Is It Possible To Bring Particle Scale Attributes To Maya?

[mrsmary]

is it possible to bring particle scale attributes to maya?

with bin format we can take particles to maya, but i can't achive to bring scale,transperancy etc according to life.can one do the sim inside houdini,and integrate it seamlesly forexample with particle cloud shader in maya?, else, shortly can we manipulate the color according to life which has arranged in houdini already?or is there any other method to do this? i mean is there any practical way,or this needs some scripting. if so a little clue would be very apreciated.

[jhiggins]

i'm afraid this would probably require some scripting unless some of the existing exporting tools available via sidefx or 3rdparty developers do this already, although i don't recall anything like this being available.

in order to do this, you would probably have to write your own exporter or something that can convert houdini .geo files into a format maya will accept while still preserving the attributes you want.

you could do this as a script and add support for it in houdini by changing the GEOio file. I don't know if there is a format maya will accept that contains attributes, I don't think obj is extensive, although i'm not particularly sure either.

[mrsmary]

jeffrey thank you. well then what is the basic steps(although i know that this is a huge topic,that can not be told with couple of sentences) to do that kind of stuff. i mean which way is to go. which wiki or something like that should one follow. any book or source can anybody advice to read to get the basics of it. i mean for example in search of lerning renderman there are some junior stuff examples just to get the the idea. long story short i need a starting point.

do i have to learn hscript or phyton,or what else? or trying to do what you want to do only in houdini is much feasible,logical etc.

[jhiggins]

well, you can approach this many different ways,

it seems all your interested in is getting particles from houdini into maya with all the writing attribute data on it that want.

so i would start by writing out a .geo file from houdini of what you want and look at what format would be good to get what need in maya. I think either the bin (which i believe is realflow type as well its binary ) or maya's PDC might be good candidates, but you would need to investigate which is better. ASCII format is ideal as its easier to debug your script!

.geo files are ascii (unlike their .bgeo counterparts), so you can open it up in an editor and see whats its structure is like, and you'de need to know the structure of your maya friendly file format as well and then its matter of writing a script that can read in the data from the .geo and output it in your target maya format.

you can do this many different languages, but i would recommend python as its support in 3d makes it ideal.

this is just my take, i'm hoping if theirs a better way someone will jump onto the forum passing their thoughts!

once you have that going then take a look at houdini's GEOio so that you instead of writing out the geo, then running your script, houdini will do that for you!!

the .gz line in the file is pretty easy to learn from how it works.

hope this helps!! good luck!!

[mrsmary]

jeffrey thank you. some of the tips you've mentioned sounds good.i'll take my chances.

[edward]

else, shortly can we manipulate the color according to life which has arranged in houdini already?or is there any other method to do this? i mean is there any practical way,or this needs some scripting. if so a little clue would be very apreciated.

Color POP using an expression involving fit() and $AGE?

[mrsmary]

Color POP using an expression involving fit() and $AGE?

sort of .i just want to make a sim inside houdini.eg according to life, i want to do something else in maya,let's say i want to color them with their life span. eg

i want to make them transparent according to their scale,and so on(but in maya).

what i've come up till now is,solid transfer of particles. which means you can't do any shader animation to them in maya.because you are unable to transfer other attributes created in houdini. now i have doubts that trying to transfer any particular attribute to another package is worth of a try.

in jeffrey's idea, i think you put the stick into the beehive. i opened the geo file with notepad. but they are more than chinese to me. is there any workchart that tells what is what. okey there are some attribute names and lots of vectors. i have no idea which number is for which attribute. is there any devolopers quide style information,for undrstanding them correctly?

and in houdini whenever you create anything,can we see the code,what so ever houdini is doing?

[symek]

Do you need this for good or just once? I used to had the same problem and fixed it in a most trivial yet brutal way (it was in H7). Since the only geo format supported by both apps is (was) an *.obj, I exported some number of sequences of obj files with attributes I needed copied into UV and N place (the only two point's attributes that obj handles). Another step was of course coping these attributes in Maya from geo A - "UV-overwrite" and B - "N-overwrite" onto geo C - "clear". Doing this just once in some emergency wasn't very tedious but this is not any serious way for production

Edited October 17, 2007 by SYmek

[3dbeing]

I've just finished the python class over at gnomon and that adds alot of power for data I/O, and I am intrested in doing the same thing, as Houdini doesn't have a hardware renderer like Maya. But I really believe the addition of python gives TD's way more cross platform power.

[mrsmary]

symek and 3dbeing thank you both. i am massaging with various sagas and what they all say in common is " why don't you just use houdini" and they are damn right. as soon as i finih things that i have to,i'll focus on houdini totaly. lack of diciplinies(shading,rendering,etc) on my side is making me think of mate two applications so far.

and for pyhton; this is the universal,global thing right. learning pyhton in maya seems much easier i guess,because you can see what maya is doing instantly. do we have the same in houdini? lets say we create a sphere, can i see the code equivelant of this anywhere in houdini?

[symek]

hou.node('/obj/geo1').asCode()

[mrsmary]

SYmek thankyou. but even for a single sphere, this piece of code bring me lots of things,i realy don't understand what it is talking abaout? i was expecting to see something human readable. but i don't know.

this is the part of the thing after i enter your code in the python shell

'hou_node_stack = [hou.node("/obj/geo1").parent()]\n\n# Code for /obj/geo1\nhou_node = hou_node_stack[-1].node("geo1")\n

hou_node.setSelectableInViewport(True)\nhou_node.showOrigin(False)\nhou_node.useXray(False)\nhou_node.setDisplayFlag(Tru

e)\nhou_node.setSelected(True)\n\n# Code for /obj/geo1.stdswitcher\nhou_parm = hou_node.parm("stdswitcher1")\nhou_parm.s

et(0)\nhou_parm.setAutoscope(False)\nhou_parm.lock(False)\n\n# Code for /obj/geo1.keeppos\nhou_parm = hou_node.parm("kee

ppos")\nhou_parm.set(0)\nhou_parm.setAutoscope(False)\nhou_parm.lock(False)\n\n# Code for /obj/geo1.pre_xform\nhou_parm

is this what should i expect?. is this something like echoing everything? if so any chance to reduce it and only bring the parts that we interested? or do i begin to be so stupid?

thank you

[symek]

No, you're not . It's just Houdini who tries to be very specific here. As you probably already know every object in Houdini can have different set of parameters. So there is nothing like a default interface for sphere for example. What you see is a set of commands Houdini must execute to build an object from scratch. Creation script. I'm not sure but as I remember Houdini used to had a different __print__ method for this, so asCode() command was returning nice formatted lines. Now you have to do it for your own (or I don't know something about it).

for line in hou.node('/obj/geo1').asCode().split('\n'): print line

not very elegant, I know. On the over hand you can easily write your own function to print asCode() in more readable manner. Put the file into your $HOME/scripts/python directory, create another file called pythonrc.py and put it there also, import your module in pythonrc.py. Now it's available in Houdini by default.

cheers,

sy.

Edited December 17, 2007 by SYmek

[mrsmary]

SYmek thank you so much. yep it works. for those who are trying this for the first time. after the code press enter twice. here you have what houdini is doing in the backround.

this is a great help thankyou.

[Jason]

Nice one, SYmek

[edward]

print hou.node("/obj/geo1").asCode()

works for me.

[Guest xionmark]

A hack that's been used (too many times) is to use the Real Flow particle file as a format to move particles in and out of Maya<->Houdini.

No need for using Real Flow iteself, just export/import particles in either package with the Real Flow plugins, and with Houdini, you can move any attributes you desire through this interface as well.

Mark