akovia (akovia1@eml.cc) wrote:

1. Can't add intermediate nodes.

There are times when I'll go to add a node between existing nodes and it won't allow me to do so. I have to walk the path until I can find a spot will it will let me and delete all the nodes to that point and build the path again. The last time this happened I had copied a path from a different gimp image and pasted it into my new drawing. I'm not sure if this always follows a paste operation or not, but will try to troubleshoot it further the next time it happens.

Make sure the path is "connected" to the path tool, e.g. by doubleclicking the path in the path dialog.

I designed the path tool to "usually" stay in Design mode. Then you can use Control to temporarily switch to Edit mode. Edit-mode on-top of a path segement should show a small "+" at the mouse cursor, clicking will result in adding a node at this point.

Control+Shift will be Edit-Mode plus "subtract/remove" - i.e. ctrl-shift-clicking on top of a node will remove it, ctrl-shift-clicking on a segment will open up the path by removing the segment.

2. Node selection precision.

No idea about that one. I don't think I've seen that.

3. Path strokes.

Quite often on big complicated paths that I try to stroke, there will be a few sharp angles that won't protrude out to a point and will just look like it was cut off.

Do you stroke with a tool? Or by "stroke line"? with which options? For the Mitre-Join the Mitre-Limit determines the amount of "allowed protrusion".

Can you provide screenshots of the problematic results?

Thanks, Simon

simon@budig.de              http://simon.budig.de/

Simon Budig wrote

akovia (

akovia1@

) wrote:

1. Can't add intermediate nodes.

Make sure the path is "connected" to the path tool, e.g. by doubleclicking the path in the path dialog.

I designed the path tool to "usually" stay in Design mode. Then you can use Control to temporarily switch to Edit mode. Edit-mode on-top of a path segement should show a small "+" at the mouse cursor, clicking will result in adding a node at this point.

Control+Shift will be Edit-Mode plus "subtract/remove" - i.e. ctrl-shift-clicking on top of a node will remove it, ctrl-shift-clicking on a segment will open up the path by removing the segment.

Yes to all above. I am very familiar with all the modifiers. If I hover my mouse above a certain segments holding Control, some segments will allow to add a node, while other segments won't. This also effects deleting line segments.
Now that I think about it I have the last instance on video from a tutorial I made. It's kinda perfect since I have it showing my key-presses as well. https://dl.dropboxusercontent.com/u/93550827/Gimp%20Tutorial%20Series/he-is-my-master_full.mkv 6:35 to around 8:30 is the problem. I also realized that this also was a copied and pasted path.

2. Node selection precision.

No idea about that one. I don't think I've seen that.

I will try to capture this as well and post a screenshot or video.

3. Path strokes.

Quite often on big complicated paths that I try to stroke, there will be a few sharp angles that won't protrude out to a point and will just look like it was cut off.

Do you stroke with a tool? Or by "stroke line"? with which options? For the Mitre-Join the Mitre-Limit determines the amount of "allowed protrusion".

Can you provide screenshots of the problematic results?

Stroke line mostly unless I'm after some sort of effect. Playing with the mitre setting does have some effect on the problem. Maybe I just can't get the expected results I want in having an even stroke all the way around. Have a look at this and maybe you can explain if there is another way. For now I have just been patching some paths together to get what I need.. https://dl.dropboxusercontent.com/u/93550827/temp/path-stroke_mitre.mkv

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Simon Budig wrote

akovia (akovia1@eml.cc) wrote:

2. Node selection precision.

No idea about that one. I don't think I've seen that.

Ok I just ran into this. This isn't a worst case as sometimes the move icon is even further away than this.
It does appear to be affected by the zoom level which I never noticed before. I usually zoom in further which normally fixes things, but this time I noticed that zooming out can also recalibrate the mouse pointer.

Maybe this will help. https://dl.dropboxusercontent.com/u/93550827/temp/Gimp%20Node%20Precision.mkv

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Akovia (akovia1@eml.cc) wrote:

Simon Budig wrote

akovia (akovia1@eml.cc) wrote:

2. Node selection precision.

No idea about that one. I don't think I've seen that.

Ok I just ran into this. This isn't a worst case as sometimes the move icon is even further away than this.
It does appear to be affected by the zoom level which I never noticed before. I usually zoom in further which normally fixes things, but this time I noticed that zooming out can also recalibrate the mouse pointer.

