another post

Author: monkstone

docs/_posts/2019-03-01-Using-Vec2D.md

@@ -0,0 +1,100 @@
+---
+layout: post
+title:  "Welcome to Vecmath Gem for Visor"
+date:   2019-03-01 10:58:08 +0000
+categories: vecmath update
+---
+
+# Example Usage
+
+```ruby
+# ===== Default : Default
+GEM_HOME = '/home/tux/.gem/ruby/2.6.0'
+require 'vecmath'
+require 'forwardable'
+
+# Here we use the JRubyArt Vec2D class, and AppRender class (for vec.to_vertex)
+# Further we use the power of ruby (metaprogramming) to make Branch enumerable
+# and use Forwardable to define which enumerable methods we want to use.
+visor_class :Branch do
+  include Enumerable
+  extend Forwardable
+  def_delegators(:@children, :<<, :each, :length)
+  # variance angle for growth direction per time step
+  THETA = Math::PI / 6
+  # max segments per branch
+  MAX_LEN = 100
+  # max recursion limit
+  MAX_GEN = 3
+  # branch chance per time step
+  BRANCH_CHANCE = 0.05
+  # branch angle variance
+  BRANCH_THETA = Math::PI / 3
+  attr_reader :position, :dir, :path, :children, :xbound, :speed, :ybound, :app
+
+  def initialize(pos, dir, speed)
+    @renderer ||= AppRender.new(graphics)
+    @position = pos
+    @dir = dir
+    @speed = speed
+    @path = []
+    @children = []
+    @xbound = Boundary.new(0, width)
+    @ybound = Boundary.new(0, height)
+    path << pos
+  end
+
+  def run
+    grow
+    display
+  end
+
+  private
+
+  # NB: use of both rotate! (changes original) rotate (returns a copy) of Vec2D
+  def grow
+    check_bounds(position + (dir * speed)) if path.length < MAX_LEN
+    @position += (dir * speed)
+    dir.rotate!(rand(-0.5..0.5) * THETA)
+    path << position
+    if (length < MAX_GEN) && (rand < BRANCH_CHANCE)
+      branch_dir = dir.rotate(rand(-0.5..0.5) * BRANCH_THETA)
+      self << Branch.new(position.copy, branch_dir, speed * 0.99)
+    end
+    each(&:grow)
+  end
+
+  def display
+    begin_shape
+    stroke(255)
+    no_fill
+    path.each { |vec| vec.to_vertex(@renderer) }
+    end_shape
+    each(&:display)
+  end
+
+  def check_bounds(pos)
+    dir.x *= -1 if xbound.exclude? pos.x
+    dir.y *= -1 if ybound.exclude? pos.y
+  end
+end
+
+# we are looking for excluded values
+Boundary = Struct.new(:lower, :upper) do
+  def exclude?(val)
+    !(lower...upper).cover? val
+  end
+end
+
+@root = Branch.new(
+    Vec2D.new(0, height / 2),
+    Vec2D.new(1, 0),
+    10.0
+)
+
+def draw
+  background(0)
+  root.run
+end
+
+```

docs/_posts/2019-03-01-welcome-to-vecmath-gem.md

@@ -1,7 +1,7 @@
 ---
 layout: post
 title:  "Welcome to Vecmath Gem for Visor"
-date:   2019-03-01 10:58:08 +0000
+date:   2019-03-01 09:58:08 +0000
 categories: vecmath update
 ---