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 Post subject: Particles Local Orientation outwards - How to?
PostPosted: 05 Sep 2012, 18:13 
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Hello guys, i'm havin an hard time to find out how to achieve this effect..

Image

I've setup this and now i want every single particle (instance) to point outwards locally, not all together.
I tried to modify the particle orientation but everything i do is done on all particles not on single also i cant find a way to have a proper orientation.

I am having this problem quite often and would be nice to create a compound that works once for all. Cause everytime i have to orient particles i have this issue.

For example, see how those points outwards based on their position?

Image


Any suggestion?

Thank you


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 Post subject: Re: Particles Local Orientation outwards - How to?
PostPosted: 05 Sep 2012, 18:32 
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Not in front of SI right now but, this would be a good application of the vector field node each vector pointing in the normal direction.

You will have to orient the triangles in the same direction as the vector field.

How do you define the triangle direction right now? (look to me they are all oriented in the -z axes)

Where is the pivot point relative to the two triangles?

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 Post subject: Re: Particles Local Orientation outwards - How to?
PostPosted: 05 Sep 2012, 18:38 
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They dont have a custom orientation atm, that geometry has the pivot in the center. Its a normal grid and i melded 2 vertices in the middle to create an arrow-like shape.


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 Post subject: Re: Particles Local Orientation outwards - How to?
PostPosted: 05 Sep 2012, 18:48 
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Image

They all move together! X(
I have to try something different i guess.


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 Post subject: Re: Particles Local Orientation outwards - How to?
PostPosted: 05 Sep 2012, 18:52 
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OK, the first thing i would do is determine the pivot orientation.

The Fibonacci algorithm give you a point in space. The point in space will determine where to put the triangle base location/pivot point (your are there from what I see).

The orientation is the angle between the origin point and the pivot/triangle base. The angle determine the direction of the tip.

So you could determine the vector direction from origin to pivot point and set the vector direction between the pivot point/triangle base to tip point with the same angle amount.

Basic vector mathematics.

Dan

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Last edited by Daniel Brassard on 05 Sep 2012, 19:08, edited 4 times in total.

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 Post subject: Re: Particles Local Orientation outwards - How to?
PostPosted: 05 Sep 2012, 18:55 
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You have to do it for each instance/particle or they will move together as a group.

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 Post subject: Re: Particles Local Orientation outwards - How to?
PostPosted: 05 Sep 2012, 19:07 
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well i think i got the math behind this, but its really hard for me to translate it into ICE nodes.
I would start with Get Data and dig into the "arrow" but i cant get what i would need. Sadly i think this is quite off my knowledge
Thank you for the help!


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 Post subject: Re: Particles Local Orientation outwards - How to?
PostPosted: 05 Sep 2012, 19:09 
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If you don't get the answer by tonight, I'll put something together for you. You are almost there.

Dan

p.s. maybe this can help in between...

http://xsisupport.com/2011/04/11/ice-modeling-aligning-copies-to-edges/

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 Post subject: Re: Particles Local Orientation outwards - How to?
PostPosted: 05 Sep 2012, 19:36 
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I think i solved it! gonna post in a few! Thanks alot!!


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 Post subject: Re: Particles Local Orientation outwards - How to?
PostPosted: 05 Sep 2012, 20:41 
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splendid that you got it , was gonna say you are barking up the wrong tree with align particle by force or whatever compound that was - it may have been using the velocity vector. It was also a bit cruel of Daniel to leave you overnight stewing like that but to be kind, in order for you to learn, sometimes one needs to be cruel ;)

Ive been using ICE since beta and I still dont fully understand rotations or quaternions or the merits of splitting rotation up into quaternion or axis and angle or euler or rotation by orientation... its not exactly crystal clear on how to do this anyways with so many options and ways to connect and sometimes the factory align compounds don't behave as expected either! :-s

but here is how I approached the problem. I knew I had to globally align to a position (the centre) then I had to rotate or tilt each particle around their axis locally. breaking it into 2 stages helped to try out various solutions and get each part working then it was just a matter of joining the two. heres my compound and screenshot, don't download unless you have solved it already!

this has got quite a bit of usage for those Motion Graphics folks too as you can alter the tilt by distance to null so the flower petals open and close - a bit like your reference picture where there is more tilt the further from centre :-bd


Attachments:
align_and_tilt.jpg
align_and_tilt.jpg [ 171.7 KiB | Viewed 926 times ]
Align to position and Tilt.xsicompound [10.77 KiB]
Downloaded 105 times

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