Geometry Nodes: Vertex group attributes removed by second node #84382

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Robert Nederhorst · 2021-01-04T18:29:54+01:00

Robert Nederhorst commented

2021-01-04 18:29:54 +01:00

Blender Version
Broken: 2.92 Jan 4 build

Using an attribute math node (I was trying to invert the paint area) results in the attribute being either ignored or wiped out.

Exact steps for others to reproduce the error
Included .blend file for ease of testing.
check out nodes in geoNodeMain object. unmute the attribute math node and watch the system ignore the attributes I painted.

{F9550659 size=full}

Attribute Math Node Bug.blend

**Blender Version** Broken: 2.92 Jan 4 build Using an attribute math node (I was trying to invert the paint area) results in the attribute being either ignored or wiped out. **Exact steps for others to reproduce the error** Included .blend file for ease of testing. check out nodes in geoNodeMain object. unmute the attribute math node and watch the system ignore the attributes I painted. {[F9550659](https://archive.blender.org/developer/F9550659/image.png) size=full} [Attribute Math Node Bug.blend](https://archive.blender.org/developer/F9550656/Attribute_Math_Node_Bug.blend)

Robert Nederhorst commented

2021-01-04 18:29:54 +01:00

Added subscriber: @RobN

Hans Goudey commented

2021-01-04 18:41:16 +01:00

Added subscriber: @HooglyBoogly

Hans Goudey commented

2021-01-04 18:41:16 +01:00

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

Hans Goudey self-assigned this 2021-01-04 18:41:16 +01:00

Hans Goudey commented

2021-01-04 18:41:16 +01:00

Thanks for the report, I'll look into this now.

Hans Goudey changed title from ~~Attribute Math (Geo Nodes) wiping out attributes~~ to Geometry Nodes: Vertex group attributes removed by second node

2021-01-04 21:23:56 +01:00

blender-admin commented

2021-01-05 00:07:10 +01:00

This issue was referenced by 102eff0bd4

This issue was referenced by 102eff0bd45e9bce2d1e98f7e3c7e91f9d36df15

Hans Goudey commented

2021-01-05 00:07:43 +01:00

Changed status from 'Confirmed' to: 'Resolved'

Hans Goudey closed this issue

2021-01-05 00:07:43 +01:00

Robert Nederhorst commented

2021-01-05 23:09:50 +01:00

That's great! Bug is sorted.
This may be the wrong place to put this information and if so please let me know ...
I am looking to modify the attribute (invert, or add a color ramp to change the falloff, etc) but while the nodes don't remove the attributes it seems like doing something (look at the attribute math node) like multiplying doesn't actually change the attribute.
thanks!

That's great! Bug is sorted. This may be the wrong place to put this information and if so please let me know ... I am looking to modify the attribute (invert, or add a color ramp to change the falloff, etc) but while the nodes don't remove the attributes it seems like doing something (look at the attribute math node) like multiplying doesn't actually change the attribute. thanks!

Hans Goudey commented

2021-01-05 23:17:08 +01:00

@RobN That works for me:
{F9551930 size=full}

@RobN That works for me: {[F9551930](https://archive.blender.org/developer/F9551930/image.png) size=full}

Robert Nederhorst commented

2021-01-06 00:00:54 +01:00

Ah ok, that's stupid user error (me = stupid user)
I would suggest that if the user doesn't add the "Result" and the choice is Attribute / Float that the system assumes that the Result = input attribute unless the user explicitly enters the Result attribute
Thanks again for the fix!

Ah ok, that's stupid user error (me = stupid user) I would suggest that if the user doesn't add the "Result" and the choice is Attribute / Float that the system assumes that the Result = input attribute unless the user explicitly enters the Result attribute Thanks again for the fix!

Robert Nederhorst commented

2021-01-06 00:30:26 +01:00

I have an additional issue here that I will attach as a blend file
2.92 alpha build 04 jan 2021
hash : 91b17e71c23a9

the node has a frame with LOOK HERE for ease of use.
I am taking scale and multiplying it and it's either taking scale to 0 or changing where the distribution goes.
attribute_math_bug_v002.blend

Here is the ultimate goal I am trying to achieve which goes beyond thus bug report but it's the spirit :)
I think it would be great to be able to draw areas of where grass should be, then place trees in the areas without grass (the inverse of the grass attrib)
Now, I would like to place different grass in the area between the main grass and the tree. Maybe it's taller, has different geo, etc.
So then I would:

multiply the grass attrib go make it larger
subtract the original grass attrib from the larger attrib, which gives me a band that would be thin but allow me to place different geo (using another distribution, instance etc) near the tree but not over the original grass area.

Ultimately it would be awesome to have some kind of intersection node that would be able to dynamically create these placement attributes so that if you need to move a tree manually (for cinematography reasons, etc) then the whole system would update.
Yes that goes beyond the scop of this but but again, I wanted to give you the thoughts behind these reports so that it helps you, the smart people, understand what the mental process is.

