Triangle in / out in one path makes other objects vanish

[Hachmann]

So far only reproduced in Inkscape 0.92.1, but not in 0.91.

1. Draw something. The issue seems to be more easily exposed when there's an ellipse in the drawing, but other paths seem to work, too.

2. Switch to Bézier tool, select triangle in or triangle out drawing mode.

3. Click a couple of times into the drawing, and finish the path. If nothing strange happens, repeat a couple of times.

4. Find that with each additional click, parts of objects will not be rendered anymore. Drawing over the other objects results in rectangular white areas being added.

5. All objects are gone. Also not visible in outline mode. Ctrl+A still selects them and draws empty bounding boxes.

6. This persists after saving / closing the file. Opening the file in Inkscape 0.91 also only shows an empty page.

7. In a web browser, everything looks fine, only the lpe path is missing.

8. There are lots of really strange coordinate numbers in the LPE path.

Attached is a zip with a file before / after this.

Haven't tested with trunk or the stable devel version, so this could be fixed already.

[Brynn (brynn4inks-deactivatedaccount)]

I don't need an ellipse to make this happen. Screenshot with one object drawn in new blank file. You can't see the mouse pointer. But the Pen tool is still enabled when I made the image.

(No, it's not a transparency issue - at least not through all the usual means. But this bug seems to introduce it.)

No other Inkscape files or instances are open when this happens.

Windows 7 Pro, 64-bit, Inkscape 0.92.1, 64-bit, exe installer Let me know if you need further info or files.

Other tid-bits.

It's not just the sudden imposition of transparency. It's rather like that wacko behavior with spiro splines, if you drag nodes too close to each other. But as you can see in the screenshot, it's not in spiro spline mode.

I haven't seen such elaborate scribbles as in the spiro spline bug. But it does make simple erratic marks, sometimes huge (100,000.00 px long, e.g.)

Note that I see that happens when I first finish drawing the path. As soon as I drag the pink node, everything goes back to normal. Whoops! Check that. Mostly back to normal - transparency is gone. But if you drag the pink node around, there seems to be a certain point where it creates the wild, strange marks. Still not as extensive as spiro spline bug - just 1 or 2 lines, straight lines usually - but just as strange!

[Brynn (brynn4inks-deactivatedaccount)]

Hhm, I thought that the triangle in/out shapes (for Pen/Bezier tool) were automatically applying both pap and powerstroke. But when I draw with that shape and open the Path Effects dialog, it's only showing the powerstroke.

If I draw a regular path (no shape, no mode) and apply the Powerstroke LPE, there is no problem. Or if I apply PAP only, there is no problem. But if I apply both PAP and Powerstroke LPEs to the same path, I get the exact same problems as with the Pen/Bezier tool in triangle in/out shape.

I don't know what consequence that might have for this problem. But fwiw :-)

[Brynn (brynn4inks-deactivatedaccount)]

So far, I've found that I can avoid this problem (I mean drawing with Pen/Bezier with triangle in/out shape) by opening the Path Effects dialog, and changing the Interpolator Type from CubicBezierJohan to CubicBezierSmooth.

However, I have not tried all the Interpolator options yet. CubicBezierFit gives a strange appearance, but I'm not sure if it's wrong.

[TylerDurden (8thrule)]

It seems the effect's point offset attribute being zero does not provide adequate direction for the stroke, interfering with the rendering of the canvas.

Changing the first offset value to a positive value >0 seems to allow proper canvas rendering. Even a very small value e.g. 0.000001 should be adequate.

For existing documents showing the issue, the canvas needs to be moved/scaled to redraw, after modifying the def offset_points attribute.

Attached example is a modified version of the file "after.svg" from above.

TD

[Brynn (brynn4inks-deactivatedaccount)]

I can't find any attribute called "point offset". The only thing I find in XML Editor referring to "point" or "offset" is in the style attribute, stroke-dashoffset:0. But changing the value to 1 did not fix the problem.

The only attribute I see with a 0 value is inkscape:connector-curvature. But changing it to 1 also did not fix the problem.

However, your XML Editor is showing something different than mine. In your style attribute, it starts with "opacity:1;vector-effect:none;fill:#......"

Mine starts "color:#000000;display:inline;overflow:......"

So I'm not sure what that means. And I still don't see anything resembling "point offset".

Any clues? Thanks :-)

[TylerDurden (8thrule)]

It's in the def for the effect.

[Brynn (brynn4inks-deactivatedaccount)]

Oh, ok. After some experimenting, I see what the offset point is/means. So the user can do that from the canvas, unless they really want the end to be as flat as possible.

I don't know enough about the situation to know if the reason is because zero doesn't give enough info. But the zero value clearly is triggering the problems.

[Brynn (brynn4inks-deactivatedaccount)]

Thanks TD :-)

[Brynn (brynn4inks-deactivatedaccount)]

Interesting note. The offset point 0 (in the defs) does not cause this problem, if you draw a regular path (no shape) and then apply powerstroke separately. Somehow, it's only the powerstroke attached to triangle in/out, which causes this.

Or as noted before, applying both powerstroke and pap via Path Effects dialog, causes the same behavior.

[jazzynico (jazzynico)]

Confirmed on Windows XP (32-bit), lp:inkscape/0.92.x rev.15420.
Not reproduced with Inkscape 0.91.

[Patrick Storz (ede123)]

Possible duplicate: Bug #1726431