I'm working on some low poly wallpapers on
inkscape 0.92, but when i use the voronoi diagram (delunay triangulation), i got this ugly result :
should i fix some thing in my design? or it's a bug on this version of inkscape?
I can't replicate the issue with Inkscape 0.92. It appears to work as expected.
The only things I can think of are to make sure you only select the dots, and nothing else, before applying the Voronoi Diagram extension. Also make sure each dot is only one dot, and not several dots on top of each other. If you select additional things like the box behind, or have hidden dots, then it will mess up.
I was having the same issue. I found some duplicate dots, but removing them didn't solve the problem. Because I had created my dots so haphazardly, I thought the stack order of them affected the results, so I chose each one, one at a time, from left to right and top to bottom, and moved it to the top, reordering the stack. That also didn't help. I concluded that I had too many dots, some of which were quite close together, but since I liked the look, I didn't want to remove some of them.
My solution was to use what the extension gave me and just manually correct the triangles that were either stretched to the wrong points, or missing altogether. To correct them, choose the node tool, turn on snap to nodes, paths, and handles, click on a misshapen triangle, and finally drag the node or nodes in the wrong location to where they should be. Snap to node is your friend here.
So I had the same issue and I found a different solution but I'm not sure if it would work with non square objects.
All I did was but the dots on one half of the object, tested to see if that half would succesfully generate, then duplicated all the dots on that half and pasted them onto the other half.
I deleted the dots in the middle that were too close to each other and the whole object generated the voronai successfully.
The problem comes because you have to be careful when copying the last circle you put. If you go create circles with the space bar and after having created the last one you release the left button of the mouse, which is with which you dragged the circle used to copy, it will put two circles at that point: the one you created when pressing the space bar and the one created by releasing the left mouse button. Using a circle with transparency is easier to see if there are any circles duplicated by mistake