SNES native 3D performance ST-NICC no SFX demo

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Señor Ventura
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Re: SNES native 3D performance ST-NICC no SFX demo

Post by Señor Ventura » Tue Aug 18, 2020 3:48 am

Stef wrote:
Tue Aug 18, 2020 1:43 am
I think the SNES native demo is interesting as it directly compare to the Titan MD version, using the mode 7 is probably the best approach here for real polygon rendering. I wonder how much it can be improved but i know the 65816 is definitely not a beast when it comes to fill memory... Still it would be interesting to see how can perform the second method (FMV like) too, using a reasonable compression (something comparable to the MD ROM size which is already a bit less demanding as SNES has 25% less pixels than MD to display).
Do you mean like the actual MSU1 videos? (there is an bad apple demo at 512x448). At 4BPP or 2BPP could be possible to send more tiles to achieve some kind of FMV, right?

P.D: Sorry, where is the other demo for megadrive/genesis?.

total
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Re: SNES native 3D performance ST-NICC no SFX demo

Post by total » Tue Aug 18, 2020 5:17 am

Really cool demo!

I found one curious thing though when looking at the ROM. It doesn't seem like $420D gets set to FastROM speeds at any point, not sure if it was intentional but I tried quickly patching the ROM to set it and it gave a noticable increase in frame rate.

Stef
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Re: SNES native 3D performance ST-NICC no SFX demo

Post by Stef » Tue Aug 18, 2020 5:21 am

Do you mean like the actual MSU1 videos? (there is an bad apple demo at 512x448). At 4BPP or 2BPP could be possible to send more tiles to achieve some kind of FMV, right?

P.D: Sorry, where is the other demo for megadrive/genesis?.
Err no.. MSU1 isn't fun at all as you don't even need to compress the data, to be honest there is no challenge in using it. The idea is at least to respect a bit the ROM size constraint. About the niccc demo, i believe it's already 16 colors / 4 bpp, of course you could achieve better frame rate using 2bpp for a FMV but here 2bpp isn't enough.

Here's the MD Titan's version of NICCC demo (start at 0'40) :
https://www.youtube.com/watch?v=LcT1XIrklhQ

Oziphantom
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Re: SNES native 3D performance ST-NICC no SFX demo

Post by Oziphantom » Tue Aug 18, 2020 5:34 am

total wrote:
Tue Aug 18, 2020 5:17 am
Really cool demo!

I found one curious thing though when looking at the ROM. It doesn't seem like $420D gets set to FastROM speeds at any point, not sure if it was intentional but I tried quickly patching the ROM to set it and it gave a noticable increase in frame rate.
I need to go hit the Atari programmer with a cricket bat, back soon.

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Nikku4211
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Re: SNES native 3D performance ST-NICC no SFX demo

Post by Nikku4211 » Wed Aug 19, 2020 4:15 pm

I wish this demo worked on my NTSC RetroDuo. I'm not European, so both my RetroDuo and my HDTV use NTSC, which the demo wasn't made for. I know PAL has 100 more lines than NTSC does, which gives you more time to render the vectors per each frame pair. At the same time, making a demo that's NTSC-compatible and does something similar to this at a similar speed would be quite a challenge.

Wait, 20 FPS is just as close to 25 FPS as 30 FPS is. :thonk:
Stef wrote:
Tue Aug 18, 2020 5:21 am
Err no.. MSU1 isn't fun at all as you don't even need to compress the data, to be honest there is no challenge in using it. The idea is at least to respect a bit the ROM size constraint.
The real challenge is getting it to fit in an SD card along with other MSU1 titles.
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Oziphantom
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Re: SNES native 3D performance ST-NICC no SFX demo

Post by Oziphantom » Wed Aug 19, 2020 10:48 pm

The issue is the VBlank time. NTSC has this tiny small useless VBlank period. While PAL has basically double the VBlank this means we can DMA an entire frame to VRAM in 1 Vblank, so we don't have to double buffer VRAM. So while we could run it on NTSC and say its 3 frames on pal, it would drop to 4 frames on NTSC. however 3/50 = 0.06 and 4/60 = 0.066666 so practically the same speed. We would have to double buffer VRAM and lose the sprites.

