Blade diagonal;

void setup () {
  size (500, 360);
  diagonal = new Blade (30, 80);
}

void draw(){
  diagonal.grow();
}

void mouseMoved(){
  diagonal.seed(mouseX, mouseY);
}

class Blade {
  float x, y;
  
  Blade (int xpos, int ypos){
    x = xpos;
    y = ypos;
  }
  
  void seed (int xpos, int ypos) {
    x = xpos;
    y = ypos;
  }
  
  void grow() {
    x += 0.5;
    y -= 1.0;
    point(x, y);
  }
}