Android - Math.atan2 的问题

发布于 2024-11-07 22:30:34 字数 1256 浏览 0 评论 0原文

因此，在我使用 andengine 制作的 Android 游戏中，我将其设置为当我触摸并拖动玩家精灵时，它会不断旋转，以便角色始终面向其行进的方向。

public class Player extends AnimatedSprite {
private float lastX = Game.centerX;
private float lastY = Game.centerY;
private static int angle = 0;

// ...

@Override
public boolean onAreaTouched(final TouchEvent sceneTouchEvent, final float touchAreaLocalX, final float touchAreaLocalY) {
    Body body = OrbCatch.physicsWorld.getPhysicsConnectorManager().findBodyByShape(this);
    if (sceneTouchEvent.getAction() == TouchEvent.ACTION_MOVE) {
        float currentX = sceneTouchEvent.getX();
        float currentY = sceneTouchEvent.getY();
        angle = (int) (Math.atan2(currentY - lastY, currentX - lastX) * 180 / Math.PI);
        lastX = currentX;
        lastY = currentY;
    }
    body.setTransform(new Vector2(sceneTouchEvent.getX(),sceneTouchEvent.getY() )
    .mul(1/PhysicsConstants.PIXEL_TO_METER_RATIO_DEFAULT),angle);
    return true;
}

}

关键是：

angle = (int) (Math.atan2(currentY - lastY, currentX - lastX) * 180 / Math.PI)

它获取最后一个已知坐标和当前坐标，计算它们之间的角度，并将其从弧度转换为度数。好吧，昨天一切都工作正常，但尽管今天没有更改任何代码，但它的行为却很奇怪。精灵的方向变化不规则，没有明显的模式。如果我沿直线移动它，它会连续在 2 或 3 个明显不同的角度之间交替（通常其中一个是正确的角度）。

编辑：已解决，见下文

原文

So in my android game I'm making with andengine, I have it set up so as I touch and drag the player sprite, it continously rotates so that the character is always facing the direction it is traveling.

public class Player extends AnimatedSprite {
private float lastX = Game.centerX;
private float lastY = Game.centerY;
private static int angle = 0;

// ...

@Override
public boolean onAreaTouched(final TouchEvent sceneTouchEvent, final float touchAreaLocalX, final float touchAreaLocalY) {
    Body body = OrbCatch.physicsWorld.getPhysicsConnectorManager().findBodyByShape(this);
    if (sceneTouchEvent.getAction() == TouchEvent.ACTION_MOVE) {
        float currentX = sceneTouchEvent.getX();
        float currentY = sceneTouchEvent.getY();
        angle = (int) (Math.atan2(currentY - lastY, currentX - lastX) * 180 / Math.PI);
        lastX = currentX;
        lastY = currentY;
    }
    body.setTransform(new Vector2(sceneTouchEvent.getX(),sceneTouchEvent.getY() )
    .mul(1/PhysicsConstants.PIXEL_TO_METER_RATIO_DEFAULT),angle);
    return true;
}

}

The key line is this:

angle = (int) (Math.atan2(currentY - lastY, currentX - lastX) * 180 / Math.PI)

It takes the last known coordinates and the current coordinates, calculates the angle between them, and converts it from radians to degrees. Well, this was all working fine yesterday, but despite changing none of this code today it's behaving strangely. The sprite's orientation changes erratically, with no apparent pattern. If I move it in a straight path, it continuously alternates between 2 or 3 distinctly different angles(usually one of them is the correct one).

edit: solved, see below

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