Spiral 2

main.lua

-- Constants
a = 1
n = 1

function spiral(theta)
   -- Work out the polar equation
   local r = a * theta ^ (1/n)
   -- Convert to cartesian coordinates
   local x = r * math.sin(theta)
   local y = r * math.cos(theta)
   return x, y
end

function love.draw()
   -- Reset graphics properties for spiral
   love.graphics.setPoint(3, "smooth")
   love.graphics.setColor(255, 255, 255, 255)
   -- Draw for theta between 0 and 3pi, with sample period of pi/100
   for theta=0, 3 * math.pi, math.pi/100 do
      local x, y = spiral(theta)
      -- Adjust the points to be in the middle of the screen, and scale by 20
      love.graphics.point(width / 2 + x * 20, height / 2 + y * 20)
   end
  
   -- Set properties for particle point
   love.graphics.setPoint(10, "smooth")
   love.graphics.setColor(0, 102, 0, 255)
   -- Draw the particle
   love.graphics.point(width / 2 + particle.x * 20, height / 2 + particle.y * 20)
end

function love.update(dt)
   -- Update the theta value. (dt is the time in seconds since update was last called)
   particle.theta = particle.theta + particle.speed * dt
   -- Update the x and y value
   particle.x, particle.y = spiral(particle.theta)
end

function love.load()
   width = love.graphics.getWidth()
   height = love.graphics.getHeight()
   love.graphics.setPoint(3, "smooth")
   love.graphics.setColor(255, 255, 255, 255)
   love.graphics.setBackgroundColor(0, 0, 0)
   
   -- Initialise the particle object
   particle = {
      x = width/2,
      y = height/2,
      speed = math.pi/10,
      theta = 0
   }
end