Colour version of exercise 13-5 in Daniel Shiffman’s Learning Processing book (2015: 249). Enjoying the effect: https://www.dropbox.com/s/k3n7y6m85y49rn7/cartesian-spiral.png?dl=0

gistfile1.txt

// Learning Processing
// Daniel Shiffman
// http://www.learningprocessing.com

// Exercise 13-5: Using Example 13-5, draw a spiral path. Start in the center and move 
// outward. Note that this can be done by changing only one line of code and adding one line 
// of code!           

// A Polar coordinate, radius now starts at 0 to spiral outwards
float r = 1; 
float theta = 0;
int c=1;

void setup() {
fullScreen();
  //  size(640, 360);
  background(255);
}

void draw() {

  // Polar to Cartesian conversion
  float x = 2*r * cos(theta);
  float y = 2*r * sin(theta);

  // Draw an ellipse at x,y
  noStroke();
  fill(c*255);
  ellipse(x + width/2, y + height/2, 16, 16); // Adjust for center of window

  // Increment the angle
  theta -= 0.01;
  r -=0.02;
  c--;
}