function environmentForces() // gravity and the like
{
		you = null;
		vec_set (temp,player.x);
		temp.z -= 4000;
		result = c_trace (player.x,temp, ignore_me + ignore_passable + ignore_passents); //distance to the ground?
		result += player.min_z;
		my_height = c_trace(player.x, temp, ignore_me + ignore_passable + ignore_passents);
		my_height = (result + 2 * my_height) / 3;
		if (16 / time_step > 10) 
		{
		abs_force.z = -0.5 * my_height; //move him up, if stuck in the ground and fps > 10
		} 
		else 
		{
		if (my_height < 0) 
			{ 
			   player.z -= my_height; 
			   vec_set (player._velocityx, nullvector);
			   vec_set (player._abs_velx, nullvector); 
			} // prevent shaking
		}
		friction = 2.1; //ground friction                  PLAYER SPEED!!!!!!!!!!!!!!!
}