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Ritual Magic

Question about Morrowind...

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Don''t know if any of you guys have ever played this. I''m currently working on a terrain engine, and although I have it (sort) of working in a very basic way, I''d like to start adding features to it. At the moment, it''s a basic heightmap. I don''t even have any textures on it or a skybox around it. I''d eventually like it to grow to something approaching the beaty of Morrowind''s environments. Now, I realise that''s a tall order, but I''m accepting limitations such as: 1) I don''t really care about multiple zones. That is, I would just like to render a really professional small area, of a size small enough to load fully. No zone swapping. 2) Alot of the effects in MW which heighten the realism are particle effects such as dust and rain. I don''t need any of that. 3) I only need OUTDOOR environments - indoor is a problem I will tackle another day What I really need is a list of some of the techniques used ( or what were probably used, as I realise none of us is likely to be sitting on the source code at the moment hehe), so I can go google them and start to add things one by one. I''ve already started googling, but I''m being overwhelmed by the sheer amount of info out there. I''d like to sort of narrow it down a bit Thanks RM. ------------------------------------------------------------ Yes. it''''s true, I DO wield the ugly stick. And I see I have beaten you with it before!

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Morrowind does not use heightmaps.

the world is just one big 3d model - this way they can have overhangs and caves. take a look at morrowind''s editor to get more info.

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Well that''s not entirely true. Morrowind does use a hightmap of sorts for the ground. Everything else in the landscape (Boulders, Trees, Buildings, etc...) is a 3D Object place on or in the heightmap terrain. No culling or anything is done, they just brute force it (I''m sure I heard one of the developers state this in an interview).

Interiors are also 3D objects attached to each other. Each hallway, room, and items is a different object. Though strangley Morrowind does no form of space partitioning on its interiors.

Like Ilici said. Check out the editor and you will learn a lot from it.

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quote:
Original post by noVum
quote:
they just brute force it

Not that this would be a good idea ... Its performance is sometimes not acceptable

It depends, usually brute force is better than some elaborate ROAM style scheme and if you don''t have insane amounts of geometry or really long view distances the benefits of LOD aren''t worth it. A lot of games (first person shooters for example) don''t have these things so they don''t benefit from LOD. Morrowind probably could have taken advantage of it in some of the larger more occluded areas and towns.

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Keep in mind that Morrowind used a 3rd party rendering engine, NDL. You know, the same one that handled Freedom Force and Star Trek Bridge Commander. Neither of those games required any special terrain system whatso ever. My best bet is that NDL has some ''very'' limited options for working it.

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quote:
Original post by Impossible
It depends, usually brute force is better than some elaborate ROAM style scheme and if you don''t have insane amounts of geometry or really long view distances the benefits of LOD aren''t worth it.



The only reason it is this way is because our graphics cards nowdays are so powerful they can pour out pixels faster than the CPU can run the LOD equations. If you tried rendering software mode you would need every LOD trick in the book.

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quote:
Original post by Drath
quote:
Original post by Impossible
It depends, usually brute force is better than some elaborate ROAM style scheme and if you don''t have insane amounts of geometry or really long view distances the benefits of LOD aren''t worth it.



The only reason it is this way is because our graphics cards nowdays are so powerful they can pour out pixels faster than the CPU can run the LOD equations. If you tried rendering software mode you would need every LOD trick in the book.




Thats not true at all.

With Geforce 4 hardware it is more efficient to cull than render 2000 triangles. I don''t know what type of hardware you are running with, but triangle reduction and culling is extremely important.

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Cull using which technique? BSP yes, other trees yes, but take a look at something like ROAM. If you go for the all out culling version you will be getting structures where you are rendering out few polygons at a time. Forcing it in this cas with today''s hardware is a lot faster.
Then take a look at some types of LOD. Reducing a mesh from 5k to 2k polygons using a real time face remover then subsequently reorganising all the various buffers will cost you more time than sticking the whole model through the pipeline.

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quote:
Original post by Captian Goatse
With Geforce 4 hardware it is more efficient to cull than render 2000 triangles. I don''t know what type of hardware you are running with, but triangle reduction and culling is extremely important.


Depends on the size of the triangles. With 2000 very large triangles, I could see that being an issue because of fillrate limitations. But at that point you might as well tesselate those triangles because modern hardware (CPUs and GPUs, not just cutting edge stuff, GF3+) can transform a lot of vertices very quickly. With 2000 small triangles culling would be unnecessary.

You won''t see a huge advantage using LOD on 2000 vertices unless you have some kind of crazy vertex shader that is extremely slow. I mean, Nvidia, ATI and Microsoft recommend that you render with batches of around 1000-2000 polygons (with less than 500 batches total), so what''s the point in reducing polygon count significantly lower than the recommended batch size?

Of course as a whole LOD and culling are important, but with 2000 polygons in the scene LOD is really not necessary, especially when the average game is drawing 25,000-200,000 polygons per frame.

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I wouldn''t worry about elaborate LOD schemes. The things to avoid are overdraw and too frequent state changes (switching textures). Sort by texture, sort objects from front to back, render as many polygons at once as you can. Even old and crummy video cards can draw 10k+ poly scenes at playable framerates when set up properly.

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