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General => Terragen Discussion => Topic started by: Harvey Birdman on March 18, 2007, 08:53:45 AM

Title: #@$%$% grass clumps...
Post by: Harvey Birdman on March 18, 2007, 08:53:45 AM
Does anyone have a step by step explanation of how to use grass/grass clumps? I've repeatedly searched the forums and have found any number of people struggling with this, but I have yet to find a definitive explanation on how to implement this that actually seems to work.

I've set the group bounding box about the region I want to populate, given the default shader a color (red! you'd think that would show up against a green surface shader...), enabled both the individual clump and the population, checked 'sit on terrain', etc,  played with number of blades, blade length, clump size, and absolutely nothing shows up.
Title: Re: #@$%$% grass clumps...
Post by: child@play on March 18, 2007, 09:02:08 AM
hey,

do you have a lot of shaders attached to your terrain? sometimes i had problems placing objects on heavy displaced terrain, when you add a 'compute terrain' as very last node in the shaders group, the problem should be solved


cheers...
Title: Re: #@$%$% grass clumps...
Post by: rcallicotte on March 18, 2007, 09:02:54 AM
Harvey, this is a useful link and it includes a very useful ZIP file - http://forums.planetside.co.uk/index.php?topic=933.0
Title: Re: #@$%$% grass clumps...
Post by: Harvey Birdman on March 18, 2007, 09:09:18 AM
Thanks for the quick replies, folks. I'll see what I can do. I'm getting a little frustrated -  spent half the night screwing with this.
Title: Re: #@$%$% grass clumps...
Post by: Harvey Birdman on March 18, 2007, 09:12:29 AM
Well, that didn't take long to get to a dead end.

>:(

child@play - just how do I add a 'compute terrain' as the last item in the shader list?
Title: Re: #@$%$% grass clumps...
Post by: child@play on March 18, 2007, 09:15:47 AM
just right click the shader group in the node-network-view.

then, create shader -> other shader -> compute normal

then, plug the output of the last shader into that 'compute terrain', and this output goes into 'planet' and the grass clumps
Title: Re: #@$%$% grass clumps...
Post by: Costaud on March 18, 2007, 09:54:29 AM
I'm not very familar with Terragen grass clump (I use obj grass) but did you play with the scale in the transform window of grass itself not the Populator?
Title: Re: #@$%$% grass clumps...
Post by: Harvey Birdman on March 18, 2007, 01:45:52 PM
Sorry for the delay - I needed to get a bit of sleep.

Costaud - I just tried increasing the scale an order of magnitude on each axis (all at the same time), creating a bounding box with 1000 time the volume of the default. Still don't see a bloody thing.
>:(

I'm going to try child@play's suggestion next; failing that, I'll look at BigBen's sample tgo (thanks for the link, calico).

So is it just me or does this feature require a bit more engineering? Yeah, I know it's a tech preview and all, but based on the volume of forum content on this subject, I'd suggest that the UI for placing/populating groups of objects is in need of some serious redesign.
Title: Re: #@$%$% grass clumps...
Post by: Buzzzzz on March 18, 2007, 02:01:23 PM
This might help with your problem.

http://www.designpaths.com/terragen-tutorials/adding-an-object-population/ (http://www.designpaths.com/terragen-tutorials/adding-an-object-population/)
Title: Re: #@$%$% grass clumps...
Post by: Harvey Birdman on March 18, 2007, 02:10:23 PM
Thanks, Buzzz, but I've read it.

This is absolute bull%$Y. I've followed the tutorials; bounding boxes are in the right places and appear to be the right size; I'm using a canned object/population, not some weird thing I've imported, and yet they seem endowed with some mystical quality that makes them invisible. Gosh, that's useful.

<edit>

My apologies for my rant(although I stand by my criticism). I have no idea what was wrong, but I just deleted the object and population I'd been struggling with and created a new, single clump, which appeared before the camera without a problem.

???

I swear I didn't mess with any opacity settings or anything like that - I was very careful to work with the default objects with their default settings (except location).

