gradient becomes one color after 'extension>modify path> perspective'

Thanks for taking the time to file a report!

Could you please attach and example SVG file so that we could try to investigate?
Thanks!

Attached

On Sat, Apr 16, 2016 at 3:18 PM, jazzynico <email address hidden>
wrote:

> Thanks for taking the time to file a report!
>
> Could you please attach and example SVG file so that we could try to
> investigate?
> Thanks!
>
> ** Tags removed: perspective
> ** Tags added: extensions-plugins
>
> --
> You received this bug notification because you are subscribed to the bug
> report.
> https://bugs.launchpad.net/bugs/1571061
>
> Title:
> gradient becomes one color after 'extension>modify path> perspective'
>
> Status in Inkscape:
> New
>
> Bug description:
> Ink 0.91
> 1). group image
> 2). object to path
> 3). extension>modify path> perspective
> 4). the perspective happens correctly except the gradient becomes one
> of the end colors
>
> To manage notifications about this bug go to:
> https://bugs.launchpad.net/inkscape/+bug/1571061/+subscriptions
>

--
-Brent

Reproduced on Windows 7 with Inkscape trunk rev. 14755.
Not reproduced with 0.91 (both 32-bit and 64-bit versions).

Could you please confirm you're using a trunk version and give details on your operating system? Thanks!

Trying to narrow down the commits:
* reproduced with trunk rev. 13432.
* not reproduced with trunk rev. 12980.

That said, the issue is probably not in the script itseft, but rather in one of its dependencies (inkex, simplepath, cubicsuperpath, simpletransform, or ffgeom).

  Ink 0.91
windows 10
64 bit
8 G RAM

trunk ?

On Mon, Apr 18, 2016 at 6:41 AM, jazzynico <email address hidden>
wrote:

> Reproduced on Windows 7 with Inkscape trunk rev. 14755.
> Not reproduced with 0.91 (both 32-bit and 64-bit versions).
>
> Could you please confirm you're using a trunk version and give details
> on your operating system? Thanks!
>
> ** Changed in: inkscape
> Status: New => Triaged
>
> ** Changed in: inkscape
> Milestone: None => 0.92
>
> ** Tags added: regression
>
> --
> You received this bug notification because you are subscribed to the bug
> report.
> https://bugs.launchpad.net/bugs/1571061
>
> Title:
> gradient becomes one color after 'extension>modify path> perspective'
>
> Status in Inkscape:
> Triaged
>
> Bug description:
> Ink 0.91
> 1). group image
> 2). object to path
> 3). extension>modify path> perspective
> 4). the perspective happens correctly except the gradient becomes one
> of the end colors
>
> To manage notifications about this bug go to:
> https://bugs.launchpad.net/inkscape/+bug/1571061/+subscriptions
>

--
-Brent

The trunk is the current development version. Where did you download you Inkscape installer?
If you have an official 0.91 version, you should see Inkscape 0.91 (for the 32-bit version) or Inkscape 0.91_64bit r13859 (64-bit) when opening the about dialog (Help>About Inkscape). If you see anything else (another revision or just 0.91 r with no number), it's probably a development version.

I thought I was using your official site. I am on my cell phone now due
to severe storm. Could you send link to what I should be using? I will
try it after storm subsides.

Thanks.
Brent
On Apr 18, 2016 8:26 AM, "jazzynico" <email address hidden> wrote:

The trunk is the current development version. Where did you download you
Inkscape installer?
If you have an official 0.91 version, you should see Inkscape 0.91 (for the
32-bit version) or Inkscape 0.91_64bit r13859 (64-bit) when opening the
about dialog (Help>About Inkscape). If you see anything else (another
revision or just 0.91 r with no number), it's probably a development
version.

--
You received this bug notification because you are subscribed to the bug
report.
https://bugs.launchpad.net/bugs/1571061

Title:
  gradient becomes one color after 'extension>modify path> perspective'

Status in Inkscape:
  Triaged

Bug description:
  Ink 0.91
  1). group image
  2). object to path
  3). extension>modify path> perspective
  4). the perspective happens correctly except the gradient becomes one of
the end colors

To manage notifications about this bug go to:
https://bugs.launchpad.net/inkscape/+bug/1571061/+subscriptions

Reproduced with Inkscape 0.47, 0.48.5, 0.91 and latest trunk (on OS X 10.7.5).

