Search⌘ K
AI Features
Home
Courses
Mazes for Programmers

Drawing Polar Grids

Explore how to subclass a grid to design polar grids with Ruby, focusing on rendering circular maze structures. Learn to calculate radii and angles, determine cell coordinates, and draw grid lines to generate visually structured circular mazes.

We'll cover the following...

The PolarGrid class

The to_png method we’ve used up to this point isn’t going to help us much with polar grids, so let’s just subclass Grid and rewrite to_png to be what we need it to be. We'll create a new file named polar_grid.rb. We’ll add the Grid subclass and to_png method to our file.

C++
require 'grid'
class PolarGrid < Grid 
  def to_png_v1(cell_size: 10)
    img_size = 2 * @rows * cell_size 
    background = ChunkyPNG::Color::WHITE
    wall = ChunkyPNG::Color::BLACK
    img = ChunkyPNG::Image.new(img_size + 1, img_size + 1, background)
    center = img_size / 2 
    each_cell do |cell|
      theta        = 2 * Math::PI / @grid[cell.row].length 
      inner_radius = cell.row * cell_size
      outer_radius = (cell.row + 1) * cell_size
      theta_ccw    = cell.column * theta
      theta_cw     = (cell.column + 1) * theta 
      ax = center + (inner_radius * Math.cos(theta_ccw)).to_i 
      ay = center + (inner_radius * Math.sin(theta_ccw)).to_i
      bx = center + (outer_radius * Math.cos(theta_ccw)).to_i
      by = center + (outer_radius * Math.sin(theta_ccw)).to_i
      cx = center + (inner_radius * Math.cos(theta_cw)).to_i
      cy = center + (inner_radius * Math.sin(theta_cw)).to_i
      dx = center + (outer_radius * Math.cos(theta_cw)).to_i
      dy = center + (outer_radius * Math.sin(theta_cw)).to_i 
      img.line(ax, ay, cx, cy, wall) unless cell.linked?(cell.north) 
      img.line(cx, cy, dx, dy, wall) unless cell.linked?(cell.east) 
    end
    img.circle(center, center, @rows * cell_size, wall) 
    img
  end
end

Code explanation

Line 4: This new to_png method starts much like the old version, computing the size of our canvas.

Line 5: In this case, though, ...