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graphic-processing-site-examples-Basics-Math-PolarToCartesian-PolarToCartesian.pde / pde



  
PolarToCartesian by Daniel Shiffman. Convert a polar coordinate (r,theta) to cartesian (x,y): x = r * cos(theta) y = r * sin(theta)

  
   
  float r;
  
  // Angle and angular velocity, accleration
  float theta;
  float theta_vel;
  float theta_acc;
  
  void setup() {
    size(200,200);
    frameRate(30);
    smooth();
    
    // Initialize all values
    r = 50.0f;
    theta = 0.0f;
    theta_vel = 0.0f;
    theta_acc = 0.0001f;
  }
  
  void draw() {
    background(0);
    // Translate the origin point to the center of the screen
    translate(width/2,height/2);
    
    // Convert polar to cartesian
    float x = r * cos(theta);
    float y = r * sin(theta);
    
    // Draw the ellipse at the cartesian coordinate
    ellipseMode(CENTER);
    noStroke();
    fill(200);
    ellipse(x,y,16,16);
    
    // Apply acceleration and velocity to angle (r remains static in this example)
    theta_vel += theta_acc;
    theta += theta_vel;
  
  }
  
  


(C) Æliens 20/2/2008

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