ginput slow when plotted a lot of points

Question

Marco 2011-9-29

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https://ww2.mathworks.cn/matlabcentral/answers/17033-ginput-slow-when-plotted-a-lot-of-points

回答： Marijan Herak 2018-3-2

Hi, i'm experiencing a strange behaviour of the ginput command.

I plotted on an axis quite a huge number of points (more than 4 millions). Everything behaves quickly (pan and zooming are fast).

When i run a ginput on this axis it becomes painfully slow. The crosshair-like pointer is lagged (it follows the actual position of the mouse with a delay of some seconds).

the only solution i found so far is to overlay a transparent axis over the real one, with the same extents, and run the ginput over this second one.

This solution actually works but is really slow to code (i often have to do it) and could cause some problems (e.g in case of zooming it's quite difficult to keep the axis aligned).

In general i don't think this solution is elegant, so my question is:

did anyone else experience the same problem and find a better solution or workaround?

Thanks!

Marco

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Paolo 2013-8-14

Hi Marco, could you please write the lines of code that you used to overlay a transparent axis with aligned axes? I'm experiencing the same problem with ginput...

Thanks, Paolo

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Answer 1

Walter Roberson 2011-9-29

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https://ww2.mathworks.cn/matlabcentral/answers/17033-ginput-slow-when-plotted-a-lot-of-points#answer_22977

linkaxes() should keep the axes aligned.

If you have to code it often, then it would seem natural to code the repeated elements in to functions and then just call upon them ?

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Marco 2011-9-29

First of all thanks for the suggestion, that's exactly what i will do if the overlaying a second axis is the only possible way to have the ginput work swiftly.

i just think it's strange that the number of points previously drawn affects the performances of such a function and that i have to code a solution (or more precisely a workaround) to a problem that in my opinion should not be there.

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Answer 2

Marijan Herak 2018-3-2

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https://ww2.mathworks.cn/matlabcentral/answers/17033-ginput-slow-when-plotted-a-lot-of-points#answer_308043

Try choosing OpenGL renderer for the figure - set(gcf,'renderer','opengl'). It works for me, and ginput is smooth and responsive again (over 100.000 points in the figure).