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Luke Franzke

Luke Franzke

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In this simple programmeprogram, we animate an ellipse to always chase a point defined by the mouse. The ellipse only ever moves a percentage of the distance between it and the mouse target destination in each step.

The PVector object is used to handle the coordinates and the simple math operations.

Code Block
PVector pos;
PVector targetPos;
float  easingFactor = 0.1;
   
PVector mousePos;
void setup() {
  size(8001000, 600);
   fill(0);
  pos = new PVector(0, 0);
  targetPos = new PVector(0, 0);
}
  
  mousePos = new PVector(width/2, height/2);
}

void draw() { 
  background(255);
  targetPos.set(mouseX,mouseYmousePos); 
  targetPos = PVector.sub(targetPos, pos);  // find the distancevector between mouse position and ellipse position on the x an y axis
  targetPos.mult(.2); // each step in the animation will move this percentage of the distance to the target position
  pos.add(targetPos);
  ellipse(pos.x, pos.y, 60, 60);
}
void mousePressed() {
  mousePos.set(mouseX, mouseY);
};


Exercise 10

Add an additional ellipse that follows the mouse at a slower rate than the first ellipse. 

Modify the code so that the ellipse always follows the mouse position.  

Replace with the ellipse with another shape (like a triangle or even a car) , and keep it pointed towards the mouse.

Exercise Solution Using Arrays

Code Block
collapsetrue
PVector[] pos;
PVector[] targetPos;
PVector mousePos;
int arrayLength = 5;
void setup() {
  size(1000, 600);
  fill(0);

  pos = new PVector[arrayLength];
  targetPos = new PVector.mult(targetPos, easingFactor); // multiply the distance by the easingFactor to slow it down
  if(targetPos.mag() > .5) { 
//magnitude is always an absolute number, so we don't need to use the abs() function 
  pos = PVector.add(pos,targetPos);
  }[arrayLength];

  for (int i = 0; i<pos.length; i++) { 
    pos[i] = new PVector(0, 0);
    targetPos[i] = new PVector(0, 0);
  }
  mousePos = new PVector(width/2, height/2);
}

void draw() {
    mousePos.set(mouseX, mouseY);
  background(255);
  
    for (int i = 0; i<pos.length; i++) { 
        targetPos[i].set(mousePos); 
        targetPos[i].sub(pos[i]);  // find the vector between mouse position and ellipse position
        targetPos[i].mult((i*0.02)+.02); // each step in the animation will move this percentage of the distance to the target position
        pos[i].add(targetPos[i]);
        ellipse(pos[i].x, pos[i].y, 60, 60);
    }
}


Solution using a class. 

classExample.zip