Author Topic: Chaos Scatter Edge Trimming Playground!  (Read 3996 times)

2022-10-01, 14:49:59
Reply #15

romullus

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I think it's the case of you misunderstanding how this feature works. It removes any mesh element that are placed outside of scattered area*. It will not remove anything if your instances consist of single element, like box, or teapot in your examples.

* i'm not exactly sure how the scatter determines when element is considered to be outside of scattered area. It looks that decision is taken not by dimensions of element bounding box, but rather by the placement of its base, which IMHO is very nice feature!
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2022-10-01, 14:51:33
Reply #16

romullus

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Bug report - edge trimming isn't working if plugged through Corona select texmap.
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2022-10-01, 15:21:55
Reply #17

romullus

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Here's quick comparison between spline areas, edge trimming and slicer. I think some people expected edge trimming to work like slicer. Personally i find current behaviour much more natural and realistic, but it seems that there are some issues with edge detection precision, which i'm sure will be fixed by the devs in future builds.
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2022-10-01, 15:23:42
Reply #18

maru

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Can you show your setup and the result that you get? There shouldn't be any "slice effect" - edge trimming is removing whole mesh elements that falls outside of scattered area.

Works with grass downloaded from cosmos, but not with geometry create by myself (cube).

A single box is a single element. Try with a clump of grass consisting of many elements.
It considers the pivot of the element, not its bounding box. So any element whose pivot is outside of the defined area will disappear (grass blade growing on a plane will be visible, grass blade growing outside of plane will disappear). We may consider the bounding box or or other methods of trimming in future versions too.
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2022-10-01, 15:27:59
Reply #19

romullus

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It considers the pivot of the element, not its bounding box. So any element whose pivot is outside of the defined area will disappear (grass blade growing on a plane will be visible, grass blade growing outside of plane will disappear). We may consider the bounding box or or other methods of trimming in future versions too.

Please make it optional, in many cases pivot point detection makes more sense than bounding box detection.
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2022-10-01, 16:48:57
Reply #20

aaouviz

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Can you show your setup and the result that you get? There shouldn't be any "slice effect" - edge trimming is removing whole mesh elements that falls outside of scattered area.

Works with grass downloaded from cosmos, but not with geometry create by myself (cube).

Ha, good find. Yes same for me! Works on a proxy I got from Chaos. Not on self-made geo.

@romullus; it's definitely working as a trimmer as I expected (see how ForestPack works)... which is exactly how it should work. Just not for all geometry at the moment.

Edit: Ah! I get it now! It only trims elements.... now I feel slightly foolish. Works like a charm I guess. Now just looking forward to it working with more ease
« Last Edit: 2022-10-01, 17:00:39 by aaouviz »
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2022-10-01, 16:56:50
Reply #21

maru

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Ha, good find. Yes same for me! Works on a proxy I got from Chaos. Not on self-made geo.

@romullus; it's definitely working as a trimmer as I expected (see how ForestPack works)... which is exactly how it should work. Just not for all geometry at the moment.

Can you share an example where it is not working with some geometry or with your own geometry?
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2022-10-01, 17:04:31
Reply #22

aaouviz

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Ha, good find. Yes same for me! Works on a proxy I got from Chaos. Not on self-made geo.

@romullus; it's definitely working as a trimmer as I expected (see how ForestPack works)... which is exactly how it should work. Just not for all geometry at the moment.

Can you share an example where it is not working with some geometry or with your own geometry?

My bad! See my edit above, please. All good.

For others who are/were also confused, see my attached image - it trims elements, not clean slicing. The gridded box to the bottom is the instanced scatter object.
Nicolas Pratt
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2022-10-01, 17:10:28
Reply #23

LorenzoS

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It considers the pivot of the element, not its bounding box. So any element whose pivot is outside of the defined area will disappear

Isn't this the normal behavior of chaoscatter?
You don't need Chaos Scatter Edge Trimming for that.

2022-10-01, 18:05:43
Reply #24

aaouviz

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Quote
It considers the pivot of the element, not its bounding box. So any element whose pivot is outside of the defined area will disappear

Isn't this the normal behavior of chaoscatter?
You don't need Chaos Scatter Edge Trimming for that.

No, it is not.

