GLfloat screen_top; /* Top of screen. */
GLfloat bg_colour[4]; /* Background colour. */
GLfloat bubble_colour[4]; /* Colour of the bubbles. */
GLfloat screen_top; /* Top of screen. */
GLfloat bg_colour[4]; /* Background colour. */
GLfloat bubble_colour[4]; /* Colour of the bubbles. */