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Author Topic: Clean edges on grass borders  (Read 874 times)

dylan86.exe

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Clean edges on grass borders
« on: October 24, 2016, 01:57:17 PM »
Hello,

I'm new to Forest pack Pro, and I've watched the tutorials online and read the documentation on the plugin, however I'm having trouble getting it to behave the way I want it too.
I have a scene where I've created a simple plane and then created a border using a spline and converted everything to an editable poly (I created everything in the same view too). But once the grass is created, it's not staying within the border - even with edge mode selected.  If I ramp down the density units - it creates patches, if I go too high, it goes past the border. I've tried playing with the density fall-off but I have to re-read it's settings. Can someone point me in the right direction with what to do? I also tried selecting the border and using it as an exclusion but this did absolutely nothing - why? I would think if I told it to exclude the border, it would stop rendering to that point...

Also, before rendering, why does it show in the viewport as the grass all over the place and not within the set boundary??

« Last Edit: October 24, 2016, 02:00:03 PM by NS7318 »

Michal Karmazín

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Re: Clean edges on grass borders
« Reply #1 on: October 24, 2016, 06:07:15 PM »
Hi,

As mentioned in this "trimmed hedge" related thread:

"The Edge Boundary Checking mode is not meant to "slice" the geometry, it's removing elements within one item that are "based out of area used for distribution". So, if there are any "overhanging faces" under one element, these will be fully removed or not, depending if the element is based inside/outside of the distribution area.

It behaves like grass blades in nature - if there is a space enough to growth from, the grass blade vegetate and later could overhang that area. Additionally, this way it doesn't affect overall performance (as massive geometry slicing would require huge additional resources).

As mentioned above, there is no "physical cut" performed while using the Edge Boundary Checking mode (as this would be extremely resource demanding). This "trimmed part" is treated by the render engine as a kind of "Matte object" internally (this way render engine ignores it for its calculations)."

For both the Lawns and Meadows presets you will see there are two versions for each type, one with a (detail) suffix and another with a (large) suffix. Unless you're filling a large area, I'd pick the detail ones.

Also, please feel free to send us your scene (ideally a simplified version of it) and we'll check it here. Thanks in advance.

Best regards,

dylan86.exe

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Re: Clean edges on grass borders
« Reply #2 on: October 25, 2016, 02:07:18 AM »
Hi,

As mentioned in this "trimmed hedge" related thread:

"The Edge Boundary Checking mode is not meant to "slice" the geometry, it's removing elements within one item that are "based out of area used for distribution". So, if there are any "overhanging faces" under one element, these will be fully removed or not, depending if the element is based inside/outside of the distribution area.

It behaves like grass blades in nature - if there is a space enough to growth from, the grass blade vegetate and later could overhang that area. Additionally, this way it doesn't affect overall performance (as massive geometry slicing would require huge additional resources).

As mentioned above, there is no "physical cut" performed while using the Edge Boundary Checking mode (as this would be extremely resource demanding). This "trimmed part" is treated by the render engine as a kind of "Matte object" internally (this way render engine ignores it for its calculations)."

For both the Lawns and Meadows presets you will see there are two versions for each type, one with a (detail) suffix and another with a (large) suffix. Unless you're filling a large area, I'd pick the detail ones.

Also, please feel free to send us your scene (ideally a simplified version of it) and we'll check it here. Thanks in advance.

Best regards,

Yes I read the "trimmed hedge" post, however I didn't see the relevance as a hedge has no set boundary, whereas mine does (modelled border). I'm not asking for the geometry to be sliced, I'm just asking for it to stay within the set boundary I provide (purple border). I understand what you're saying, but If I tell it not to go through an object (exclude the border) and it stays within the set distribution area - why does it poke through as shown in the render I provided? Surely I've given it enough information to do what I need it to do. How can grass grow "through" a solid border?
I want the render I'm working on to look clean with no grass overlapping the wooden border around the grass area I set - much like the tutorial where the grass meets the stone path with the crosses.

I'll upload the simplified scene tonight and see if you can make me understand.
« Last Edit: October 25, 2016, 04:23:01 AM by NS7318 »

dylan86.exe

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Re: Clean edges on grass borders
« Reply #3 on: October 25, 2016, 01:31:18 PM »
Ok I'm getting a much better result now. The problem was the grass blades were too high and resulted in them growing over the edge. So I simply adjusted the blade height on the Z axis.
However, I still get blades coming "through" the border.
See attached image. Link to .max file: https://drive.google.com/open?id=0B7YMoZ3zuhdMNHpqNVZRdFZiVjQ

Also worth mentioning I'm using the Viz people "real grass" library and the "cut grass" preset.

Michal Karmazín

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Re: Clean edges on grass borders
« Reply #4 on: October 25, 2016, 04:47:55 PM »
Hi,

Thanks for provided scene. Generally, it's good to have Pivot Points of used items placed somewhere near to the centre (as Forest Pack uses the Item's (Custom Object's) Pivot Point position to place each item). Also, in many cases using a Spline Area instead of the Surface Area result in more precise control - optionally, to ensure, that no blades will overhang - an Offset about 1cm can be applied to such spline.

Attaching screens-shots and sending modified scene by WeTransfer. Hope you'll find it useful.

Best regards,

dylan86.exe

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Re: Clean edges on grass borders
« Reply #5 on: October 26, 2016, 12:17:31 AM »
Hi,

Thanks for provided scene. Generally, it's good to have Pivot Points of used items placed somewhere near to the centre (as Forest Pack uses the Item's (Custom Object's) Pivot Point position to place each item). Also, in many cases using a Spline Area instead of the Surface Area result in more precise control - optionally, to ensure, that no blades will overhang - an Offset about 1cm can be applied to such spline.

Attaching screens-shots and sending modified scene by WeTransfer. Hope you'll find it useful.

Best regards,

That's fantastic! Thank you. One question though, how did you separate the different grass blades into clumps like that?? When I generate to a selected area - it automatically creates one mesh for the whole area.

Michal Karmazín

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Re: Clean edges on grass borders
« Reply #6 on: October 26, 2016, 09:25:47 AM »
Hi,

You're welcome. Glad to hear, that it helped.

All used imported items are stored inside of the "forest_templates" layer (by default hidden and frozen), which can be handled as any other 3ds max's layer - you can easily unfreeze it and edit any of those objects.

Let me add a handy tip about quick selecting used objects - having selected the Forest object, you can easily access the Select Forest Custom Object tool from the quad menu (right-click).

Best regards,