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Re: SNES native 3D performance ST-NICC no SFX demo

Post by Nikku4211 » Thu Aug 20, 2020 2:42 pm

Oziphantom wrote:
Wed Aug 19, 2020 10:48 pm
The issue is the VBlank time. NTSC has this tiny small useless VBlank period. While PAL has basically double the VBlank this means we can DMA an entire frame to VRAM in 1 Vblank, so we don't have to double buffer VRAM. So while we could run it on NTSC and say its 3 frames on pal, it would drop to 4 frames on NTSC. however 3/50 = 0.06 and 4/60 = 0.066666 so practically the same speed. We would have to double buffer VRAM and lose the sprites.
Losing the sprites would be okay. If I recall, you're using mode 7 anyway, so it'd be better if it filled the screen rather than having a border around it.
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lidnariq
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Re: SNES native 3D performance ST-NICC no SFX demo

Post by lidnariq » Thu Aug 20, 2020 3:01 pm

Right now, it uploads 99 scanlines of mode 7 nametables (i.e. 99*128 = 13kB = 77 scanlines of DMA) on the relevant vblanks. I think it should be doable to extend blanking mostly by shaving off the top of the fake CRT and only a few scanlines of Vanna White^W^WVanessa's legs ;P

But I'm probably missing something about the sprites, because I'm unclear why Oziphantom said he was having such problems with it...

turboxray
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Re: SNES native 3D performance ST-NICC no SFX demo

Post by turboxray » Thu Aug 20, 2020 4:44 pm

Oziphantom wrote:
Wed Aug 19, 2020 10:48 pm
The issue is the VBlank time. NTSC has this tiny small useless VBlank period. While PAL has basically double the VBlank this means we can DMA an entire frame to VRAM in 1 Vblank, so we don't have to double buffer VRAM. So while we could run it on NTSC and say its 3 frames on pal, it would drop to 4 frames on NTSC. however 3/50 = 0.06 and 4/60 = 0.066666 so practically the same speed. We would have to double buffer VRAM and lose the sprites.
Yeah, but still PAL *only* demos are pretty lame for systems that are not PAL only.

Erockbrox
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Re: SNES native 3D performance ST-NICC no SFX demo

Post by Erockbrox » Thu Aug 20, 2020 11:53 pm

Did anyone make a youtube video of the demo the original poster made. I saw links to a MD demo and Super FX demo, but didn't see the demo of the original poster. Thanks.

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Re: SNES native 3D performance ST-NICC no SFX demo

Post by lidnariq » Thu Aug 20, 2020 11:55 pm

... did you click on the link in the original post?

psycopathicteen
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Re: SNES native 3D performance ST-NICC no SFX demo

Post by psycopathicteen » Fri Aug 21, 2020 7:01 am

You'll cut down on bandwidth a lot by only updating the non-solid tiles.

Oziphantom
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Re: SNES native 3D performance ST-NICC no SFX demo

Post by Oziphantom » Fri Aug 21, 2020 7:03 am

Here is the 100% version https://www.youtube.com/watch?v=NANeUldKAfI aka Fast mode enabled.
turboxray wrote:
Thu Aug 20, 2020 4:44 pm
Oziphantom wrote:
Wed Aug 19, 2020 10:48 pm
The issue is the VBlank time. NTSC has this tiny small useless VBlank period. While PAL has basically double the VBlank this means we can DMA an entire frame to VRAM in 1 Vblank, so we don't have to double buffer VRAM. So while we could run it on NTSC and say its 3 frames on pal, it would drop to 4 frames on NTSC. however 3/50 = 0.06 and 4/60 = 0.066666 so practically the same speed. We would have to double buffer VRAM and lose the sprites.
Yeah, but still PAL *only* demos are pretty lame for systems that are not PAL only.
30 or so years of PAL only C64 and Amiga demos hasn't been a problem. For Demos you want the more powerful version, so they tend to be PAL only to get more out of them. It seems silly to cripple a demo because NTSC exists. This is technically not true on a C64 as the Drean model is the most powerful however they are really really rare so nobody actually targets them.
It's a shame we don't have any PAL required SNES games.
psycopathicteen wrote:
Fri Aug 21, 2020 7:01 am
You'll cut down on bandwidth a lot by only updating the non-solid tiles.
Every tile is solid ;) but you will also spend a lot of time working out which ones are and aren't need to be updated and it is probably faster to just blanket DMA the lot.

psycopathicteen
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Re: SNES native 3D performance ST-NICC no SFX demo

Post by psycopathicteen » Fri Aug 21, 2020 7:15 am

I mean solid as in the 8x8 tile is one solid color, and update the tilemap as well as the tiles.

Oziphantom
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Re: SNES native 3D performance ST-NICC no SFX demo

Post by Oziphantom » Fri Aug 21, 2020 7:26 am

if you could update the span buffers to be 8 tall and hence you go through a whole "tile"s worth at once, it might work out faster to plot custom chars, update the map and then DMA fill with known solid tiles. It would save DMA bandwidth but I'm not sure it wouldn't cost more in terms of rasterise time.

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