10. November 2010

In this assignment we had to animate the forward and backward movement of the ball on the drawn line. Here I had alot of problems defining the PVector numbers and understanding how the work. At first they where initialized wrong so i had errors using the if else statement.

PVector     startPos = new PVector();
PVector     endPos = new PVector();
int         curTime = 0;
int         animSpeed = 5;
int         animTime = 2000;
boolean     drawFlag=false;

boolean forward = true;
PVector pos;
PVector dir;


void setup()
{
  size(640, 480);
  smooth();
}

void draw()
{
  background(51);

  // calc. the anim time
  curTime += animSpeed;
  if(curTime >= animTime){
    forward=!forward;
    curTime = 0;
  }
  
  // calc. the current time in the animation
  float normTime = curTime * 1.0 / animTime;

  if(drawFlag)
  {
    stroke(255);
    line(startPos.x,startPos.y,
         endPos.x,endPos.y);

   if (forward) {
    // calculate the position of the circle on the line
    dir = PVector.sub(endPos,startPos);
    pos = PVector.add( startPos , PVector.mult(dir,normTime));
   
   } else {
     dir = PVector.sub(startPos,endPos);
     pos = PVector.add( endPos , PVector.mult(dir,normTime));
   }
     ellipse(pos.x,pos.y, 20,20);
  }

}

void mousePressed()
{
  drawFlag = true;
  curTime = 0;
  startPos.set(mouseX,mouseY,0);
  endPos = startPos.get();
}

void mouseDragged()
{
  endPos.set(mouseX,mouseY,0);
}

void mouseReleased()
{
  // drawFlag = false;  Makes the line dissapear.
  println("released");
}