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How to select what sprite or texture to render first?

I'm making a game using libgdx and I encountered a problem when rendering textures
batch.draw(background, x, y, width, height);
sprite.draw(batch); //of course the background will be rendered first
And when I do this:
sprite.draw(batch);
batch.draw(background, x, y, width, height); //the background will cover the sprite
My problem is that I use two cameras, on is static and the other is non-static. So I need a way on how to select which sprite or texture to be rendered first so that it wont be covered by other textures.

positioning a sprite in libgdx

I've got a problem to draw a sprite to my project.
I have a map (960x900) divided into tiles (64x64).
As you can see in the picture, when i click on the bottom left corner of the purple square, the position is (0;0), and when I click on the top right corner of purple square, the position is (36;47)
The problem is that the picture of the purple square has a size of 32x32, and when I draw this picture with libgdx on the screen, the size doesn't match.
Another example: the square with black border has a size of 64x64. So if I draw the purple square in front of the black, the purple should be the half (in height and in width) of the black, no?
Does anyone know why libgdx resizes the purple square?
Sprite sprite = new Sprite(new Texture("assets/purpleSquare.png"));
i draw it in a method
public void render(SpriteBatch batch) {
batch.draw(sprite, 0, 0);
}
I don't know why the picture is resized by libgdx.. I have also tried to do
batch.draw(sprite, 0, 0, width, heigth);
To precise the sprite's size but it doesn't work too..

The size on screen bears no direct relation to the size of the original image. When you draw a sprite you provide the SpriteBatch with a position, width, and height in world coordinates. The sprite will be stretched to fit these world coordinates, regardless of the original image size.
When you click the screen, you are clicking in screen coordinates. The relation between screen and world coordinates is determined by the projection matrix that you use with the SpriteBatch. The projection matrix is typically controlled with a Camera or Viewport object, which you can use to convert between the two coordinate systems using the project and unproject methods.

I'm happy to see that after many hours i found a solution, even if i know which is not correct.
I would like some help to understand the problem's origin.
With this parts of code :
public void update(float delta) {
batch.begin();
drawBackground(); // Draw the background
drawButton(); // Draw the play/pause button
batch.end();
drawMap(); // draw a tmx map made with tiled
batch.begin();
if(!world.isInitial()) {
renderMonster(); // method which draw the monster
}
renderTower(); // method which draw the tower's level
batch.end();
}
I don't understand why i have to do "batch.begin()" and "batch.end()" twice.
I dont' understant why with this code, the purple square is resized.
With this code :
public void update(float delta) {
batch.begin();
drawBackground();
drawButton();
batch.end();
drawMap();
------->sb = new SpriteBatch();
sb.begin();
if(!world.isInitial()) {
renderMonster();
}
renderTower();
sb.end();
}
this line that i add fix the bug with the purple square. If i work with two SpriteBatch (because with one, if i reinitialize SpriteBatch in update method, my pause/play button diseapper) and i initialise the second (SpriteBatch sb) in the update method.
It is correct to initialise a SpriteBatch every time i'm passing on the update method ? There's no method with a SpriteBatch to avoid this problem ?

Image/Texture scroll/shift (wrap)

Does anyone know whether libGDX has a method for scrolling/shifting an image/texture within itself?
To explain; I would like to be able to scroll the contents (pixels) of an image, either vertically or horizontally within its own region. For example, if an image is shifted 1 pixel to the right, all pixels move 1 to the right and those on the right-most-edge are wrapped to the left-most-edge. The image size does not change, only the positioning of the pixels within it change.
I have mainly been working with the Sprite class, it can do a lot (scale, rotate, etc) but shift/scroll as I need it, isn't there.
Before writting the method myself, I thought I'd ask here...
The following worked for me, this was provided by Kush:
float delta = 0f;
// In the Actors act method
delta += Gdx.graphics.getDeltaTime();
// Horizontal
batch.draw(texture, 0, 0, width, height, 0 + delta * 10, 1, 1 + delta * 10, 0);
// Vertical
batch.draw(texture, 0, 0, width, height, 1, 0 + delta * 10, 0, 1 + delta * 10);

You won't need Sprite for this, draw directly Texture using batch. For wrapping first set
Texture texture = new Texture("example.png");
texture.setWrap(TextureWrap.Repeat, TextureWrap.Repeat);
then draw using uv
batch.draw(texture, x, y, width, height, u, v, u2, v2);
or any other method that suits you in SpriteBatch.

opengl rotation texture off center

I wrote some code to get a plain 2d box to face the mouse. It rotated just fine around its center, and everything was working great, but when i put a texture on the box, it did not rotate around the center anymore.
The code:
float imgWidth = texture.getImageWidth()*scale;
float imgHeight = texture.getImageHeight()*scale;
glLoadIdentity();
texture.bind();
glTranslatef(x, y, 0);
glRotated(rotation - 90, 0, 0, 360);
glBegin(GL_QUADS);
glTexCoord2f(0, 0);
glVertex2f(-imgWidth, -imgHeight);
glTexCoord2f(1, 0);
glVertex2f(imgWidth, -imgHeight);
glTexCoord2f(1,1);
glVertex2f(imgWidth, imgHeight);
glTexCoord2f(0, 1);
glVertex2f(-imgWidth, imgHeight);
glEnd();

