Re: Frame complexity

Wow, thanks for such a detailed response! I'd say I don't need a frame rate
higher than 24fps at this point, so that should work out nicely in terms of
how much I can draw per "frame". I assume that if I draw a lot of small
lines close together, IE, to fill a shape in, then that would draw out
pretty quickly, since the beam doesn't have to jump too much from line to
line?

On Mon, May 21, 2012 at 4:32 PM, Clay Cowgill <c.cowgill@comcast.net> wrote:

> **
> > I'm trying to get a handle on just how far I can push the drawing
> capabilities of my G05-802 monitor.
> > Is there some sort of example out there, game or otherwise, of the
> largest number of lines I could get
> > away with per frame? I know that it's a limitation of the monitor
> itself, not the software; it's just hard
> > for me to grasp what I can actually get away with. Imagine if I were
> to just draw lines randomly from
> > one edge to another, how many of those lines could I draw per frame?
> What happens if I just keep
> > drawing lines and never refresh the screen?
>
> It depends on the type of vector generator and what sort of frame rate you
> want to achieve but if, for example, you want to do 60fps (which would be
> quite high for a vector game) that works out to about 16.66ms per 'frame'.
> A ZVG on the G05 setting will draw at about 15us per inch. If you were to
> consider all 'movement' of the beam to be drawing time (ie, no high speed
> 'jumps' to a new position while the beam is off) you could do something
> like 16.66ms / 15us = 1111 inches per frame.
>
> If the monitor is roughly 19" diagonal and a 4:3 aspect ratio, it's about
> 15" wide and 11.25" tall. So, dividing 1111 by 15" you get about 74 full
> length lines running the width of the screen. (Practically speaking these
> will all be "approximately"-- so for compatibility I wouldn't plan on
> pushing things right up to the theoretical limits to be safe...)
>
> Most vector games run slower than 60Hz though. At, say, 30Hz-- that
> number's more like 148 lines, etc.
>
> The G05 can 'jump' faster than the vector generator will normally draw, so
> practically speaking "black" (moves) can be faster than "white" (draws)
> which saves you some vector time.
>
> If you keep drawing lines (but never 'redraw' then in them same place)
> it's about like an analog oscilloscope -- they just fade away. You need to
> redraw all the lines every ~1/30th of a second or so for a stable image.
> (ie, refresh the screen) There's really no fixed frame rate on the vector
> display. It can vary depending on what's going on, so like in ESB it can
> get flickery and start looking a tad bit like a slide show and the frame
> rate drops. For 'easy' and to keep things consistent you can have the
> vector generator triggered with 'fixed' frame rate and then just be sure
> that what you're telling it to draw fits in the time allotted.
>
> If you have a fixed 'frame' rate that tells the VG to start drawing at a
> particular interval always and it's not done drawing the previous frame of
> data, you'll just "lose" things on the screen. Similarly, if you try to
> jump the beam too fast and don't allow enough settling time, you can get
> vectors that 'curl' because the brightness is turned on before the coils
> really had a chance to deflection the beam to the final destination. (You
> see that if you try to run Star Trek on a stock WG6100 for example-- or
> even my Sega Multigame menu 'arrow' would do that too.)
>
> You need to keep in mind as well that the spot killer can activate if
> there's not enough deflection around the screen. In Vector Breakout I
> actually draw a big box around the entire playfield (a couple of times,
> IIRC) because the spot killer was activating otherwise-- presumably because
> the display is rather 'top heavy' with all the bricks on one side and then
> only the paddle and a couple other elements down low.
>
> One other thing to mention... On the color monitors the dark glass in
> front of the CRT makes a HUGE difference in reducing visible frame rate
> flicker. I was a little freaked out when working on Vector Breakout
> because if seemed quite flickery to me on a bare CRT, but with the glass in
> front I'd say 90% of the effect totally disappeared.
>
> -Clay
>
>

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Received on Mon May 21 16:39:43 2012