I think I'll go work in the yard for a while.  :-X

</edit>
Title: Re: #@$%$% grass clumps...
Post by: Buzzzzz on March 18, 2007, 02:25:19 PM
Quote from: Harvey Birdman on March 18, 2007, 02:10:23 PM
Thanks, Buzzz, but I've read it.

This is absolute bull%$Y. I've followed the tutorials; bounding boxes are in the right places and appear to be the right size; I'm using a canned object/population, not some weird thing I've imported, and yet they seem endowed with some mystical quality that makes them invisible. Gosh, that's useful.

OK, now that that's cleared up. I have ran into this problem where there seems to be a bug where displacements cover the grass pops. Do you have extreme displacements in your tgd? If not keep @%$$^&*%^(*&^%#$ because I don't know what to tell you unless you post the tgd for us to look at?
Title: Re: #@$%$% grass clumps...
Post by: Harvey Birdman on March 18, 2007, 03:04:11 PM
I was just thinking the same thing (about posting the file). Unfortunately at about that time I tried to change blade length on the one clump I was playing with. I used the slider instead of the text box; TG apparently gagged on it's attempt to repeatedly recalculate the model parameters, totally hung, and in the end I had to reboot. The only thing missing since the last save was the clump of grass, so I've put it back in front of the camera like it was just before it crashed. I haven't changed the color or anything; I did increase the y scale by a factor of 10 (seemed safer than trying to change blade length again).

So is there something exceptionally weird about this terrain?

Title: Re: #@$%$% grass clumps...
Post by: Buzzzzz on March 18, 2007, 03:29:28 PM
Great, I'll take a look as soon as this little patch of water finishes. Don't know if I will be of much help but I'll surely try. I'm sure others with more knowledge than myself will tackle it also. Hopefully we can get to the bottom of this thorn in your side.  :)
Title: Re: #@$%$% grass clumps...
Post by: Harvey Birdman on March 18, 2007, 03:32:02 PM
Cool... thanks. Sorry if I became a little abrasive. I was up most of the night trying to get this to work. It doesn't seem as if it should be that difficult, but I had no luck at all. Fact is I love the product - this is the first bad experience I've had with it.
Title: Re: #@$%$% grass clumps...
Post by: Costaud on March 18, 2007, 03:52:56 PM
I don't know if it's the effect you're looking for but I just increased the scale of the clump and the grass apperared (even in the water).
Title: Re: #@$%$% grass clumps...
Post by: child@play on March 18, 2007, 03:55:58 PM
yep, same here, you beat me to it ^^
Title: Re: #@$%$% grass clumps...
Post by: Buzzzzz on March 18, 2007, 04:07:26 PM
To start with this file has a Individual object where as an Object population is easier to control simply by checking set on terrain. Single objects need to be set manually which can cause one to curse loudly! LOL  ;D What I do to control the area of coverage of a population is to create a overhead camera or just move the existing one up a couple thousand meters and look down at -90 degrees. Then you can check and uncheck your pop show b-box a couple of times to see where it is and what to move. First I size the pop to my desired coverage area and then select it via the cross hairs and drag it to where you want it. I don't put much pop behind the camera for obvious reasons. Do you want the entire scene covered by grass? If so I will see if I can set it up for you, then you can see what I have done? If not I'll shut up now.  ;)
Title: Re: #@$%$% grass clumps...
Post by: child@play on March 18, 2007, 04:09:04 PM
buzzzzz *cough* , pass this guy some grass ;)
Title: Re: #@$%$% grass clumps...
Post by: Harvey Birdman on March 18, 2007, 05:22:28 PM
Buzzzz -

I know the file has a single object; I understand the difference between a single object and a population. If you read the sequence of postings, I was initially working with an object and population - the object being a member of the population. No objects would appear although their bounding boxes were properly placed. It was only after deleting the original object and population, then inserting a single object, that anyhting at all appeared. And as I said (quite clearly), the 'set on terrain' checkbox was checked.

