MyFrameBufferTest.java

package com.orangepixel.framebuffertest;

import com.badlogic.gdx.ApplicationAdapter;
import com.badlogic.gdx.Gdx;
import com.badlogic.gdx.controllers.Controller;
import com.badlogic.gdx.controllers.Controllers;
import com.badlogic.gdx.graphics.GL20;
import com.badlogic.gdx.graphics.OrthographicCamera;
import com.badlogic.gdx.graphics.Texture;
import com.badlogic.gdx.graphics.Pixmap.Format;
import com.badlogic.gdx.graphics.Texture.TextureFilter;
import com.badlogic.gdx.graphics.g2d.SpriteBatch;
import com.badlogic.gdx.graphics.g2d.TextureRegion;
import com.badlogic.gdx.graphics.glutils.FrameBuffer;

public class MyFrameBufferTest extends ApplicationAdapter {

	SpriteBatch batch;
	Texture img;

	FrameBuffer frameBuffer;
	TextureRegion frameBufferRegion = null;

	OrthographicCamera camera;

	boolean created = false;

	@Override
	public void create () {
		batch = new SpriteBatch();
		img = new Texture("badlogic.jpg");

		camera = new OrthographicCamera();
		
		created = true;
		generateFrameBuffers(240, 160);
	}

	@Override
	public void render () {

		frameBuffer.begin();

		Gdx.gl.glClearColor(0.1f, 0, 0.6f, 1);
		Gdx.gl.glClear(GL20.GL_COLOR_BUFFER_BIT);

		camera.setToOrtho(true, frameBuffer.getWidth(), frameBuffer.getHeight());
		camera.update();

		Gdx.gl.glClearColor(1.0f, 1.0f, 1.0f, 255 / 255.0f);

		batch.begin();
		batch.draw(img, 0, 0);
		batch.end();

		frameBuffer.end();

		camera.setToOrtho(true, Gdx.graphics.getWidth(), Gdx.graphics.getHeight());
		camera.update();

		// render pixel-art buffer to screen
		batch.setProjectionMatrix(camera.combined);
		batch.begin();
		batch.setBlendFunction(GL20.GL_SRC_ALPHA, GL20.GL_ONE_MINUS_SRC_ALPHA);
		batch.setColor(1, 1, 1, 1);
		batch.draw(frameBufferRegion, 0, 0, Gdx.graphics.getWidth(), Gdx.graphics.getHeight());
		batch.end();
	}

	@Override
	public void dispose () {
		img.dispose();
		batch.dispose();
		if (frameBuffer != null) {
			frameBuffer.dispose();
		}
	}

	@Override
	public void resize (int width, int height) {
		// the problem, moving this to outside resize will also fix the problem
		generateFrameBuffers(width, height);
	}

	public final void generateFrameBuffers (int width, int height) {
		if (!created) return;
		if (frameBuffer != null)
			frameBuffer.dispose();
		
		frameBuffer = new FrameBuffer(Format.RGB888, width, height, false);
		frameBuffer.getColorBufferTexture().setFilter(TextureFilter.Nearest, TextureFilter.Nearest);
		frameBufferRegion = new TextureRegion(frameBuffer.getColorBufferTexture(), 0, 0, width, height);
		frameBufferRegion.flip(false, false);
	}

}