This library cannot compete with StructureSynth which is a much more refined and complete program. However if you are used to ruby it may be easier to write your rules in ruby, rather than in the EisenScript syntax. The funky extra thing is, because it is based on processing you have the animation possibilities of the 'draw' loop. My monster in some directions could be seen as a beating heart.
To use the library, create a folder for you work say "work", create a sub-folder "library" and sub-sub-folder "test_free" (or whatever better name you can think of for the library). Put the library "test_free.rb" in the sub-sub-folder. Write you sketches in the "work" directory, and run them with "rp5 run my_sketch.rb". If you want to do it the really neat way use JEdit as your editor and my macro and commando tools, then you can run the sketch from the editor. The link to the tools describes live editing, which I haven't tried with this library so I would recommend just using the run mode for now.
If you are not a ruby meddler just get StructureSynth, and learn the EisenScript language. Otherwise you will need to get ruby-processing see link in my blog header to see how. My blog header also has link to the original Jeremy Ashkenas context-free.rb on github.
The test_free.rb library
# A Context-Free library for Ruby-Processing, inspired by
# contextfreeart.org and StructureSynth
# Built on Jeremy Ashkenas context free DSL script
module Processing
class ContextFree
include Processing::Proxy
attr_accessor :rules, :app, :xr, :yr, :zr
AVAILABLE_OPTIONS = [:x, :y, :z, :rx, :ry, :rz, :size, :color, :hue, :saturation, :brightness, :alpha]
HSB_ORDER = {:hue => 0, :saturation => 1, :brightness => 2, :alpha => 3}
# Define a context-free system. Use this method to create a ContextFree
# object. Call render() on it to make it draw.
def self.define(&block)
cf = ContextFree.new
cf.instance_eval &block
cf
end
# Initialize a bare ContextFree object with empty recursion stacks.
def initialize
@app = $app
@graphics = $app.g
@finished = false
@rules = {}
@rewind_stack = []
@matrix_stack = []
@xr = 0
@yr = 0
@zr = 0
end
# Create an accessor for the current value of every option. We use a values
# object so that all the state can be saved and restored as a unit.
AVAILABLE_OPTIONS.each do |option_name|
define_method option_name do
@values[option_name]
end
end
# Here's the first serious method: A Rule has an
# identifying name, a probability, and is associated with
# a block of code. These code blocks are saved, and indexed
# by name in a hash, to be run later, when needed.
# The method then dynamically defines a method of the same
# name here, in order to determine which rule to run.
def rule(rule_name, prob=1, &proc)
@rules[rule_name] ||= {:procs => [], :total => 0}
total = @rules[rule_name][:total]
@rules[rule_name][:procs] << [(total...(prob+total)), proc]
@rules[rule_name][:total] += prob
unless ContextFree.method_defined? rule_name
self.class.class_eval do
eval <<-METH
def #{rule_name}(options)
merge_options(@values, options)
pick = determine_rule(#{rule_name.inspect})
@finished = true if @values[:size] < @values[:stop_size]
unless @finished
get_ready_to_draw
pick[1].call(options)
end
end
METH
end
end
end
# Rule choice is random, based on the assigned probabilities.
def determine_rule(rule_name)
rule = @rules[rule_name]
chance = rand * rule[:total]
pick = @rules[rule_name][:procs].select {|the_proc| the_proc[0].include?(chance) }
return pick.flatten
end
# At each step of the way, any of the options may change, slightly.
# Many of them have different strategies for being merged.
def merge_options(old_ops, new_ops)
return unless new_ops
# Do size first
old_ops[:size] *= new_ops[:size] if new_ops[:size]
new_ops.each do |key, value|
case key
when :size
when :x, :y, :z
old_ops[key] = value * old_ops[:size]
when :rz, :ry, :rx
old_ops[key] = value * (Math::PI / 180.0)
when :hue, :saturation, :brightness, :alpha
adjusted = old_ops[:color].dup
adjusted[HSB_ORDER[key]] *= value
old_ops[:color] = adjusted
when :width, :height
old_ops[key] *= value
when :color
old_ops[key] = value
else # Used a key that we don't know about or trying to set
merge_unknown_key(key, value, old_ops)
end
end
end
# Using an unknown key let's you set arbitrary values,
# to keep track of for your own ends.
def merge_unknown_key(key, value, old_ops)
key_s = key.to_s
if key_s.match(/^set/)
key_sym = key_s.sub('set_', '').to_sym
if key_s.match(/(brightness|hue|saturation|alpha)/)
