Develop Reference

Libgdx | Framebuffer not displaying anything when drawn

I am trying to draw a bunch of tiles (10,000 sprites) for a minimap. It lags on android when drawing individually, so I am trying to use a framebuffer. For some reason, I can't get anything drawn to the screen with the buffer. I will show the relevant code.
buffer = new FrameBuffer(Pixmap.Format.RGBA8888, Main.VIRTUAL_WORLD_WIDTH, Main.VIRTUAL_WORLD_HEIGHT, false);
OrthographicCamera cam = new OrthographicCamera(Main.VIRTUAL_WORLD_WIDTH, Main.VIRTUAL_WORLD_HEIGHT);
buffer.begin();
batch.begin();
batch.setProjectionMatrix(cam.combined);
for(Tile[] tiles : world.level.getGrid()){
for(Tile tile : tiles){
tile.getSprite().draw(batch);
}
}
batch.end();
buffer.end();
tiles = new Sprite(buffer.getColorBufferTexture());
The above code creates the framebuffer in the create method.
And this renders
batch.setProjectionMatrix(camera.combined);
batch.begin();
tiles.draw(batch);
batch.end();
Note, The position of the tiles sprite is 0, 0. I have tried changing all kids of stuff with this code, but can never get it to draw on the screen. The actual tiles aren't a problem, they all function correctly. My camera is setup correctly, so are my viewports.

libgdx - snap sprite to cursor

I am currently trying to snap a crosshair sprite to my game's cursor using libgdx. The game is top-down view:
Texture crosshair_text = new Texture(Gdx.files.internal("data/crosshair1.png"));
this.crosshair = new Sprite(crosshair_text, 0, 0, 429, 569);
//...
#Override
public void render() {
Gdx.gl.glClearColor(1, 1, 1, 1);
Gdx.gl.glClear(GL10.GL_COLOR_BUFFER_BIT);
cam.update();
batch.setProjectionMatrix(cam.combined);
batch.begin();
//.. sprites that scale based on camera (top-down view)
batch.end();
//draws 'ui' elements
floatingBatch.begin();
//...
//snap to cursor
this.crosshair.setPosition( Gdx.input.getX(), (Gdx.graphics.getHeight()-Gdx.input.getY()) );
//transform
this.crosshair.setScale(1/cam.zoom);
//draw
this.crosshair.draw(floatingBatch);
floatingBatch.end();
}
Sorry if there are errors that I didn't catch, this isn't an exact copy of my code. The problem here is that 1. The sprite doesn't snap to the correct position and 2. the crosshair sprite lags behind the current position of the mouse on the screen. Can anyone give me insight on how to fix either of these two issues?

Your position might not be correct because the screen location isn't necessarily the right location to draw onto using your OrthographicCamera, try using the unproject first. E.g:
Vector3 mousePos = new Vector3( Gdx.input.getX(), (Gdx.graphics.getHeight()-Gdx.input.getY()), 0); //Get the mouse-x and y like in your code
cam.unproject(mousePos); //Unproject it to get the correct camera position
this.crosshair.setPosition(mousePos.x, mousePos.y); //Set the position
Plus you need to make sure your floating batch is set to the projection matrix of the camera, add the following code:
floatingBatch.setProjectionMatrix(cam.combined);

Instead of drawing a Sprite at the mouse position, you could change the cursor image:
Gdx.input.setCursorImage(cursorPixMap, hotspotX, hotspotY);
Where cursorPixMap is a PixMap of the new cursor image an hotspotX and hotspotY is the "origin" of the PixMap/cursor image. In your case it would be the center of the crosshair.
So basicly the Gdx.input.getX() and Gdx.input.getY() return the current position of the hotspotX and hotspotY.
I suggest to read the wiki artikcle about the cursor.

Attaching body to SpriteBatch

Im trying to get a SpriteBatch drawn to sync up to the position of a body.
Im not sure if this is the proper way to do this (in andengine you would just use physics connectors) But i tried drawing the sprite at the position the body was storing.
Gdx.gl.glClearColor(1, 0, 0, 1);
Gdx.gl.glClear(GL20.GL_COLOR_BUFFER_BIT);
camera.update();
elapsedTime += Gdx.graphics.getDeltaTime();
batch.setProjectionMatrix(camera.combined);
batch.begin();
batch.draw(walkAnimation.getKeyFrame(elapsedTime, true),
mrsaiBody.getPosition().x, mrsaiBody.getPosition().y, width/2, height/2);
batch.end();
mWorld.step(1/30f, 6, 2);
mRenderer.render(mWorld, camera.combined);
The problem im having with this is, on the screen i see mrsaiBody's shape and i see the ground i made. When the shape makes contact with the ground the x and y values still continue to be affected by gravity even though the shape isnt. How can i get the current position of this shape to match up with position when i use batch.draw?

