在libGDX中获取Actor的舞台坐标

2022-01-12 00:00:00 coordinates java libgdx

我想创建一个浮动帮助气泡来介绍我的游戏的基本功能.这个气泡应该漂浮在我想要解释的 Actor 上方，如下图所示.

I want to create a floating help bubble to introduce the basic functioning of my game. This bubble should float above the Actor I want it to explain, like shown in the picture below.

为此，我需要 Actor 的坐标，在本例中为左按钮，然后我可以将气泡 Actor 添加到舞台上其他所有内容的前面.最后一部分很简单，但我正在努力检索按钮的实际坐标，因为它在表格中.

To accomplish this, I want the coordinates of the Actor, in this case the left button, and then I can add the bubble Actor to the Stage in front of everything else. The last part is easy enough, but I'm struggling with retrieving the actual coordinates of the button, as it is in a table.

这两个按钮被添加到一个表格中，如下所示:

The two buttons are added to a Table like this:

t.add(btnLab).expandX().center();
t.add(btnSea).expandX().center();

我尝试了最明显的方法:

I've tried the most obvious approach:

Vector2 loc = new Vector2(a.getX(), a.getY());
System.out.println("Loc: " + loc);
a.localToStageCoordinates(loc);
System.out.println("Loc: " + loc);

这给了我(按系统输出的顺序):[0.0, 0.0] 和 [40.0, 130.0].最后一个位置其实就是Table的位置，填满了屏幕的蓝色区域.所以这个位置显然遗漏了 Table 用来放置 Actor 的一些东西，并且不能使用(因为我最终只得到了 Table 的位置).

This gives me (in the order of the sysouts): [0.0, 0.0] and [40.0, 130.0]. The last position is actually the position of the Table, which fills the blue area of the screen. So this location obviously misses something the Table does to place the Actor, and cannot be used (as I only end up with the location of the Table).

(我也尝试在这里使用 t.localToStageCoordinates，t 是表格.结果相同.)

(I've also tried using t.localToStageCoordinates here, t being the Table. Same results.)

我尝试的另一个解决方案是递归搜索所有父母:

Another solution I tried was to recursively search through all Parents:

private static Vector2 getLoc(Actor a) {
    return getLoc(new Vector2(a.getX(), a.getY()), a.getParent());
}

private static Vector2 getLoc(Vector2 loc, Actor g) {
    System.out.println("Location: " + loc + ", Actor: " + g);
    loc.x += g.getX();
    loc.y += g.getY();
    if(g.getParent() == null) return loc;
    return getLoc(loc, g.getParent());
}

不幸的是，这给了我同样的结果.sysouts 提供以下信息:

Unfortunately, this gives me the same. The sysouts gives the following:

Location: [0.0:0.0], Actor: Table 40.0,130.0 944.0x508.0
Location: [40.0:130.0], Actor: Group 0.0,0.0 0.0x0.0
Location: [40.0:130.0], Actor: Group 0.0,0.0 0.0x0.0

所以我似乎无法获得表格中组/演员的实际位置.

So I can't seem to get the actual positions of the Groups/Actors within the Table.

我该怎么做?

推荐答案

我想我明白你在哪里弄糊涂了.获取演员的舞台坐标实际上非常简单(假设屏幕对齐、未旋转、未缩放演员).

I think I understand where you got confused. It is actually very simple to get the stage coordinates of an actor (assuming screen aligned, unrotated, unscaled actors).

您需要做的就是:

public static Vector2 getStageLocation(Actor actor) {
    return actor.localToStageCoordinates(new Vector2(0, 0));
}

您做错的事情是尝试获取演员相对于桌子的位置(通过使用 actor.getX() 和 actor.getY())，然后将该位置转换为舞台.这最终会为您提供桌子的位置，因为它将添加演员的位置.你真正要知道你的演员内部的新向量2(0，0)点在哪里.这告诉你演员的左下角在哪里.如果你想要左上角，你可以使用 new Vector2(0, actor.getHeight())，并以类似的方式使用其他角.

What you are doing wrong is trying to get the location of the actor relative to the table (by using actor.getX() and actor.getY()), and then transform that location to the stage. That will end up giving you the location of table because it will be adding the location of the actor. What you really what is to know where point new Vector2(0, 0) inside your actor is. This tells you where the bottom left corner of the actor is. If you want top left you would use new Vector2(0, actor.getHeight()), and the other corners in a similar manner.

