# What is drawnow doing?

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Alessandro Masullo 2015 年 11 月 13 日
コメント済み: Alessandro Masullo 2015 年 11 月 18 日
Hello everyone.
I'm working on a code where I need to alternate the display of two complex plots in a very short time. The time for creating each plot is quite high (4-5 seconds) and I want to alternate them with a lag of 0.1 seconds. Creating a new plot every 0.1 seconds is therefore completely useless.
My idea was to create the two plots in two different axes and alternate the visibility of them. The problem is that drawnow keeps taking a very long time just to show one axes instead of the other.
Is there any way I can speed up this process?
Example of code:
figure
x1 = rand(100000,1);
y1 = rand(100000,1);
x2 = rand(100000,1);
y2 = rand(100000,1);
t = tic;
delay = 0.5;
flag = 0;
while 1
if toc(t) > delay
if flag
plot(x1,y1,'.')
flag = 0;
else
plot(x2,y2,'.')
flag = 1;
end
drawnow
end
end

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### 回答 (1 件)

Walter Roberson 2015 年 11 月 13 日

figure
x1 = rand(100000,1);
y1 = rand(100000,1);
x2 = rand(100000,1);
y2 = rand(100000,1);
p1 = plot(x1,y1,'.', 'visible', 'off');
p2 = plot(x2,y2,'.', 'visible', 'off');
t = tic;
delay = 0.5;
flag = 0;
while 1
if toc(t) > delay
if flag
set(p2, 'visible', 'off');
set(p1, 'visible', 'on');
flag = 0;
else
set(p1, 'visible', 'off');
set(p2, 'visible', 'on');
flag = 1;
end
drawnow
end
end
##### 9 件のコメント7 件の古いコメントを表示7 件の古いコメントを非表示
Mike Garrity 2015 年 11 月 17 日
It's really not an answer yet. We need to figure out why you are getting softwareopengl. There are a couple of reasons this might happen. Two common reasons.
1. We have a blacklist for some drivers we've seen a lot of problems with.
2. The system that reports crashes back to us looks at the call stack. If the crash was in your graphics card driver, we'll set your default to softwareopengl to prevent it happening again.
Could you start MATLAB with the -hardwareopengl switch and then do opengl info again? That's probably the easiest way to get all of the details about your graphics card. I'll see if I can find someone who can help figure out what's going on. Hopefully it'll be as simple as updating your driver to a different version.
Alessandro Masullo 2015 年 11 月 18 日
Someone suggested me to set opengl to software many months ago, because of a bug that I was experiencing with surf.
I don't remember the exact post, but it was something like this issue: http://www.mathworks.com/matlabcentral/answers/52943-mesh-or-surf-display-problem-on-windows-7
It happened on a previous version of matlab. So far I haven't experienced the bug on the R2015a.

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