Oolite Bulletins

jh145 wrote:

I was planning on updating the Scanner Alerting Enhancement to check for escape pods, but I am reluctant to call system.filteredEntities() or similar. Is there a good workaround? I'd like to run the scan every second or so.

What really confuses me is how can a vector be used to define coordinates? Which way is the arrow pointing?

Day wrote:

EDIT2:

What really confuses me is how can a vector be used to define coordinates? Which way is the arrow pointing?

You have to imagine a vector as an arrow from the origin (0, 0, 0) to its coordinates (x, y, z).

Phasted wrote:

Day wrote:

EDIT2:

What really confuses me is how can a vector be used to define coordinates? Which way is the arrow pointing?

You have to imagine a vector as an arrow from the origin (0, 0, 0) to its coordinates (x, y, z).

From the origin... I had that 100% all wrong!

So clearly, my idea is all wet...

Which leaves me with the problem: How do I determine the compass bearing/azimuth (in degrees) to B from A?

Day wrote:

A vector is not really an arrow, this is just an easy geometrical representation. Mathematically, a vector in a n-dimensional system is a group of n values relative to these n dimensions.
For example:
- in 2D, a coordinate can be represented by a vector (x, y) which is a couple of values.
- in 3D, a coordinate can be represented by a vector (x, y, z) which is a triplet of values.
- in 26D, a coordinate can be represented by a vector (a, b, c, ..., z) which is a 26-group of values.

Now, it's really easy too use vectors to represent things in 2D or 3D, so we use them. The math domain is called Vectorial spaces (well, at least in France).
But we use them for things with a lot more dimensions, like the preferences of a user:
- user intensity of preference of character 1 in a game,
- user intensity of preference of character 2 in a game,
- user intensity of preference of character 3 in a game,
- user intensity of preference of character 4 in a game,
- user intensity of preference of character 5 in a game,
- user intensity of preference of character 6 in a game.
Now we represent the intensity of preference for a user as a vector (0, 4, 6, 2, 5, 10).
And do this for all users.
And notice that the users are in groups, visible when representing geometrically all these vectors simultaneously (those liking character 1 not liking the character 3).

And do that for marketing or spam, to identify which people are likely to succumb to product X based on what we already know of them, and what already known similar people (those with near vectors) have succumbed to...

Wildeblood wrote:

Tell more, please.

Day wrote:

Wildeblood wrote:

Tell more, please.

Really? I would have thought to be rather boring.

On which part? The math part, or the usage part?

Day wrote:

Wildeblood wrote:

Tell more, please.

Really? I would have thought to be rather boring.

this._prepareForNextSystem = function(type)
{
  if(type === "galactic") {return;}
  var d, t = System.infoForSystem(galaxyNumber, player.ship.targetSystem);
  function findEconBalance() {}
  function findDistance(sys)
  {
    function findBearing()
    {
      var c = "coordinates", V3D = Vector3D;
      var from = V3D([t[c].x, t[c].y, 0]), North = V3D([0, -1, 0]), to = V3D([sys[c].x, sys[c].y, 0]);
      var adj_c = convertCoordinates(), angle = radToDeg(North.angleTo(adj_c)), bearing = angleToBearing();
      function angleToBearing() {if(from.x > to.x) {return 360 - angle;} else {return angle;}}
      function convertCoordinates() {return V3D([(to.x - from.x), (to.y - from.y), 0]);}
      function radToDeg(rad) {return rad * (180 / Math.PI);}
      log(ns.RLE_IM.name, "Bearing from " + t.name + " to " + sys.name + ":  " + bearing + " degrees.");
    }
    d = t.distanceToSystem(sys);
    findBearing();
  }
  this._cluster = t.systemsInRange(7);
  //this._group = t.systemsInRange(14);
  //this._sector = t.systemsInRange(21);
  //this._quadrant = t.systemsInRange(28);
  this._cluster.forEach(findDistance);

Phasted wrote:

Day wrote:

Wildeblood wrote:

Tell more, please.

Really? I would have thought to be rather boring.

Far from boring... in fact, quite useful. Thanks to your very helpful insight on visualizing vectors and your suggestion about converting the coordinates, I was able to solve my problem... or the first part of it anyway...

Phasted wrote:

Code: Select all

    function findBearing()
    {
      var c = "coordinates", V3D = Vector3D;
      var from = V3D([t[c].x, t[c].y, 0]), North = V3D([0, -1, 0]), to = V3D([sys[c].x, sys[c].y, 0]);
      var adj_c = convertCoordinates(), angle = radToDeg(North.angleTo(adj_c)), bearing = angleToBearing();
      function angleToBearing() {if(from.x > to.x) {return 360 - angle;} else {return angle;}}
      function convertCoordinates() {return V3D([(to.x - from.x), (to.y - from.y), 0]);}
      function radToDeg(rad) {return rad * (180 / Math.PI);}
      log(ns.RLE_IM.name, "Bearing from " + t.name + " to " + sys.name + ":  " + bearing + " degrees.");
    }

Tested and bug-free. Thanks.

function angleToBearing() { return from.x > to.x ? 360 - angle : angle;}

Day wrote:

Is this working, even the exact first time it is called? I'm puzzled at the fact you use functions before declaring them (convertToCoordinates, radToDeg, angleToBearing).

Phasted wrote:

Day wrote:

Is this working, even the exact first time it is called? I'm puzzled at the fact you use functions before declaring them (convertToCoordinates, radToDeg, angleToBearing).

In JavaScript, function definitions are "hoisted" to the top of the enclosing function or code. So, as long as all of the variables are declared and defined BEFORE the function is called, you can put the function definition just about anywhere,,,

This one is tricky. The variables have to be defined in a certain order (c before from and to; from and to before adj_c, etc.) But it works...

var thingie = function() {alert("Hello World!";)}