Thanks for your help.
Title: Re: #@$%$% grass clumps...
Post by: Buzzzzz on March 18, 2007, 06:05:55 PM
Quote from: Harvey Birdman on March 18, 2007, 05:22:28 PM
Buzzzz -

I know the file has a single object; I understand the difference between a single object and a population. If you read the sequence of postings, I was initially working with an object and population - the object being a member of the population. No objects would appear although their bounding boxes were properly placed. It was only after deleting the original object and population, then inserting a single object, that anyhting at all appeared. And as I said (quite clearly), the 'set on terrain' checkbox was checked.

Thanks for your help.
So sorry, I guess the file causing the problem would have helped if you had been able to save it. Sorry I upset you, just trying to be of help. I guess I should keep to myself as I normally do.
Title: Re: #@$%$% grass clumps...
Post by: twistednoodle on March 19, 2007, 12:08:59 AM
@ Harvey - don't worry, you are not the only one to have had a nervous breakdown over populations - I've bought some shares in a wig factory!!!  I can now pretty much place the pops where I want (... mostly) but my initial attempts were incredibly frustrating!  I'm still trying to change the colour of the grass but with little success I just don't have the time to wait for the renders AND I've been trying to get nice &^&%$#$ cumulous clouds.  I can pretty much predict that you will start a thread %&%$# cumulous clouds (unless I beat you to it!) LOL, anyhow I'm hoping that it makes you feel better that others have had their tanties as well, my computer was lucky to survive mine!!   ::)
Title: Re: #@$%$% grass clumps...
Post by: Oshyan on March 19, 2007, 03:53:50 AM
Harvey, I certainly agree that the population and object positioning controls need some work. Keep in mind of course that you're working with a pre-release Technology Preview so there is a ways to go. We will certainly be improving the object handling systems for the final release.

That being said I do think it's reasonably straightforward to work with objects right now. They key I would say is to not go too fast and jump in to a complex or unusual scene from the get-go. Start with the default scene and make a grass population. If you can get that to work (it should be dead simple), then add a procedural terrain and again adjust so that it works as expected. This simple approach should give you a better handle on how populations work and also give you more confidence that you can even make them work at all - there is nothing as singularly frustrating as never getting any results at all. Once you've been able to get those scenarious to work you can start getting more complicated, but don't necessarily jump straight to adding the grass to an existing scene. You may instead learn more by building up the example scene to a more complex level, keeping the grass population working as you go.

I've taken a look at your current scene and it's unfortunate that you couldn't include your original population since I can't now see what the problems might have been with it. I do note that your planet is heavily displaced and your current scen is significantly *below* the normal surface of the planet. This can cause problems sometimes. In particular it makes positioning of the population bounding box difficult since it is always referenced to the surface of the planet. The objects should still sit on the terrain properly because they are feeding off the Compute Terrain node which provides surface positioning, but the bounding box will appear to be in the wrong place, floating well above your terrain. The preview instances should show correctly at least.

With a few minutes of tinkering I've managed to get the grass rendering in your scene by scaling them up a bit and offsetting the base object vertically a bit. This is a quick fix when objects are below the terrain for some reason. Usually "Sit on terrain" will work but in some cases it doesn't seem to get proper samples for the terrain or perhaps is not accurate enough and thus you need to apply some manual adjustment to positioning, particularly in the vertical. This should be done through the base object that is being populated, inside the population node. You can see an example of this in the attached .tgd illustrating my changes to make the grass appear.

I hope this will be of some help. Do rest assured that things will get easier as development continues, and in the future I recommend you not spend hours struggling with a problem before asking for help. Don't assume the problem is you when you're dealing with early software such as this - it's probably the software's fault. ;D

- Oshyan
Title: Re: #@$%$% grass clumps...
Post by: Harvey Birdman on March 19, 2007, 04:05:59 PM
Thanks Oshyan, thanks, T.N.; no problem, Buzzzzz.

;)