子类不显示处理

Question

我正在做一项作业，需要创建一棵基础 class 树和子 class 花。但我不知道我在哪里弄错了，按下鼠标时树上没有出现花，只有树出现了。到目前为止，这是我的代码，

Tree tree;
ArrayList<Tree> treeList = new ArrayList<Tree>();

Flower flowers;
ArrayList <Flower> flowerList = new ArrayList<Flower>();

void setup() {
  size(800, 800);
  tree = new Tree(mouseX, mouseY, HALF_PI, height/12);
  flowers = new Flower(mouseX, mouseY, HALF_PI, height/12);
}

void draw() {
  background(255);

  //current tree
  for (int j =0; j < treeList.size(); j++)
  {
    tree = treeList.get(j);
    tree.drawTree(tree.xPos, tree.yPos, tree.rotation, tree.tall);
  }

  //current flower
  for(int i = 0; i < flowerList.size(); i ++){
    flowers = flowerList.get(i);
    flowers.drawFlower();
  }
drawMouseTree(mouseX, mouseY, HALF_PI, height/12);

}

void mousePressed() {
  treeList.add(new Tree(mouseX, mouseY, HALF_PI, height/12));
  flowerList.add(new Flower(mouseX, mouseY, HALF_PI, height/12));
}

void drawMouseTree(float xPos, float yPos, float rotation, float tall) {
  //growing branch 
  float endX = xPos - tall * cos(rotation);
  float endY = yPos - tall * sin(rotation);

  //draw a tree
  stroke(0);
  strokeWeight(2);
  line(xPos, yPos, endX, endY);

  //create 2 branches 
  if (tall > 5 ) {
    drawMouseTree(endX, endY, rotation - PI/5, tall * 0.7); //left
    drawMouseTree(endX, endY, rotation + PI/5, tall * 0.7); //right
  }

  //create flowers each branch
  if (tall > 5 ) {

    stroke(255,102,178);
    fill(255, 102, 178);
    ellipse(endX, endY, 5, 5);
  }
}


class Tree {
  float xPos, yPos;
  float rotation;
  float tall, endX, endY;

  Tree(float xPos, float yPos, float rotation, float tall) {
    this.xPos = xPos;
    this.yPos = yPos;
    this.rotation = rotation;
    this.tall = tall;
  }

  void drawTree(float xPos, float yPos, float rotation, float tall) {
    //end of a branch
    float endX = xPos - tall * cos(rotation);
    float endY = yPos - tall * sin(rotation);

    //draw a tree
    stroke(0);
    strokeWeight(2);
    line(xPos, yPos, endX, endY);

    //create 2 branches 
    if (tall > 5) {
      drawTree(endX, endY, rotation - PI/5, tall * 0.7); //left
      drawTree(endX, endY, rotation + PI/5, tall * 0.7); //right
    }
  }
}

class Flower extends Tree {

  Flower(float xPos, float yPos, float rotation, float tall) {
    super(xPos, yPos, rotation, tall);
  }


  void drawFlower() {
    super.drawTree(xPos, yPos, rotation, tall);

    //create flowers each branch
    if (tall < 40 && tall > 5) { //so the flowers will appear around top of tree


      stroke(255, 102, 178);
      fill(255, 102, 178);
      ellipse(endX, endY, 5, 5);
    }
  }
}

我对 super-child class 概念还是陌生的。非常感谢任何解决此问题的帮助！

编辑： 找出我在 drawFlower() 中使用 endX, endY 的错误。这是新代码：

class Flower extends Tree {

  Flower(float xPos, float yPos, float rotation, float tall) {
    super(xPos, yPos, rotation, tall);
  }

  void drawFlower() {
    super.drawTree(xPos, yPos, rotation, tall);
    //create flowers each branch

    if (tall > 5 ) {
      //draw flower

      stroke(255, 102, 178);
      fill(255, 102, 178);
      ellipse(finX, finY, 5, 5);

    }
  }
}
class Tree {
  float xPos, yPos;
  float rotation;
  float tall, finX, finY;

  Tree(float xPos, float yPos, float rotation, float tall) {
    this.xPos = xPos;
    this.yPos = yPos;
    this.rotation = rotation;
    this.tall = tall;
  }

  void drawTree(float xPos, float yPos, float rotation, float tall) {
    //end of a branch
    float endX = xPos - tall * cos(rotation);
    float endY = yPos - tall * sin(rotation);
    finX = endX;
    finY = endY;

    //draw a tree
    stroke(0);
    strokeWeight(2);
    line(xPos, yPos, endX, endY); //branch

    //create 2 branches 
    if (tall > 5) {

      drawTree(endX, endY, rotation - PI/5, tall * 0.7); //left
      drawTree(endX, endY, rotation + PI/5, tall * 0.7); //right
    }
  }
}

然而，结果是：http://i.imgur.com/gNLeKsB.png 无论如何，树的 每个末端分支 都有一朵花吗？像这样：http://i.imgur.com/wz2iNgP.png

Answer 1

你的window的height是800。

您传递给 Tree 或 Flower 构造函数的最后一个参数是 height/12.

800/12 是 66.6666...，它被截断为 66。

换句话说，tall 变量保存值 66。然后，您在此 if 语句中使用该变量：

if (tall < 40 && tall > 5) {

此 if 语句永远不会计算为真，因为 66 不小于 40.

您可以轻松地自行测试，只需在 if 语句之前打印出 tall 的值：

println(tall);

即使你把if那句话评论出来，你也看不到花。同样，println() 函数来拯救：

  stroke(255, 102, 178);
  fill(255, 102, 178);
  println(endX + ", " + endY); //prints 0.0, 0.0
  ellipse(endX, endY, 50, 50);

此时endX和endY的值总是0。这对您如何使用它们很有意义。

我明白你的意思了，但此时在代码中你实际上无法访问分支的结束位置。

如果我是你，我会从简单的开始。不要使用递归函数来绘制树，而是从顶部有一朵花的单行开始，然后从那里开始。

子类不显示处理

Subclass doesn't display Processing

processing

tree

superclass

flower

display