View Full Version : Limit L-system growth inside a shape

08 August 2011, 04:13 AM
I am new to Houdini. I have been reading the documentation for the l-system functionality at the following link.

The text I am reading has been copied here as follows.

"Limit L-system growth inside a shape

The L-system node’s meta-test input lets you generate rules that will cause the system to stop when it reaches the edges of a defined shape, like a topiary hedge.

Create a metaball or merged metaballs that define the volume in which the L-system can grow.

Connect the metaball node’s output to the Meta-test input of the L-system node.

Use a conditional statement (:) with an “in” test. For example:



Rule 1
A: in(x,y,z) = F [+FA] -FA : 80

Rule 2
A: ! in(x,y,z) = A%

This L-system checks to see if the next iteration of growth will be within the Meta-test bounds, and if not it prunes the current branch.

Rule 1 executes 80% of the time when the branch is within the meta-test boundary.

Rule 2 executes when the branch is not within the meta-test boundary (the ! negates the in(x,y,z) condition). The % command ends the branch."

Can someone explain to me how to make this work. I have been following the instructions and I can't get it. I think I am not connecting the L-system and the metaball correctly.

"Connect the metaball node’s output to the Meta-test input of the L-system node."

What is the Meta-test input? How do I find it?

Thank you in advance for your help. I greatly appreciate any advice you can give.

08 August 2011, 05:26 AM
I think it's last (aka rightmost) input of the node.

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08 August 2011, 05:26 AM
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