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Running Vector Games on your Arcade Monitor
The basic idea with vector games on a raster monitor is to try and get as high a resolution as possible
So - if the MAME SVGA drivers work with your card, use 640x480
The tweak option comes into play here, which has a slightly different meaning for
arcade montitor/TV modes (which are all 'tweaked')
If tweak is set to 'yes' - tweaked 'hires' VGA modes will be used to run hires games
If tweak is set to 'no' - the SVGA mode will be used to run hires games
Vector Games and the ATI driver
If you're using an ATI card supported by MAME's ATI driver -
the display will be interlaced, that is, it will be drawn in 2 passes to create a 'true' hires display
but because the display is drawn in 2 passes....
If the game's video buffer is being updated between these 2 passes it can lead to the situation where
horizontal lines within the video buffer are consistently not displayed.
noticable in some games; undetectable in others (Asteroids is about the worst)
What happens is this -
a horizontal line is draw (say, the bottom segment of an asteroid) on an even line,
the screen is displayed , and the video card draws it's first pass of odd lines.
The segment of the asteroid is on an even line so it's not displayed on the arcade monitor.
The game code moves on and the asteroid moves one pixel vertically,
the asteroid segment is now on an odd line
Once again the displayed is updated - this time with even lines, so again
the asteroid segment is not displayed
If the asteroid continues to move one pixel at a time vertically the horizontal segment will never be displayed on the arcade monitor
To get round this problem, use the 'waitinterlace' option
You should only use it where you can see a line drop problem, and it's not neccessary for raster games
Using 'waitinterlace' will automatically set the frame rate to ,or below, 30FPS.
(this is generally what vector games run at anyway)
Vector Games and the 'Generic' driver
If your card works with the 'generic' SVGA driver in MAME, you will get a non-interlaced 640x480 display
The way this works is to only display every other horizontal line in the display,
effectively giving you a 640x240 display, but with the aspect ratio of 640x480
To compenstate for the missing display lines, you need to set the beam option in MAME to
be '2' (this produces a surprisingly effect result)
If your card does not work with either of MAME's SVGA drivers - you need to pick a standard VGA mode
MAME's vector games run with an aspect ratio of 4/3 (640x480,800x600 etc.) so for the best results you need to run in a mode with a similar aspect ratio - such as 320x240
You can use the 'hires' VGA modes (512x448,512x512)
but ,again, you'll again need to set 'beam' to '2'
