mattdesl · October 10, 2024 22:05
diff --git a/FBOTestLibGDX.java b/FBOTestLibGDX.java
 import com.badlogic.gdx.ApplicationListener;
 import com.badlogic.gdx.Gdx;
 import com.badlogic.gdx.backends.lwjgl.LwjglApplication;
 import com.badlogic.gdx.backends.lwjgl.LwjglApplicationConfiguration;
 import com.badlogic.gdx.graphics.GL10;
 import com.badlogic.gdx.graphics.OrthographicCamera;
 import com.badlogic.gdx.graphics.Pixmap.Format;
 import com.badlogic.gdx.graphics.Texture;
 import com.badlogic.gdx.graphics.g2d.SpriteBatch;
 import com.badlogic.gdx.graphics.g2d.TextureRegion;
 import com.badlogic.gdx.graphics.glutils.FrameBuffer;

 public class FBOTest implements ApplicationListener {

 	public static void main(String[] args) {
 		LwjglApplicationConfiguration cfg = new LwjglApplicationConfiguration();
 		cfg.useGL20 = true;
 		cfg.width = 640;
 		cfg.height = 480;
 		cfg.resizable = false;

 		new LwjglApplication(new FBOTest(), cfg);
 	}

 	Texture atlas;
 	TextureRegion track, thumb;
 	FrameBuffer fbo;
 	TextureRegion fboRegion;

 	SpriteBatch batch;
 	OrthographicCamera cam;

 	@Override
 	public void create() {
 		atlas = new Texture(Gdx.files.internal("data/slider.png"));

 		if (Gdx.gl20 == null)
 			throw new IllegalStateException(
 					"this demo uses GL20 for non-power-of-two and glBlendFuncSeparate");

 		// ideally you would use a texture packer like in LibGDX
 		track = new TextureRegion(atlas, 0, 0, 64, 256);
 		thumb = new TextureRegion(atlas, 65, 0, 64, 128);

 		// for this demo we'll make our frame buffer the same size as our screen
 		// if our device doesn't support NPOT textures, we might get an error
 		// here
 		// also if the screen resizes we'll need to accomodate for that...

 		// the reason we make it the same size is so that we don't need to
 		// upload a new projection
 		// matrix to our SpriteBatch when rendering to the FBO
 		fbo = new FrameBuffer(Format.RGBA8888, Gdx.graphics.getWidth(),
 				Gdx.graphics.getHeight(), false);

 		// this will just be the size of our slider track
 		fboRegion = new TextureRegion(fbo.getColorBufferTexture(), 0, 0,
 				track.getRegionWidth(), track.getRegionHeight());
 		fboRegion.flip(false, true); // FBO uses lower left, TextureRegion uses
 										// upper-left

 		batch = new SpriteBatch();
 		cam = new OrthographicCamera(Gdx.graphics.getWidth(),
 				Gdx.graphics.getHeight());
 		cam.setToOrtho(false);

 		renderSlider();
 	}

 	protected void renderSlider() {
 		// make our offscreen FBO the current buffer
 		fbo.begin();

 		// we need to first clear our FBO with transparent black
 		Gdx.gl.glClearColor(0f, 0f, 0f, 0f);
 		Gdx.gl.glClear(GL10.GL_COLOR_BUFFER_BIT);

 		// start our batch
 		batch.begin();

 		// render some sprites to our offscreen FBO
 		float x = 0;
 		float y = 0;
 		int val = 40; // example value amount

 		// use -1 to ignore.. somebody should fix this in LibGDX :\
 		batch.setBlendFunction(-1, -1);

 		// setup our alpha blending to avoid blending twice
 		Gdx.gl20.glBlendFuncSeparate(GL10.GL_SRC_ALPHA,
 				GL10.GL_ONE_MINUS_SRC_ALPHA, GL10.GL_ONE, GL10.GL_ONE);

 		// draw sprites
 		batch.setColor(1f, 1f, 1f, 1f);
 		batch.draw(track, x, y);
 		batch.draw(thumb, x, y + val);

 		// end (flush) our batch
 		batch.end();

 		// unbind the FBO
 		fbo.end();

 		// now let's reset blending to the default...
 		batch.setBlendFunction(GL10.GL_SRC_ALPHA, GL10.GL_ONE_MINUS_SRC_ALPHA);
 	}

 	@Override
 	public void render() {
 		// nice smooth background color
 		float L = 233 / 255f;
 		Gdx.gl.glClearColor(L, L, L, 1f);
 		Gdx.gl.glClear(GL10.GL_COLOR_BUFFER_BIT);

 		// whenever the slider moves we will need to call renderSlider() to
 		// update the offscreen texture

 		// render the offscreen texture with "premultiplied alpha" blending
 		batch.setBlendFunction(GL10.GL_ONE, GL10.GL_ONE_MINUS_SRC_ALPHA);

 		batch.begin();

 		// due to our different blend funcs we need to use RGBA to specify opacity
 		// tinting becomes unavailable with this solution
 		float a = 0.5f;
 		batch.setColor(a, a, a, a);

 		batch.draw(fboRegion, 0, 0);

 		batch.end();
 	}

 	@Override
 	public void resize(int width, int height) {
 		cam.setToOrtho(false, width, height);
 		batch.setProjectionMatrix(cam.combined);
 	}