Maybe this will help. https://dl.dropboxusercontent.com/u/93550827/temp/Gimp%20Node%20Precision.mkv

I strongly suspect that in this case the behaviour is caused by the guides. The "hot spot" of the mouse cursor is dragged towards the guide (within the snapping distance) and hence the click does not happen at the anchor.

Not sure if this is fixable, since placing new points along a guide is a desireable behaviour as well.

Try to disable snapping.

Bye, Simon

simon@budig.de              http://simon.budig.de/

Akovia (akovia1@eml.cc) wrote:

If I hover my mouse above a certain segments holding Control, some segments will allow to add a node, while other segments won't. This also effects deleting line segments.

Hmm. Is this usually happening when having a huge zoom level?

There is a funky problem there: for determining the closest point along a bezier the bezier segment is approximated by line segments to a certain precision. The precision used does not take the zoom level into account. This is usually no problem, since it is < 1 pixel and "close enough" for the usual zoom levels.

However there are corner cases in huge zoom levels, where the (invisible) line approximation is off by a significant fraction of a pixel, so that the net result is an active area disconnected from the drawn bezier segment. You can verify this by searching on the "inside" of the curved bezier segment for an active area.

I'd consider this a bug that might have been introduced when we introduced cairo-based rendering for the tool graphics (earlier the drawn path used the same line approximation as the detection code).

Probably a bit tricky to fix...

Bye, Simon

simon@budig.de              http://simon.budig.de/

If I hover my mouse above a certain segments holding Control, some

segments

will allow to add a node, while other segments won't. This also effects deleting line segments.

Weird.

Right?

Now that I think about it I have the last instance on video from a

tutorial

I made. It's kinda perfect since I have it showing my key-presses as well. https://dl.dropboxusercontent.com/u/93550827/Gimp%20Tutorial%20Series/he-is-my-master_full.mkv 6:35 to around 8:30 is the problem. I also realized that this also was a copied and pasted path.

Really weird. I cannot reproduce this here though. *shrug*

Where did you copy/paste the path from? Inkscape?

Earlier the video you can see that I copied it from another gimp drawing.

Ok, I think what you're seeing there is expected behaviour. The problem is, that when you move two tangents closely together (i.e. you have a very sharp corner) the end point of the stroke moves towards infinity, i.e. you need to cap this at some point. The parameter controlling this is the mitre limit. We use cairo for rendering and the behaviour is described as follows in the cairo documentation:

If the current line join style is set to CAIRO_LINE_JOIN_MITER (see cairo_set_line_join()), the miter limit is used to determine whether the lines should be joined with a bevel instead of a miter. Cairo divides the length of the miter by the line width. If the result is greater than the miter limit, the style is converted to a bevel.

[...]

The default miter limit value is 10.0, which will convert joins with interior angles less than 11 degrees to bevels instead of miters. For reference, a miter limit of 2.0 makes the miter cutoff at 60 degrees, and a miter limit of 1.414 makes the cutoff at 90 degrees.

A miter limit for a desired angle can be computed as: miter limit = 1/sin(angle/2)

There is no way to completely disable the miter limit, but maybe the range of the limit in the UI is not sufficient.

I hope this helps, Simon

I will play around with the mitre limit some more and see what I can come up with. Thanks for the tips.

Simon Budig wrote

Akovia (

akovia1@

) wrote:

Simon Budig wrote

akovia (

akovia1@

) wrote:

2. Node selection precision.

No idea about that one. I don't think I've seen that.

Ok I just ran into this. This isn't a worst case as sometimes the move icon
is even further away than this.
It does appear to be affected by the zoom level which I never noticed before. I usually zoom in further which normally fixes things, but this time
I noticed that zooming out can also recalibrate the mouse pointer.

Maybe this will help. https://dl.dropboxusercontent.com/u/93550827/temp/Gimp%20Node%20Precision.mkv

I strongly suspect that in this case the behaviour is caused by the guides. The "hot spot" of the mouse cursor is dragged towards the guide (within the snapping distance) and hence the click does not happen at the anchor.

Not sure if this is fixable, since placing new points along a guide is a desireable behaviour as well.

Try to disable snapping.

