Curve Primitive Nodes #89220

New Issue

Hans Goudey · 2021-06-16T23:08:42+02:00

Hans Goudey commented

2021-06-16 23:08:42 +02:00

With curve support in geometry nodes we have an opportunity to add useful curve primitives.

Here is an initial list, more should be added:

		Outputs a poly spline in a perfect circle portion that intersects the three points.
		A second mode to the arc node that uses the center point. Which side is filled can depend on the order.
		Outputs a poly spline with an evaluated quadratic bezier spline. Bezier splines in Blender are cubic.
		Outputs a bezier segment. This is just a parametric version of the first item in the curve add menu. Handles should be aligned.

More types to be considered:

Spiral Many types of spirals exist. Which are most commonly useful?
** Reference: http://nortikin.github.io/sverchok/docs/nodes/generators_extended/spiral_mk2.html
Line We already have a mesh line node, but there is really no reason not to have a "Curve Line" node as well.
Circle We already have a mesh circle node also, but there could be a specific curve circle node as well.
Vectors to Curve Could have a multi-input socket of vectors, useful in some situations probably.

With curve support in geometry nodes we have an opportunity to add useful curve primitives. Here is an initial list, more should be added: | ![image.png](https://archive.blender.org/developer/F10176018/image.png) | ![image.png](https://archive.blender.org/developer/F10175964/image.png) | Outputs a poly spline in a perfect circle portion that intersects the three points. | -- | -- | -- | | ![image.png](https://archive.blender.org/developer/F10176010/image.png) | ![image.png](https://archive.blender.org/developer/F10176012/image.png) | A second mode to the arc node that uses the center point. Which side is filled can depend on the order. | ![image.png](https://archive.blender.org/developer/F10175977/image.png) | ![image.png](https://archive.blender.org/developer/F10175972/image.png) | Outputs a poly spline with an evaluated quadratic bezier spline. Bezier splines in Blender are cubic. | ![image.png](https://archive.blender.org/developer/F10175985/image.png) | ![image.png](https://archive.blender.org/developer/F10175982/image.png) | Outputs a bezier segment. This is just a parametric version of the first item in the curve add menu. Handles should be aligned. More types to be considered: * **Spiral** Many types of spirals exist. Which are most commonly useful? ** Reference: http://nortikin.github.io/sverchok/docs/nodes/generators_extended/spiral_mk2.html * **Line** We already have a mesh line node, but there is really no reason not to have a "Curve Line" node as well. * **Circle** We already have a mesh circle node also, but there could be a specific curve circle node as well. * **Vectors to Curve** Could have a multi-input socket of vectors, useful in some situations probably.

Hans Goudey commented

2021-06-16 23:08:42 +02:00

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

Hans Goudey commented

2021-06-16 23:08:42 +02:00

Added subscriber: @HooglyBoogly

Johnny Matthews commented

2021-06-17 00:11:41 +02:00

Added subscriber: @guitargeek

Johnny Matthews commented

2021-06-17 00:11:41 +02:00

Do any of the "Profile" options in the Extra Curves menu make sense for primitive nodes?

Hans Goudey commented

2021-06-17 00:28:45 +02:00

Yeah, I think some of them would. Feel free to add to this list @guitargeek. We can always remove them later if we deem them not important enough.

Johnny Matthews commented

2021-06-18 18:51:41 +02:00

For the arc mode, wouldn't the center need to be always equidistant from the 2 points to work? Or am I missing your point? (no pun intended)

Hans Goudey commented

2021-06-18 18:56:33 +02:00

Hrmm, for the "Center" mode I think you're right. Maybe that doesn't work as a node.

Hans Goudey commented

2021-06-18 21:30:22 +02:00

@guitargeek On second thought, I think it might still make sense if we specified the radius in that mode instead of the center point. And actually that sounds more useful anyway.

Johnny Matthews commented

2021-06-18 21:35:35 +02:00

In #89220#1178947, @HooglyBoogly wrote:
@guitargeek On second thought, I think it might still make sense if we specified the radius in that mode instead of the center point. And actually that sounds more useful anyway.

Sounds good!

> In #89220#1178947, @HooglyBoogly wrote: > @guitargeek On second thought, I think it might still make sense if we specified the radius in that mode instead of the center point. And actually that sounds more useful anyway. Sounds good!

