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[feature request]Flycast still doesn't have full screen anti aliasing.

Open tails101 opened this issue 1 year ago • 7 comments

Yesterday i played on a real Dreamcast and we compared to flycast. And flycast seems to have a big feature of the Dreamcast missing. The Dreamcast had a very smooth image due to a feature called full screen anti aliasing. It was very noticeable on games like sonic adventure and dead or alive. Current emulators make the Dreamcast look more like the playstation 2 due to this smoothing missing.

tails101 avatar Nov 30 '24 07:11 tails101

Full screen anti aliasing? Never heard of this on the dreamcast. Can you point me to the source of this information?

flyinghead avatar Nov 30 '24 09:11 flyinghead

Full screen anti aliasing? Never heard of this on the dreamcast. Can you point me to the source of this information?

well i think it was called super sampling aa. there is a few mention here and there but no real source. it was on n64 and dreamcast. it use anti aliasing on the whole image to look smoother and a bit blurrier it was very noticeable when we used a pal dreamcast hooked by scart on a sony trinitron tv.

tails101 avatar Nov 30 '24 10:11 tails101

https://www.reddit.com/r/dreamcast/comments/kp8q2o/dreamcast_vs_gamecube_sonic_adventure_both/?show=original

https://www.reddit.com/r/dreamcast/comments/1h2enu/what_dreamcast_games_use_antialiasing/

https://forum.beyond3d.com/threads/did-most-dreamcast-games-use-super-sampling.15197/

few mention of the feature here and there with side to side on real hardware.

tails101 avatar Nov 30 '24 10:11 tails101

Dreamcast can render at 1280 horizontal resolution, which is then downsampled to 640. Only one game I can think of uses this mode: Wacky Races. Flycast supports this AA mode. Another way is to do horizontal filtering in 480i mode. There are a few variations of this mode. Flycast doesn't support interlacing so this isn't implemented (and not needed). The only exception iirc is with Full Framebuffer Emulation enabled when the game renders at 480 but outputs at 240p (not very common.)

Anyway, Flycast supports pretty much unlimited upscaling, so anti-aliasing is there if you need it.

flyinghead avatar Nov 30 '24 10:11 flyinghead

Dreamcast can render at 1280 horizontal resolution, which is then downsampled to 640. Only one game I can think of uses this mode: Wacky Races. Flycast supports this AA mode. Another way is to do horizontal filtering in 480i mode. There are a few variations of this mode. Flycast doesn't support interlacing so this isn't implemented (and not needed). The only exception iirc is with Full Framebuffer Emulation enabled when the game renders at 480 but outputs at 240p (not very common.)

Anyway, Flycast supports pretty much unlimited upscaling, so anti-aliasing is there if you need it.

yea but upscalling tend to mess with crt shaders. im trying to go with a original console look in retroarch but sadly it doesn't look as good without this feature and the shader doesn't work outside the native resolution. the other issue with upscaling is,it blur any 2d asset making the difference very obvious between 2d and 3d. maybe separate internal resolution and window resolution could be a quick and dirty implementation

tails101 avatar Nov 30 '24 10:11 tails101

Sorry but I still don't understand which Dreamcast feature is missing. Internal resolution and window/screen resolution are unrelated so this can be used for anti-aliasing. And the blurriness of upscaling 2d assets will be eliminated by the downsampling.

flyinghead avatar Nov 30 '24 11:11 flyinghead

Sorry but I still don't understand which Dreamcast feature is missing. Internal resolution and window/screen resolution are unrelated so this can be used for anti-aliasing. And the blurriness of upscaling 2d assets will be eliminated by the downsampling.

Strange the last time i check flycast we can't set a render resolution and a screen resolution separate in full screen unless you use a separate upscaller like lossless upscaling. And as i said dead or alive 2 and sonic adventure are known to use this feature.

tails101 avatar Nov 30 '24 11:11 tails101

details of the changelog to see if it is really completed?.... i don't like to reopen for the 3rd time.

tails101 avatar Jul 06 '25 16:07 tails101

You say that Flycast is missing a feature present on original hardware but I still don't know what it is and I don't see any reference to it.

flyinghead avatar Jul 06 '25 16:07 flyinghead

https://dcemulation.org/phpBB/viewtopic.php?t=105441 dreamcast high resolution modes. dreamcast output resolution https://consolemods.org/wiki/Dreamcast:Video_Output_Notes#:~:text=The%20Dreamcast%20natively%20supports%20240p,and%20a%20few%20support%20240p. games that use downscaling https://gamefaqs.gamespot.com/boards/916412-dreamcast/77015168

tails101 avatar Jul 06 '25 20:07 tails101

Everything mentioned in these threads is supported by flycast: render to texture, 1280x480 downscaling, non-default resolutions (640x240, 320x240), etc. Note that render-to-texture doesn't allow upscaling on original hardware and that the image shown is obviously from Flycast (you can tell by the use of the xBRZ texture filter): Image

Here is an answer that is accurate and clearly says that 640x480 is the maximum possible output resolution: https://dcemulation.org/phpBB/viewtopic.php?p=1058509&sid=45f15fdc05c0147f8437ff831e7083e9#p1058509

flyinghead avatar Jul 06 '25 20:07 flyinghead

Yea but it doesn't support downscaling so rendering at internal higher resolution in a 680x480 output.

tails101 avatar Jul 07 '25 07:07 tails101

It does, in at least 2 ways. See above.

flyinghead avatar Jul 07 '25 08:07 flyinghead

above?

tails101 avatar Jul 07 '25 09:07 tails101

btw separate internal and output resolution will be usefull for adding crt shaders, it will be a good idea as well to add bfi and subframe shader for crt beam simulation for that crt motion clarity i should add that as a new feature request

tails101 avatar Jul 07 '25 09:07 tails101