basic examples

examples/README.md

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+## Contributing picrate examples
+
+Share your enthusiasm for coding by submitting an example for inclusion here, provisional versions are acceptable if they demonstrate something interesting (and work), but we would prefer that you followed the style guide. But naturally we expect that you to aspire to the principal of code as art eventually (not many original examples survive without amendment).
+
+### Style guide
+
+* Prefer `Vec2D` and `Vec3D` to `PVector` (it is confusing and sometimes plain wrong).
+* Prefer `Struct` over `Vec2D` and `Vec3D` if you don't need their methods.
+* No trailing whitespace.
+* Use spaces not tabs.
+* Avoid explicit return statements.
+* Avoid using semicolons.
+* Don't use `self` explicitly anywhere except class methods (`def self.method`)
+  and assignments (`self.attribute =`).
+* Prefer `&:method_name` to `{ |item| item.method_name }` for simple method
+  calls.
+* Use `CamelCase` for classes and modules, `snake_case` for variables and
+  methods, `SCREAMING_SNAKE_CASE` for constants.
+* Use `def self.method`, not `def Class.method` or `class << self`.
+* Use `def` with parentheses when there are arguments.
+* Don't use spaces after required keyword arguments.
+* Use `each`, not `for`, for iteration.
+
+When translating a sketch from vanilla processing (or some other codebase), you should credit the original author, unless the rubified version is unrecognizable from the original.  It is often worth running rubocop on sketch code to avoid the most egregious errors.

examples/Rakefile

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+# Simple demo Rakefile to autorun samples in current directory
+# adjust path to jruby executable, and or opts as required
+
+SAMPLES_DIR = './'
+
+desc 'run demo'
+task default: [:demo]
+
+desc 'demo'
+task :demo do
+  samples_list.shuffle.each { |sample| run_sample sample }
+end
+
+def samples_list
+  files = []
+  Dir.chdir(SAMPLES_DIR)
+  Dir.glob('*.rb').each do |file|
+    files << File.join(SAMPLES_DIR, file)
+  end
+  return files
+end
+
+def run_sample(sample_name)
+  puts "Running #{sample_name}...quit to run next sample"
+  open("|jruby --dev #{sample_name}", 'r') do |io|
+    while l = io.gets
+      puts(l.chop)
+    end
+  end
+end

examples/animator.rb

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+#!/usr/bin/env jruby
+require 'picrate'
+
+class Animator < Processing::App
+  FRAME_COUNT = 12
+
+  def settings
+    size 350, 350
+    # pixel_density(2) # for HiDpi screens
+    # smooth see https://processing.org/reference/smooth_.html
+  end
+
+  def setup
+    sketch_title 'Animator'
+    @frames         = []
+    @last_time      = 0
+    @current_frame  = 0
+    @draw           = false
+    @back_color     = 204
+    stroke_weight 4
+    background @back_color
+    FRAME_COUNT.times { @frames << get }
+  end
+
+  def draw
+    time = millis
+    if time > @last_time + 100
+      next_frame
+      @last_time = time
+    end
+    line(pmouse_x, pmouse_y, mouse_x, mouse_y) if @draw
+  end
+
+  def mouse_pressed
+    @draw = true
+  end
+
+  def mouse_released
+    @draw = false
+  end
+
+  def key_pressed
+    background @back_color
+    @frames.size.times { |i| @frames[i] = get }
+  end
+
+  def next_frame
+    @frames[@current_frame] = get
+    @current_frame += 1
+    @current_frame = 0 if @current_frame >= @frames.size
+    image(@frames[@current_frame], 0, 0)
+  end
+end
+
+Animator.new

