Work flow and Geo Shadow lods

[dissaifer 10]

Hey guys,

Learning how to do geo and shadow lods... and had a question about workflow with them. I use blender and export to .obj files. I just saw a maya tut that has the modeler making the triangles up front, which I thought was curious.

Anyway, I'm trying to figure out the fastest way to create these.

It seems that the geo is just the model imported again and the shadow is a 1000 vert limit of the original and scale it down a bit (lucky for me I just remove the sub divide modifier). <-- this is how I think it goes.

I tried these steps http://community.bistudio.com/wiki/Oxygen_2_-_Manual to my geo lod and now the model is all goofy, should I be worried about that? Because now the model won't import.

[max power 21]

A goofy looking shadow LOD is not such a big deal so long as the shadows are looking okay. You can't actually get a lot of information from the shadow itself so if it's simple or somewhat inaccurate, it doesn't matter.

The engine creates shadows by figuring out which polygons on your shadow LOD are 'lit', and extruding them 'infinitely' in direction the light is shining. Areas on polygons that bisect this extruded volume are then rendered with diffuse lighting only.

Since your shadow LOD doesn't need to contain texture information, you're not really destroying anything by altering the uvs or topology. In certain instances it might be easier just to create a new mesh that fits inside of your first few resolution LODs. I say the first few, because shadows aren't rendered after a certain distance, and it's not wort the pain and torment trying to get something that looks good fitting inside your early and late LODs both.

In most instances I would take one of your mid resolution LODs and then shrink it per vertex on the axis of your vertex normals, and then fix any hiccups. For structures that are very thin you can use a 2 sided polygon strip or even the res LOD geo turned inside out. Just make sure all of your final shadow geometry is closed.

If your shadow geometry is not closed, I would do what you can to fix the problem manually. I would NOT user the O2 function to automagically close meshes. I have had a few messed up models result from that including O2 invisibly doubling the pcount of my shadow volume but still not fixing the non-closed problem.

As a last step, triangulate and hard shade your shadow mesh in O2. It takes two button pushes and literally requires no effort. Doing it any sooner or outside of O2 is pointless because you're only really making your mesh harder to handle if you have to remodel some part of it.

[Messiah 2]

A point og note is that the 1000 face limit is a myth/old standard.

Obviously the less faces it contains the better, in terms of efficiency, no need to make an 8000 face shadow LOD when 500 will do ;)

[das attorney 857]

Re: ShadowVolume, could someone please update the BIKI for consistency?

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This link advises: "ShadowVolume 0.100 (same amount of features as the main visual model (i.e. equipment, weapon systems, etc)" (ShadowVolume 0.100 == typo?)..

http://community.bistudio.com/wiki/LOD#ShadowVolume

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This link advises: "The shape should not exceed 1st LOD volume. Maximum polycount for shadowVolume is 1000 triangles. "

Also: "LOD must be nammed ShadowVolume 0.000,ShadowVolume 10.000 or ShadowVolume 1000.000"

http://community.bistudio.com/wiki/Oxygen_2_-_Manual#ShadowVolume_LOD

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This link advises: "Duplicate the 0.000 LOD and turn it into a „Shadow Volume“ LOD. make sure you enter the Value "1" in the list of the different LOD-Types when having selected the Shadow Volume. "

No mention about poly-count (or shadowVolume 10).

http://community.bistudio.com/wiki/Mondkalb's_Addon_Tutorial#Shadow_Volume:

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As beginner, I read all three pages and still had to search through forums for answers.

Edited May 1, 2013 by Das Attorney

[dissaifer 10]

Thanks for the help Max! I got the shadow lod working... so that is a huge relief. Now to fix the geo lod, the model is just sinking into the ground when it is there.

[max power 21]

Sounds like a land contact point thing.

If you can't get this resolved, we had a problem with our su25s sinking into the ground at mission start, it had some weird thing to do with dependency. I can ask Mikero.

