Strange behavior on subplots with surf

Today I noticed a very strange behavior in a rather complex creation of a figure. To see the actual problem, I broke down the code to the essential parts: I create a figure with two subplots in one figure. But whenever I add a surface plot to the second subplot (instead of a normal 2D plot) the properties of the first subplot change. Please run the following code, compare the figures to see the differences:

x=1:20; 
y1=randn(20,1); 
y2=ones(20,1);
figure; 
subplot(2,2,[1,2]); 
plot(x,y1,x,y1);hold on; 
plot(x,y2,'--b','LineWidth',2); hold off;
subplot(2,2,[3,4]); 
surf(x,x,y1*y1','LineStyle','none');
figure; 
subplot(2,2,[1,2]);
plot(x,y1,x,y1); hold on; 
plot(x,y2,'--b','LineWidth',2); hold off ;
subplot(2,2,[3,4]);
plot(x,y1);

Is there an explantion for this change (especially for the dashed line)? How can I change the properties of the second figure to the unintended and changed properties of figure 1?

I use Matlab R2013b! Thanks for the support!

[dpb]

No klew...it acts the same way in R2012b(*), btw, so it's not the new graphics engine.

For some reason the lines are rendered differently despite style and width parameters being the same. I went side-by-side and retrieved the handles to the two lines and set the properties manually to a range of line widths and the rendering still isn't the same between the two. I could observe no properties that were different that are visible.

Looks like an official support topic at www.mathworks.com

BTW, why use

subplot(2,2,[1,2]);

instead of the syntactically simpler

subplot(2,1,1);

for full-width, two-high suplots??

ADDENDUM

(*) Just out of curiosity, I tried the earliest version I have installed (R11). The difference isn't quite as noticeable but they're still different. With it the apparent width is almost indistinguishable between the two but there's a notable difference in the length of the dashed line segments between the two.

Really, really, bizzaro!!! Be interesting to hear what TMW has to say on this one...

[Sven]

Thanks for your respond :)

The "subplot(2,2,[1,2])" syntax is from my more complex code. But you are right, it is not needed here.

Answer 1

[Andrew Newell]

It appears that surf chooses OpenGL for the renderer (see Figure properties for an explanation of the renderer). Since this is a property of the entire figure, it redraws the first subplot as well. You could add the line

set(gcf,'Renderer','painters')

to restore the default renderer for the first figure.

[Sven]

Thx Andrew,

do you also know a way to change the renderer of the second figure (in the way that it looks like figure 1)?

Because figure 1 delivers nicer print outputs (a very nice dashed line)...

[dpb]

Sure, you can use renderer of choice...

set(gcf,'renderer','OpenGL')

I hadn't thought of the renderer itself, Sven, good catch. I shoulda' thunk of it as a likely culprit when the styles changed.

[Sven]

Thank you very much Andrew!

That is actually a good way to increase the quality of printed figures. Especially when it comes to dashed lines!