I've got a list of colours (RGB) in an array and I want to build a background with vertical lines, each representing a colour from my list.

The process is too simple to put in a TL;DR :)

If my list of colours is, Array<Vector3> cols, then the process is as follows:

  • Create a pixmap:

    Pixmap pix = new Pixmap(cols.size, 1, Pixmap.Format.RGB888);

  • Set one pixel with the corresponding colour in the list:

    Vector3 color;
for (int i = 0; i < cols.size; i++) {
color = cols.get(i);
pix.drawPixel(i, 0, Color.rgba8888(color.x, color.y, color.z, 1));
}

  • Create a texture off the pixmap:

    Texture texture = new Texture(pix);

  • Create a Sprite and resize it:

    Sprite sprite = new Sprite(texture);
sprite.setSize(mApp.camera.viewportWidth, mApp.camera.viewportHeight);
sprite.setPosition(0, 0);

    This will create a sprite as large as your screen.

    Note: You'll need to declare the sprite as a class member because you need to use it in render() .

  • In render() / draw() , render :) :

    sprite.draw(batch);

Now, when you render, you'll get the striped background.

Horizontal stripes

If you want horizontal stripes, then all you need to do is to create a vertical pixmap:

Pixmap pix = new Pixmap(1, cols.size, Pixmap.Format.RGB888);

and fill it up accordingly (hint: invert the coordinates in drawPixel()).

Note: The code above is taken from an Actor code.

HTH,