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Question about scaling of HLSL effects - absolute or relative?
#359825 - 10/22/16 06:25 PM
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Hello, I have a question for the good folks here regarding HLSL effects.
I'm about to get a much better PC, and I therefore upgraded my MAME emulator to access all the effects I couldn't use before, such as HLSL. For now, I'm using the raster.ini and vector.ini files given by default with MAME 0.178. I'm currently designing artworks for each game I have in my list so the games are displayed at the perfect resolution on my widescreen 1920x1080 TV, but I noticed something weird while working on my 1280x1024 monitor (my monitor and TV are both wired to my PC):
When, to get a quick look, I display vector games embedded in their widescreen artwork on my 5:4 1280x1024 monitor (and therefore appearing in a quite tiny area in the middle of the screen since the artwork is widescreen and I don't crop it), the bloom effect seems intense relatively to the game. But when I display the same game with the same settings on my monitor with the artwork cropped, the bloom effect is extremely minimal, like it is on the TV.
I conclude that the bloom effect doesn't scale to the game itself, and is instead absolute. Why is that? Raster games have effects that seem to scale according to the games (to my naked eye), but not vectors? What effects are absolute vs. relative to game area on screen? Is it just bloom that doesn't scale relatively to the game? I'm trying to understand how it all works and I'm a bit confused by this specific point.
Thanks.
EDIT: just in case - I'm using MAMEUI64 (I don't think it makes any difference, but you never know).
Edited by Simbabbad (10/22/16 06:33 PM)
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Re: Question about scaling of HLSL effects - absolute or relative?
[Re: Simbabbad]
#359898 - 10/24/16 10:34 PM
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The basic idea is to have all effects resolution independent; source (game resolution) and target (your screen resolution).
The bloom effect uses a Gaussian blur approximation by downsampling the source image several times and adding these bloom-layers together.
I've never noticed the problem you describe, but it makes totally sense. Vector games have no defined source resolution like raster games and the source resolution is simply the same as the target resolution. Therefore the downsampled bloom-layers will differ for different target resolutions and result in different intensities.
To correct the issue a fixed source resolution for vector games has be used when downsampling the bloom-layers. But I'm not sure if I'll still fix it in v179.
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Re: Question about scaling of HLSL effects - absolute or relative?
[Re: Jezze]
#359935 - 10/26/16 03:25 AM
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Thank you for your answer. It's not really an issue, I was just surprised that displaying the game in a smaller area didn't result in the same effect relatively to the game, and I wondered if it was exclusive to vector games.
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