On Dec 28, 11:10 am, donb <[email protected]> wrote:
> How exactly does one DO that so it is acceptable to GPolygon()? I
> swapped out an array of GLatLng with an array like this:
>
> [{"x":"-85.9375839233398440","y":"39.9271392822265630"},
> {"x":"-85.9373779296875000"},"y":"39.9264373779296870"]
The above looks wrong to me.
1. I would expect the anonymous objects to look like:
{x: -85.9375839233398440, y:39.9271392822265630}
(unless you really like converting the strings to floats)
2. The last/second entry is different (typo? which is why a link
would be better...)
-- Larry
>
> (this is shortened to two points for illustration purposes) in my call
> to GPolygon() and I get nothing at all, despite it working perfectly
> (although slowly) with an array of GLatLng.
>
> don
>
> On Nov 26, 8:05 pm, bratliff <[email protected]> wrote:
>
> > On Nov 26, 10:30 pm, "Michael Geary" <[email protected]> wrote:
>
> > Thanks Mike,
>
> > > GPolygon goes through multiple function calls for every point. You have to
> > > create a GLatLng for each point, ang GPolygon converts each lat/lng to a
> > > pixel coordinate by going through quite a bit of general purpose code.
>
> > It baffles me why people use an array of [new GLatLng(Lat,Lon)]
> > objects instead of an array of [{x:Lon,y:Lat}] objects to build a
> > GPoly object. The speed advantage of GPoly.fromEncoded() vanishes
> > with the later approach.
>
> > > PolyGonzo uses a tight inner loop for the points within a single polygon,
> > > with separate inner loops for IE (generating VML directly) and other
> > > browsers (using Canvas). It makes no JavaScript function calls in these
> > > inner loops, and precalculates as much of the coordinate conversion as
> > > possible outside the inner loop. This conversion is hard coded to use
> > > Mercator at the moment.
>
> > > In addition, all of the variables used in the inner loop are local
> > > variables. There's an eachShape() function in polygonzo.js that has a
> > > surprisingly long list of function parameters. These parameters are there
> > > so
> > > that the references to them are truly local variables. This saves on name
> > > lookups in the inner loop.
>
> > > Here's the innermost loop for IE:
>
> > > for( var iCoord = -1, coord; coord = coords[++iCoord]; ) {
> > > vml[iVml++] = round( coord[0] * 10 );
> > > vml[iVml++] = ',';
> > > vml[iVml++] = round( coord[1] * 10 );
> > > vml[iVml++] = ' l ';
> > > }
>
> > I might have joined elements in the outer loop but concatenated
> > elements in the inner loop. I am surprised four elements incur much
> > penalty.
>
> > Concatenation degrades for long strings exceeding their allocated
> > space.
>
> > str+=round( coord[0] * 10 );
> > str+=',';
> > str+=round( coord[1] * 10 );
> > str+=' l ';
>
> > is slow but
>
> > str[i++]=round( coord[0] * 10 )+','+round( coord[1] * 10 )+' l ';
>
> > ought to be fast.
>
> > The conversion from float to string is done automatically.
>
> > Is your own "round" function (interpreted) more efficient than the
> > built-in "Math.round" function (compiled) ?
>
> > > The use of "vml[iVml++] = ...." in the IE version is itself one of the
> > > optimizations. It's quite a bit faster than the "vml.push(...);" that I
> > > would prefer to use.
>
> > Interesting. I like to do the same thing using the loop counter for
> > an index but it is simply dumb luck.
>
> > > > For my own JS enlightenment, I am not sure I understand the
> > > > purpose of the unnamed / anonymous "()" function. Is it to
> > > > keep clutter out of the global namespace ? I believe Google
> > > > is using a similar trick with their classic loader. Do you
> > > > anticipate a conflict ?
>
> > > Yes, that's precisely what it's for - to create a local namespace. The
> > > particular form that I used in polymap.js and testmap.js is popular in
> > > jQuery code:
>
> > I have been looking for a way to avoid namespace pollution. I was
> > afraid to redefine the "()" function. Google's "main.js" already uses
> > it.- Hide quoted text -
>
> > - Show quoted text -
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