About the eyeballing game

Some people are bothered by pictures on the wall hanging slightly crooked. Others may not even be aware that something may be amiss.

If you are somebody who is into woodworking or construction, its good to be one of the people who notice when things are crooked. But I suspect the ability to notice that things might be just a little off square, off centre, or not quite straight, varies greatly. I thought it would be fun for people to try to test their abilities to see if things are straight or crooked in a little game.

And thanks to LCD monitors, its possible to display geometry with absolute accuracy on a computer now. So what better way to try this game concept than to put it on the web!

How the game works

The best way to figure out how the game works is to simply play it.

The game works by showing you a series of geometries that need to be adjusted a little bit to make them right. A square highlights the point that needs to be moved or adjusted. Use the mouse to drag the blue square or arrowhead where you feel it is 'right'. Once you let go of the mouse, the computer evaluates your move, so don't let up on the mouse button until you are sure. The 'correct' geometry is also shown in green, so you can see where you went wrong.

You will be presented with each challenge three times. The table to the right shows how you did on each challenge each time.

Once you have done each challenge three times, the computer tallies up your average error. The lower your average error, the better. A theoretically perfect score would be zero. The error is measured in pixels, and in degrees times two for the bisection and right angle problems.

The computer keeps a best scores table, one for everybody, and one for just your computer. If your score is better (lower) than the bottom score on either list, you get to enter your name in the best scores.

The best scores only show scores in the last 500 plays. So your scores will fall off the best scores list after 500 more games have been played, even if nobody beats your score. This will allow mere mortals in the best scores list as well. The game also keeps track of the best of the last 10,000 plays on the best scores page

The local best scores are stored on your computer only, and never expire. Although you can clear them.

Right angles and monitor adjustment
Its very important that your computer's display aspect ratio matches that of your monitor. I frequently get emails from people claiming that the right angles are not quite right angles. Some even send screenshots, which allows me to be doubly certain that it's their display that's the problem.

If you are using an LCD display, your screen resolution should be set to match the display's native resolution. For example, 17" or 18" non-widescreen monitor tend to have a resolution of 1280x1024. That's a 5:4 aspect ratio. If you set your computer to 1024x768, that's a 4:3 aspect ratio, which is not quite the same as 5:4. The image thus gets scaled and stretched vertically more so than horizontally. This makes right angles not look like right angles (unless they were aligned with horizontal and vertical). It also makes circles look like ovals, and makes the other solutions look subtly incorrect.

Distortions can get much worse if a widescreen display is used without setting the PC's video output to something that matches the monitor. So if right angles don't appear quite square, is not a problem with the game, it's a problem with your display. Please check your display settings before emailing me, because I'll just send you a link to this page!

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