我最近尝试进入游戏编程。我对 Java 很有经验，但对游戏编程没有经验。我读了 http://www.koonsolo.com/news/dewitters-gameloop/并使用以下代码实现了那里提出的游戏循环:

private static int UPDATES_PER_SECOND = 25;
private static int UPDATE_INTERVAL = 1000 / UPDATES_PER_SECOND * 1000000;
private static int MAX_FRAMESKIP = 5;

public void run() {
    while (true) {
        int skippedFrames = 0;
        while (System.nanoTime() > this.nextUpdate && skippedFrames < MAX_FRAMESKIP) {
            this.updateGame();
            this.nextUpdate += UPDATE_INTERVAL;
            skippedFrames++;
        }

        long currentNanoTime = System.nanoTime();
        double interpolation = (currentNanoTime + UPDATE_INTERVAL - this.nextUpdate) / UPDATE_INTERVAL;
        this.repaintGame(interpolation);
    }
}

If in the 10Th gametick the position is 500, and the speed is 100, then in the 11Th gametick the position will be 600. So where will you place your car when you render it? You could just take the position of the last gametick (in this case 500). But a better way is to predict where the car would be at exact 10.3, and this happens like this:
view_position = position + (speed * interpolation)
The car will then be rendered at position 530.

private static int UPDATES_PER_SECOND = 25;
private static int UPDATE_INTERVAL = 1000 / UPDATES_PER_SECOND * 1000000;
private static int MAX_FRAMESKIP = 5;

private long nextUpdate = System.nanoTime();

public void run() {
    while (true) {
        int skippedFrames = 0;
        while (System.nanoTime() > this.nextUpdate && skippedFrames < MAX_FRAMESKIP) {
            long delta = UPDATE_INTERVAL;
            this.currentState = this.createGameState(delta);
            this.newPredictedNextState = this.createGameState(delta + UPDATE_INTERVAL, true);

            this.nextUpdate += UPDATE_INTERVAL;
            skippedFrames++;
        }

        double interpolation = (System.nanoTime() + UPDATE_INTERVAL - this.nextUpdate) / (double) UPDATE_INTERVAL;
        this.repaintGame(interpolation);
    }
}

public GameState createGameState(long delta, boolean ignoreNewInput) {
    //Handle User Input and stuff if ignoreNewInput=false

    GameState newState = this.currentState.copy();
    Sprite charSprite = newState.getCharacterSprite();
    charSprite.moveByX(charSprite.getMaxSpeed() * delta * charSprite.getMoveDirection().getX()); 
    //getMoveDirection().getX() is 1.0 when the right arrow key is pressed, otherwise 0.0
}

public void paint(Graphics g) {
    super.paint(g);

    Graphics2D g2d = (Graphics2D) g;

    Sprite currentCharSprite = currentGameState.getCharacterSprite();
    Sprite nextCharSprite = predictedNextState.getCharacterSprite(); 
    Position currentPos = currentCharSprite.getPosition();
    Position nextPos = nextCharSprite.getPosition();
    //Interpolate position
    double x = currentPos.getX() + (nextPos.getX() - currentPos.getX()) * this.currentInterpolation;
    double y = currentPos.getY() + (nextPos.getY() - currentPos.getY()) * this.currentInterpolation;
    Position interpolatedCharPos = new Position(x, y);
    g2d.drawImage(currentCharSprite.getImage(), (int) interpolatedCharPos.getX(), (int) interpolatedCharPos.getY(), null);
}

最佳答案

不要将您的游戏逻辑建立在更新间隔恒定的假设之上。包括一个精确测量两次更新之间耗时的游戏时钟。然后，您可以根据延迟进行所有计算，而不必担心实际更新率。

在这种情况下，汽车速度将以单位/秒为单位给出，增量将是自上次更新以来的总秒数:

car.position += car.velocity * delta;

关于java - "deWiTTERS Game Loop"是否假设不间断电源？，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/15100348/