此外，如果您正在处理活动并想知道活动的舞台位置，您只需执行以下操作:

Additionally, if you are working with events and want to know the stage location of an event you would simply do the following:

@Override public void touchUp(final InputEvent event, final float x, final float y, final int pointer, final int button) {
    if (pointer == Buttons.LEFT) {
        Gdx.app.log("Event", "x: " + event.getStageX() + " y: " + event.getStageY());
    }
}

有关更完整的示例，请查看以下代码:

For a more complete example look at the following code:

import com.badlogic.gdx.ApplicationListener;
import com.badlogic.gdx.Gdx;
import com.badlogic.gdx.graphics.GL20;
import com.badlogic.gdx.math.Vector2;
import com.badlogic.gdx.scenes.scene2d.InputEvent;
import com.badlogic.gdx.scenes.scene2d.Stage;
import com.badlogic.gdx.scenes.scene2d.ui.*;
import com.badlogic.gdx.scenes.scene2d.utils.ClickListener;

public class ActorStage implements ApplicationListener {
    private Stage stage;
    private Skin skin;

    @Override public void create() {
        Gdx.app.log("CREATE", "App Opening");

        this.stage = new Stage(Gdx.graphics.getWidth(), Gdx.graphics.getHeight(), false);
        Gdx.input.setInputProcessor(this.stage);

        this.skin = new Skin(Gdx.files.internal("skin/uiskin.json"));
        this.skin.hashCode();

        final Table table = new Table();
        table.setFillParent(true);

        final Button btnLab = new TextButton("Lab", skin);
        final Button btnSea = new TextButton("Sea", skin);


        setupButton(table, btnLab);
        setupButton(table, btnSea);

        this.stage.addActor(table);

        Gdx.gl20.glClearColor(0f, 0f, 0f, 1);
        Gdx.gl20.glBlendFunc(GL20.GL_SRC_ALPHA, GL20.GL_ONE_MINUS_SRC_ALPHA);
    }

    private void setupButton(Table table, final Button button) {
        table.add(button).expandX().center();

        button.addListener(new ClickListener() {
            @Override public void clicked(InputEvent event, float x, float y) {
                Gdx.app.log("XY", "[" + x + ", " + y + "]");
                Gdx.app.log("Event", "[" + event.getStageX() + ", " + event.getStageY() + "]");
                Gdx.app.log("Actor", "[" + button.getX() + ", " + button.getY() + "]");

                Vector2 loc = new Vector2(button.getX(), button.getY());
                Vector2 stageLoc = button.localToStageCoordinates(loc);
                Gdx.app.log("ActorStage", "[" + stageLoc.x + ", " + stageLoc.y + "]");

                Vector2 zeroLoc = button.localToStageCoordinates(new Vector2());
                Gdx.app.log("ZeroStage", "[" + zeroLoc.x + ", " + zeroLoc.y + "]");
            }
        });
    }

    @Override public void render() {
        this.stage.act();

        Gdx.gl20.glClear(GL20.GL_COLOR_BUFFER_BIT);
        Gdx.gl20.glEnable(GL20.GL_BLEND);

        this.stage.draw();
    }

    @Override public void dispose() {
        Gdx.app.log("DISPOSE", "App Closing");
    }

    @Override public void resize(final int width, final int height) {
        Gdx.app.log("RESIZE", width + "x" + height);
        Gdx.gl20.glViewport(0, 0, width, height);
        this.stage.setViewport(width, height, false);
    }

    @Override public void pause() {}

    @Override public void resume() {}
}

点击一次btnLab，点击一次btnSea，然后关闭窗口，输出:

When clicking btnLab once, clicking btnSea once and then closing the window, outputs:

CREATE: App Opening
RESIZE: 800x600
XY: [18.0, 13.0]
Event: [200.0, 296.0]
Actor: [182.0, 283.0]
ActorStage: [364.0, 566.0]
ZeroStage: [182.0, 283.0]
XY: [6.0, 23.0]
Event: [588.0, 306.0]
Actor: [582.0, 283.0]
ActorStage: [1164.0, 566.0]
ZeroStage: [582.0, 283.0]
DISPOSE: App Closing

如您所见，您需要ZeroStage"消息，因为它可以为您提供演员在舞台上的位置.

As you can see you want the "ZeroStage" message because that gives you the location of the actor on the stage.

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