{
    Rippled roofing iron
    P.D.Bourke
    September 1991

    One parameter, A1 = number of cycles per unit distance
}
theta = 4 * PI * (frac(A1*2*PI*Px) - 0.5);
zcor = 1 + cos(theta);
xcor = zcor * sin(theta);
ycor = 0;