Hans Goudey commented

2021-06-23 16:31:03 +02:00

Mockups based on further conversations:
{F10191095 size=full}

This one is a bit further out since we don't support expressions yet, and the way they would work hasn't really been designed, but creating curves like this would be quite nice.
One could also imagine building a "field" node network and plugging it into expression sockets

{F10191112 size=full}

Mockups based on further conversations: {[F10191095](https://archive.blender.org/developer/F10191095/image.png) size=full} This one is a bit further out since we don't support expressions yet, and the way they would work hasn't really been designed, but creating curves like this would be quite nice. One could also imagine building a "field" node network and plugging it into expression sockets {[F10191112](https://archive.blender.org/developer/F10191112/image.png) size=full}

Johnny Matthews was assigned by Hans Goudey

2021-06-27 05:21:25 +02:00

Hans Goudey commented

2021-06-27 05:21:25 +02:00

Just "assigning" this to you Johnny for organization.

Mikhail Rachinskiy commented

2021-06-28 20:18:13 +02:00

Added subscriber: @MikhailRachinskiy

Mikhail Rachinskiy commented

2021-06-28 20:18:13 +02:00

Does squiggly shape of Quadratic and Bezier Segment primitives serve any purpose?

Hans Goudey commented

2021-06-28 20:40:12 +02:00

What do you mean "squiggly"? Note that the defaults in the patches are slightly different than my mockups

Mikhail Rachinskiy commented

2021-06-28 21:02:39 +02:00

Bezier Segment primitive is tilde like shape in the mockup, does it not shaped like that in the patch?

blender-admin commented

2021-06-30 05:00:29 +02:00

This issue was referenced by 86c6769e20

This issue was referenced by 86c6769e203366d5f039869cb26e9f4d85ca205b

blender-admin commented

2021-06-30 05:20:54 +02:00

This issue was referenced by 21ebee2580

This issue was referenced by 21ebee258027f8c8bae0d51bb8d655013c5ee0a3

Hans Goudey commented

2021-06-30 05:34:13 +02:00

Just so this is somewhere besides the meeting notes, I'm adding the notes from our discussion of the primitives at our meeting today here:

* - [x] [D11648: Geometry Nodes: Curve Primitive Bezier Segment](https://archive.blender.org/developer/D11648)
    * Start/End -> Start/End Point
    * Another mode where the handles are relative to the start and end points
* - [x] [D11649: Geometry Nodes: Curve Primitive Quadratic Bezier Segment](https://archive.blender.org/developer/D11649)
    * Remove "Segment" from this and the previous
        * We were a bit divided on this point, but this name is quite long with that word...
* - [x] [D11650: Geometry Nodes: Curve Primitive Circle](https://archive.blender.org/developer/D11650)
    * "Start" "Middle" "End" -> "Point 1/2/3"
    * Default mode should be radius
    * It can output the center of the circle as well (for the Points mode)
    * Default radius of 1m
    * Make sure it "sorts" the inputs so they can work in any order
        * If that doesn't break the rotation order behavior
* - [x] [D11713: Geometry Nodes: Curve Primitive Arc](https://archive.blender.org/developer/D11713)
    * Default can be radius
    * Default radius of 1m
    * It can output the center of the circle as well (for the Points mode)
    * Make sure it works for the colinear case
* - [x] [D11609: Geometry Nodes: Curve Primitive Spiral](https://archive.blender.org/developer/D11609)
    * Curve reverse node makes the "reverse" input not necessary
        * *This input actually changes, the shape, so this comment doesn't apply*
    * Resolution can be at the top
* - [x] [D11665: Geometry Nodes: Curve Primitive Quadrilateral](https://archive.blender.org/developer/D11665)
    * Square should be the default
    * Different modes would make the options more obvious
        * Square: Only a size input
        * Rectangle: Width and height inputs
        * Parallelogram: Full controls of the current node
* - [x] [D11653: Geometry Nodes: Curve Primitive Star](https://archive.blender.org/developer/D11653)
* - [x] [D11639: Geometry Nodes: Curve Primitive Phyllotaxis Spiral](https://archive.blender.org/developer/D11639)
    * "Resolution" should be "Points" to differentiate it from the other spiral
    * The different uses-- the "crazy" output for instancing and the smooth "spiral-like" output seem to conflict a bit
        * Mostly this isn't really an actionable point
        * But make sure the "smooth" output with a lower angle is also useful

