[BDZ]

(I posted this about 2 days ago at Pete's QB Site...and no one seems to have the answer.)

A little background first. I'm using QuickBasic 4.0 on a Pentium II 333Mhz (Win98.) The other day I discovered from some tutorials about using OUT and INP to adjust the palette in Screen 13, so I wrote some subs for my RPG to fade the screen in and out.

I was a little disgusted by the flicker though, so I read further. I then experimented with "WAIT &H3DA, 8" and "WAIT &H3DA, 8, 8" to try to wait for the vertical retrace before messing with the palette in each iteration of the loops that fade and "unfade" the screen. These commands caused a delay, but they didn't really seem to affect the flicker much; it still remained.

I read in one of the shorter tuts that "WAIT &H3DA, 8" worked best on 486s and slower Pentiums. What I'm wondering is, is there a good way to wait for the vertical retrace in my program? I don't want to resort to ASM. I'd like my RPG to be pure QB.

Thanks for your help.

(I'd like your help even if you aren't using QB.)

[Terry]

What you're doing sounds like it's correct, so I don't know why it isn't working for you.

I'm not sure about this, but I think it's possible that you don't need the second WAIT &H3DA, 8, 8 line. The first line waits until the vertical retrace is at the bottom of the screen, but as far as I know, the retrace actually keeps going for a few nanoseconds. The second waits until it gets back to the top.

If that's the case (and I stress, I'm not sure about this), then you should simply do a single WAIT &H3DA, 8, and then update your palette.

If you're working in screen 13 in pure QB, you're going to find it difficult to keep the game from flickering. Unless you use a fast offscreen buffer, it's pretty much unavoidable. You'll also probably going to have problems when you try to enhance your game with music and a decent keyboard handler. Why not just use an ASM lib?

Or Freebasic? I hear it's pretty good. Plus that way, your game isn't limited to people who have pre WinXP operating systems on their PCs.
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[Nodtveidt]

SCREEN 13 is probably the fastest mode available to native QB. The WAIT needs to be executed at the correct time though...just shoving it anywhere in your code isn't going to help much unless you got lucky and put it exactly where it needs to go.
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If you play a Microsoft CD backwards you can hear demonic voices. The scary part is that if you play it forwards it installs Windows. - wallace

[BDZ]

[BadMrBox]

It was quite awhile since I used the WAIT command, when I still coded QB I used Rellib. I'll recommend you to use it, it's easy to use and flicker is no problem for you.

Otherwise, test to put your WAIT just before NEXT.

[Terry]

[RedSlash]

So are we talking about flickering or tearing? If flickering, it is likely the fact that VGA mode13h mode runs under 60Hz, which does has a noticable flicker. Tearing on the other hand is solved by vsync.

[BDZ]

[Nodtveidt]

That's palette snow, it happens when you alter the palette during vertical retrace (as far as I remember).
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If you play a Microsoft CD backwards you can hear demonic voices. The scary part is that if you play it forwards it installs Windows. - wallace

[BDZ]

Dang...It's a problem with Win98 (I think perhaps the drivers for the cheap on-board video card in my PC)...on pure DOS on the same computer and my other Windows XP computer adding the "waits" makes it near flickerless...thanks guys.