Question

I know that the whole sprite sheet needs to be in powers of two but when I only use a section of it, does the section also need to be in powers of two?

Answer 1

No. The texture coordinates are from 0 to 1 as floats.

Texture Coordinates Ex:

    final float texCoords[] = {
            0.0f, 0.0f,
            0.0f, 1.0f,
            1.0f, 1.0f,
            1.0f, 0.0f
    };

To get a certain position get the ‘percent’

Ex:

quad.SetTexCoordinates( ((float) posX / texture.Width), //X
        ((float) posY / texture.Height),                //Y
        ((float) width / texture.Width),                //Width
        ((float) height / texture.Height));             //Height 
//All are between 0 and 1 as a 'percent'