Just so this is somewhere besides the meeting notes, I'm adding the notes from our discussion of the primitives at our meeting today here: * - [x] [D11648: Geometry Nodes: Curve Primitive Bezier Segment](https://archive.blender.org/developer/D11648) * Start/End -> Start/End Point * Another mode where the handles are relative to the start and end points * - [x] [D11649: Geometry Nodes: Curve Primitive Quadratic Bezier Segment](https://archive.blender.org/developer/D11649) * Remove "Segment" from this and the previous * We were a bit divided on this point, but this name is quite long with that word... * - [x] [D11650: Geometry Nodes: Curve Primitive Circle](https://archive.blender.org/developer/D11650) * "Start" "Middle" "End" -> "Point 1/2/3" * Default mode should be radius * It can output the center of the circle as well (for the Points mode) * Default radius of 1m * Make sure it "sorts" the inputs so they can work in any order * If that doesn't break the rotation order behavior * - [x] [D11713: Geometry Nodes: Curve Primitive Arc](https://archive.blender.org/developer/D11713) * Default can be radius * Default radius of 1m * It can output the center of the circle as well (for the Points mode) * Make sure it works for the colinear case * - [x] [D11609: Geometry Nodes: Curve Primitive Spiral](https://archive.blender.org/developer/D11609) * Curve reverse node makes the "reverse" input not necessary * *This input actually changes, the shape, so this comment doesn't apply* * Resolution can be at the top * - [x] [D11665: Geometry Nodes: Curve Primitive Quadrilateral](https://archive.blender.org/developer/D11665) * Square should be the default * Different modes would make the options more obvious * Square: Only a size input * Rectangle: Width and height inputs * Parallelogram: Full controls of the current node * - [x] [D11653: Geometry Nodes: Curve Primitive Star](https://archive.blender.org/developer/D11653) * - [x] [D11639: Geometry Nodes: Curve Primitive Phyllotaxis Spiral](https://archive.blender.org/developer/D11639) * "Resolution" should be "Points" to differentiate it from the other spiral * The different uses-- the "crazy" output for instancing and the smooth "spiral-like" output seem to conflict a bit * Mostly this isn't really an actionable point * But make sure the "smooth" output with a lower angle is also useful

blender-admin commented

2021-06-30 05:39:08 +02:00

This issue was referenced by d3788207aa

This issue was referenced by d3788207aae6e7a3546850a5d6e71ed552030cc0

blender-admin commented

2021-06-30 07:03:55 +02:00

This issue was referenced by 8884d2d61b

This issue was referenced by 8884d2d61b3d60d44d4f8aecaba1d0fd121b0bf3

blender-admin commented

2021-07-01 02:17:28 +02:00

This issue was referenced by c1fc180861

This issue was referenced by c1fc18086118012637bdc5a32c5ced1742d69dac

Mikhail Rachinskiy commented

2021-07-01 19:15:57 +02:00

So Bezier and Quadratic Bezier primitives do have squiggly/bent shape. Why? Does it have a purpose?

So Bezier and Quadratic Bezier primitives do have squiggly/bent shape. Why? Does it have a purpose? ![primitive_shape.png](https://archive.blender.org/developer/F10208068/primitive_shape.png)

Hans Goudey commented

2021-07-01 19:34:06 +02:00

That's just the default, you can shape them however you want. In your opinion, what would be a better default and why?

Mikhail Rachinskiy commented

2021-07-01 21:47:04 +02:00

I would expect both primitives to be a straight line.

Though with current implementation it's not important as point handle is just a vector value, which is easy to reset. I was expecting to have control over individual bezier points and their handles later in the node tree, kinda what we have in Py API right now (and where resetting bezier primitive default shape get trickier).
I guess that'll come with curve nodes.

I would expect both primitives to be a straight line. Though with current implementation it's not important as point handle is just a vector value, which is easy to reset. I was expecting to have control over individual bezier points and their handles later in the node tree, kinda what we have in Py API right now (and where resetting bezier primitive default shape get trickier). I guess that'll come with curve nodes.

Hans Goudey commented

2021-07-05 18:46:40 +02:00

You will have control over handle positions in the node tree, but they should definitely have a non-straight shape by default, that helps so much to explain how the work visually.