Emu#dreams Forum | Download | RSS | IRC | ADD NEWS | last 7 days | last 31 days | MUSEUM

Altirra 3.20 Test13 [454][witek], 2019-02-06 17:03:30

[Source: http://atariage.com/forums/topic/281825-altirra-310-released/page-15]

- Adjusted command line parsing to fix issue with partial switch matching: /disk1 is no longer interpreted as /disk 1.
- Color map utility on Additions disk now supports CTIA. (also attached to post)
- AltirraOS 3.13 and SIO patch now set A=0 on exit from SIOV.
- Started a couple of new pages in Configure System, an overview page and a recommendations page. The recommendations page has hyperlinks to change settings based on the current settings and whether youre looking for compatibility, accuracy, or performance.
- Added an Open Source File List command to the debugger. It displays a dialog with all of the source files referenced by currently loaded symbols. This makes it easier to see what source files actually have line debug info associations and to open those files directly without having to manually find it if the debugger can do so on its own.

Regarding the scanline artifacts, thats an aliasing effect. Its most severe with point sampling because in that mode the scaler can only duplicate pixels, never blend them. At non-integer ratios some rows have to be scaled bigger than others, leading to the uneven stepping. Scanlines makes this worse for two reasons: the fine comb pattern makes the artifact really obvious, and it doubles the height. For instance, full 240 height turns into 480 with scanlines. On a 1366x768 display, theres only enough vertical room to do 1x, and at 1920x1080, theres only room for 2x.

This effect is the reason for the sharp bIlinear option being the default: it renders blocky pixels but with a bit of blending on the edges to reduce the aliasing. Point sampling is only good at exact integer multiples; it looks like #&$* at any other ratio.

As for the hardware acceleration for screen effects option, yes, that does make scanlines look better. The reason for this is that it allows the scanline pattern to be generated at full screen resolution rather than getting stretched along with the image, so theres less error in it. This requires HW acceleration because otherwise the image has to be scaled and masked on the CPU, which is dreadfully slow. I recommend turning on bloom in View > Adjust Screen Effects too, as this will help brighten scanlines to the same level as the non-scanline display.