LibGDX - 自定义类的 Sprite 未显示

Question

我已经尝试了大约 6 个小时了... 我有 2 个类（Player 和 UiButton），它们都是 extends Sprite。 问题是 Player 中的 Sprite 正在渲染，而 UiButton 中的 Sprite 没有强>。

这里，看一下代码：

Player.java（简化）

public class Player extends Sprite
{
    public Player( float posX, float posY )
    {
        super( new Texture( Gdx.files.internal( "character/char_idle.png" ) ) );
        super.setPosition( posX, posY );
    }
}

UiButton.java

import com.badlogic.gdx.Gdx;
import com.badlogic.gdx.graphics.Texture;
import com.badlogic.gdx.graphics.g2d.Sprite;

public class UiButton extends Sprite
{
    public UiButton( Texture texture, float posX, float posY, float rotation )
    {
        super( new Texture( Gdx.files.internal( "ui/arrow.png" ) ) );

        setPosition( posX, posY );
        setRotation( rotation );
    }

    public UiButton( UiButton button )
    {
        super( );
    }

    public void setSize( float toWidth, float toHeight )
    {
        float scaleX = toWidth / super.getWidth( );
        float scaleY = toHeight / super.getHeight( );

        setScale( scaleX, scaleY );
    }

    public boolean isTouched( int touchX, int touchY )
    {
        if( touchX >= getX( ) && touchX <= getX( ) + getWidth( ) )
            if( touchY >= getY( ) && touchY <= getY( ) + getHeight( ) )
                return true;

        return false;
    }

}

GameEngine.java（不是整个文件，而是所需的函数和变量）

public class GameEngine extends ApplicationAdapter implements ApplicationListener
{
    private SpriteBatch spriteBatch;
    private Player      player;
    private Sprite      grid;

    private UiButton arrow_right;
    private UiButton arrow_left;
    private UiButton arrow_down;
    private UiButton arrow_up;

    @Override public void create( )
    {
        /** Setting InputProcessor **/
        InitializeInputProcessor( );

        /** Initializing SpriteBatch **/
        spriteBatch = new SpriteBatch( );
        spriteBatch.maxSpritesInBatch = 10;

        /** Creating UI **/
        GenerateUiArrows( 10, Gdx.graphics.getHeight( ) / 4 );

        /** Creating Player **/
        player = new Player( 100, 100 );

        /** Creating background grid **/
        grid = new Sprite( new Texture( generateGrid( 50 ) ) );
    }

    @Override public void dispose( )
    {
        spriteBatch.dispose( );
    }

    public void doUpdating( )
    {
        player.update( );
    }

    public void doRendering( )
    {
        /** Clearing the screen **/
        Gdx.gl.glClearColor( 1, 1, 1, 1 );
        Gdx.gl.glClear( GL20.GL_COLOR_BUFFER_BIT );

        /** Beginning SpriteBatch rendering **/
        spriteBatch.begin( );

        /** Drawing background grid **/
        grid.draw( spriteBatch );

        /** Drawing Player **/
        player.draw( spriteBatch );

        /** Drawing UI **/
        arrow_right.draw( spriteBatch );
        arrow_left.draw( spriteBatch );
        arrow_down.draw( spriteBatch );
        arrow_up.draw( spriteBatch );

        /** Ending SpriteBatch rendering **/
        spriteBatch.end( );
    }

    @Override public void render( )
    {
        doUpdating( );
        doRendering( );

        /******************************************/
        /** Here was a loop to control framerate **/
        /******************************************/
    }

    private Pixmap generateGrid( int interval )
    {
        /** Creating temporary Pixmap **/
        Pixmap tempMap = new Pixmap( Gdx.graphics.getWidth( ), Gdx.graphics.getHeight( ), Pixmap.Format.RGBA8888 );

        /** Setting lines color to BLACK **/
        tempMap.setColor( Color.BLACK );

        /** Creating horizontal lines **/
        for( int i = interval; i < Gdx.graphics.getWidth( ); i += interval )
            tempMap.drawLine( i, 0, i, Gdx.graphics.getHeight( ) );

        /** Creating vertical lines **/
        for( int i = interval; i < Gdx.graphics.getHeight( ); i += interval )
            tempMap.drawLine( 0, i, Gdx.graphics.getWidth( ), i );

        /** Returning the result **/
        return tempMap;
    }

    private void GenerateUiArrows( float padding, float button_size )
    {
        arrow_right = new UiButton( new Texture( Gdx.files.internal( "ui/arrow.png" ) ), button_size * 2 + padding * 3, padding, 90 );
        arrow_right.setSize( button_size, button_size );

        arrow_left = new UiButton( new Texture( Gdx.files.internal( "ui/arrow.png" ) ), padding, padding, 270 );
        arrow_left.setSize( button_size, button_size );

        arrow_down = new UiButton( new Texture( Gdx.files.internal( "ui/arrow.png" ) ), button_size + padding * 2, padding, 180 );
        arrow_down.setSize( button_size, button_size );

        arrow_up = new UiButton( new Texture( Gdx.files.internal( "ui/arrow.png" ) ), button_size + padding * 2, button_size + padding * 2, 0 );
        arrow_up.setSize( button_size, button_size );
    }

}

不显示错误或警告。只是 UiButtons 没有被渲染。我还没有设置 OrthographicCamera。所以也不应该是这样……

Answer 1

您的问题出在 UiButton 类中的 setSize() 方法中：

    public void setSize( float toWidth, float toHeight )
    {
        //System.out.println("super.width = " + super.getWidth() + ", super.height = " + super.getHeight() ); - you can uncomment it to see the super width/height value in the console

        float scaleX = toWidth / super.getWidth( );
        float scaleY = toHeight / super.getHeight( );

        setScale( scaleX, scaleY );
    }

super.getWidth() 和 super.getHeight() 都返回零（因为您没有为超类对象设置任何宽度/高度）。然后在 scaleX/scaleY 变量中，您有 infinity 值 - 您可以通过取消注释我的代码中的标记行来查看它。

有趣的是，Java 允许您除以浮动零 - 返回提到的 infinity 值 (read more here)，这就是为什么您没有异常的原因。

解决方案是通过调用 super.setSize(width,height) 来修复此方法，或者干脆将其删除并依靠默认的 Sprite 类 setSize() 方法实现。

---

还有一件事 - 解决问题后，您会发现旋转问题 - 它与原点有关。您可以将 setSize 方法更改为

    @Override
    public void setSize(float w, float h)
    {
        super.setSize(w,h);

        setOrigin(w/2f, h/2f);
    }

它会做的事情