Our geometries are mutable, so they can be modified without
creating garbage by changing coordinates in place and calling
setGeometry afterwards. But this also means that we need to
create a deep clone of the coordinates.
Previously, the tests were using eql to make assertions about matching geometries. This is inappropriate for structures with circular references (as with goog.events.EventTarget);
In the typical sequence of parse-transform-render the most efficient place to transform coordinate values is deep within the parser immediately after values have been read (this would avoid a second pass over whatever structure is used to back geometries). To accomplish this transform during parsing, we could add back parser read options to pass the transform function around.
Until then, a transform method on geometries is straightforward to implement. This means we do a second pass through coordinate structures to transform, but this is typically done only once immediately after parsing.
KML and WKT don't specify a winding order, so we write those out in CW/CCW order (for exterior/interior). GML references ISO 19107 that specifies CCW/CW, so we serialize in that winding order.
Having hand generated all this GML data the first time around, I reserve the right to modify it for the tests.
As suggested by @tschaub in #674, geom.pointInPoly is not needed
if we have geom.LinearRing#containsCoordinate. This pull request
also adds tests and documentation on the limitations of the
containsCoordinate method.
I think for now it is ok to keep geometry/topology functions as
simple as possible in ol3. If we decide to not rely on third
party libraries like jsts for topology operations, we can always
refine what we have and e.g. port topology operations over from
ol2.
Previously, a lookup object containing start indexes was also used. This allowed us to remove arrays of vertices and properly update the start indexes for remaining coordinate values. In order to provide callers with stable identifiers and to work with arrays of integers alone, we cannot support a remove method. I think this is worth revisiting. Even if the array length cannot be changed in WebGL, we don't need to also impose the restriction outside. Instead, the WebGL renderer could be notified when array sizes change and update itself accordingly. I think there is more value in providing geometries with stable identifiers.
This common structure is used to store vertices for all geometry types. A slight optimization could be made by creating yet another structure to store point vertices - since these don't need to have a counts array (always 1). Creating a new structure would mean saving memory at the expense of more lib code to transport. The coordinate value lookups are not negatively impacted by using the same structure for points and higher order geometries. Since the first change above goes against my instincts, I'm not making this second change (to add another structure for shared point vertices).
Its not clear that we will be able to leverage the Float64Array. It may also be that the overhead of constructing these small arrays negates any benefit of faster access. And for all coordinate arrays, we'll need arrays that grow/shrink.
