java - 如何在 Java 中平滑地移动图形对象 360 度？

Question

我正在尝试制作一款几何 war 风格的游戏，但遇到了障碍。我一直在试图找出一种方法来平滑地移动我的图形对象。但它只向一个方向移动。例如，如果我按向上按钮，那么它就会上升，然后当我按其顶部的右侧按钮时，我会沿对角线向右上角移动。但我希望我的对象能够顺利地从直线向上转向右上角。这是我到目前为止的代码:

public class MoveTest extends JPanel implements ActionListener, KeyListener {

Timer t = new Timer(5, this);
double x = 0, y = 0, velX = 0, velY = 0;
 private Set<Integer> pressed = new HashSet<Integer>();
private static int WIDTH = 800;
private static int HEIGHT = 600;
private double d = 0;
private double topSpeed = 0;
private boolean stop = false;
private double a = 0;

PVector location;
PVector velocity;
PVector acceleration;

public MoveTest() {
  location = new PVector(WIDTH/2,HEIGHT/2);
  velocity = new PVector(0,0);
  acceleration = new PVector(0,0);
  topSpeed = 5.0;
  t.start();
  addKeyListener(this);
  setFocusable(true);
  setFocusTraversalKeysEnabled(false);
}

public void paintComponent(Graphics g) {
  super.paintComponent(g);
  Graphics2D g2 = (Graphics2D) g;
  g2.setColor(Color.GREEN);
  g2.drawOval((int)location.x, (int)location.y, 40, 40);
}

void update() {
  velocity.add(acceleration);
  if(stop == false) {
    velocity.limit(topSpeed);
  }
  else {
    velocity.decellerate(0);
  }
  location.add(velocity);    
}

public void north() {
  acceleration = new PVector(0,-5);
}

public void south() {
  acceleration = new PVector(0,5);
}

public void west() {
  acceleration = new PVector(-5,0);
}

public void east() {
  acceleration = new PVector(5,0);
}

public void northEast() {
  acceleration = new PVector(5,-5);
}

public void northWest() {
  acceleration = new PVector(-5,-5);
}

public void southEast() {
  acceleration= new PVector(5,5);
}

public void southWest() {
  acceleration = new PVector(-5,5);
}

public void stop(){
  stop = true;
}


public void actionPerformed(ActionEvent arg0) {
  //System.out.println("" + velocity.x + " " + velocity.y);
  repaint();
  update();
  checkEdges();
}

public void keyPressed(KeyEvent e) {

int code = e.getKeyCode();

stop = false;

pressed.add(code);

if(pressed.size() > 1) {
  if(pressed.contains(KeyEvent.VK_W) && pressed.contains(KeyEvent.VK_D)) {
    northEast();
  }
  if(pressed.contains(KeyEvent.VK_W) && pressed.contains(KeyEvent.VK_A)) {
    northWest();
  }
  if(pressed.contains(KeyEvent.VK_S) && pressed.contains(KeyEvent.VK_D)) {
    southEast();
   }
  if(pressed.contains(KeyEvent.VK_S) && pressed.contains(KeyEvent.VK_A)) {
    southWest();
  } 
}

else if(pressed.size() == 1){
  if(code == KeyEvent.VK_W) {
    north();
  }
  if(code == KeyEvent.VK_S) {
    south();
  }
  if(code == KeyEvent.VK_D) {
    east();
  }
  if(code == KeyEvent.VK_A) {
    west();
  }
}
}

public void keyReleased(KeyEvent e) {
  pressed.remove(e.getKeyCode());
  if(pressed.size() == 0) {
    stop();
  }
}

public void keyTyped(KeyEvent e) {

}

void checkEdges() {
  if(location.x > WIDTH) {
    location.x = 0;
  }
  else if(location.x < 0) {
    location.x  = WIDTH;
  }
  if(location.y > HEIGHT) {
    location.y = 0;
  }
  else if(location.y < 0) {
    location.y = HEIGHT;
  }
}

}

如有任何帮助，我们将不胜感激。

Answer 1

//MoveTest
topSpeed = 5.0;

//update
velocity.add(acceleration);
if(stop == false) {
  velocity.limit(topSpeed);

//south
acceleration = new PVector(0,5);

因此，如果您按下按键，您的加速度始终为 5 或 7(这可能是一个错误)单位。然后将其添加到速度中，速度限制为 5。您的加速度非常强，几乎没有惯性。尝试较小的加速度或较大的 topSpeed，它应该会变得更平滑。

旁白:你们会补偿帧速率吗？我在您的代码中没有看到它，但我不知道 PVector 实现。