circles for dragonruby

circles.rb

module GTK
  class Runtime
    def draw_circle c
      radius = c.radius.to_i || 0
      xc = c.x.to_i + radius
      yc = c.y.to_i + radius
      t = c.thickness || 1
      r = c.r || 0
      g = c.g || 0
      b = c.b || 0
      a = c.a || 255

      x = 0
      y = radius
      d = 3 - 2 * radius
      while y >= x
        d = d.positive? ? d + 4 * (x - (y -= 1)) + 10 : d + 4 * x + 6
        @ffi_draw.draw_solid(xc + x, yc + y, t, t, r, g, b, a)
        @ffi_draw.draw_solid(xc - x, yc + y, t, t, r, g, b, a)
        @ffi_draw.draw_solid(xc + x, yc - y, t, t, r, g, b, a)
        @ffi_draw.draw_solid(xc - x, yc - y, t, t, r, g, b, a)
        @ffi_draw.draw_solid(xc + y, yc + x, t, t, r, g, b, a)
        @ffi_draw.draw_solid(xc - y, yc + x, t, t, r, g, b, a)
        @ffi_draw.draw_solid(xc + y, yc - x, t, t, r, g, b, a)
        @ffi_draw.draw_solid(xc - y, yc - x, t, t, r, g, b, a)
        x += 1
      end
    end

    def draw_solid_circle c
      radius = c.radius.to_i || 0
      xc = c.x.to_i + radius
      yc = c.y.to_i + radius
      r = c.r || 0
      g = c.g || 0
      b = c.b || 0
      a = c.a || 255

      x = 0
      y = radius
      d = 3 - 2 * radius
      while y >= x
        d = d.positive? ? d + 4 * (x - (y -= 1)) + 10 : d + 4 * x + 6
        @ffi_draw.draw_line(xc - x, yc - y, xc + x, yc + y, r, g, b, a)
        @ffi_draw.draw_line(xc - y, yc - x, xc + y, yc + x, r, g, b, a)
        @ffi_draw.draw_line(xc - x, yc + y, xc + x, yc - y, r, g, b, a)
        @ffi_draw.draw_line(xc - y, yc + x, xc + y, yc - x, r, g, b, a)
        x += 1
      end
    end

    def draw_primitive p
      return draw_circle p if p.primitive_marker == :circle
      return draw_solid_circle p if p.primitive_marker == :solid_circle
      super
    end
  end
end

main.rb

def tick args
  args.outputs.primitives << { x: 640-100, y: 360-100, radius: 50, thickness: 2, **Color::GREEN, primitive_marker: :circle }
  args.outputs.primitives << { x: 640-100, y: 360-100, radius: 50, **Color::BLUE, primitive_marker: :solid_circle }
end