 	@Override
 	public void pause() {
 		// TODO Auto-generated method stub

 	}

 	@Override
 	public void resume() {
 		// TODO Auto-generated method stub

 	}

 	@Override
 	public void dispose() {
 		// TODO Auto-generated method stub

 	}

 }
	import com.badlogic.gdx.ApplicationListener;
	import com.badlogic.gdx.Gdx;
	import com.badlogic.gdx.backends.lwjgl.LwjglApplication;
	import com.badlogic.gdx.backends.lwjgl.LwjglApplicationConfiguration;
	import com.badlogic.gdx.graphics.GL10;
	import com.badlogic.gdx.graphics.OrthographicCamera;
	import com.badlogic.gdx.graphics.Pixmap.Format;
	import com.badlogic.gdx.graphics.Texture;
	import com.badlogic.gdx.graphics.g2d.SpriteBatch;
	import com.badlogic.gdx.graphics.g2d.TextureRegion;
	import com.badlogic.gdx.graphics.glutils.FrameBuffer;

	public class FBOTest implements ApplicationListener {

	public static void main(String[] args) {
	LwjglApplicationConfiguration cfg = new LwjglApplicationConfiguration();
	cfg.useGL20 = true;
	cfg.width = 640;
	cfg.height = 480;
	cfg.resizable = false;

	new LwjglApplication(new FBOTest(), cfg);
	}

	Texture atlas;
	TextureRegion track, thumb;
	FrameBuffer fbo;
	TextureRegion fboRegion;

	SpriteBatch batch;
	OrthographicCamera cam;

	@Override
	public void create() {
	atlas = new Texture(Gdx.files.internal("data/slider.png"));

	if (Gdx.gl20 == null)
	throw new IllegalStateException(
	"this demo uses GL20 for non-power-of-two and glBlendFuncSeparate");

	// ideally you would use a texture packer like in LibGDX
	track = new TextureRegion(atlas, 0, 0, 64, 256);
	thumb = new TextureRegion(atlas, 65, 0, 64, 128);

	// for this demo we'll make our frame buffer the same size as our screen
	// if our device doesn't support NPOT textures, we might get an error
	// here
	// also if the screen resizes we'll need to accomodate for that...

	// the reason we make it the same size is so that we don't need to
	// upload a new projection
	// matrix to our SpriteBatch when rendering to the FBO
	fbo = new FrameBuffer(Format.RGBA8888, Gdx.graphics.getWidth(),
	Gdx.graphics.getHeight(), false);

	// this will just be the size of our slider track
	fboRegion = new TextureRegion(fbo.getColorBufferTexture(), 0, 0,
	track.getRegionWidth(), track.getRegionHeight());
	fboRegion.flip(false, true); // FBO uses lower left, TextureRegion uses
	// upper-left

	batch = new SpriteBatch();
	cam = new OrthographicCamera(Gdx.graphics.getWidth(),
	Gdx.graphics.getHeight());
	cam.setToOrtho(false);

	renderSlider();
	}

	protected void renderSlider() {
	// make our offscreen FBO the current buffer
	fbo.begin();

	// we need to first clear our FBO with transparent black
	Gdx.gl.glClearColor(0f, 0f, 0f, 0f);
	Gdx.gl.glClear(GL10.GL_COLOR_BUFFER_BIT);

	// start our batch
	batch.begin();

	// render some sprites to our offscreen FBO
	float x = 0;
	float y = 0;
	int val = 40; // example value amount

	// use -1 to ignore.. somebody should fix this in LibGDX :\
	batch.setBlendFunction(-1, -1);

	// setup our alpha blending to avoid blending twice
	Gdx.gl20.glBlendFuncSeparate(GL10.GL_SRC_ALPHA,
	GL10.GL_ONE_MINUS_SRC_ALPHA, GL10.GL_ONE, GL10.GL_ONE);

	// draw sprites
	batch.setColor(1f, 1f, 1f, 1f);
	batch.draw(track, x, y);
	batch.draw(thumb, x, y + val);

	// end (flush) our batch
	batch.end();

	// unbind the FBO
	fbo.end();

	// now let's reset blending to the default...
	batch.setBlendFunction(GL10.GL_SRC_ALPHA, GL10.GL_ONE_MINUS_SRC_ALPHA);
	}

	@Override
	public void render() {
	// nice smooth background color
	float L = 233 / 255f;
	Gdx.gl.glClearColor(L, L, L, 1f);
	Gdx.gl.glClear(GL10.GL_COLOR_BUFFER_BIT);

	// whenever the slider moves we will need to call renderSlider() to
	// update the offscreen texture

	// render the offscreen texture with "premultiplied alpha" blending
	batch.setBlendFunction(GL10.GL_ONE, GL10.GL_ONE_MINUS_SRC_ALPHA);

	batch.begin();

	// due to our different blend funcs we need to use RGBA to specify opacity
	// tinting becomes unavailable with this solution
	float a = 0.5f;
	batch.setColor(a, a, a, a);

	batch.draw(fboRegion, 0, 0);

	batch.end();
	}

	@Override
	public void resize(int width, int height) {
	cam.setToOrtho(false, width, height);
	batch.setProjectionMatrix(cam.combined);
	}

	@Override
	public void pause() {
	// TODO Auto-generated method stub

	}

	@Override
	public void resume() {
	// TODO Auto-generated method stub

	}

	@Override
	public void dispose() {
	// TODO Auto-generated method stub

	}

	}