"tree" sample from ruby-processing, ported to Visor.

tree.rb

# http://processing.org/learning/topics/tree.html
# by Joe Holt

color_mode RGB, 1
smooth
@x = 0.0
@dx = width / 100

def draw

  background 0
  stroke 1, 1, 1
  # Let's pick an angle 0 to 90 degrees based on the mouse position
  a = (@x / width) * 90
  # Convert it to radians
  @theta = a * Math::PI / 180
  # Start the tree from the bottom of the screen
  translate(width / 2, height)
  # Draw a line 60 pixels
  h = height / 3
  line(0, 0, 0,  -h)
  # Move to the end of that line
  translate(0,-h)
  # Start the recursive branching!
  branch(h)
  
  @x += @dx
  if @x > width || @x < 0
    @dx = - @dx
    @x += @dx * 2
  end
end

def branch(h)
  # Each branch will be 2/3rds the size of the previous one
  h *= 0.66  
  # All recursive functions must have an exit condition!!!!
  # Here, ours is when the length of the branch is 2 pixels or less
  if h > 2
    push_matrix       # Save the current state of transformation (i.e. where are we now)
    rotate(@theta)   # Rotate by theta
    line(0, 0, 0, -h)   # Draw the branch
    translate(0, -h)  # Move to the end of the branch
    branch(h)        # Ok, now call myself to draw two new branches!!
    pop_matrix        # Whenever we get back here, we "pop" in order to restore the previous matrix state
    
    # Repeat the same thing, only branch off to the "left" this time!
    push_matrix
    rotate(- @theta)
    line(0, 0, 0, -h)
    translate(0, -h)
    branch(h)
    pop_matrix
  end
end

# The MIT License (MIT)
# 
# Copyright (c) 2019 Jay McGavren
# 
# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:
# 
# The above copyright notice and this permission notice shall be included in all
# copies or substantial portions of the Software.
# 
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
# SOFTWARE.