(十一)processing中的向量运算方法

    //实现弹球程序
    PVector location;
    PVector veclocity;
    
    void setup(){
      size(480, 100);
      smooth();
      location = new PVector(random(0, width), random(0, height));
      veclocity = new PVector(0.5, 1);
      frameRate(180);
    }
    
    void draw(){
      background(255);
      location.add(veclocity);
      
      if((location.x > width) || (location.x < 0)){
        veclocity.x = veclocity.x*-1;
      }
      if((location.y > height) || (location.y < 0)){
        veclocity.y = veclocity.y*-1;
      }
      noStroke();
      fill(255, 255, 0, 255);