LCD Scrolling

Ok, this may sound weird but I am sure you laptop/LCD monitor people out there know what I am talking about.

I have a 2D side-scrolling demo going. Looks great on my CRT monitor but when I run it on any laptop or LCD-monitor computer, it looks good until the actual scrolling begins. WHen that happens, the screen actually "dims" and appears to "smear" accross the screen.

I believe I know why this is happening. It is probably due to the fact that CRT monitors have a verticle refresh and LCD monitors (like in laptops) don't really have a normal refresh. Instead, every pixel is always on and doesn't get turned off on the verticle refresh.

Now, I *think* a work around is possible because I can play Starcraft (original) and when I scroll the map around, it looks perfect. (probably due to Blizzard's huge budget..lol)

Anyway, any clues?

Thanks

cb

LCD displays have often had this problem. If Starcraft doesn't do it, then I'm not sure what they've done.

Yeah, they may do something with the actual timing while drawing? Man, this has be stumped. Wonder if Blitz can do it?

cb

My understanding is that LCD screens do this because the pixels cannot change color fast enough, especially when going black->white->black. The rate at which they can do this is called the pixel response rate. If it's too slow, you'll see ghosting.

Perhaps starcraft scrolls slower, or doesn't change color as drastically... ?

your guess is as good as mine. I don't think there's anything you can do about it (programmatically) besides slow down the scrolling... It's basically a hardware limitation.

Yes, it's because LCD screens are typically slower than CRTs and leave more afterimage behind. It's more noticable on high contrast/high colour saturation images. The only possible reason starcraft doesn't do it (as much) is that starcraft is mostly all grey.

Don't worry about it; there's nothing you can do about it except change your monitor!

Yeah, I was thinking the exact same thing.

The biggest reason is my laptop. My desktop at work and at home make great game programming environments. I was wanting that with my laptop too. I will just have to accept LCD monitors suck when it comes to side-scrollers.

Still, have you noticed 3D games don't suffer as much either??

cb

When I was in Curry's a good while back, I ran the DirectX spinning cube test on various laptops to get an idea of the smearing/ghosting effect of each LCD display.
I think the Sony & Toshiba models came out pretty good with Acer suffering the worst. Mind you, I had to suss the password protection out by getting one of the assistants to show me some stuff and watching they're fingers enter the code :-0

It deals with how voltage is held inside each cell of the LCD, like DRAM it "refreshes" and then "drains" like a capacitor, Yeah. :D

So instead of a full wipe (Clear screen!) of voltage it pours out like a bucket of water.

I'm probally wrong, evilly wrong, confusing you till you end up shooting yourself in the face. Questioning life due to this problem. Then you go to howstuffworks.com right before you pull the trigger, and your questions are answered..

http://electronics.howstuffworks.com/lcd4.htm

The problem is, you already pulled the trigger, and instead of reading it fully, you die.. blead to death.

Indeed I have. I think it might have something to do with the way that, in 3d games, you're mostly focussing on the centre of the screen (the point you're moving towards) as you move... and that part of the screen is actually moving quite slowly. In a 2d game, everything is scrolling at the same rate, and the image is static, so the smearing becomes really obvious.