Feature Article: Game Glitches 101

[Attebery]

Wayne Santos has an interesting new story up on game graphics glitches, give it a gander!

http://www.highdefdigest.com/news/sh...tches_101/1737

[michealo]

good read, thanks

[sakanagai]

That was a good read and a surprisingly detailed summary, Wayne.

Pop-up has been an interesting case over the past few years. Selective drawing in particular has been employed with varying levels of success to give the appearance of greater draw distance. Southpeak's Two Worlds, though a poorly rated game that suffered from an awful framerate in early versions, was able to acheive a seemingly unrivaled draw-distance by rendering only a certain proportion of common objects, like trees and rocks, based on distance so that when they did pop up they were far less noticeable. You actually had to look for instances where a tree would blink into existence. Oblivion did it to a smaller scale, but only because of the processing required to render the shrubbery.

Do you know if blurring is still used as a method of anti-aliasing? I know that hardware methods today can produce far better results, but handhelds might not have the power needed.

[Raptor007]

Excellent read; despite being outside the normal focus of the site, you've presented very accurate and detailed information. You did your homework, and it shows.


I'm going to elaborate on the Vsync/tearing issue, because it's actually pretty complicated.

After a frame is completed in a Double Buffered system, no more rendering work can be done until that frame is displayed (swapped from the back buffer to the front buffer). So, for the best framerates, some games swap buffers as soon as they're done drawing a frame. But if this buffer swap happens in the middle of a screen refresh, you get tearing, because the bottom half is now the new frame.

Vsync solves the tearing issue by only allowing buffer swapping during the monitor's vertical blanking interval. This isn't a problem for simple high-framerate games; why render 200fps when your display can only display 60fps?

But let's say you have a game that consistently takes 1/59th of a second to render each frame. Without Vsync, you've got 59fps, but with Vsync, you end up with only 30fps. This is because each frame is not ready for the first monitor refresh, and always has to wait for the next one (in this example).

Fortunately, there is a way to use Vsync without constraining the framerate much. If you add a third frame buffer, the game can immediately begin rendering the next frame while the back buffer is still waiting to display. Thus tearing is eliminated without significantly impacting the framerate.

The only disadvantage of Triple Buffering is that it can add a slightly higher latency between when the game believes it's rendering and when the monitor actually displays the frame. But it's a very insignificant latency increase; it's a shame Triple Buffering isn't used more often.

(The latest Nvidia drivers actually have a "render frames ahead" option, which can smooth framerates even more at the cost of even higher latencies.)

[Shoeless]

Originally Posted by sakanagai

Do you know if blurring is still used as a method of anti-aliasing? I know that hardware methods today can produce far better results, but handhelds might not have the power needed.

Blurring is still occasionally used as a means of AA in some games. If I'm not totally senile on my facts, I believe the most high-profile case of this in recent months is Devil May Cry 4, the multi-platform title. At first there was quite a bit of argument amongst the devoted of either console when in stills/screenshots for the game, the PS3 version looked "blurry" and eventually Capcom did indeed admit that a certain amount of motion blur was incorporated to help smooth out the animation and visuals of the game to a minor degree. When the game is actually in motion, this obviously did help improve the visuals somewhat, but in stills it did cause some initial debate amongst the console faithful.

[RugerRell]

Yeah, sometimes I get some bad pop-in on GTA IV for the PS3 and the FPS can drop pretty bad too. I wonder if it would help if the developers just installed the whole game too the hardrive.

[Badger3920]

Thanks for a great read. The example pictures were particularly interesting.

That gt5p screenshot looks realistic... jeez

[Master X]

Halo CE pic.... ahhh the good old days

[Raptor007]

Originally Posted by RugerRell

Yeah, sometimes I get some bad pop-in on GTA IV for the PS3 and the FPS can drop pretty bad too. I wonder if it would help if the developers just installed the whole game too the hardrive.

It's not just disc reading that causes it; loading and processing objects into RAM and textures into VRAM takes time too, even from a hard drive.

[ben1080p]

Nice Article..Ill be honest I only read the captions of the Pics and the Pics,, it got the facts across.
But keep up the love for Gamers.

[inferno100]

That screenshot from prologue is a bit misleading, its from the replay system rather than "real in game". Prologue actually has a surprising amount of jaggies

[Kaprikawn]

So draw in is that thing that happens a lot with the Unreal 3 engine games (GoW, Mass Effect etc.) where the game starts without the textures loaded and then they slowly appear?

[ericede]

Originally Posted by Kaprikawn

So draw in is that thing that happens a lot with the Unreal 3 engine games (GoW, Mass Effect etc.) where the game starts without the textures loaded and then they slowly appear?

Yeah it's also called depth culling when you see things being drawn on the horizon, but considering what these games are doing I don't see how it's a valid complaint. Oblivion loads the game on the fly (without zoning). Your gaming system would need an incredible amount of RAM to preload all the textures and objects for the entire gaming environment at once. The game could wait for all objects to load before dropping you into the game but nobody likes to wait for an area to load either. I grew up with adventure games that required you to change out floppies anytime you went anywhere. With all the advances in gaming I think it's strange to say, "It's not good enough! I want tomorrows advances today!"

It's this kind of short attention span gaming that drives graphics over content. We want the eye candy that only the huge developers can bring us and usually we don't seem to care that we can play through the entire game in 7 hours. These gaming systems are designed to out-graphics the competition. All that horsepower just to increase the texture size, generate algorithmic textures, and increase the polygon count. All too often the content suffers.