Rob

I have an additional issue here that I will attach as a blend file 2.92 alpha build 04 jan 2021 hash : 91b17e71c23a9 the node has a frame with LOOK HERE for ease of use. I am taking scale and multiplying it and it's either taking scale to 0 or changing where the distribution goes. [attribute_math_bug_v002.blend](https://archive.blender.org/developer/F9551996/attribute_math_bug_v002.blend) Here is the ultimate goal I am trying to achieve which goes beyond thus bug report but it's the spirit :) I think it would be great to be able to draw areas of where grass should be, then place trees in the areas without grass (the inverse of the grass attrib) Now, I would like to place different grass in the area between the main grass and the tree. Maybe it's taller, has different geo, etc. So then I would: - multiply the grass attrib go make it larger - subtract the original grass attrib from the larger attrib, which gives me a band that would be thin but allow me to place different geo (using another distribution, instance etc) near the tree but not over the original grass area. Ultimately it would be awesome to have some kind of intersection node that would be able to dynamically create these placement attributes so that if you need to move a tree manually (for cinematography reasons, etc) then the whole system would update. Yes that goes beyond the scop of this but but again, I wanted to give you the thoughts behind these reports so that it helps you, the smart people, understand what the mental process is. Rob

Hans Goudey commented

2021-01-06 05:17:07 +01:00

Yeah, that's not a bug. Consider that the geometry coming out of the point distribute node only consists of a bunch of points. There's nothing to scatter on.

It's clear we need a better way to indicate the types of geometry each node creates. Or a viewer. That would make figuring this stuff out much easier. I see what you mean about an intersection node, that would indeed be helpful. Though I would call it something more like "Attribute from Distance".

Maybe this helps?
{F9552289 size=full}

Cheers,
Hans

Yeah, that's not a bug. Consider that the geometry coming out of the point distribute node only consists of a bunch of points. There's nothing to scatter on. It's clear we need a better way to indicate the types of geometry each node creates. Or a viewer. That would make figuring this stuff out much easier. I see what you mean about an intersection node, that would indeed be helpful. Though I would call it something more like "Attribute from Distance". Maybe this helps? {[F9552289](https://archive.blender.org/developer/F9552289/image.png) size=full} Cheers, Hans

Robert Nederhorst commented

2021-01-06 06:49:54 +01:00

Thanks for the screen shot. Very helpful!
Attribute from Distance is great. It would need to be able to support a collection so that if multiple trees were moved around the system would dynamically update.
Yes there is a modifier that does this but of course the goal is to keep it inside the node system.
Attribute from Image/Texture would be awesome as well. This would allow for animated attributes which currently is not as straightforward.

So my little query about being able to adjust scale...how would I go about that?
I'd want to set it so that as the grass items get closer to the tree, the grass item would get smaller/larger.

Being able to view the output would be awesome. I know there is a way to see weights in the viewport but it's only in edit mode which doesn't work to be able to visualize what's happening to the data in the node graph

Thanks for your thoughtful replies!
Rob

Thanks for the screen shot. Very helpful! Attribute from Distance is great. It would need to be able to support a collection so that if multiple trees were moved around the system would dynamically update. Yes there is a modifier that does this but of course the goal is to keep it inside the node system. Attribute from Image/Texture would be awesome as well. This would allow for animated attributes which currently is not as straightforward. So my little query about being able to adjust scale...how would I go about that? I'd want to set it so that as the grass items get closer to the tree, the grass item would get smaller/larger. Being able to view the output would be awesome. I know there is a way to see weights in the viewport but it's only in edit mode which doesn't work to be able to visualize what's happening to the data in the node graph Thanks for your thoughtful replies! Rob

Hans Goudey commented

2021-01-06 19:58:09 +01:00

For adjusting scale you can use the scale or radius attributes before the instance node. I realized we didn't have any information about that in the manual, so I added a bit more (rBM7543).

For adjusting scale you can use the `scale` or `radius` attributes before the instance node. I realized we didn't have any information about that in the manual, so I added a bit more (rBM7543).

Robert Nederhorst commented

2021-01-07 02:14:40 +01:00

So I tried that

However, doing that also removes or sets the scale to 0. Hard to know what it's doing but the spheres in my case cease to exist :)
Again the goal is to be able to mult the scale * placement to be able to change scale as the distributed items get closer to the tree (or whatever)
Thanks again!

So I tried that ![image.png](https://archive.blender.org/developer/F9553702/image.png) However, doing that also removes or sets the scale to 0. Hard to know what it's doing but the spheres in my case cease to exist :) Again the goal is to be able to mult the scale * placement to be able to change scale as the distributed items get closer to the tree (or whatever) Thanks again!

Hans Goudey commented

2021-01-07 05:26:35 +01:00

Without more context it's a bit hard to tell, mind uploading a file? By the way, this would be easier on blender.chat if you're logged in there.

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Geometry Nodes: Vertex group attributes removed by second node #84382