I know it take a tiny bit of getting used to... to explain:

Scatter places OBJECTS on a surface.

An object can have multiple ELEMENTS inside of it.

Scatter with edge trimming on removes the ELEMENTS of each object outside of the desired bounds.

Again, check my screenshot of the cubes scattered. See how some cubes are removed?

Sorry to reduce it in such a simple manner, but hopefully this has helped.
Nicolas Pratt
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2022-10-01, 18:08:24
Reply #25

Basshunter

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It considers the pivot of the element, not its bounding box. So any element whose pivot is outside of the defined area will disappear (grass blade growing on a plane will be visible, grass blade growing outside of plane will disappear). We may consider the bounding box or or other methods of trimming in future versions too.

The problem I see with this method is that in many cases it won't give us the desired result. As long as the pivot point of a element is inside the scattering area, the tool won't delete that element.



I think that having an additional option to use some objects from the scene (like the sidewalk) as the "trimmers" would be a better solution than just relying on the pivot of the elements.
« Last Edit: 2022-10-01, 18:20:35 by Basshunter »

2022-10-01, 18:16:59
Reply #26

LorenzoS

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Quote
It considers the pivot of the element, not its bounding box. So any element whose pivot is outside of the defined area will disappear

Isn't this the normal behavior of chaoscatter?
You don't need Chaos Scatter Edge Trimming for that.

No, it is not.

I know it take a tiny bit of getting used to... to explain:

Scatter places OBJECTS on a surface.

An object can have multiple ELEMENTS inside of it.

Scatter with edge trimming on removes the ELEMENTS of each object outside of the desired bounds.

Again, check my screenshot of the cubes scattered. See how some cubes are removed?

Sorry to reduce it in such a simple manner, but hopefully this has helped.

Now i undesrstand what Chaos Scatter Edge Trimming do.
thanks aaouviz

2022-10-02, 11:55:35
Reply #27

romullus

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The problem I see with this method is that in many cases it won't give us the desired result. As long as the pivot point of a element is inside the scattering area, the tool won't delete that element.

I think that having an additional option to use some objects from the scene (like the sidewalk) as the "trimmers" would be a better solution than just relying on the pivot of the elements.

Don't forget that element's pivot point is at its selection center, not at its base, so in your example those marked blades would be trimmed by the scatter. I'd suggest to actually try the feature and see if it really fails in most practical scenarios. In my opinion, which is based on short testing, current implementation works great and might be even superior over bounding box detection.
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2022-10-03, 09:45:59
Reply #28

rowmanns

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Bug report - edge trimming isn't working if plugged through Corona select texmap.
Hi,

Thanks for reporting this :)

Rowan

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2022-10-03, 11:31:28
Reply #29

Frood

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Some thoughts about trimming:

Would it not be possible to handle ChaosScatterEdgeTrimming internally? Looks like even this setup

OpacityMap -> ForestEdge -> ChaosScatterEdgeTrimming -> MaterialOpacitySlot

works. A ChaosScatterEdgeTrimming map as first map in the opacity slot even handles assets prepared for ForestPack it seems - cool. And it offers the option to reuse already prepared assets of any kind without changes to the materials.

User friendly, simple and extremely advanced compared to ForestPack would be a solution which adds ChaosScatterEdgeTrimming internally at rendertime, triggered by a "Use edge trimming" switch in the scatter object. Just like rayswitch is used internally if you disable cast shadow or visible to camera in any objects properties.

Speaking as a long term user of ForestPackPro: The concept of a ChaosScatterEdgeTrimming map leads to the same issues as with ForestPro and its EdgeMap where you need some fancy scripts to prepare assets material  for trimming (there is the "Material Optimizer" in the "Forest Tools" which can at least add the edge map to materials of ForestPackPro objects). Usually, stuff you want to scatter has multisub materials with a lot of slots everywhere.

Additionally, you cannot quickly compare trimming on/off with ChaosScatter and there is not even a script/tool currently to add/remove the ChaosScatterEdgeTrimming map automatically. The minimum we need is an on/off toggle in the ChaosScatterEdgeTimming map to be able to switch edge trimming functionality by a one-liner script without changing material nodes for the moment and a utility to add ChaosScatterEdgeTrimming to materials.


Good Luck



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