L-system Bonus Lesson
-or the long term called the Lindenmayer system
-bunch of symbols to create trees, plant and geo shapes
-evolve from young to complex trees
-good for creating mid and far field trees
-animate the growth of trees
Here are some of the examples I found.
This veins test using Houdini l-system looks pretty good.
Forward to 31 sec.
The way the braches grow is really nice and how the butterfly coming out of the cocoon looks realistic.
L System has four input node, J,K,M,Meta Test Input
J,K,M are used to create leaves, tree and branches.
The L-system nodes 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.
There are a lot of default shapes/values to l system that I can already use and edit from there.
L system parameter definitions
Premise
- Is the initial state of the tree when it is at generation 0
-Initiator, initial the growth of rules of the system
Rules
- generator, growth of trees
Generation
-generator, the greater the generation, the more branches as it is more mature
(EDGE REWRITING)
F - go straight and draw a line (1 unit)
F = F+F-F
+ means turn right
- means turn left
f - going a full step without drawing anything
h - going a half step without drawing anything
When I change the generation to 1, I get F+F-F
But when I change my generation to 2, I get this,
At first I did not understand what I get such irregular shape.
Then after Ari explained, I understand how it is been calculated.
Generation 1 : F = F+F-F
Generation 2 : F+F-F + F+F-F - F+F-F
By adding [] i can create trees, branches and twigs
Example
F = F[+F]F[-F]F
F = F
F = F[+F]
F = F[+F]F[-F]
F = "F[+F]F[-F]Fby adding " I can scale the lsystem by going to the values tab and adjusting the step size scale.
F = "TF[+F]F[-F]Fby adding T I can add gravity on the branches and twigs by changing the values of the gravity.
However, the main structure stays the same. In order to add gravity to the main structure add a value after the T and now the main structure will deform as well according to the gravity values
F = "T+(1)F[+F]F[-F]F
NODE REWRITING
-creating new variable eg) X
The variable X will be the premise for the next generation.
Multiple Rules
I do not quite understand about the multiple rules but this forum gave me an idea on how it is used.
! - multiply the thickness; - multiply current angle
~ - random l system up to a degree
eg)
X = !T~(20)F[;+X][-X]FX
3D TREES
+ - Rotate Right- - Rotate Left
& - Pitch Up
^ - Pitch Down
\ - Roll Clockwise
/ - Roll Anti-Clockwise
eg)
X = !/(140)~F[+FJ]X:0.5
Conditionals
t< 4 = F+F[F][-F]
EG)t< 4 = F+F[F][-F]
(it means how many generations produced)
First Steps - Light, Shade, Render (Scene Setup)
In the first 12 minutes of the lesson, it teaches us how to create our own project folder in Houdini. It does not work the same way as maya, however, we are able to create a project files anywhere we want.
http://forums.odforce.net/
By reading this forum, I am able to understand more on how it can be used.
One other thing that houdini has is the $HIP
It allows me to access all my files easily as I do not have to keep clicking and choosing the folder I want.
I was also taught how to set up the desktop for lighting and shading.
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