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ashishdantu
02-21-2005, 05:52 PM
Hi people,

I would like to share the chat i had with Peter regarding AfterBurn. I thought it might help understand this tool..

========================================
Hi Peter,

well, i've been trying to work with afterburn for quite sometime now and have been recomending it to few
others at CGTALK..

Would appreciate if you can go through the following links, when you are free and help us with
implemetation queries regarding getting the shading right after we have tweaked our particle dynamics...
Links:
http://cgtalk.com/showthread.php?t=197430 (http://showthread.php?t=197430)
http://cgtalk.com/showthread.php?t=211064 (http://showthread.php?t=211064)
http://cgtalk.com/showthread.php?t=210420 (http://showthread.php?t=210420)
http://cgtalk.com/showthread.php?t=209509 (http://showthread.php?t=209509)

Would request for a tutorial where implementation of afterburn examples can be used / customized for a real
world project. I have some doubts in the case of how to use Afterburn and make missile trails, Vehicle
Blasts and Smoke from Volcano erruption.

Thanx for the AfterBurn 1.1 update . One last doubt.. Say i have my particle
setupin the scene. So can we select that particle and somehow use ur preset , say "smoke" or "tendril" -
shader applied to it ?

regards,
ashish

====================================

Hi,


I went through the posts and i can understand you guys -the particle/fluid setup is really tricky.
There is no strightforward way to do it, everything depends on per shot/camera/distance/light basis.

The only thing i can say is that you must spend good time to understand how the things are interacting togather, after that
you will know what to expect by every manipulation over the PP controled fluid attributes. All this sounds too obvious, but
i learned bunch of guys in my previous studio how to do it and i understand that only the time playing with the stuff matterss.
I also noticed that most of the guys just dont need so mutch control they just blow away many of the PP attributes, ramps, arrayMappers,
etc.and focus only over the important ones needed for the shot.

The basic idea is to have a ramp which returns values bethween 0 and 1, then with arrayMapper i can remap these 0 to one values to -123934853
to +3459834589 or whatever i want values. To do that easily i have min max attributes added to the particleShape, they are connecteed to
arrayMapper's min/max value.

In this way we have parametrized random values - no more crazy rand() / sphrand () stuff. Then this arrayMapper returns these
remaped values to my PP attribute, this PP attribute is connected to particleSamplerInfo node
connected to some fluidShape attribute. In this way i'm passing PP data bethween
particles and fluids ( or whatever other i want ).

The easyiest way to create nice looking fluid paritcles is to create a new fluidContainer
and to start tweaking it, after you are quite lucky with the result save a preset, then load
this preset in your fluid container which is coloring your particles.

Of course many attributes of this container are connected to particleSmaplerInfo node and the
first and second fluids are looking too different. Now you are ready to start tweaking your PP
attributes ( to control your fluid ). For every fluid ttribute connected to PP attribute you
must compare the values of the first ( already nice looking fluid ) and to adjust the related
PP atributes ( here i'm talking for the ramp color values and the min max attributes added to the
particle shape ).

I'm sure very fast you will understand how the things are going. About your idea to apply fluids to already existing particleShapes - i
like it. One of the problems i can see is that most of these particleShapes in most cases will have already PP attributes like
radiusPP, lifespanPP, whatewerPP and i must implement good logic what is going on, otherwise i will overwrite them and this will damage
already coocked stuff. From my point of view is better to add to your scene
some of the presets and then using dynamicRelationShip editor to connect the
new particleShapes to the needed fields/emiters/collisions etc, the rest is
some tweaking.

About 1.1 - in fact i have couple of more things to add, but for now i just have not
time to do it.

Thanks

Peter

===================================================================
Hey , this is my 100th post !! UUmmm.. good to be here.

ashishdantu
02-21-2005, 06:02 PM
Hello Peter Shipkov,

coming to the idea of assigning the preset on chosen particleShapes, ya, i guess you are correct that we will have to check for existing PP connections. I guess we can add some kind of "PP attributes found. DO u want to replace them 100 % or give them an option of
blending as to how much they want "..

Some thing like what happens in this tool found it on highend >FluidsTools.mel v0.1:: [ By Alex Ongaro ] -
Link:
http://www.highend3d.com/files/dl.3d?group=melscripts&file_loc=FluidsTools-v0.1-.mel&file_id=2553

in which he has given provision for selecting source container and target and we can fetch and assign color
/ incand / opacity / environment ramps values. he uses "gAEAttrPresetBlend;"..

Last thing, can i copy and paste ur email in cgtalk so i can share it with others ?

-regards,
>ashish

=======================================
hi again

i checked the possibilities to add the fluid stuff to already existing particleShapes and i think it is a pain.
If the particleShapes have some PP attributes with attached to them dynamicExpressions, ramps, arrayMappers, whatewer other, then the tings
are going tricky. I dont know a stable way how to merge the existing expressions with these created by AfterBurn - i have few things in mind
but in most cases they will damage more than help. Why that i decided to keep the things as they are - we prefere something stable instead of
half backed solutions. In fact i never had serious problem to delete my existing particleShape and to attach the "fluidParticles" to emitters,
collisions, fields. But the best way is always stable pipeline +
thinking before acting :)

One of the guys asked how to create a tornado effect - i would say that the dynamic part can be easily represented in Maya, but Maya's shading
possibilities are not enough to cover the needed result - we can use some sprites + shading nodes ( stroika plug-ins are very helpfull for
that ), but to create big scale volumetrics we need something like Houdini's i3d stuff - pointClouds. I dont think afterburn will be very
helpfull for this kind of FX.

Also i checked out the fluidTools - very interesting, but i cant apply them over expressions, i can create new PPattributes and to merge the
outputs bethween them, but i need to put big efforts to make this working stable. And of course you can share everything we are talking about with the
rest of the gang.

Thanks

Peter

thematt
02-21-2005, 08:48 PM
thanks for that very of peter giving eplanation.and very kind of you leting us now.
Great tool by the way.

cheers

ftaswin
02-22-2005, 10:28 PM
Thanks hips Peter,

Afterburn has been my fav toy this past 2 weeks

HowardM
01-01-2006, 09:28 PM
Thanks Peter! Great stuff!
:D

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