Contents

# Ported from http://processing.org/learning/topics/simpleparticlesystem.html

# Particles are generated each cycle, fall with gravity and fade out over
# time. A ParticleSystem (Array) object manages a variable size list of
# particles.
load_library :vecmath

attr_reader :ps

def setup
  size(640,360)
  @ps = ParticleSystem.new(Vec2D.new(width/2, 50))
end

def draw
  background(0)
  ps.add_particle
  ps.run
end

module Runnable
  def run
    self.reject! { |item| item.lifespan <= 0 }
    self.each    { |item| item.run   }
  end
end

class ParticleSystem 
  extend Enumerable 
  include Runnable
  
  attr_reader :origin, :particle_system

  def initialize(loc)
    @particle_system = []
    @origin = Vec2D.new(loc.x, loc.y)
  end
  
  def each &block
    particle_system.each &block    
  end
  
  def add_particle
    particle_system << Particle.new(origin) 
  end
  
  def reject! &block
    particle_system.reject! &block
  end
  
  def dead?
    particle_systems.empty?
  end 

end

# A simple Particle class

class Particle 
  include Processing::Proxy 
  
  attr_reader :loc, :vel, :acc, :lifespan
  def initialize(loc) 
    @acc = Vec2D.new(0, 0.05)
    @vel = Vec2D.new(rand(-1.0 .. 1), rand(-2.0 .. 0))
    @loc = loc    # loc.clone is unecessary in ruby
    @lifespan = 255.0
  end

  def run
    update
    display
  end

  # Method to update loc
  def update
    @vel += acc
    @loc += vel
    @lifespan -= 1.0
  end

  # Method to display
  def display
    stroke(255,lifespan)
    fill(255,lifespan)
    ellipse(loc.x, loc.y, 8, 8)
  end
  
end

Version data entries

4 entries across 4 versions & 1 rubygems

Version	Path
ruby-processing-2.4.4	samples/processing_app/library/vecmath/simple_particle_system.rb
ruby-processing-2.4.3	samples/processing_app/library/vecmath/simple_particle_system.rb
ruby-processing-2.4.2	samples/processing_app/library/vecmath/simple_particle_system.rb
ruby-processing-2.4.1	samples/processing_app/library/vecmath/simple_particle_system.rb