Re: [matplotlib-devel] distorted patches

Gary Ruben wrote:
> I've been rewriting the Arrow class in patches.py to improve the look 
> of quiver plots and am getting generally good results. The problems 
> with current quiver plots are that arrows representing very small 
> values are scaled along their length but not in width and also that 
> arrowheads are not of a constant size. I have addressed both of these 
> problems and getting results much more like Matlab quiver plots now. 
> However, now that I am scaling arrow patches down to very small sizes, 
> I see weird shaped arrows at some zoom levels but when I zoom in close 
> enough to see the shape properly they look nicely formed. Is there a 
> known problem, perhaps with Agg doing some fancy truncation in order 
> to achieve good speed, where patches are distorted if their vertices 
> are very close together at a particular magnification? I can provide 
> code and graphic examples if it would help.

Wow, serendipitously I'm working on exactly the same thing at the 
moment.  Question: when you zoom, do you ensure that the x-direction in 
your window is the same length as the y-direction?  My current theory on 
this is the distorted arrows are the result of quiver measuring 
everything in the x-y space of the plot, instead of in absolute terms.  
Setting axis('equal') or axis('scaled') seems to improve the arrow 
appearance...

Jordan