fibonacci-spiral.rb

require 'victor'

scale = 1000 # scale up the result by this factor
first_n = 1 # index of first logo
last_n = 10000 # index of last logo
SCALE = 0.18 # scale up the individual logos by this factor
ALPHA = -15 # for smaller values, logos will shrink faster going out. for positive values, logos will shrink going in.

def get_r i
    i**(1/(2.0-ALPHA))
end

def get_t i
    i*137.507764/180*Math::PI # golden angle: 137.507764 degrees
end

def get_scl i
    SCALE*Math.sqrt(get_r(i)**ALPHA)
end

def get_pos i
    [get_r(i)*Math.sin(get_t(i)),
     get_r(i)*Math.cos(get_t(i))]
end

w = 2*get_r(last_n)*scale # width of the final image

svg = Victor::SVG.new width: w, height: w

first_n.upto(last_n) do |n|
        pos = get_pos(n)
        scl = get_scl(n)

        # circle
        #svg.circle cx: 0, cy: 0, r: scl*scale, fill: "black", transform: "translate(#{pos[0]*scale+w/2.0}, #{pos[1]*scale+w/2.0})"

        # arrow
        #svg.path d: "M0 -0.5 L0.5 0 L0.2 0 L0.2 0.5 L-0.2 0.5 L-0.2 0 L-0.5 0 Z", fill: "black", transform: "translate(#{pos[0]*scale+w/2.0}, #{pos[1]*scale+w/2.0}) scale(#{scl*scale}) rotate(#{180-get_t(n)*180/Math::PI})"

        # triangle
        #svg.path d: "M0 -0.8 L0.5 0 L-0.5 0 Z", fill: "black", transform: "translate(#{pos[0]*scale+w/2.0}, #{pos[1]*scale+w/2.0}) scale(#{scl*scale}) rotate(#{180-get_t(n)*180/Math::PI})"

        # heart
        svg.path d: "M0 -1 L1 0 L 0 1 A0.7071 0.7071 0 0 1 -1 0 A0.7071 0.7071 0 0 1 0 -1 Z", fill: "black", transform: "translate(#{pos[0]*scale+w/2.0}, #{pos[1]*scale+w/2.0}) scale(#{scl*scale}) rotate(#{270-get_t(n)*180/Math::PI})"
end

svg.save "fibonacci-spiral.svg"