---------- Post added at 16:21 ---------- Previous post was at 16:14 ----------

A point og note is that the 1000 face limit is a myth/old standard.

Obviously the less faces it contains the better, in terms of efficiency, no need to make an 8000 face shadow LOD when 500 will do ;)

Yeah, there's a performance impact but it's not clear what the upper limit for that stuff should be. Nod Unit has got away with some high numbers in his cockpit LOD... but it's possible to have a vehicle with a shadow passing through several fields of smoke and casting on many objects in the exterior LODs.

[dissaifer 10]

Well, I changed the geo model to convex hull so that simplified the shape and threw a mass on it ... and it is still there in the ground, when I take it off (mask)... tried taking into a building to see if that would fix it and it didn't. Obviously, I could still be doing something wrong as I'm pretty new to this, but at this point... stuck.

Edited May 1, 2013 by Dissaifer

[max power 21]

Land contact LOD?

http://community.bistudio.com/wiki/Oxygen_2_-_Manual#LandContact

Check out the example models to get a look on what that looks like.

[meshcarver 12]

Hey guys,

are there ANY updates about the poly/tri/vert limit for SHADOWlods please.?

1000 tris seems not a lot really..?

[nodunit 397]

I know I'm very late to the party but you can push well beyond 1K, one of my projects pushed into 8.5K tri's and it worked without a problem, just got to make sure you close all faces and don't accidentally weld something somewhere that shouldn't be <.<

[meshcarver 12]

I know I'm very late to the party but you can push well beyond 1K, one of my projects pushed into 8.5K tri's and it worked without a problem, just got to make sure you close all faces and don't accidentally weld something somewhere that shouldn't be <.<

Sorry to necro this thread, but is Nodunit referring to SHADOWlods yes? So we can have well over 8K tri's for SHADOWlods?

Some of my structures, as they're falling apart and rotting need a bit more love in the Shadows dept so I could do with the extra tri count if possible?

[da12thMonkey 1943]

Yes he's referring to the ShadowLOD.

It's because back in early games in the series we were limited to 1000 faces per shadowLOD. But now they're just subject to the same vetex limit that exists for all models, so you can make them as detailed as your top resolution LOD.

Though ideally you should try to optimise them as mush as possible compared to the res LODs ;) - e.g. it's not like you need nice, round cylinders with >10 sides in a shadow LOD, when it's there to generate a 2D shadow projection on the ground. And if you do start with a high-ish poly shadow LOD it's worth thinking about adding two or three lower poly ones to go with it.

[meshcarver 12]

Thanks man- this part really puts a smile on my face: "But now they're just subject to the same vertex limit that exists for all models, so you can make them as detailed as your top resolution LOD" :)

I understand to make it as low poly as possible though, I get that but sometimes you have to have a fairly extensive SHADOWlod but nothing stupid aye.

It's really good to know that there's no limit though- appreciated.

[p1nga 23]

As said above, the most important thing, is if you have a shadow volume that has > 1000 Verts, you should really ensure that there are lower detail LOD's.......you don't want to be rendering 8k shadows at any sort of distance greater than 100m, even 50m. If you force the shadow to be a shadow-buffer as opposed to the standard stencil shadow, you can get away with having even lower detailed shadows in close.

[da12thMonkey 1943]

you don't want to be rendering 8k shadows at any sort of distance greater than 100m, even 50m.

In part it's a little negated by the shadow view distance slider that the players have available in their video settings, which will stop shadows rendering at more than a couple of hundred meter anyway (I forget what the maximum shadow rendering distance is but it's a lot less than object distance).

I think you only really need a couple of extra, nicely optimised shadow LODs to bear the strain in highly populated areas where there are a lot of objects casting shadows, rather than a full suite of 5-10 LODs like you would establish for the model's resolution LOD set that is routinely used to render the object out to thousands of meters.

[meshcarver 12]

Excellent explanations lad, cheers... Aye, I'll be giving all my objects multiple SHADOWlods for sure- I want NOVA ZONA to run like a beast.