double getTheta(vec4 pos)
{
vec2 reference = vec2(1.0,0.0) ;
vec2 planar_angle = vec2(pos.x, pos.z) ;
float dotPdt = dot( reference, planar_angle ) ;
double theta = acos(dotPdt/(length(reference)*length(planar_angle)));
if ( pos.z < 0.0 )
{
theta = 2 * M_PI - theta ;
}
return theta ;
}
/**
* Updates the size of the screen.
* @param x The new width.
* @param y The new height.
*/
void Screen::size( int x, int y ) {
size( vec2( x, y ) );
}