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



  
Arctangent. Move the mouse to change the direction of the eyes. The atan2() function computes the angle from each eye to the cursor.

  
   
  Eye e1, e2, e3, e4, e5;
  
  void setup() 
  {
    size(200, 200);
    smooth();
    noStroke();
    e1 = new Eye( 50,  16,  80);
    e2 = new Eye( 64,  85,  40);  
    e3 = new Eye( 90, 200, 120);
    e4 = new Eye(150,  44,  40); 
    e5 = new Eye(175, 120,  80);
  }
  
  void draw() 
  {
    background(102);
    
    e1.update(mouseX, mouseY);
    e2.update(mouseX, mouseY);
    e3.update(mouseX, mouseY);
    e4.update(mouseX, mouseY);
    e5.update(mouseX, mouseY);
  
    e1.display();
    e2.display();
    e3.display();
    e4.display();
    e5.display();
  }
  
  class Eye 
  {
    int ex, ey;
    int size;
    float angle = 0.0;
    
    Eye(int x, int y, int s) {
      ex = x;
      ey = y;
      size = s;
   }
  
    void update(int mx, int my) {
      angle = atan2(my-ey, mx-ex);
    }
    
    void display() {
      pushMatrix();
      translate(ex, ey);
      fill(255);
      ellipse(0, 0, size, size);
      rotate(angle);
      fill(153);
      ellipse(size/4, 0, size/2, size/2);
      popMatrix();
    }
  }
  
  


(C) Æliens 20/2/2008

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