Let's Play Ancient Greek Geometry | Hacker News Reader

Let's Play Ancient Greek Geometry

blog.sciencevsmagic.net

125 pointsivank38 comments

This is awesome!

Thoughts: after clicking, sometimes I decide I want to cancel drawing from that point. I can click on the original point to cancel, it would be nice to be able to press ESC or SPACE to cancel drawing (just noticed that Z for undo cancels).

For the "game" side, it is very important to have simple tasks that almost all players can complete to get started. I would add an even simpler first challenge, such as make two overlapping circles.

I would love to be able to share constructions. I'm thinking a button I press that pops up a URL that I can share. When visited it shows an animation drawing the construction, then when done lets you do more drawing. That would be cool.

The URL in the location bar seems to update with the steps you've done (here's one showing the first construction: http://www.sciencevsmagic.net/geo/#0A1.1L0.1A0.3L0.3L1). Undo/Redo can then give an animation like appearance.

You can actually press reset and then redo, redo, redo to replay construction without having to undo first.

Another vote for ESC cancelling the current construction.

It's just a new condition in onkeydown:

  else if (e.keyCode === 27) {
    deselect();
  }

While we're at it, make Shift+z redo.

  else if (e.keyCode === 90) {
      //"z"
      if (e.shiftKey) {
          changes.redo();
      }
      else {
          changes.undo();
          changes.record(1);
      }
  }

And let's not clutter up the user's history. Swapping

  window.location.hash=currenthash;
  ...
  window.location.hash=hash;

with

  window.location.replace(currenthash);
  ...
  window.location.replace(hash);

fixes that one.

It's the little things in life, man…

I've added the esc and space to deselect, and shift+redo. Thanks, once you get used to your own hotkeys it gets hard to imagine what other people might want.

As for the hash, the original reason why I went with hash= was to preserve back and forward, but I guess that might not be so necessary considering I have undo and redo.

I know that my clutter can be a bit obnoxious, but just changing it to window.replace(hash) breaks a few other things, so it's left the way it is for now.

There is probably some HTML5 history API way to do it that lets me have back and forward without saving every history entry, I'll look into it.

Perhaps map key codes to object properties with, you know, real names so comparisons to e.keyCode mean something in the future.

  var appKeys = { "Esc": 27 };

  else if (e.keyCode === appKeys.Esc) {

Some JS libs do this for you and there are some nice libs that make key handling convenient and powerful as well.

Great tip. But I generally only use each reference once, so I'm not sure it would have been worth it in my case.

There are lots of libraries that could have made things more convenient. But a big part of this project was to learn as much as I could about coding, and the browser as an environment, so early on I committed to writing everything myself.

I'd be interested in hearing whether or not other people think this is a good strategy for self teaching.

+1 on doing everything yourself the first time for self-teaching. But I'm sure people are on the far end of both sides -- do it all yourself, or use libraries for everything.

>There is probably some HTML5 history API way to do it that lets me have back and forward without saving every history entry, I'll look into it.

Do you mean the Back & Forward buttons in the browser?

If you can go back/forward to different states, why wouldn't those show up as history entries? I don't think you can decouple the displayed "history" drop-down list from the behavior of the back/forward buttons (for reasons that are probably obvious).

http://html5doctor.com/history-api/

This guy's got lots of neat toys. http://www.sciencevsmagic.net/fractal/#0090,0180,2,2,1,0,5

If you want to go farther: a powerful, open, and fully-featured tool for doing this on the desktop (and soon tablet), along with a CAS and other facilities is GeoGebra: http://www.geogebra.org/cms/en/

If you want to go deeper: http://www.woodenbooks.com/ which are, for want of a better term, 'rigorous mysticism.'

This is damned cool. Having something like this makes it easy and convenient to explore geometry without the inconveniences imposed by physical media. Having specific goals to work towards and target move counts is icing on the cake.

Thank you for making this. Find a way to get this out there to geometry teachers. They (and their students) will love it.

Suggested improvements:

+ Option to switch between a couple colors or line types, to make it easier to track what one's doing. (E.g., laying down foundational lines in black, then experimental lines in blue or dashed lines.

+ One minor thing I'd like to see fixed: the proximity of the numerical goals to the shapes they're associated with doesn't make it clear whether (e.g.) the 8 move goal is an easy version of the "build a triangle in X moves," or whether 8 moves is the least amount of moves for building a triangle inside an origin circle.

