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Redneckerz

FastDoom: DOS Vanilla Doom optimized for 386/486 processors

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On 6/20/2024 at 12:10 PM, MrFlibble said:

Can you give a rough estimate of how much one would need to sacrifice in terms of level geometry's complexity (and/or internal structure of the data) for a speed improvement? Or would it be just "easier" to write a completely new rendering engine from scratch that'd be optimized for the 386 architecture?

 

If we just put Doom aside, do you think that it is possible to create an engine that would be more advanced than that of Wolf3D and replicate at least some of Doom's features, but run better on a 386DX at least?

 

BTW, have you considered rendering distance as a detail level variable? For example, both Bethesda's Arena and Daggerfall have this "detail" slider that actually controls the viewing distance, which affects the frame rate quite notably.

A viewing distance in Doom would be hard since it operates very differently from a hardware based renderer. In Doom you have to draw to every pixel in order to avoid garbage from a previous frame. In a hardware render you blank the screen and most likely fill whatever is left when rendering the near geometry with a sky box. That is why distant mountains pop up when you get closer.

Doom spends a lot of time just writing the pixels to memory so there is very little to gain. You have to write something there anyway.

I suppose you could have normal pixels in the central area and potato pixels near the edges to reduce the amount of writes but make the main play area / aim area reasonably good looking. Doubt there would be much to gain, since it complicates the rendering algorithms a bit.

There could perhaps be some minor gains from hand-writing assembly for that specific cpu, if you are an asm expert.

There are probably some gains to be had in improving the data structures used to render the imagery. If I'm not mistaken the order the BSP tree is very cache-unfriendly. Maybe fixing that when loading could improve the rendering slightly.

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Posted (edited)

So I tried the latest FastDoom VESA version, it's much better than the previous releases, good job, @viti95

A minor disatvantage here is that the actors still look as bright as if their rendering trick is still that brighter error

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New dev updates. I've added untextured column rendering, it's faster but crimples gameplay a lot:

 

Untextured walls:

 

dos4gw_000.png.33645941b394482d1691f7020f855e67.png

 

Untextured walls + no diminished lightning

 

dos4gw_001.png.a8cc5f5a39a6bbb122569f86d0885803.png

 

As a side effect, also sprites can be rendered untextured:

 

dos4gw_002.png.6d723f0684a3b572202ce4f0a109f336.png

dos4gw_003.png.93740f51c1fa55f16a4380c0c2dbef27.png

 

This will be available on the next release

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SNES Doom mode, but more than the flats are, well, flat colors :)

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That way it's going to work fast on a 386sx-16 finally. I guess this trick could be utilized for drawing distant geometry and sprites too.

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10 hours ago, viti95 said:

New dev updates. I've added untextured column rendering, it's faster but crimples gameplay a lot:

 

Untextured walls:

 

dos4gw_000.png.33645941b394482d1691f7020f855e67.png

 

Untextured walls + no diminished lightning

 

dos4gw_001.png.a8cc5f5a39a6bbb122569f86d0885803.png

 

As a side effect, also sprites can be rendered untextured:

 

dos4gw_002.png.6d723f0684a3b572202ce4f0a109f336.png

dos4gw_003.png.93740f51c1fa55f16a4380c0c2dbef27.png

 

This will be available on the next release

 

DOOM 64Kb

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The truth is that miniwad is actually very playable and looks pretty neat too.

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8 hours ago, viti95 said:

 

https://x.com/viti95/status/1812065740133920798?t=Q8s0Rihq8t0skCN2U-Em9Q&s=19

 

This is a test on my 386sx-33, still far from being playable with decent graphics lol

I don't care about that cpu tbh, the thing is that it doubles the performance without sacrficing image quality and triples it on the real modern hardware under dos, this is amazing.


Any 486 since 33MHz, Pentiums - all really favor your fdoom13h.exe. The higher resolution versions are also great, especially 400r.

 

The only disatvantage in contrast to the original exes is opl music, which I wrote about before, it sounds considerably worse and if you only could at least get Chocolate Doom code in there to make it better.

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