code: public void startUse() {
  		if (inUse != null) {
  			throw new RuntimeException("Attempt to start use of a sprite sheet before ending use with another - see endUse()");
  		}
  		inUse = this;
  		init();
  
  		Color.white.bind();
  		texture.bind();
  		GL.glBegin(SGL.GL_QUADS);
  	}
docs: Start using this sheet. This method can be used for optimal rendering of a collection
  of sprites from a single sprite sheet. First, startUse(). Then render each sprite by
  calling renderInUse(). Finally, endUse(). Between start and end there can be no rendering
  of other sprites since the rendering is locked for this sprite sheet.