Curve Deform Node #88702

New Issue

Dalai Felinto · 2021-05-31T14:19:21+02:00

Dalai Felinto commented

2021-05-31 14:19:21 +02:00

NOTE: The design below is outdated. A curve deform node should be a field node now, with a vector input and output, and a curve input. Arguably it should just be a node group too.

{F10152887 size=full}	{F10152878 size=full}	{F10152882 size=full}

This is task is for a port of the "Curve" modifier to a node.
{F10150643, size=50%}

Details

Any geometry component with a position attribute is supported by this node.
Only the first spline of the curve is used for deformation.
Two input modes modes are available.
The position mode uses point positions for the curve parameters.* The position input is provided for convenience. In most common cases, a single axis of the position is used as a parameter for the curve.
*The position is mapped to the curve based on length. So "x=5m" means, transform by traveling 5m along the spline. This is how the modifier works. The attribute input mode uses any float attribute between zero and one, as a factor along the length of the curve.
** For convenience, a "Float" option is available for the attribute when the whole geometry should have the same parameter.
Extrapolation should be handled by a separate node that can extrapolate a spline.

Further Questions

Is an "influence" attribute input really necessary? The same thing could be achieved by mixing a copied position attribute before starting the operation.
** The answer to this question will apply to other operations as well.
Which of the three "Curve Deform" settings are necessary in this node? "Use Radius" is likely not necessary, the attribute could just be filled beforehand.

Related Nodes

A "Curve Sample" node could do a similar operation, but instead of deforming positions, it would sample an attribute along the length of a curve based on the same mapping controls.
** This could be useful to have more flexible control of attributes with curves.

Implementation
The implementation should be straightforward. Sampling arbitrary points along the curve is an natural extension of the uniform sampling that is already implemented.
Curve parameters should be sorted before, and then changed into evaluated point indices and factors.
Then, interpolation between the transform of neighboring evaluated points should be quite simple.

NOTE: The design below is outdated. A curve deform node should be a field node now, with a vector input and output, and a curve input. Arguably it should just be a node group too. | {[F10152887](https://archive.blender.org/developer/F10152887/image.png) size=full}| {[F10152878](https://archive.blender.org/developer/F10152878/image.png) size=full} | {[F10152882](https://archive.blender.org/developer/F10152882/image.png) size=full} | | -- | -- | -- | This is task is for a port of the "Curve" modifier to a node. {[F10150643](https://archive.blender.org/developer/F10150643/image.png), size=50%} **Details** * Any geometry component with a position attribute is supported by this node. * Only the first spline of the curve is used for deformation. * Two input modes modes are available. **The position mode uses point positions for the curve parameters.*** The position input is provided for convenience. In most common cases, a single axis of the position is used as a parameter for the curve. ***The position is mapped to the curve based on length. So "x=5m" means, transform by traveling 5m along the spline. This is how the modifier works.** The attribute input mode uses any float attribute between zero and one, as a factor along the length of the curve. ** For convenience, a "Float" option is available for the attribute when the whole geometry should have the same parameter. * Extrapolation should be handled by a separate node that can extrapolate a spline. **Further Questions** * Is an "influence" attribute input really necessary? The same thing could be achieved by mixing a copied position attribute before starting the operation. ** The answer to this question will apply to other operations as well. * Which of the three "Curve Deform" settings are necessary in this node? "Use Radius" is likely not necessary, the attribute could just be filled beforehand. **Related Nodes** * A "Curve Sample" node could do a similar operation, but instead of deforming positions, it would sample an attribute along the length of a curve based on the same mapping controls. ** This could be useful to have more flexible control of attributes with curves. **Implementation** The implementation should be straightforward. Sampling arbitrary points along the curve is an natural extension of the uniform sampling that is already implemented. Curve parameters should be sorted before, and then changed into evaluated point indices and factors. Then, interpolation between the transform of neighboring evaluated points should be quite simple.

Dalai Felinto commented

2021-05-31 14:19:21 +02:00

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

Dalai Felinto commented

2021-05-31 14:19:21 +02:00

Added subscriber: @dfelinto

Hans Goudey changed title from ~~Curve deform node~~ to Curve Deform Node

2021-06-01 16:35:18 +02:00

Hans Goudey self-assigned this 2021-06-07 06:05:24 +02:00

Hans Goudey commented

2021-06-14 08:16:56 +02:00

I'll note that the patch for this task strays from the above design, since much of it doesn't really make sense. I'll update more tomorrow.

Dalai Felinto commented

2021-06-14 14:45:06 +02:00

Hans needs help testing this already, specially in regard to the options and the differences between the modifier and the node.

Piotr Adamowicz commented

2021-09-16 11:27:35 +02:00

Added subscriber: @MadMinstrel

Piotr Adamowicz commented

2021-09-16 11:27:35 +02:00

"Only the first spline of the curve is used for deformation."

I've always found this to be very problematic with the Curve modifier. Can't this be done for each spline?

"Only the first spline of the curve is used for deformation." I've always found this to be very problematic with the Curve modifier. Can't this be done for each spline?

lictex_ commented

2021-10-15 14:56:55 +02:00

Added subscriber: @lictex_1