Java 在FBO中进行遮罩时背景不可见

我试图在LibGDX中将前景纹理遮罩到背景纹理上。在屏幕上绘制时效果很好，但在FBO中绘制时背景消失

以下是如何绘制遮罩：

batch.draw(background, x, y);
batch.flush();

Gdx.gl.glColorMask(false, false, false, true);
batch.setBlendFunction(GL20.GL_ONE, GL20.GL_ZERO);
batch.draw(mask, x, y);
batch.flush();

Gdx.gl.glColorMask(true, true, true, true);
batch.setBlendFunction(GL20.GL_DST_ALPHA, GL20.GL_ONE_MINUS_DST_ALPHA);
batch.draw(foreground, x, y);
batch.flush();

batch.setBlendFunction(GL20.GL_SRC_ALPHA, GL20.GL_ONE_MINUS_SRC_ALPHA);

下面是我如何绘制常规的和FBO的：

常规

batch.begin();
batch.enableBlending();
batch.setProjectionMatrix(camera.combined);

drawFull(32, 600 - (64 * 4) - 32);

batch.end();

FBO

// draw the FB mask

fb.begin();
batch.begin();
batch.setProjectionMatrix(fbcamera.combined);
batch.enableBlending();

Gdx.gl.glClear(GL20.GL_COLOR_BUFFER_BIT);

drawFull(0, 0);

batch.end();
fb.end();

// draw the FB mask to the main batch

batch.begin();
batch.enableBlending();
batch.setProjectionMatrix(camera.combined);

batch.draw(fb.getColorBufferTexture(), 32, 600 - (64 * 7) - 32);

batch.end();

---

我在将FBO绘制到屏幕时禁用了混合，从而解决了这个问题。这样做的缺点是我们不能用不透明度绘制FBO

// draw the FB mask to the main batch

batch.begin();
batch.disableBlending();
batch.setProjectionMatrix(camera.combined);

batch.draw(fb.getColorBufferTexture(), 32, 600 - (64 * 7) - 32);

batch.end();