The answer is simple but with a complicated background that has to be understood.
OpenGL always rotate something not around its center but takes as center the point (0;0).
This can be an issue because if you translate your object somewhere and then your rotate it, it will rotate not on its center but around the (0;0) point (origin) creating a big rotation, I will say as a planet around the Sun.
Also OpenGL works with matrix, that with very barbaric simplification means that the operation are executed bottom to top.
// store the current model matrix
GL11.glPushMatrix();
// bind to the appropriate texture for this image
this.texture.bind();
// translate to the right location and prepare to draw
GL11.glColor3f(1, 1, 1);
GL11.glTranslated(x + (this.texture.getImageWidth() / 2), y + (this.texture.getImageHeight() / 2), 0);
GL11.glRotated(this.angle, 0, 0, 1);
GL11.glTranslated(-this.texture.getImageWidth() / 2, -this.texture.getImageHeight() / 2, 0);
// draw a quad textured to match the sprite
GL11.glBegin(GL11.GL_QUADS);
{
GL11.glTexCoord2f(0, 0);
GL11.glVertex2f(0, 0);
GL11.glTexCoord2f(0, this.texture.getHeight());
GL11.glVertex2f(0, this.texture.getImageHeight());
GL11.glTexCoord2f(this.texture.getWidth(), this.texture.getHeight());
GL11.glVertex2f(this.texture.getImageWidth(), this.texture.getImageHeight());
GL11.glTexCoord2f(this.texture.getWidth(), 0);
GL11.glVertex2f(this.texture.getImageWidth(), 0);
}
GL11.glEnd();
// restore the model view matrix to prevent contamination
GL11.glPopMatrix();
This means that first I am moving the texture to have its center positioned at (0;0) that means translating it backward half the dimensions.
Then I rotate it, and this is the crucial point, because you are using a strange way to rotate it, maybe the problem it's here, take a look to the javadoc:
SPECIFICATION
void glRotated( GLdouble angle,<br>
GLdouble x,<br>
GLdouble y,<br>
GLdouble z )<br>
void glRotatef( GLfloat angle,<br>
GLfloat x,<br>
GLfloat y,<br>
GLfloat z )<br>
PARAMETERS<br>
angle Specifies the angle of rotation, in degrees.
x, y, z<br>
Specify the x, y, and z coordinates of a vector, respectively.
DESCRIPTION<br>
glRotate produces a rotation of angle degrees around the<br>
vector (x,y,z).
First of all all x,y,z values should be between 0 and 1, if you want to rotate a 2d image then you should use the z axis, so the third param will be 1 that mean that you are rotating your image around the unit vector z.
The angle should be in degree and can be either positive or negative.
Try to change your code according to the documentation and you will have your problem solved.
Also with your quad you are drawing a 2x scaled quad, you are starting from -imageWidth to +imageWidth that means 2 times the width...

Text field using OpenGL

So, I'm new to OpenGL and trying to create a 2D Multiplayer game, I know how to do all of the networking, although the graphics portion is honestly kicking my buttox.
I have tried looking at NiftyGUI aswell as TWL as they have been recommended a-lot, although I can't seem to get a grasp of them as there aren't very many tutorials and no videos to help explain what's going on, not to mention the OpenGL Documentary page is just horribly laid out.
I've attemped drawing a black rectangle, which I was going to go ahead and outline in white somehow and making that a temporary textbox, by drawing white font onto it, although I don't even know how to draw font. These are just a few of the things I'm strugling with that I can't find and I'm aware that I'm going to have to use some libraries, so I'll name the ones I have implemented currently.
LWJGL
Slick2D
I don't have any others currently, besides for TWL but I can't figure out how to use it for the life of me.
Here's the code that I made myself while trying to get a small black rectangle going
void drawTextBox(int fromLeft, int fromTop, int width, int height) {
glColor3f(1.0f, 1.0f, 1.0f);
glBegin(GL_QUADS);
glTexCoord2f(0, 0);
glVertex2i(fromLeft, fromTop); // Upper Left
glTexCoord2f(1, 0);
glVertex2i(fromLeft - width, fromTop); // Uppright
glTexCoord2f(1, 1);
glVertex2i(fromLeft - width, fromTop + height); // Bottom right
glTexCoord2f(0, 1);
glVertex2i(fromLeft, fromTop + height); // bottom left
glEnd();
}
This is working correctly, all but one part... It's drawing the last texture that I have loaded, even though I'm not binding it anywhere in the program, because I've made sure of it. Then it's scaling it to fit into the dimensions of the text-box.
Could someone help me resolve this error and direct me to where I can learn how to set the opacity of quads as-well as draw some text?

Try binding the texture you want right before calling the function. Without knowing how you've "made sure" that the other texture is not being bound, that's all I can say. Also, for changing opacity simply use one of GL11.glColor4_ functions; the last parameter is the alpha (opacity) of the color.

void drawTextBox(int fromLeft, int fromTop, int width, int height) {
glEnable(GL_BLEND);
glBlendFunc(GL_SRC_ALPHA,GL_ONE_MINUS_SRC_ALPHA);
glColor4f(1.0f, 1.0f, 1.0f, <B>0.5f</B>);
glBegin(GL_QUADS);
glTexCoord2f(0, 0);
glVertex2i(fromLeft, fromTop); // Upper Left
glTexCoord2f(1, 0);
glVertex2i(fromLeft - width, fromTop); // Uppright
glTexCoord2f(1, 1);
glVertex2i(fromLeft - width, fromTop + height); // Bottom right
glTexCoord2f(0, 1);
glVertex2i(fromLeft, fromTop + height); // bottom left
glEnd();
glDisable(GL_BLEND);
}
This block of code allows you to draw a white rectangle with %50 opacity.
Take a look at the BOLDED part (0.5f). This float number defines the opacity of your rectangle. The bigger this number is (0.0f~1.0f), the more the opacity of the rectangle is.