How do long distance models work?

[Ronsemberg]

I noticed that, while walking around in the NV world, some objects (like the lucky 38) are visible even at very high distance, while others are completely invisible. I am curious to know how to create such rendered-at-high-distance models.

 

I am creating some very large models to be rendered at high distance, but as a default they are loaded only when the cell they are in is loaded.

You know, it's weird to walk around and suddently have this huge skyscraper to appear in front of you...

I would like for a low lod model to be always loaded no matter what the distance, and an high lod model to be loaded when you're close enought to it.

How do I do that?

 

(PS: I do know how to tweak the .ini file to increase the draw distance. That's not what I want to do- I want a low detail model to be rendered no matter what the distance (like the vanilla lucky 38 building) and an high detail model to be rendered when you're close enought to its position).

 

Anyone willing to help?

[Xaranth]

sounds like you want to know about LOD

[TrickyVein]

First read about LOD through the link Xaranth provided.

 

In building your own LOD models, keep these things in mind:

 

The UV coordinates for the model cannot extend beyond the dimensions of the LOD texture it uses. This is because when you go to generate LOD models for your worldspace, every texture used by each of your LOD models is 'stitched' together into a giant texture. So if the UV coordiantes for one model extended beyond those of the texture it uses, it would actually extend into another texture entirely and this would show up on the final LOD model.

 

LOD models should be as low-poly as you can afford to make them. Make use of stencil-techniques and the alpha channel in creating your LOD texture.

 

LOD textures are small. The largest ones used in the vanilla game (I think) only have dimensions of 256² and most are smaller. This is because there is finite space in which to 'stitch' all of the LOD textures for your worldspace together. Obviously, this limits resolution and may force you to increase the polycount of your LOD model especially when needing to texture across large, flat surfaces. Parts of the LOD texture may need to be tiled for best effect.

 

You may read more about the actual process of generating LOD inside of the GECK, here.

 

Also, more considerations: triangles for LOD models cannot be made to be 2-sided. You must provide two faces for stencils. Also, as a bonus, you *can* make use of 8-bit alpha for LOD and opacity. I should make a tutorial for this stuff. :sleep:

Edited January 10, 2013 by TrickyVein

[Ronsemberg]

Quite useful. Kudos to both :D will reply again to this when I did some progress.