[WIP] GP Bezier Tool Design #58777

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Charlie Jolly · 2018-12-05T10:54:11+01:00

Charlie Jolly commented

2018-12-05 10:54:11 +01:00

Discussion of GP Bezier Tool

Charlie Jolly commented

2018-12-05 10:54:11 +01:00

Added subscriber: @CharlieJolly

Charlie Jolly commented

2018-12-05 11:04:11 +01:00

I've got a patch for adding a gp bezier tool based on the MyPaint curve tool.

I've not added it to the tracker yet pending D4030.

Current sequence of actions:
Left click drag release to draw initial curve.
Shift click and drag curve.
Enter to apply.

The modify behaviour first detects if the mouse is near the start or end of the line within a threshold, failing that it uses the control point for nearest end.
Ctrl-shift drag moves both control points to the same place (for effectively a cubic bezier).
Cursor changes to hand when in modify mode.
The control points aren't shown so the shift action feels more like sculpting.

I've got a patch for adding a gp bezier tool based on the MyPaint curve tool. I've not added it to the tracker yet pending [D4030](https://archive.blender.org/developer/D4030). ![gp_bezier.gif](https://archive.blender.org/developer/F5832179/gp_bezier.gif) Current sequence of actions: Left click drag release to draw initial curve. Shift click and drag curve. Enter to apply. The modify behaviour first detects if the mouse is near the start or end of the line within a threshold, failing that it uses the control point for nearest end. Ctrl-shift drag moves both control points to the same place (for effectively a cubic bezier). Cursor changes to hand when in modify mode. The control points aren't shown so the shift action feels more like sculpting.

Charlie Jolly commented

2018-12-05 15:23:19 +01:00

Polyline using AKEY to add a new line.
New ring cursor for moving line ends,

Polyline using AKEY to add a new line. New ring cursor for moving line ends, ![gp_bezier_polyline.gif](https://archive.blender.org/developer/F5834434/gp_bezier_polyline.gif)

Antonio Vazquez commented

2018-12-05 15:49:07 +01:00

Added subscribers: @mendio, @pepe-school-land, @antoniov

Antonio Vazquez commented

2018-12-05 15:49:07 +01:00

Firstly, I like the idea of primitives with Bezier curves, but do we want only this? I mean, maybe we need to think in a new whole type of strokes "Curves" and keep all the information to allow editing. Sometimes you could need to refine or reshape the curve. Anyway, I like the primitive that you describe, but maybe we need to be "careful" with the name we give, Bezier curves are too wide and the users will expect more of this type of tool.

@pepe-school-land @mendio What do you think?

Firstly, I like the idea of primitives with Bezier curves, but do we want only this? I mean, maybe we need to think in a new whole type of strokes "Curves" and keep all the information to allow editing. Sometimes you could need to refine or reshape the curve. Anyway, I like the primitive that you describe, but maybe we need to be "careful" with the name we give, Bezier curves are too wide and the users will expect more of this type of tool. @pepe-school-land @mendio What do you think?

Charlie Jolly commented

2018-12-05 16:09:48 +01:00

I suppose there are two aspects, one from artists and one from a technical point of view.

For artists, the primitive tools allow them to create smooth curves and other geometric shapes which will be generated as regular GP strokes. As a comparison to MyPaint, at least you can delete the strokes you don't want.

Technically. allowing strokes to be editable as Beziers would probably mean implementing a curve fitting function to convert a GP point stroke back to a Bezier after scultpting and other actions. This has other impacts such as memory use.

Maybe it should be an initial goal to give artists more useful tools then at a later time investigate curve fitting functions.

I suppose there are two aspects, one from artists and one from a technical point of view. For artists, the primitive tools allow them to create smooth curves and other geometric shapes which will be generated as regular GP strokes. As a comparison to MyPaint, at least you can delete the strokes you don't want. Technically. allowing strokes to be editable as Beziers would probably mean implementing a curve fitting function to convert a GP point stroke back to a Bezier after scultpting and other actions. This has other impacts such as memory use. Maybe it should be an initial goal to give artists more useful tools then at a later time investigate curve fitting functions.

Antonio Vazquez commented

2018-12-05 16:13:18 +01:00

@CharlieJolly Yes, agree. Real Beziers is totally different, but we can add this primitive now.

Could you load the patch to test it?

Maybe, you could apply the patch to greasepencil-object branch and we can test all before moving to 2.8.

@CharlieJolly Yes, agree. Real Beziers is totally different, but we can add this primitive now. Could you load the patch to test it? Maybe, you could apply the patch to greasepencil-object branch and we can test all before moving to 2.8.

Matias Mendiola commented

2018-12-05 16:22:40 +01:00

Agree @antoniov , the tool is very useful but this require more research and test before land in Grease Pencil as a complete bezier curves system.
I suggest to move all this new tools development that @CharlieJolly is doing to the greasepencil-object branch first.

Agree @antoniov , the tool is very useful but this require more research and test before land in Grease Pencil as a complete bezier curves system. I suggest to move all this new tools development that @CharlieJolly is doing to the greasepencil-object branch first.

