did scale up in the y but they did not angle the direction they were traveling. so the sparks were just vertical lines staying vertical for their whole life. Please help.


I don’t know if you need to plug something in or w/e like change it’s alignment to velocity or something. There are not much info in particle documentation beyond basics.

By copying the docs:

Scales the size of a particle by a portion of its speed. It contains the following member(s):

Property Description
Size [is currently empty in docs]
Speed Scale This is used to set the scale amount in the X and Y axes for the sprite.
Max Scale Provides a maximum scale size, functioning like a clamp.

During both Spawn and Update, the Particle.Size value is multiplied by the retrieved scale value times the velocity of the particle at that time.

I think the fix to your issue is in the required tab to set align to velocity or something. Have a look see if it works.

That worked. Thank you! I have another question. in the explosion that comes in the starter pack it only fires one time. How do i set my particle system to only go off once?

In the required module set it’s duration to 0. That will stop it from looping.

ok thanks. In theirs though, it still loops inside the particle system. mine doesnt though.

dont set the “duration” to zero but the “emitter loops” to 1.