#macro f(q,c,p)
    isosurface {
        function { z-7+q*mod(p*y*(7*(z-7)*pow(abs(x),.5) + 
                   max(y,0)*(y+.1)+3.5*abs(x)),4) }
        contained_by { sphere{7*z,3} }
        open
        pigment{rgb c}
    }
#end 

f(0.40 ,9, 0.97)
f(0.50 ,3, 1.00)
f(0.45 ,4, 0.98)