contour plot control in Surfc function

I have some questions in handling surfc functions

In, surfc functions

[rr,thth]=meshgrid(0:0.005:0.7,0:1:360);
xx=rr.*cosd(thth);
yy=rr.*sind(thth);
rrr=1/4.5*(sqrt(xx.^2+yy.^2)).^3-1/8*(sqrt(xx.^2+yy.^2)).^2+0.25;%rrr=1/4*(sqrt(xx.^2+yy.^2)).^4-1/2*(sqrt(xx.^2+yy.^2)).^2-cosd(8*thth)
rrr(:)=(rrr(:)-min(min(rrr)))/(max(max(rrr))-min((min(rrr))));
zzz=sin(rrr)./rrr;
surfc(xx,yy,rrr); shading flat; caxis([0 1.0]);
 ylim([-2 2]);xlim([-2 2])
zlim([-1 1]);
view(45,70);

In the above codes, I want to change the contour level step to 0.05 and contour position at z=-0.8, not z=0 (in default)

How can I change it ?

If I type contour('LevelStep',0.05) as contour examples, blank figures are pop up.

Also I cannot find the reference to control contour plot positions.

Can anyone help me ? Thanks.

[Johannes Eyb]

I can only help you with the first question as i am looking for the answer to the second on my own:

surfc(xx,yy,rrr,'LevelStep',0.05)

should do the trick

Answer 1

[Star Strider]

I did not see this before.

For the second, see: Customizing contour plots part 2 I asked about this a while ago, and MathWorks provided the solution that I then brought to Yair Altman’s attention. He posted it on his Undocumented MATLAB site.

[Youngki Yeo]

Thank you. This is the answer what I was exactly looking for !

[Star Strider]

As always, my pleasure!