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General => Image Sharing => Topic started by: Dune on July 22, 2014, 01:31:16 AM

Title: Grass
Post by: Dune on July 22, 2014, 01:31:16 AM
Testing windblown grass... (basically still one object).
Title: Re: Grass
Post by: yossam on July 22, 2014, 01:40:56 AM
Cool............... :)
Title: Re: Grass
Post by: Tangled-Universe on July 22, 2014, 03:50:15 AM
Pretty cool :)
Can you show how a single instance of your model looks?

I suppose you can't raytrace the objects now? I can't remember the exact story anymore since TG3 introduced an extra way of rendering displaced objects/populations.

Looking at this I suppose you displace with a PF...if so, perhaps you can introduce more warp in the PF itself (so no warp shader).
Or instead of increasing warp factor you can also decrease the lead-in scale of the fractal, since that determines the size of the fractal warp pattern.
I usually like it better to do warping this way instead of a warp shader, because the warp is derived from the fractal itself and thus tends to have a more natural look. In some occassions though,  a warp shader gives better results I reckon.

Looking forward to see where you're taking this :)

Cheers,
Martin
Title: Re: Grass
Post by: TheBadger on July 22, 2014, 03:50:23 AM
Liking where this is going! ^^ after reading martins post and re reading OP, I would like more explanations of what you did in the first place, as martin asked about, but with a simple explanation for me ;D
Title: Re: Grass
Post by: mhaze on July 22, 2014, 05:25:23 AM
Clever stuff.
Title: Re: Grass
Post by: Dune on July 22, 2014, 07:46:22 AM
It's not that clever, it's not what you think, although I had made a note about testing the mesh displacement (never did, actually). This is just an object with the grass blades tilted to one side, and reduced rotation in the pop.
In this version, I used three different 'bent grass objects'.
Title: Re: Grass
Post by: archonforest on July 22, 2014, 08:45:40 AM
Clever or not, looks very good to me ;)
Title: Re: Grass
Post by: zaxxon on July 22, 2014, 09:00:26 AM
"Leaves of grass" indeed! Love the high grass flowing in the wind (hope the archer is properly compensating!). This would be a wonderful animation, wonder if that type of movement could be done in TG? Your works are often like a 'classroom' with interesting and inspiring examples. Looking forward to the next iteration.
Title: Re: Grass
Post by: Upon Infinity on July 22, 2014, 10:38:54 AM
Looks great.  You could probably make a few bucks selling this at NWDA.
Title: Re: Grass
Post by: Dune on July 22, 2014, 11:19:57 AM
I'll put it up at NWDA. Make some more first.
Title: Re: Grass
Post by: choronr on July 22, 2014, 07:32:06 PM
And, I'll buy them for sure. Very good coverage of the populations with a bit of color variation.
Title: Re: Grass
Post by: bigben on July 23, 2014, 03:26:59 AM
Quote from: zaxxon on July 22, 2014, 09:00:26 AM
"Leaves of grass" indeed! Love the high grass flowing in the wind (hope the archer is properly compensating!). This would be a wonderful animation, wonder if that type of movement could be done in TG? Your works are often like a 'classroom' with interesting and inspiring examples. Looking forward to the next iteration.

This can be done in TG either with a sequence of models or an application that can generate models on the fly via command line (e.g. Arbaro), combined with command line rendering.  For still images though, I just find it looks odd when there are lots of realistic looking plants but they are all dead straight.  With a few combinations of bent grass you could create a set of masks using a PF and colour adjust shaders to create "bands" of plants at similar angles to simulate the waves of wind.
Title: Re: Grass
Post by: Oshyan on July 23, 2014, 11:49:10 PM
This "static" bent grass technique could not be animated really, however the Mesh Displacer input does allow that, *and* works with Raytrace Objects. You cannot *subdivide* object geometry in the raytracer still, but if you're just displacing/deforming existing mesh geometry in the object, it works with the Mesh Displacer. One possibility to consider for animation would be to use these bent-over grasses to get the correct larger-scale shape (which would be hard to achieve with a procedural input to the Mesh Displacer), and then work on adding a subtle waving motion through a Mesh Displacer driven by a Power Fractal or something...

- Oshyan
Title: Re: Grass
Post by: TheBadger on July 24, 2014, 01:30:39 AM
Animating it? This will be interesting!
Title: Re: Grass
Post by: Dune on July 24, 2014, 02:52:56 AM
QuoteWith a few combinations of bent grass you could create a set of masks using a PF and colour adjust shaders to create "bands" of plants at similar angles to simulate the waves of wind.
That is what I did here (the latter image has 5 objects), but only with one PF and its opposite for another angle, about 50ยบ turned. Didn't have the patience to elaborate on it, you'd have to account for the transition zones as well, where the angle would be less different, etc. Too much work.
I've also tried some mesh displacement, but couldn't get it to work. But, I only looked at the preview, and I vaguely remember it can't be seen there. So, if time allows, I'd have to take that a bit further. Indeed, I also tried using a world space warp, but never rendered anything, just looked at it frustratedly. But I wonder if you could bend only the tops of each object, or the whole object will be bent. You'd kind of need a height restriction, but that wouldn't work in hilly country, unless you bend them first, then raise their ground (which works in other circumstances, like masking the wet edge of a stream going downhill, by height restriction solely).
It would be terrific if you could take a straight grass and bend the tops by world space warped fractal or redirect, or VDISP.  ::) 
Title: Re: Grass
Post by: bigben on July 24, 2014, 08:10:23 AM
Here's a basic demo of how I split up a mask by multiplying colour adjust nodes
Title: Re: Grass
Post by: Dune on July 24, 2014, 10:34:42 AM
Thanks, Ben. Something to study. I still can't get the black-black mask, I'll have a good thinking session about it.
Title: Re: Grass
Post by: bobbystahr on July 24, 2014, 02:52:04 PM
yup def. cool....
Title: Re: Grass
Post by: bigben on July 24, 2014, 06:15:21 PM
Just to explain that TGD briefly, from the bottom up.  Multiplying 2 colour adjust nodes with opposite slopes provides a narrow mask within a set range of values from 0-1.  The white levels of all of the colour adjust nodes are set to provide full coverage across the 0-1 range. The black levels provide the overlap between bands.  Moving up, The PF provides the distribution pattern of the variant populations and this just needs to be masked by the overall distribution of the objects. By splitting the problem up into it's various components you get a lot of flexibility to tweak a single component without causing widespread change.

The first and last multiply nodes have some redundancy in them (effectively multiplying one colour adjust node by 1) but I built it from the middle out
Title: Re: Grass
Post by: Oshyan on July 24, 2014, 06:52:03 PM
Mesh displacement on populations will only show up in the 3D preview when you repopulate. But it will...

- Oshyan
Title: Re: Grass
Post by: Dune on July 25, 2014, 02:56:43 AM
Yes, I just noticed, thanks. I did a few minutes of testing, but got distracted again. I wonder if you need a world space for the displacement or whether it's world space already... I will get back to this.