View Full Version : Paint effects growth

01 January 2011, 10:53 PM
Hi all,

Does anyone know if it's possible to offset twig growth over time based on the height of a tree? I basically have a tree that I'm growing by keyframing alot of attributes over time (not using time flow). While I have quite a nice result, I'd like to be able to have the higher twigs growing at a later time than the lower ones.

Currently I'm animating the twig length (along with lots of other things), though all the growth happens at the same time. I know you have a ramp to control the length of the leaves from tree base to top but you can't really animate this for the effect I'm after..

Anyone have any suggestions, or is this even possible?

ps: Will post a link on Vimeo when its encoded...

Thanks in advance..

01 January 2011, 11:08 PM
Oh wait...Just found the `modifier` which might solve my problem though I'd still be interested if it was possible via the standard controls...


edit: Nope, after trying out the modifier, It seems like this won't be a solution for me. Here's a link to a playblast showing the twig growth.

01 January 2011, 12:37 AM
If branchAfterTwigs is on( which I think it is for that tree ) then you can key the values of the twigLengthScale ramp indices to do what you want. Both the position and value of the indices may be keyed (rightmouse over selected position/value to key).


01 January 2011, 10:06 AM
Thanks Duncan - that worked very well...Initially I thought using the graph to animate would be too fiddly but its pretty straightforward. On a side note - I was thinking it might be nice to have an input bias on these graphs to allow for further manipulation...:)

Thanks again.

01 January 2012, 04:10 PM
Since there is this thread about paint effects, I didn't want to start another. Sorry for that...

ANY idea how to make a stroke to start using the turbulence type - Grass Wind?


I've made a custom grass modifying "grass carpet" and now I want it to move about like
Grass Wind Wide..!!

I played with all the attributes under the turbulence drop down, but the stroke does seem to budge rather it just adjusts its curves. Doesn't play along time.

01 January 2012, 08:42 PM
I'm not sure exactly what you are asking, but 2 possible interpretations:
1. Turbulence is not updating in the viewport. This a bug where turbulence doesn't animate sometimes in playback. One can either open the "time" block in the attribute editor for the stroke, or key some attribute to force updates.

2. You want the base stroke path to show effects of turbulence, not the emitted tubes. One can't affect the stroke path with turbulence, but one can create a brush such that it creates a single tube that follows the stroke path exactly. Turbulence can then affect that tube. If you select a simple brush(one with tubes off) you can type "makeTubeOn" which will modify the settings of the brush so it looks the same but uses tubes. Then assign the current brush to your stroke or paint with it. You may need to lower the path follow on the brush to see the effects of turbulence force( although displacement will work fine).

01 January 2012, 10:51 AM
my apologies Duncan...
rather than typing I will make a video and post it here.

01 January 2012, 07:38 PM
Re-reading your post it looks like the first issue I mentioned. Does your grass move if you render a sequence( as opposed to playing back in the interactive )?

01 January 2012, 08:43 PM
Duncan, you are a genius.
Thanks a mill again.....

They all are working in a rendered seq.

Okay all is well, but how will we test the speed and movement of these strokes if they do not animate on the viewport?
any idea for that?

01 January 2012, 09:00 PM
It is simply a problem where it doesn't realize that the draw cache is dirty. If you simply open the Flow Animation block in the attribute editor it will do a getAttr on brush.time, which wakes things up. If anything on the brush is animated it will also work. If you animate with keyframes the value needs to change over time to get an update. However expressions will always force updates, so for example you could type "= 0" into the flowspeed attribute in the attribute editor (using "=" in the attribute editor cells automatically sets up an expression).


01 January 2012, 07:08 AM
Will do that.

Thank You Duncan.


UPDATE - after doing what Duncan said :thumbsup:

Everything seems to work. Even the strokes which I din't put an expression of "=0," worked too on the viewport, after I put that expression in one of the PFX stroke's flow animation>flow speed.

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