[sldev] The "flashing particles" bug isn't a flashing particles bug...

Nicholaz Beresford nicholaz at blueflash.cc
Thu Jun 14 14:26:22 PDT 2007


Argent/Farallon,

I'm pretty clueless about particles, and I'm glad you figured
that out before I found it through hours of debugging, but here's
my take on it.

I'm not sure, but I'd follow the "code is law" approach (it never
worked, it doesn't work now [just in a different way]), so let's
keep it.

Also, the wiki is pretty clear about it:

  PSYS_SRC_BURST_RADIUS
  Specifies the distance from the emitter where particles will be
  created. This rule is ignored when the PSYS_PART_FOLLOW_SRC_MASK
  flag is set.

Given the Wiki and backward compatibility I'd vote for
killing burst radius when FOLLOW_SRC is there.  (Also I seem to
remember a JIRA were someone said something about previously
mutually exclusive parameters now having changed their behavior,
I just could not find that one again when I was looking for it,
maybe this one was involved).



Btw, while we're at it there's also
https://jira.secondlife.com/browse/VWR-1154


Nick


Second Life from the inside out:
http://nicholaz-beresford.blogspot.com/



Argent Stonecutter wrote:
> OK, I've been working with Farallon on this, and I've figured it out.
> 
> The problem is that if you have "PSYS_PART_FOLLOW_SRC_MASK" then 
> "PSYS_SRC_BURST_RADIUS" is ignored... you can't create a particle system 
> that uses "PSYS_PART_FOLLOW_SRC_MASK" and starts the particle emission 
> at a distance. Why not, I don't know, it's always been an annoyance to 
> me, but I'd just gotten used to it. Farallon had some particle systems 
> he'd modified that had a non-zero radius set, and he hadn't zeroed them 
> out...
> 
> Before 1.15 or so, it acted as if "PSYS_SRC_BURST_RADIUS" was zero.
> 
> Now it seems to create the particles at "PSYS_SRC_BURST_RADIUS" then 
> applies the "PSYS_PART_FOLLOW_SRC_MASK" rule on the following frame.
> 
> The correct "fix" is uncertain.
> 
> It seems to me that "PSYS_PART_FOLLOW_SRC_MASK" shouldn't prevent 
> "PSYS_SRC_BURST_RADIUS" from working, and this should be fixed so that 
> particles can be created at a distance and still follow source. that is, 
> the original behavior is a bug.
> 
> However, that would possibly make some existing particle systems act 
> funny. Now me, I'd go ahead and say "well, you created an undefined 
> particle system, it's legal for Second Life to make demons fly out of 
> your nose" (nasal demons look like red sparks. Who knew?). There's 
> precedent for this, and I've not seen these sparks outside Seal Cove so 
> I suspect there's not that many particle systems out there with the 
> problem. Plus, there's probably some systems out there where people have 
> set this and figured that when the bug got fixed their particle systems 
> would start working right.
> 
> The alternate fix, simply zeroing out "PSYS_SRC_BURST_RADIUS" when 
> "PSYS_PART_FOLLOW_SRC_MASK" is set, seems miserly to me. We should be 
> looking for ways to fix old bugs like this.
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