float x1,y1,x2,y2;
float x,y,xD,yD;
int steps,count;

void setup() {
  size(400,400);
  framerate(20);
  
  x1=50;
  y1=50;
  x2=150;
  y2=350;
  xD=x2-x1;
  yD=y2-y1;
  
  x=x1;
  y=y1;
  
  steps=100;
  xD=xD/(float)steps;
  yD=yD/(float)steps;
  count=0;
  
  ellipseMode(CENTER_DIAMETER);
}

void loop() {
  ellipse(x,y, 20,20);
  if(count<steps) {
    x=x+xD;
    y=y+yD;
  }
  count++;
}