ID:2652407
 
Resolved
Particle effects didn't cause the map to redraw if no other icon animations or changes were in use.
BYOND Version:514.1543
Operating System:Windows 10 Pro 64-bit
Web Browser:Chrome 84.0.4147.89
Applies to:Dream Seeker
Status: Resolved (514.1544)

This issue has been resolved.
Descriptive Problem Summary:
When attached to a mob the particles on the clients screen only move when the mob it is attached to moves.

Numbered Steps to Reproduce Problem:
Press CreateSnow() the snow only falls when the mob moves.

Code Snippet (if applicable) to Reproduce Problem:
particles/snow
width = 500 // 500 x 500 image to cover a moderately sized map
height = 500
count = 2500 // 2500 particles
spawning = 10 // 3 new particles per client tick
bound1 = list(-1000, -300, -1000) // end particles at Y=-300
lifespan = 600 // last 600 client ticks max
fade = 50 // fade out over the last 50 ticks if still on screen
// spawn within a certain x,y,z space
// control how the snow falls
gravity = list(0, -3.2)
friction = 0.2 // shed 20% of velocity and drift every client tick
obj/snow
screen_loc = "CENTER"
New()
..()
particles = new/particles/snow
particles.position = generator("box", list(-300,250,0), list(300,300,100))
particles.drift = generator("sphere", 0, 2)

mob
verb/CreateSnow()
client?.screen += new/obj/snow


Expected Results:
The particles move once they are attached to the mob.

Actual Results:
The particles only move when the mob moves, when the mob stops the particles stop and resume when the mob moves again.

Does the problem occur:
Every time? Or how often? Every time
In other games? N/A
In other user accounts? N/A
On other computers? N/A

When does the problem NOT occur? Always occurs

Did the problem NOT occur in any earlier versions? If so, what was the last version that worked? N/A

Workarounds:

to clarify: 'when mob moves' means 'when a client render thread is triggered by the mob moving or an icon state animating'
I need a test case for this. My own test project does not show this problem even though I think I have an idea what's causing it. I need a way to reproduce it.
Your ref example code, as said in the OP, reproduces it.

Here's a .zip of it in a world (fixed for issues):
https://www.dropbox.com/s/1n2anmleddu8rza/ TestEnvironment.zip?dl=1
Lummox JR resolved issue with message:
Particle effects didn't cause the map to redraw if no other icon animations or changes were in use.