Impact

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6 years ago by sunnybubblegum

I've noticed this occurrence for a long time, but never thought to ask until now.

I have this issue in my Impact games where there are occasional flickers of 1-pixel wide black lines that span the game frame.

These lines usually flicker near the extremities of the canvas as I walk along my map, both horizontally (near the top) and vertically (near the left). They seem to line up with the edges of my map tiles. They may be black because of the black game background. This occurs in Weltmeister too.

Sometimes if I stop moving in my game, I can get the black line to remain in place on the map. So it's not a truly random flicker -- it's tied to movement against the background.

It's strange because I don't notice this on any of the Impact samples, from which I derived many of my games (Pong, Jump 'n Run, Drop). The originals all render as smooth and flawless.

Is there something I'm doing wrong in my code, or is there some other explanation for these flickering lines (i.e. JavaScript engine, my nVidia drivers)?

Thanks!

System info:
Ubuntu 12.04 32-bit, Unity DE
nVidia GeForce GT 240
nVidia 310.14 drivers
Firefox 21.0 (Mozilla Firefox for Ubuntu, Canonical - 1.0)

(Note: I've noticed this issue over several versions of my operating system, video card drivers, browsers, and even computers)

Update 1: I tried to take a screenshot to post on here, but as soon as I opened my screen capture program, the black line I had paused disappeared. Very strange.

6 years ago by Graphikos

What is ig.System.drawMode set at?

http://impactjs.com/documentation/class-reference/system#ig-system-drawmode

Note that not all browsers support SUBPIXEL drawing. Depending on your game, subpixel positioning may lead to visual artifacts, such as seams between tiles. In most browsers it also comes with the price of a bit of performance.

6 years ago by sunnybubblegum

Hey Graphikos,

Good thinking. That sounds a lot like what I'm seeing ('seams between tiles').

I checked my main.js file, but couldn't find any call to ig.System.drawMode. It would be set at whatever the Jump 'n Run sample was set at. So I assume it's default (SMOOTH).

Thanks for replying. Any other ideas?

6 years ago by Joncom

Might be helpful if you posted a video of this, or maybe a baked copy of your working version.

6 years ago by sunnybubblegum

I managed to take a screenshot of the issue I've been describing.

/><br />
<em>Notice the thin black line spanning the frame near the top</em><br />
<br />
These lines appear both horizontally (like in the example) and vertically (usually along the left) as I walk up and down my map. I can get them to pause if I stand on just the right place.<br />
<br />
Strangely, once again the line disappeared the moment the screenshot was taken, and I couldn't reproduce it. Does this mean the issue has something to do with the display server of my operating system (Ubuntu's X Server)?			</div>
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