Bye, Simon

That just might be possible. It never occurred to me since there is no visible snapping of the mouse. I will check that for sure the next time it happens and report back. I really hope that's it. Thanks

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Simon Budig wrote

Akovia (

akovia1@

) wrote:

If I hover my mouse above a certain segments holding Control, some segments
will allow to add a node, while other segments won't. This also effects deleting line segments.

Hmm. Is this usually happening when having a huge zoom level?

Not really. Like I said, sometimes I can "walk" the path and find where I can insert or delete as normal. I do this at the same zoom level. It's like the path got corrupted and I have to delete the corrupted part of the path and rebuild it, then everything works fine again.

Simon Budig wrote

There is a funky problem there: for determining the closest point along a bezier the bezier segment is approximated by line segments to a certain precision. The precision used does not take the zoom level into account. This is usually no problem, since it is < 1 pixel and "close enough" for the usual zoom levels.

However there are corner cases in huge zoom levels, where the (invisible) line approximation is off by a significant fraction of a pixel, so that the net result is an active area disconnected from the drawn bezier segment. You can verify this by searching on the "inside" of the curved bezier segment for an active area.

I'd consider this a bug that might have been introduced when we introduced cairo-based rendering for the tool graphics (earlier the drawn path used the same line approximation as the detection code).

Probably a bit tricky to fix...

Bye, Simon

I'm wondering if my clipboard manager isn't screwing things up. I discovered a problem within inkscape that is apparently affected by it and everything works as it should when I turn it off. Can you discern anything from this bug report that might affect gimp as well?
https://bugs.launchpad.net/inkscape/+bug/418242

I will try disabling my clipman next time and repeat the copy+paste to see what happens.

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Akovia (akovia1@eml.cc) wrote:

Not really. Like I said, sometimes I can "walk" the path and find where I can insert or delete as normal. I do this at the same zoom level. It's like the path got corrupted and I have to delete the corrupted part of the path and rebuild it, then everything works fine again.

Well, the path data structure is unlikely to be corrupted in a way that could have these effects. *If* it gets corrupted this'd more likely mean that GIMP would crash. The data used for locating the mouse pointer is the same as the data used for drawing, the only plausible difference to me is the precision. But this is always better than 1 image-pixel.

Hrm.

Bye, Simon

simon@budig.de              http://simon.budig.de/

Simon Budig wrote

Akovia (

akovia1@

) wrote:

Not really. Like I said, sometimes I can "walk" the path and find where I can insert or delete as normal. I do this at the same zoom level. It's like
the path got corrupted and I have to delete the corrupted part of the path
and rebuild it, then everything works fine again.

Well, the path data structure is unlikely to be corrupted in a way that could have these effects. *If* it gets corrupted this'd more likely mean that GIMP would crash. The data used for locating the mouse pointer is the same as the data used for drawing, the only plausible difference to me is the precision. But this is always better than 1 image-pixel.

Hrm.

Inspecting the structure of an svg convinces me you're right about corruption not being the issue. I don't see how it could produce the results I'm seeing.
If memory serves (no guarantees), I didn't see this before 2.8, so you are probably right about the cairo connection. Would you like me to send you the xcf the next time it happens?

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This just creeped up again. I can add nodes between certain node pairs, but not others.
I made this path by joining two paths, then was going back to round the corners.
Happens with guides on or off and at any zoom level.

Here is a small vid of it. https://dl.dropboxusercontent.com/u/93550827/temp/Path-add-nodes.mkv

I'm happy to up the xcf if you think it will help. Cheers

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and I also keep getting stroke problems as well where it will be an inconsistent broken up stroke.

https://dl.dropboxusercontent.com/u/93550827/temp/path%20stroke.mkv

The path was all made in the xcf and no merging or copy+paste was involved.

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Am 01.11.2013 22:26, schrieb Akovia:

and I also keep getting stroke problems as well where it will be an inconsistent broken up stroke.

https://dl.dropboxusercontent.com/u/93550827/temp/path%20stroke.mkv

The path was all made in the xcf and no merging or copy+paste was involved.

Can you convert this video to a different codec, e.g. Theora? H.264 doesn't work here.

P.S. also see http://xiphmont.livejournal.com/61927.html about why it may be a good idea to avoid H.264 altogether.

Regards,
Michael
GPG: 96A8 B38A 728A 577D 724D 60E5 F855 53EC B36D 4CDD

https://dl.dropboxusercontent.com/u/93550827/temp/path%20stroke.ogv

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