AFAIU this is to be expected: SVG gradients for paint servers are stored in Inkscape with absolute coordinates/transformations - adjusting the position of the gradient stops for perspective rendering via extension scripts might be technically possible for linear gradients (though rather cumbersome), but the interpolation would still be linear (i.e. perspectively wrong). Radial gradients can't really be perspectively transformed in SVG 1.1 (maybe described/represented by offsetting the focal point to achieve a similar impression - I haven't investigated that particular aspect though).

To the best of my knowledge, the perspective extension script does not adjust the transformations of any particular style properties perspectively (be it e.g. gradients and patterns, or stroke widths and the length of individual stroke dashes) - it only recalculates the positions of nodes, and their handles.

In my understanding this report would be a feature request, similar to the one requesting to support gradients for the interpolate paths extension, the result though cannot be fully correct for perspective transformations due to limitations in the file format (SVG).

@JazzyNico - there is a regression in trunk with perspective used in files created with 0.91, see bug #1508400 (the overall scale is wrong due to different drawing scale). It does not concern style properties though.

Ok. I finally got back to my PC. I see Inkscape 0.91 r13725 with no
reference to bits.
I downloaded from: https://inkscape.org/en/download/

*Windows*

*32-bit*: installer (msi)
<https://inkscape.org/en/gallery/item/3950/inkscape-0.91.msi>, installer
(exe) <https://inkscape.org/en/gallery/item/3944/Inkscape-0.91-1.exe>, portable
app
<https://inkscape.org/en/gallery/item/4460/InkscapePortable_0.91.paf.exe>,
binary
archive (7z)
<https://inkscape.org/en/gallery/item/3932/Inkscape-0.91-1-win32.7z>, binary
archive (7z, debug files archive)
<https://inkscape.org/en/gallery/item/3926/Inkscape-0.91-1-win32-debug.7z>

*64-bit*: installer (msi)
<https://inkscape.org/en/gallery/item/3956/inkscape-0.91-x64.msi>, binary
archive (7z)
<https://inkscape.org/en/gallery/item/3938/Inkscape-0.91-1-win64.7z>, binary
archive (7z, debug files archive)
<https://inkscape.org/en/gallery/item/3920/Inkscape-0.91-1-win64-debug.7z>
Where should I be downloading it? The 64 bit installer (msi) installed. I
did not know what to do with the binary files.
Thansk
Brent

On Mon, Apr 18, 2016 at 8:16 AM, jazzynico <email address hidden>
wrote:

> The trunk is the current development version. Where did you download you
> Inkscape installer?
> If you have an official 0.91 version, you should see Inkscape 0.91 (for
> the 32-bit version) or Inkscape 0.91_64bit r13859 (64-bit) when opening the
> about dialog (Help>About Inkscape). If you see anything else (another
> revision or just 0.91 r with no number), it's probably a development
> version.
>
> --
> You received this bug notification because you are subscribed to the bug
> report.
> https://bugs.launchpad.net/bugs/1571061
>
> Title:
> gradient becomes one color after 'extension>modify path> perspective'
>
> Status in Inkscape:
> Triaged
>
> Bug description:
> Ink 0.91
> 1). group image
> 2). object to path
> 3). extension>modify path> perspective
> 4). the perspective happens correctly except the gradient becomes one
> of the end colors
>
> To manage notifications about this bug go to:
> https://bugs.launchpad.net/inkscape/+bug/1571061/+subscriptions
>

--
-Brent

@su-v - Thanks for your explanation!

Now I can reproduce with 0.91 too, with a file created with 0.91.
The file created with the trunk seemed to work when used in 0.91 to create a perspective, but it was due to the fact that the modified object moved to a place where parts if the gradients still applied (see attachment).

Related: bug #1160941 "interpolation of gradient does not work properly" <https://bugs.launchpad.net/inkscape/+bug/1160941>

The perspective has been working on most gradients. However it does not work on the attachment which is more complex usual. Thanks for your help so far.