Contents

# quad.rb

module Ruby2D
  class Quad
    include Renderable
    # Coordinates in clockwise order, starting at top left:
    # x1,y1 == top left
    # x2,y2 == top right
    # x3,y3 == bottom right
    # x4,y4 == bottom left
    attr_accessor :x1, :y1, :c1,
                  :x2, :y2, :c2,
                  :x3, :y3, :c3,
                  :x4, :y4, :c4

    attr_reader :color

    def initialize(opts = {})
      @type_id = 2

      @x1 = opts[:x1] || 0
      @y1 = opts[:y1] || 0
      @x2 = opts[:x2] || 100
      @y2 = opts[:y2] || 0
      @x3 = opts[:x3] || 100
      @y3 = opts[:y3] || 100
      @x4 = opts[:x4] || 0
      @y4 = opts[:y4] || 100

      @z = opts[:z] || 0

      self.color = opts[:color] || 'white'
      add
    end

    def color=(c)
      @color = Color.from(c)
      update_color(@color)
    end

    # The logic is the same as for a triangle
    # See triangle.rb for reference
    def contains?(x, y)
      self_area = triangle_area(@x1, @y1, @x2, @y2, @x3, @y3) +
                  triangle_area(@x1, @y1, @x3, @y3, @x4, @y4)

      questioned_area = triangle_area(@x1, @y1, @x2, @y2, x, y) +
                        triangle_area(@x2, @y2, @x3, @y3, x, y) +
                        triangle_area(@x3, @y3, @x4, @y4, x, y) +
                        triangle_area(@x4, @y4, @x1, @y1, x, y)

      questioned_area <= self_area
    end

    private

    def triangle_area(x1, y1, x2, y2, x3, y3)
      (x1*y2 + x2*y3 + x3*y1 - x3*y2 - x1*y3 - x2*y1).abs / 2
    end

    def update_color(c)
      if c.is_a? Color::Set
        if c.length == 4
          @c1 = c[0]
          @c2 = c[1]
          @c3 = c[2]
          @c4 = c[3]
        else
          raise ArgumentError, "Quads require 4 colors, one for each vertex. #{c.length} were given."
        end
      else
        @c1 = c
        @c2 = c
        @c3 = c
        @c4 = c
      end
    end
  end
end

Version data entries

2 entries across 2 versions & 1 rubygems

Version	Path
ruby2d-0.4.1	lib/ruby2d/quad.rb
ruby2d-0.4.0	lib/ruby2d/quad.rb