Suggested fix: make that more apparent by tweaking the order of the symbols (e.g. Triangle, 5, 8, OriginTriangle) and/or adding a divider of some manner to make them stand apart more.

Love it! But I am having a hard time figuring out when exactly I can/can't "pick up" a point from somewhere else: sometimes tick marks appear at the distance I'm looking for, sometimes not. Also, it seems odd that I can't just draw a line (as opposed to line segment), since iirc the straightedge is theoretically infinite. (There are definitely a few times I've wanted to lay down the full line traversing two points, for later use in the construction....)

EDIT: it looks like the tick marks are the straight line extensions; if so, it's exceedingly strange that I can use them "for free" (without drawing the line) as, say, guides for the radius of a circle (I can't put the centre there, but I can "end" the circle there), but I can't just have the line itself.

that one threw me too. Keep an eye on the move counter, extending a line doesn't count as a move.

Oh! That makes so much more sense now. Thanks!

Me:

   A Hexagon in 10 moves or less? How does that even...

   oh... OH... neat.

Fun game.

http://www.sciencevsmagic.net/geo/#0A1.1A0.2A0.0L1.2L1.2L0.1...

Arg I think it might be too big for the in original circle challenge. Darn it, how do you do this one?!

http://sciencevsmagic.net/geo/#0A1.1A0.2A0.N.2A0.4A0.5A1.3A0...

Here's how I did it.

Great app and a super achievement for someone who's only been working in JS for 8 months.

Hey, this is neat! One note: Hitting "reset" doesn't immediately reset the move counter; I have to hit "undo" afterward to get it to actually go back to 0.

Good spot! I think I've fixed it now.

Inspiring!

(1) Geometric stained glass windows. Anyone know how to cheaply source/cut coloured glass? Best mechanism for rounded portions of potential framing? I don't mind if it takes awhile to build, just that it sustains the weight and enough wind. Preferably thicker rather than thinner glass.

(2) Might be useful for some 3D printing based crafting projects.

An option to export SVG would be useful (and feasible, given the vector nature of construction).

I got a triangle made inside a circle. Can someone tell me why the triangle in origin circle thing doesn't complete?

http://www.sciencevsmagic.net/geo/#0A1.1A0.0L2.0L1.1L2.1L6.2...

It has to be in a circle of "origin" size, that is the radius of the circle must be the distance between the two starting dots.

Thanks, the phrase "origin circle" did not suggest that meaning to me at all. I thought maybe it meant that it had to be at the origin, but i couldn't figure out where that was.

I'm still stumped. Isn't this an 'origin circle' then? Radius == the pt-pt distance.

http://www.sciencevsmagic.net/geo/#0A1.1A0.2A0.0L2.2L7.4L1.1...

Scratch that - the same thing works if rotated:

http://www.sciencevsmagic.net/geo/#1A0.0A1.2A0.1L5.2L0.0L9.9...

It actually has to be one of the first circles you can draw (a point on the edge and a point on the radius). Not just the same radius.

It's great. I wish I had something like this back in higschool when learning geometry; doing it on paper with the accumulating inaccuracies and no undo option made it all much less fun than this.

I love this! Only complaint is that after playing for a few minutes, my browser's back button is completely worthless. Web is such a hacky place to develop.

Takes me back to high school geometry class. For a while I was carrying a compass and a straight edge /everywhere/. First math class I really enjoyed.

I second the vote for select-able colors. Even though I'm color blind, I think having multiple colors would help keep myself organized while creating.

This is very neat. Because some of the more complicated constructions get very busy, it would be helpful to be able to erase unwanted arcs/lines.

I used the new layer button to accomplish this. It greys out the complications, but the guides from what you've constructed still function.

This is amazingly fun. I'm a little stuck on the pentagon, but I'll keep thinking.

Side note: You should add "Square the Circle" as a super bonus ;)

That's cruel. Use something that can be constructed such as the regular 65537-gon.

That's it, I'm abandoning my lesson plans for today and I'm going to let the kids have a go at these challanges instead. Well done.

Reminds me of kig [ http://edu.kde.org/kig/ ].

So much for getting anything done this morning . . .

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