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Comment by madmoose | Hacker News Reader

Blade Runner didn't actually use voxels, they used a rather unique technique that they called "slice animations".

The 3D models were sliced from bottom to top into a couple of hundred slices (depending on desired quality) by intersecting the model with a horizontal plane and storing the resulting polygons.

The engine can only rotate the models around the vertical axis.

I made a hacky javascript version of the renderer a long time ago: http://thomas.fach-pedersen.net/bladerunner/mccoy_anim_13_fr...

EDIT: Let me also plug our WIP Blade Runner engine for ScummVM: https://github.com/scummvm/scummvm/tree/master/engines/blade...

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That's really cool. Great job!

https://en.wikipedia.org/wiki/Blade_Runner_%281997_video_gam...

Seems that the people that developed the game considers it voxel based.

Read on: https://en.wikipedia.org/wiki/Blade_Runner_(1997_video_game)...

Reads to me like they used voxels for the grunt work and then painted the result on some otherwise unimpressive polygons at the end (aka voxels plus as they put it themselves).

The page you linked quotes Louis Castle:

> What we are using is not voxels, but sort of 'voxels plus.'

So "not voxels". Louis Castle probably called it voxel-like because he didn't want to get too technical in an interview. Their technique has not been described in detail in the press but see http://deadendthrills.com/future-imperfect-the-lost-art-of-w... for an article that calls it a "slice model"-technique.

I'm not an expert on voxels but I've reverse engineered and reimplemented most of the Blade Runner rendering engine and in my opinion it doesn't count as voxels. For one, you're never going to be able to rotate the models around any axis other than the vertical.

Fun! Yeah, we stored our data as slices for space and restricted rotation to the Y axis. Both were optimization since each frame of an animation was a full model there was no need to rotate them. The renderer could render them from any angle though so I still consider them voxels. More like voxels lite then voxel plus. We also used a lot of sprite cards with zdepth and a quick normal hack for lighting. You had to cut corners where you could back then!!

So that's why you didn't include the Deckard -vs- Pris scene where she rotates around the X-axis! ;)

https://youtu.be/e9t5ikxjAQ4?t=1m9s

Hello Louis!

I've certainly had a lot of fun figuring out how you did what you did, so thank you for that, no matter what you call it :)

You certainly crammed a lot of tech into one engine! Full screen 15 BPP videos with full z-buffer with smaller alpha-channeled videos rendered on top, character models with lighting. Even the UI is looping videos.

Once I get proper path finding working Blade Runner will be a lot more playable in our ScummVM engine.

I've probably rewatched the opening scene of the game a thousand times while working on it...

I only wished that you had used a scripting language for your game code instead of compiling it to DLLs. I know you optimized heavily for speed but it would have made our task a lot easier :)

Fun indeed!

Can you talk about how the artists authored the original models? Was it an automated conversion from a standard polygon model or from a full voxel model? Or was it all drawn in this special slice format directly somehow?

Not Louis, but the article I linked above says they used 3D Studio Max and converted it to the slice model format.

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