[Openmsx-bugs] [ openmsx-Bugs-2898187 ] SDL 3x without effects still shows blur

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Bugs item #2898187, was opened at 2009-11-15 22:27
Message generated for change (Comment added) made by manuelbi
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Category: Graphics
Group: None
Status: Open
Resolution: None
Priority: 4
Private: No
Submitted By: Manuel Bilderbeek (manuelbi)
Assigned to: Nobody/Anonymous (nobody)
Summary: SDL 3x without effects still shows blur

Initial Comment:
When doing these settings:
set scale_factor 3
set renderer SDL
set noise 0
set scanline 0
set glow 0
set blur 0

you expect razor sharp images. But when taking a screenshot of the 8250 logo screen, you can still see vertical blurriness in the image.
When using SDLGL-PP all works as expected: razor sharp, no blurring. Wrong (SDL) and correct (SDLGL-PP) images attached.

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>Comment By: Manuel Bilderbeek (manuelbi)
Date: 2009-11-15 23:13

Message:
Oops, I attached the wrong SDLGL-PP screenshot. Fixed now.

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Comment By: Wouter Vermaelen (m9710797)
Date: 2009-11-15 22:57

Message:
There are two parts in this problem:
 
First, the screenshot of SDLGL-PP is taken at scale_factor4, the SDL one
at 3x (because there is no 4x for SDL). The boot logo is using msx
resolution 512x212, to stretch that to 768x636 (scale factor 3, both
resolutions don't include borders), you have to stretch by a non-integer
ratio, so it cannot be 'razor sharp'. Either there is some blurring or not
all source pixels are stretched (repeated) by the same amount. For scale
factor 4 there is no such problem.

The second problem is a real difference between SDL and SDLGL-PP. SDL will
always draw the 'scanline' as an interpolation between MSX pixels. SDLGL-PP
does the same except for the special case of blur=0/scanline=0. So this
means there is a big visual difference between e.g. blur=0/scanline=0 and
blur=0/scanline=1. I'm not sure which of these two is better. Probably the
latter.



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Comment By: Manuel Bilderbeek (manuelbi)
Date: 2009-11-15 22:48

Message:
Oh, all of this was on the simple scaler, of course.

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You can respond by visiting: 
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