Daniel Martinez Lara commented

2018-12-05 22:36:32 +01:00

I like a lot this tool @Charlie. Great for the cleanup process and the implemetnation for the user seems ok, (need to test it)
A good improvement will be that you can see the final GP stroke during maipulation (like in mypaint) instead the current preview orange line and
the otherone is have a option to taper the stroke start/end in the toolbar. See the attached gif

I like a lot this tool @Charlie. Great for the cleanup process and the implemetnation for the user seems ok, (need to test it) A good improvement will be that you can see the final GP stroke during maipulation (like in mypaint) instead the current preview orange line and the otherone is have a option to taper the stroke start/end in the toolbar. See the attached gif ![maypaint3.gif](https://archive.blender.org/developer/F5842282/maypaint3.gif)

Matias Mendiola commented

2018-12-05 23:05:44 +01:00

The final stroke preview should be not only for this bezier curve tool, but also for all the other primitives

Antonio Vazquez commented

2018-12-06 09:15:05 +01:00

@CharlieJolly To get the preview while drawing you need fill the stroke buffer with the points. Also, we need to be sure the buffer is cleared at the end of the operator (you can see an example in gpencil_paint.c)

Also look at gp_session_validatebuffer()

@CharlieJolly To get the preview while drawing you need fill the stroke buffer with the points. Also, we need to be sure the buffer is cleared at the end of the operator (you can see an example in gpencil_paint.c) Also look at gp_session_validatebuffer()

Antonio Vazquez commented

2018-12-06 10:49:07 +01:00

@CharlieJolly I have been thinking and IMHO it's mandatory to do all this stuff in greasepencil-object branch. Add new/change operators and add real stroke drawing in primitives can break the current 2.8 version, and now we have users, so we cannot test things there (if something is broken we will receive a lot of bugs and we will need time to manage them).

The plan is:

Move the changes to greasepencil-object branch. We do all work here.
Implement real drawing and other changes.
Test and polish.
Merge to 2.8

@CharlieJolly I have been thinking and IMHO it's mandatory to do all this stuff in greasepencil-object branch. Add new/change operators and add real stroke drawing in primitives can break the current 2.8 version, and now we have users, so we cannot test things there (if something is broken we will receive a lot of bugs and we will need time to manage them). The plan is: 1) Move the changes to greasepencil-object branch. We do all work here. 2) Implement real drawing and other changes. 3) Test and polish. 4) Merge to 2.8

Charlie Jolly commented

2018-12-06 11:29:33 +01:00

@antoniov Ok, I'll get setup on the greasepencil-object branch.

Antonio Vazquez commented

2018-12-06 12:06:03 +01:00

I just merge 2.8 in GP branch.

Antonio Vazquez commented

2018-12-06 13:18:48 +01:00

In the branch the stroke is drawn while do the primitive (2bcc5f8bdef7)

Not sure if we must draw the orange line, but as you use Cyclic for Rectangles and Circles, during the drawing this is a help.

In the branch the stroke is drawn while do the primitive (2bcc5f8bdef7) Not sure if we must draw the orange line, but as you use Cyclic for Rectangles and Circles, during the drawing this is a help.

Albert commented

2018-12-06 14:07:46 +01:00

Added subscriber: @wevon-2

Albert commented

2018-12-06 14:07:46 +01:00

As shown in this video fragment,

https://youtu.be/0CnfsU4cKDY?t=136

Retopoflow allows you to create strips with and edit them with a curve, but unlike the first version, it allows you to select any curve fragment and edit it with a curve that adapts to the length of the selection. . I think that adapting this Grease Pencil tool so that it can work in Edit Mode, can be very interesting.

As shown in this video fragment, https://youtu.be/0CnfsU4cKDY?t=136 Retopoflow allows you to create strips with and edit them with a curve, but unlike the first version, it allows you to select any curve fragment and edit it with a curve that adapts to the length of the selection. . I think that adapting this Grease Pencil tool so that it can work in Edit Mode, can be very interesting.

Charlie Jolly commented

2019-01-08 10:47:07 +01:00

@wevon-2 it is on my todo list to look into implementing this

Albert commented

2019-01-08 20:23:50 +01:00

In #58777#595898, @CharlieJolly wrote:
@wevon-2 it is on my todo list to look into implementing this

Apart from being able to edit any fragment I think it could also soften them. Although there is the smoothing brush, as an editing tool it can be useful.
This is how I imagine it, by adding a ring on the tool.

Another option would be to put the ring on the ends and scale it to adjust the influence radius of the smoothing.

> In #58777#595898, @CharlieJolly wrote: > @wevon-2 it is on my todo list to look into implementing this Apart from being able to edit any fragment I think it could also soften them. Although there is the smoothing brush, as an editing tool it can be useful. This is how I imagine it, by adding a ring on the tool. ![Smooth stroke.jpg](https://archive.blender.org/developer/F6222669/Smooth_stroke.jpg) Another option would be to put the ring on the ends and scale it to adjust the influence radius of the smoothing.

Albert commented

2019-01-10 17:39:29 +01:00

Without wanting to stretch longer since it is out of topic.
I have improved the design, I have made a video and I have uploaded it to RightClickSelect to explain myself better, I hope it is useful Charlie, thanks for your attention.

https://blender.community/c/rightclickselect/V4cbbc/edit-sections-of-grease-pencil

https://youtu.be/F1bSeTSoCq0

Without wanting to stretch longer since it is out of topic. I have improved the design, I have made a video and I have uploaded it to RightClickSelect to explain myself better, I hope it is useful Charlie, thanks for your attention. https://blender.community/c/rightclickselect/V4cbbc/edit-sections-of-grease-pencil https://youtu.be/F1bSeTSoCq0

Antonio Vazquez commented

2020-08-18 12:32:26 +02:00

Changed status from 'Needs Triage' to: 'Archived'

Antonio Vazquez closed this issue

2020-08-18 12:32:26 +02:00

Antonio Vazquez self-assigned this 2020-08-18 12:32:26 +02:00

Antonio Vazquez commented

2020-08-18 12:32:26 +02:00

Added subscriber: @filedescriptor

Antonio Vazquez commented

2020-08-18 12:32:26 +02:00

We can close this task because it have been replaced by GSoC Bezier project by @filedescriptor

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[WIP] GP Bezier Tool Design #58777