libgdx FrameBuffer如何工作

Question

我目前正在使用libgdx开发一个简单的游戏。我正在使用FrameBuffers渲染游戏中的屏幕过渡。该代码正常工作正常。处理屏幕过渡的代码是这样的（它在主游戏类中）：

 @Override
        public void render () {
            float delta = Gdx.graphics.getDeltaTime();

            if (nextScreen == null) { // no transition
                if (currentScreen != null) {
                    currentScreen.render(delta);
                }
            } else {
                transitionInProgress = true;
                transitionTime = Math.min(transitionTime + delta, getTransitionDuration());

                // render to texture only once for performance
                if (!renderedToTexture) {
                    renderScreensToTexture();
                    renderedToTexture = true;
                }

                // update transitions
                updateTransitions();
            }
        }

private void updateTransitions() {

        // transition just finished or no transition is specified
        if (screenTransition == null || transitionTime >= getTransitionDuration()) {

            if (currentScreen != null) {
                currentScreen.hide();
                if (nextScreen != null && !(nextScreen instanceof BaseOverlay)) currentScreen.dispose(); // don't dispose the current screen if next screen is instance of BaseOverlay
            }

            // resume next screen
            if (nextScreen != null) {
                nextScreen.resumeLogic();
                Gdx.input.setInputProcessor(nextScreen.getInputProcessor());
            }

            // switch screens and reset
            currentScreen = nextScreen;
            nextScreen = null;
            screenTransition = null;
            currentFrameBuffer.dispose();
            nextFrameBuffer.dispose();
            currentFrameBuffer = null;
            nextFrameBuffer = null;
            renderedToTexture = false;
            transitionInProgress = false;
            return;

        }
        float percentage = transitionTime / getTransitionDuration();
        Gdx.app.log(TAG, "updateTransitions: " + percentage);

        // the textures are auto disposed when the frame buffer objects are disposed
        Texture currentScreenTexture = currentFrameBuffer.getColorBufferTexture(), nextScreenTexture = nextFrameBuffer.getColorBufferTexture();

        // render transition to screen
        transitionSpriteBatch.setProjectionMatrix(transitionViewport.getCamera().combined);
        screenTransition.render(transitionSpriteBatch, currentScreenTexture, nextScreenTexture, percentage);
    }

private void renderScreensToTexture() {
        if (currentScreen != null) {
            currentFrameBuffer.begin();
            currentScreen.render(0); // 0 to render first frame
            currentFrameBuffer.end();
        }

        if (nextScreen != null) {
            nextFrameBuffer.begin();
            nextScreen.render(0);
            nextFrameBuffer.end();
        }
    }

问题是这样的：过渡不适用于我的屏幕覆盖。我仅通过使用在其render方法中渲染前一个屏幕的屏幕来实现屏幕覆盖。但是一旦开始过渡，叠加层就可以进行完美的过渡，但是下面的屏幕根本无法渲染。我认为这与FrameBuffers有关，但是我最近才了解它们，所以我了解的不多。有什么解决方案？

这是我的屏幕覆盖的代码：

@Override
public void render(float delta) {
    super.render(delta);
    prevScreen.render(delta);   // render the previous screen

    screenUI.renderUI();
}