cant get a 2D Camera in LWJGL working (beginner)

OpenGL Development
#1

Hi all,

I am working on a 2D Game and I try to set up a simple camera for it (just moving and zooming).
Unfortunatly, I don’t get it working at all.
Since I am new to LWJGL and OpenGL in general I have no idea, if I am missing out on something very basic
or if the problem is more complex.

With my googling I found out that there are 3 approaches:
1.) Use glScalef and glTranslatef (this seems to be very easy… in theoriy…)
2.) Use gluLookAt and gluPerspective (this seems to be more sophisticated, but maybe too much for a 2D Game?)
3.) Hardcode the “camera” position and zoom level into each draw call (now that seems to be a terrible way to go, even though I am sure I could do that…)

The most effort so far I put into the glScalef and glTranslatef approach.
My code is compiling, but neither the scaling nor the translating has any
effect on the screen.

Maybe somebody can take a look at my code and help me out

So here is my code:


// called once at start
protected void create() {
		// Enable blending
		glEnable(GL_BLEND);
		glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
	// enable textures since we're going to use these for our sprites
		glEnable(GL_TEXTURE_2D);
		 
		// disable the OpenGL depth test since we're rendering 2D graphics
		glDisable(GL_DEPTH_TEST);
		glMatrixMode(GL_PROJECTION);
		glLoadIdentity();
		 
		glOrtho(0, WIDTH, HEIGHT, 0, -1, 1);
		glMatrixMode(GL_MODELVIEW);
		glLoadIdentity();
		glViewport(0, 0, WIDTH, HEIGHT);
		// Set clear to transparent black
		glClearColor(0f, 0f, 0f, 0f);
}

// called every frame
protected void render(){
    // Clear the screen
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
    glMatrixMode(GL_MODELVIEW);
    glLoadIdentity();
    float centerX = WIDTH * 0.5f;
    float centerY = HEIGHT * 0.5f;
    //Move to center of scene
    glTranslatef(centerX,centerY,0);   
    //Scale at center
    glScalef(2,2,1);          
    //Move back to origin
    glTranslatef(-centerX,-centerY,0); 
    glPushMatrix();
		// ... render our game here ...
		spriteBatch.begin();
                         // next line is Pseudo-Code, but this is the way i draw all my graphics. 
                         // I pass the spriteBatch to all my Entities, and they are drawn in the fashion shown below
		         spriteBatch.draw( textureRegion, x, y, width, height );
		spriteBatch.end();
     glPopMatrix();
}

The SpriteBatch I use is not by me.
I use this one here: https://github.com/mattdesl/lwjgl-basics/blob/master/src/mdesl/graphics/SpriteBatch.java
Might it be the source of my problem? I tried to wrap my head around what actually is happening in that SpriteBatch,
but it is way beyond me :frowning: