[Bf-funboard] Particles

[Martin Poirier]

> >> There's also the important topic of memory
> >> consumption, and having a
> >> system that can be evaluation at any timeframe
> (as
> >> opposed to needing
> >> to do it in forward timesteps). The choice for
> >> keypositions in Blender
> >> particles is based on that.
> >
> > I think the best way to do that while still using
> > little memory would be the variable time interval
> > keyframe thing that I was explaining earlier.
> 
> I don't find that info at our mailing list, if you
> mean at the forums,  
> can you provide a link to that?

Oh, I thought I had explained this earlier. Anyway,
the concept is simple: instead of keyframing at a
fixed interval, you only keyframe when it is necessary
to do it (basicly, it would work on the same kind of
algorithm that removes superfluous CVs from NURBS
curves).

Those keyframe would contain this kind of data:
- Time
- Position
- From and Away vector (their length are not fixed,
they help in the interpolation both of the position
and of the time, just like bezier handles).



Advantages: 
- saves memory
- faster load/save of big particles system
- the ability to define keyframe at non-whole time
(fram 10.5 for example) when extraordinary event
(collisions) happens that disturb the smooth motion of
the particle.
- Contrary to fixed keyframes, the motion between two
keyframes is always a curve, you don't have to mix
data between keyframes to create smooth motion in
between keyframes.

Disadvantge
- Slower to recalculate (could be optimized probably)
- a little slower to calculate the motion of the
particles. Since the keyframes are not fixed, you have
to iterate through the list until you find those you
need to use.

that's about it, I spared you that math part, since
it's mostly in my head and not written already.

Martin

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