Knife Project Resolution is View Dependent #43896

New Issue

Carlo Andreacchio · 2015-03-05T08:22:32+01:00

Carlo Andreacchio commented

2015-03-05 08:22:32 +01:00

System Information
Windows 7, x64, gtx 580

Blender Version
Broken: 85c38e7

Short description of error
Knife project resolution seems to be based on the camera zoom level. Artists are expecting that it wouldnt operate like this, ending up with meshes which look inaccurate.

Exact steps for others to reproduce the error

Open attached file
knife project
zoom in a lot
notice how horrible it is
undo
knife project
notice the difference

knifebug.blend

**System Information** Windows 7, x64, gtx 580 **Blender Version** Broken: 85c38e7 **Short description of error** Knife project resolution seems to be based on the camera zoom level. Artists are expecting that it wouldnt operate like this, ending up with meshes which look inaccurate. **Exact steps for others to reproduce the error** 1. Open attached file 2. knife project 3. zoom in a lot 4. notice how horrible it is 5. undo 6. knife project 7. notice the difference [knifebug.blend](https://archive.blender.org/developer/F147379/knifebug.blend)

Carlo Andreacchio commented

2015-03-05 08:22:32 +01:00

Changed status to: 'Open'

Carlo Andreacchio commented

2015-03-05 08:22:32 +01:00

Added subscriber: @candreacchio

blender-admin commented

2015-03-05 08:22:32 +01:00

#44297 was marked as duplicate of this issue

Campbell Barton was assigned by Antonis Ryakiotakis

2015-03-05 18:05:17 +01:00

Antonis Ryakiotakis commented

2015-03-05 18:05:17 +01:00

Added subscriber: @Psy-Fi

Antonis Ryakiotakis commented

2015-03-05 18:05:17 +01:00

Campbell, what do you think?

Julian Eisel commented

2015-03-05 18:25:00 +01:00

Added subscriber: @JulianEisel

Julian Eisel commented

2015-03-05 18:25:00 +01:00

Argh, it really depends a lot on the zoomlevel. Even getting weird results like this: Doesn't work better with older Blender versions... :/

Argh, it really depends **a lot** on the zoomlevel. Even getting weird results like this: ![knife_project.png](https://archive.blender.org/developer/F147444/knife_project.png) Doesn't work better with older Blender versions... :/

Carlo Andreacchio commented

2015-03-05 22:21:45 +01:00

@JulianEisel, are you projecting from ortho or perspective?

This is the difference i am getting, top is zoomed out, bottom is zoomed in -- https://i.imgur.com/5jI0kUz.png

@JulianEisel, are you projecting from ortho or perspective? This is the difference i am getting, top is zoomed out, bottom is zoomed in -- https://i.imgur.com/5jI0kUz.png

Julian Eisel commented

2015-03-05 23:12:07 +01:00

The one from the screenshot was done in perspective mode, but I think that's not important here (just wanted to demo which weird things are happening).

Edit: I thought I didn't zoom after doing the knife projection but now I'm not sure if I didn't do it by accident :P

The one from the screenshot was done in perspective mode, but I think that's not important here (just wanted to demo which weird things are happening). Edit: I thought I didn't zoom after doing the knife projection but now I'm not sure if I didn't do it by accident :P

Carlo Andreacchio commented

2015-03-05 23:30:16 +01:00

To me, the edges are align fine both in perspective & in orthographic.... knife projections should always be done in orthographic though (due to the camera lens on perspective)... The main thing that the artists are commenting about the resolution being dependent on the view... our current workflow is a bit of a work around, by framing in on one vertex before knife cutting.

Campbell Barton commented

2015-03-06 16:06:27 +01:00

The knife tool is view resolution dependent, uses pixel size to determine how to snap for example,
and knife project is simply using the knife tool's code (so everythings projected into pixel-space before cutting).

Reports recently show that people like to use this as some precision modeling tool like boolean.

While we can extend the knife tool further... its code isn't really ideal for this and it might be better to use bmesh_intersect.c for such operations.

Will investigate making this case work better but think this isn't really a bug. (at least its intentional that it works exactly like the knife tool which happens to be in pixelspace)

The knife tool is view resolution dependent, uses pixel size to determine how to snap for example, and knife project is simply using the knife tool's code (so everythings projected into pixel-space before cutting). Reports recently show that people like to use this as some precision modeling tool like boolean. While we can extend the knife tool further... its code isn't really ideal for this and it might be better to use `bmesh_intersect.c` for such operations. Will investigate making this case work better but think this isn't really a bug. *(at least its intentional that it works exactly like the knife tool which happens to be in pixelspace)*

Julian Eisel commented

2015-03-08 18:34:57 +01:00

Marking as Todo then! (Will leave open though)

Julian Eisel commented

2015-04-13 18:37:58 +02:00

Added subscriber: @bliblubli

mathieu menuet commented

2015-04-14 19:03:09 +02:00

the bug I reported was more about the wrong selection (the precision issue was just a side-note). I added a new version of the file in #44297.

blender-admin commented

2016-01-20 10:46:25 +01:00

This issue was referenced by 6fa5d22109

This issue was referenced by 6fa5d22109e276dd5f732f50445a4247a8f3c22b

Campbell Barton commented

2016-01-20 10:54:00 +01:00

Changed status from 'Open' to: 'Resolved'

Campbell Barton closed this issue

2016-01-20 10:54:00 +01:00

Campbell Barton commented

2016-04-01 16:30:36 +02:00

Changed status from 'Resolved' to: 'Open'

Campbell Barton reopened this issue

2016-04-01 16:30:36 +02:00

Campbell Barton commented

2016-04-01 16:30:36 +02:00

Had to revert this, caused #48023

Campbell Barton removed their assignment 2016-08-11 06:35:12 +02:00

Campbell Barton commented

2016-08-11 06:35:12 +02:00

Removed subscriber: @ideasman42

Adam commented

2016-10-04 03:33:42 +02:00

Added subscriber: @arountre

Adam commented

2016-10-04 03:33:42 +02:00

Would it be possible to set snap distance? Even when holding shift to disable snapping, resulting cuts are rough when made zoomed out apparently due to snapping at some finer level? I have not been able to determine a way to cleanly slice large (2 to 5 million face) meshes in Blender (Boolean tends to fail on these large meshes).

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Knife Project Resolution is View Dependent #43896