Cascade spawn rate - distribution float constant curve not working as expected

Created a new particle system, clicked the Spawn module in the default Emitter. Then in the Details panel, under Spawn…Rate…Distribution selected ‘Distribution Float Constant Curve’. Then I clicked the little graph icon on the Spawn module and set a couple of points in the Curve Editor. For this example, first point is at time 0 with value 1 and second point is at time 2 with value 5.

With the curve described above, I would expect 1 particle/second at start and then after 2 seconds it should increase to 5/second. Instead, it seems to be taking approximately the average of the two values and producing about 3 per second the entire time.

The Lifetime module seems to have the same sort of behavior.

Am I doing something wrong? How else would one change the spawn rate over time?

Thanks,
Pagan

Still would love to get this working the way it seems like it ought to, but did a workaround in C++…

For anyone else wanting to do that, use a ‘Distribution Float Particle Parameter’ and change its value in code. De-select ‘Can be Baked’ or else it just uses the value in ‘Constant’.

i am experiencing this same issue. It seems to act this way for anything where the curve relies on the emitters lifetime being longer than 1. Anything from 0-1 works as expected but anything set to change over the course of more than 1 second just doesn’t happen. I most recently had this issue with velocity cone’s velocity property. I wanted it to slow from 500 to 0 over the course of 4 seconds to simulate loss of pressure. Instead it slows a little, then stays constant until dropping off at the end.

For me it works fine when I use “Rate” AND “Rate Scale”.

Rate: 1 Particle
Rate Scale (Constant Curve):
0s = 10 Particles
8s = 0 Particles