Using filledcircle and pixmap in libgdx

I am using Libgdx.
I want to simulate fog in my game using pixmap, but I have a problem during generating the "fogless" circle. First, I make a pixmap, filled with black (it is transparent a little bit). After filling I want to draw a filled circle onto it, but the result is not that I expected.
this.pixmap = new Pixmap(640, 640, Format.LuminanceAlpha);
Pixmap.setBlending(Blending.None); // disable Blending
this.pixmap.setColor(0, 0, 0, 0.9f);
this.pixmap.fill();
//this.pixmap.setColor(0, 0, 0, 0);
this.pixmap.fillCircle(200, 200, 100);
this.pixmapTexture = new Texture(pixmap, Format.LuminanceAlpha, false);
In the procedure render()
public void render() {
mapRenderer.render();
batch.begin();
batch.draw(pixmapTexture, 0, 0);
batch.end();
}
If I use Format. Alpha when creating the Pixmap and Texture, I neither see the more translucent circle.
Here is my problem:
Problem
Could somebody help me? What should I do, what should I init before to draw a full transparent circle? Thanks.
UPDATE
I have found the answer for my problem. I have to disable blending to avoid the problem.
Now my code:
FrameBuffer fbo = new FrameBuffer(Format.RGBA8888, 620, 620, false);
Texture tex = EnemyOnRadar.assetManager.get("data/sugar.png", Texture.class);
batch.begin();
// others
batch.end();
fbo.begin();
batch.setColor(1,1,1,0.7f);
Gdx.gl.glClear(GL20.GL_COLOR_BUFFER_BIT);
batch.begin();
batch.draw( tex, 100, 100);
batch.end();
fbo.end();
But I don't see the circle (it's a png image, represents transparent bg, white filled circle).

I am not sure if this works for you but i just share it:
You could use FrameBuffers and do the following:
Draw everything you want to draw on screen.
End your SpriteBatch and begin your FrameBuffer, begin the SpriteBatch again.
Draw the Fog, which fills the whole "screen" (FrameBuffer) with a black, non transparent color.
Draw the "Fogless" circle as a white circle, at the position you want to delete the fog.
Set the FrameBuffers alpha channel (transparancy) to 0.7 or something like that.
End the SpriteBatch and the FrameBuffer to draw it to screen.
What happens? You draw the normal scene, without fog. You create a "virtual screen", fill it with black and overdraw the black with a white circle. Now you set a transparacy to this "virtual screen" and overdraw your real screen with it. The part of the screen, which is under the white circle seems to be bright, while the black rest makes your scene darker.
Something to read: 2D Fire effect with libgdx, more or less the same as fog.
My question to this: Libgdx lighting without box2d
EDIT: another Tutorial.
Let me know if it helps!
EDIT: Some Pseudocode:
In create:
fbo = new FrameBuffer(Format.RGBA8888, width, height, false);
In render:
fbo.begin();
glClearColor(0f, 0f, 0f, 1f); // Set the clear color to black, non transparent
Gdx.gl.glClear(GL20.GL_COLOR_BUFFER_BIT); // Clear the "virtual screen" with the clear color
spriteBatch.begin(); // Start the SpriteBatch
// Draw the filled circles somehow // Draw your Circle Texture as a white, not transparent Texture
spriteBatch.end(); // End the spritebatch
fbo.end(); // End the FrameBuffer
spriteBatch.begin(); // start the spriteBatch, which now draws to the real screen
// draw your textures, sprites, whatever
spriteBatch.setColor(1f, 1f, 1f, 0.7f); // Sets a global alpha to the SpriteBatch, maybe it applies alo to the stuff you have allready drawn. If so just call spriteBatch.end() before and than spriteBatch.begin() again.
spriteBatch.draw(fbo, 0, 0); // draws the FBO to the screen.
spriteBatch.end();
tell me if it works

OpenGL cannot Draw lines, but quad is working

I can't figure out why this:
glPushMatrix();
GL11.glBindTexture(this.target, this.textureID);
glColor3f(1, 1, 1);
glTranslated(posX, posY, 0);
glBegin(GL_QUADS);
{
glTexCoord2d(posXLeft, posYTop);
glVertex2d(0, 0);
glTexCoord2d(posXLeft, posYBottom);
glVertex2d(0, verH);
glTexCoord2d(posXRight, posYBottom);
glVertex2d(verW, verH);
glTexCoord2d(posXRight, posYTop);
glVertex2d(verW, 0);
}
glEnd();
glPopMatrix();
is working perfectly, where posX and posY are obviously the position in pixels, posXLeft etc is the ratio of the texture to show.
But this:
glPushMatrix();
GL11.glBindTexture(this.target, this.textureID);
glColor3f(1, 1, 1);
glTranslated(posX, posY, 0);
glBegin(GL_LINES);
{
glVertex2d(10, 10);
glVertex2d(800, 600);
}
glEnd();
glPopMatrix();
isn't. And it should be even easier to draw lines instead of a piece of a texture.
What I want to reach is to add some zig-zag lines on a texture to simulate cracks as it is damaged or broken, but I can't even draw a single line, so I am stuck here.
Any advice?

You still got texturing enabled in your line drawing code. But you don't specify texture coordinates, so you'll draw your line with a solid color as defined by texture at the currently set texture coordinate.
My suggestion: Disable texturing for drawing that line.

As said by datenwolf you have to disable the texturing, thes thing is that than you have to re-enable it, although you will have problems the next cycle of drawing if that property is not set correctly.
the solution is:
glPushMatrix();
GL11.glBindTexture(this.target, this.textureID);
glColor3f(1, 1, 1);
glDisable(GL_TEXTURE_2D);
glTranslated(posX, posY, 0);
glBegin(GL_LINES);
{
glVertex2d(10, 10);
glVertex2d(800, 600);
}
glEnd();
glEnable(GL_TEXTURE_2D);
glPopMatrix();
and that should solve your problem.