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libretro / dosbox-svn

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[Help] Scaling VGA to 240p #37

Open vol-2 opened 4 years ago

vol-2 commented 4 years ago

Is there any path to pixel-perfect (or close to it) scaling in this branch of dosbox? I'm outputting to an arcade monitor at 15kHz, trying to figure out it there is some combo of settings I can use.

I want the same effect as: @ 1600x1000 (exactly 320x200 times 5) and then scaled back down to 320x240, but I can't output to the monitor at above 240p vertical, so I would need some software solution.

Is there some combo in libretro+ dosbox-svn that would allow me to do this?

Thanks,

realnc commented 4 years ago

I've been told you can use a shader for this, and in the shader preset use:

scale_y0 = "240"

in the shader preset file. However, I never done this myself and have no idea what shader exactly you're supposed to use with this. I would suggests asking in the libretro forums about it.

vol-2 commented 4 years ago

I've been told you can use a shader for this, and in the shader preset use:

scale_y0 = "240"

in the shader preset file. However, I never done this myself and have no idea what shader exactly you're supposed to use with this. I would suggests asking in the libretro forums about it.

Thanks for the reply realnc, this give me something to go on. I'll see what I can dig up. If you want me to come back here and post my findings, you can leave this open and I'll do it. Otherwise, feel free to close.

hizzlekizzle commented 4 years ago

I think in this case you would want to use a stock shader pass at 5x scale with nearest neighbor filtering and then another stock pass using linear filtering and "don't care" scale to make it fit the screen. However, I don't think this will look very good, as there's just not enough lines of resolution to average the lines well.

I think you'd be better-served with a 320x200 modeline.

vol-2 commented 4 years ago

I think you'd be better-served with a 320x200 modeline.

Oh man. I did try this. I was able to get results, but it isn't the easiest solution because the raspberry pi exhibits a lot of dot-crawl issues when you try to force the vertical resolution down that low. The guy who created the VGA adapter for the pi says that it's an issue with the lines being to close together or some such thing. I suppose I can give it another try. lol