adjusted = old_ops[:color].dup
adjusted[HSB_ORDER[key_sym]] = value
old_ops[:color] = adjusted
else
old_ops[key_sym] = value
end
end
end
# Doing a 'split' saves the context, and proceeds from there,
# allowing you to rewind to where you split from at any moment.
def split(options=nil, &block)
save_context
merge_options(@values, options) if options
yield
restore_context
end
# Saving the context means the values plus the coordinate matrix.
def save_context
@rewind_stack.push @values.dup
@matrix_stack << @graphics.get_matrix
end
# Restore the values and the coordinate matrix as the recursion unwinds.
def restore_context
@values = @rewind_stack.pop
@graphics.set_matrix @matrix_stack.pop
end
# Rewinding goes back one step.
def rewind
@finished = false
restore_context
save_context
end
# Render the is method that kicks it all off, initializing the options
# and calling the first rule.
def render(rule_name, starting_values={})
@values = {:x => 0, :y => 0, :z => 0,
:rz => 0, :ry => 0, :rx => 0,
:size => 1, :width => 1, :height => 1,
:start_x => width/2, :start_y => height/2, :start_z => 0,
:color => [0.5, 0.5, 0.5, 1],
:stop_size => 1.5}
@values.merge!(starting_values)
@finished = false
@app.reset_matrix
@app.rect_mode CENTER
@app.ellipse_mode CENTER
@app.no_stroke
@app.color_mode HSB, 1.0
@app.translate @values[:start_x], @values[:start_y], @values[:start_z]
self.send(rule_name, {})
end
def rotate_x rt
@xr = rt
end
def rotate_y rt
@yr = rt
end
def rotate_z rt
@zr = rt
end
# Before actually drawing the next step, we need to move to the appropriate
# location.
def get_ready_to_draw
@app.translate(@values[:x], @values[:y], @values[:z])
@app.rotate_x(@values[:rx] + xr)
@app.rotate_y(@values[:ry] + yr)
@app.rotate_z(@values[:rz] + zr)
end
# Compute the rendering parameters for drawing a shape.
def get_shape_values(some_options)
old_ops = @values.dup
merge_options(old_ops, some_options) if some_options
@app.fill *old_ops[:color]
return old_ops[:size], old_ops
end
# The shape primitives are sphere and cube
def cube(some_options=nil)
size, options = *get_shape_values(some_options)
rotz = options[:rz]
roty = options[:ry]
rotx = options[:rx]
@app.rotate_x rotx unless rotx.nil?
@app.rotate_y roty unless roty.nil?
@app.rotate_z rotz unless rotz.nil?
@app.translate(options[:x] * size, options[:y] * size , options[:z] * size)
@app.box(size)
@app.rotate_z(-1 * rotz) unless rotz.nil? # unwind rotations in an ordered way
@app.rotate_y(-1 * roty) unless roty.nil?
@app.rotate_x(-1 * rotx) unless rotx.nil?
end
def sphere(some_options=nil)
size, options = *get_shape_values(some_options)
rotz = options[:rz]
roty = options[:ry]
rotx = options[:rx]
@app.rotate_x rotx unless rotx.nil?
@app.rotate_y roty unless roty.nil?
@app.rotate_z rotz unless rotz.nil?
@app.translate(options[:x] * size, options[:y] * size , options[:z] * size)
@app.sphere_detail 10
@app.sphere(size)
@app.rotate_z(-1 * rotz) unless rotz.nil? # unwind rotations in an ordered way
@app.rotate_y(-1 * roty) unless roty.nil?
@app.rotate_x(-1 * rotx) unless rotx.nil?
end
end
end
My Test Script monster.rb
load_libraries :test_free, :control_panel
attr_reader :xrot, :yrot, :zrot
def setup_the_spiral
@spiral = ContextFree.define do
rule :monster do
5.times do |i|
split do
cone :ry => 72 * i
rewind
end
end
end
rule :cone do # two equally weighted cone rules creates the beat
sphere :brightness => 1
cone :size => 0.96, :y => -0.24
end
rule :cone do
sphere :brightness => 1
cone :size => 0.97, :y => -0.28
end
end
end
def setup
size 800, 800, P3D
configure_control
smooth
setup_the_spiral
end
def configure_control
control_panel do |c|
c.title = "Attitude Control"
c.slider :xrot, -3.1..3.1, 0.5
c.slider :yrot, -3.1..3.1, 0.5
c.slider :zrot, -3.1..3.1, 1.0
end
end
def draw
background 0.8
lights
@spiral.render :monster, :start_x => 0, :start_y => 10, :start_z => -30, :size => height/200, :stop_size => 1, :color => [0, 0.8, 0.8]
@spiral.rotate_x xrot
@spiral.rotate_y yrot
@spiral.rotate_z zrot
end
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