examples/bezier_playground.rb

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+#!/usr/bin/env jruby
+# frozen_string_literal: true
+require 'picrate'
+
+X1, Y1, X2, Y2 = 50.0, 50.0, 250.0, 250.0
+REDDISH = [250, 100, 100].freeze
+RADIUS = 7
+
+# A Bezier playground. Click to shape the curve. Drag to move it.
+# Arrows toggle between curves, delete removes them.
+# You can print out the parametric equations for t = 0..1
+class BezierPlayground < Processing::App
+  load_libraries :control_panel, :curve
+  include Olap
+  attr_reader :curves, :c1x, :c1y, :c2x, :c2y
+
+  def settings
+    size 300, 300
+    # pixel_density(2) # for HiDpi screens
+    # smooth # see https://processing.org/reference/smooth_.html
+  end
+
+  def setup
+    sketch_title 'Bezier Playground'
+    @curves = []
+    @hide = false
+    control_panel do |c|
+      c.look_feel 'Nimbus'
+      c.button :new_curve
+      c.button :print_equations
+    end
+    generate_curve
+  end
+
+  def draw
+    background 50
+    draw_control_tangent_lines
+    draw_curves
+    draw_current_control_points
+  end
+
+  def print_equations
+    curves.each_with_index { |c, i| c.print_equation(i + 1) }
+  end
+
+  def control_points
+    return c1x, c1y, c2x, c2y
+  end
+
+  def set_control_points(*points)
+    @c1x, @c1y, @c2x, @c2y = points.any? ? points : [X1, Y1, X2, Y2]
+  end
+
+  def generate_curve
+    curves << current_curve = Curve.new
+    @current = curves.length - 1
+    set_control_points(*current_curve.control_points)
+  end
+
+  def current_curve
+    curves[@current]
+  end
+
+  def new_curve
+    current_curve.set_control_points(c1x, c1y, c2x, c2y)
+    generate_curve
+  end
+
+  def clicked_control_point?
+    x, y = mouse_x, mouse_y
+    return :one if Olap.overlaps(c1x, c1y, x, y)
+    return :two if Olap.overlaps(c2x, c2y, x, y)
+  end
+
+  def mouse_pressed
+    switch_curve_if_endpoint_clicked
+    @control = clicked_control_point?
+    return if @control
+    curve = curves.detect { |c| c.contains(mouse_x, mouse_y) }
+    @end_point = curve.contains(mouse_x, mouse_y) if curve
+  end
+
+  def mouse_released
+    @control, @end_point = nil, nil
+    @hide = false
+  end
+
+  def mouse_dragged
+    offs = compute_offsets
+    return if offs.map(&:abs).max > 100
+    return move_control_point(*offs) if @control
+    return move_end_point(*offs) && move_control_point(*offs) if @end_point
+    move_current_curve(*offs)
+  end
+
+  def switch_curve_if_endpoint_clicked
+    become = curves.detect { |c| c.contains(mouse_x, mouse_y) }
+    return unless become && become != current_curve
+    current_curve.set_control_points(*control_points)
+    set_control_points(*become.control_points)
+    @current = curves.index(become)
+  end
+
+  def move_current_curve(x_off, y_off)
+    @c1x += x_off; @c2x += x_off
+    @c1y += y_off; @c2y += y_off
+    current_curve.set_control_points(*control_points)
+    current_curve.x1 += x_off; current_curve.x2 += x_off
+    current_curve.y1 += y_off; current_curve.y2 += y_off
+  end
+
+  def move_control_point(x_off, y_off)
+    case @control || @end_point
+    when :one then @c1x += x_off and @c1y += y_off
+    when :two then @c2x += x_off and @c2y += y_off
+    end
+    current_curve.set_control_points(*control_points)
+  end
+
+  def move_end_point(x_off, y_off)
+    c = current_curve
+    case @end_point
+    when :one then c.x1 += x_off and c.y1 += y_off
+    when :two then c.x2 += x_off and c.y2 += y_off
+    end
+  end
+
+  def compute_offsets
+    return mouse_x - pmouse_x, mouse_y - pmouse_y
+  end
+
+  def draw_curves
+    stroke 255
+    no_fill
+    stroke_width 2
+    curves.each(&:draw)
+  end
+
+  def draw_current_control_points
+    fill color(*REDDISH)
+    no_stroke
+    oval c1x, c1y, 5, 5
+    oval c2x, c2y, 5, 5
+  end
+
+  def draw_control_tangent_lines
+    c = current_curve
+    stroke color(*REDDISH)
+    stroke_width 1
+    line c1x, c1y, c.x1, c.y1
+    line c2x, c2y, c.x2, c.y2
+  end
+end
+
+BezierPlayground.new

examples/chladni.rb

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+#!/usr/bin/env jruby
+# frozen_string_literal: true
+require 'picrate'
+
+# Chladni plate interference surfaces
+# —
+# Based on :
+# http://paulbourke.net/geometry/chladni/
+#
+# —
+# Developed on:
+#   - Processing 2.1.1 on MacOSX (10.9.2)
+# Julien Gachadoat aka v3ga
+# www.v3ga.net
+# www.2roqs.com
+#
+# Translated and tested on:
+#   - picrate
+# Martin Prout
+
+class Chladni < Processing::App
+
+  attr_reader :m, :n, :epsilon, :recompute
+
+  def settings
+    size(500, 500, P2D)
+  end
+
+  def setup
+    sketch_title 'Chladni'
+    @epsilon = 0.05
+    @recompute = true
+    @m = 10
+    @n = 2
+  end
+
+  def draw
+    return unless recompute
+    @recompute = false
+    background(255)
+    load_pixels
+    grid(width, height) do |x, y|
+      chladni = cos(n * PI * x / width) * cos(m * PI * y / width) - cos(m * PI * x / width) * cos(n * PI * y / width)
+      pixels[x + y * width] = 0 if chladni.abs <= epsilon
+    end
+    update_pixels
+    format_string = "m= %d n = %d \nepsilon= %0.3f"
+    infos = format(format_string, m, n, epsilon)
+    fill(255, 0, 0)
+    text(infos, 4, 16)
+  end
+
+  def key_pressed
+    case key
+    when '+'
+      @epsilon += 0.01
+    when '-'
+      @epsilon -= 0.01
+    when CODED
+      case key_code
+      when UP
+        @m += 1
+      when DOWN
+        @m -= 1
+      when LEFT
+        @n -= 1
+      when RIGHT
+        @n += 1
+      end
+    end
+    @recompute = true
+    @m = constrain(m, 1, 20)
+    @n = constrain(n, 1, 20)
+  end
+end
+
+Chladni.new