# LibGdx效果

libGdx效果

### 橡皮擦除

```java
public class EarserTest extends Group {
    private Image bg = null;
    private Image brush = null;
    private Image cachu = null;
    private FrameBuffer frameBuffer = null;
    private TextureRegion region ;

    public EarserTest(Stage stage) {
        setSize(1080,1920);
//        bg = new Image(new Texture("smiley_color.png"));
        //笔刷是一张20*20的透明图片
        brush = new Image(new Texture("cirwhite.png"));
        //需要擦除的图片
        cachu = new Image(new Texture(Gdx.files.internal("BG.png")));

        //framebuffer
        frameBuffer = new FrameBuffer(Pixmap.Format.RGBA8888, Gdx.graphics.getWidth(), Gdx.graphics.getHeight(), true);

        region = new TextureRegion(frameBuffer.getColorBufferTexture());
        region.flip(false,true);
        //先把被擦除的图片渲染进frameBuffer

        stage.addListener(new ClickListener(){
            @Override
            public void touchDragged(InputEvent event, float x, float y, int pointer) {
                super.touchDragged(event, x, y, pointer);
                System.out.println("-------------");
                brush.setPosition(event.getStageX()*2-brush.getHeight()/2,event.getStageY()*2-brush.getHeight()/2);
            }
        });

        addActor(brush);
        addActor(cachu);
    }

    private boolean isDraw;
    public void drawFrame(Batch batch){
        if (isDraw) {
            return;
        }
        isDraw = true;
        frameBuffer.begin();
        batch.flush();
        cachu.draw(batch,1);
        batch.flush();
        frameBuffer.end();
    }


    @Override
    public void draw(Batch batch, float parentAlpha) {
        drawFrame(batch);
        drawFrameBrush(batch);
        batch.setBlendFunction(GL20.GL_SRC_ALPHA, GL20.GL_ONE_MINUS_SRC_ALPHA);
        batch.draw(region, 0f, 0f);
    }

    private void drawFrameBrush(Batch batch) {
        frameBuffer.begin();
        batch.flush();
        batch.setBlendFunction(GL20.GL_ZERO, GL20.GL_ONE_MINUS_SRC_ALPHA);
        batch.enableBlending();
        brush.draw(batch,1);
        batch.flush();

        frameBuffer.end();
    }
}
```



<img src="C:\Users\Administrator\AppData\Roaming\Typora\typora-user-images\image-20220329141922969.png" alt="image-20220329141922969" style="zoom:50%;" />











### 使用Mesh绘制线



效果：通过拉动贝塞尔曲线上的点控制线的弯曲程度

![image-20220329143120855](C:\Users\Administrator\AppData\Roaming\Typora\typora-user-images\image-20220329143120855.png)