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The shared vertices structure now works with integer arrays only

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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).
This commit is contained in:
Tim Schaub
2013-03-05 11:40:08 +01:00
parent 54d8d45fc9
commit a968a5ca66
5 changed files with 95 additions and 120 deletions
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97
test/spec/ol/geom/sharedvertices.test.js
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@@ -43,8 +43,24 @@ describe('ol.geom.SharedVertices', function() {
it('returns an identifier for coordinate access', function() {
var vertices = new ol.geom.SharedVertices();
var id = vertices.add([[1, 2], [3, 4]]);
expect(typeof id).toBe('string');
expect(typeof id).toBe('number');
});
it('returns the index of the added vertices', function() {
var vertices = new ol.geom.SharedVertices();
var first = vertices.add([[1, 2]]);
var second = vertices.add([[3, 4], [5, 6]]);
var third = vertices.add([[7, 8], [9, 10], [11, 12]]);
expect(vertices.coordinates).toEqual(
[1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12]);
expect(first).toBe(0);
expect(second).toBe(1);
expect(third).toBe(2);
});
});
describe('#get()', function() {
@@ -98,6 +114,17 @@ describe('ol.geom.SharedVertices', function() {
});
});
describe('#getCounts()', function() {
it('returns the counts array', function() {
var vertices = new ol.geom.SharedVertices();
var first = vertices.add([[2, 3], [3, 4], [4, 5]]);
var second = vertices.add([[5, 6], [6, 6]]);
var third = vertices.add([[7, 8]]);
expect(vertices.getCounts()).toEqual([3, 2, 1]);
});
});
describe('#getDimension()', function() {
it('returns 2 by default', function() {
var vertices = new ol.geom.SharedVertices();
@@ -123,57 +150,43 @@ describe('ol.geom.SharedVertices', function() {
});
describe('#getStart()', function() {
it('returns the start of the identified vertex array', function() {
it('returns the start index of an identified vertex array', function() {
var vertices = new ol.geom.SharedVertices();
var first = vertices.add([[1, 2]]);
var second = vertices.add([[3, 4], [5, 6]]);
var third = vertices.add([[7, 8], [9, 10], [11, 12]]);
var first = vertices.add([[2, 3], [4, 5], [6, 7]]);
var second = vertices.add([[8, 9], [10, 11]]);
var third = vertices.add([[12, 13]]);
expect(vertices.coordinates).toEqual(
[1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12]);
[2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13]);
// 0 1 2 3 4 5 6 7 8 9 10 11
expect(vertices.getStart(first)).toBe(0);
expect(vertices.getStart(second)).toBe(2);
expect(vertices.getStart(third)).toBe(6);
expect(vertices.getStart(second)).toBe(6);
expect(vertices.getStart(third)).toBe(10);
});
});
describe('#remove()', function() {
it('removes a vertex array', function() {
describe('#getStarts()', function() {
it('returns the counts array', function() {
var vertices = new ol.geom.SharedVertices();
var first = vertices.add([[2, 3], [3, 4], [4, 5]]);
var second = vertices.add([[5, 6], [6, 6]]);
var third = vertices.add([[7, 8]]);
expect(vertices.getStarts()).toEqual([0, 6, 10]);
});
});
describe('#coordinates', function() {
it('is a flat array of all coordinate values', function() {
var vertices = new ol.geom.SharedVertices();
var first = vertices.add([[1, 2], [3, 4]]);
var second = vertices.add([[5, 6]]);
var third = vertices.add([[7, 8], [9, 10], [11, 12]]);
expect(vertices.remove(second)).toEqual([[5, 6]]);
expect(vertices.coordinates).toEqual([1, 2, 3, 4, 7, 8, 9, 10, 11, 12]);
expect(vertices.remove(first)).toEqual([[1, 2], [3, 4]]);
expect(vertices.coordinates).toEqual([7, 8, 9, 10, 11, 12]);
expect(vertices.remove(third)).toEqual([[7, 8], [9, 10], [11, 12]]);
expect(vertices.coordinates).toEqual([]);
expect(vertices.coordinates).toEqual(
[1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12]);
});
it('adjusts returned vertices by offset', function() {
var vertices = new ol.geom.SharedVertices({offset: [10, 20]});
var first = vertices.add([[1, 2]]);
var second = vertices.add([[3, 4]]);
var third = vertices.add([[5, 6]]);
expect(vertices.remove(second)).toEqual([[3, 4]]);
expect(vertices.coordinates).toEqual([-9, -18, -5, -14]);
expect(vertices.remove(third)).toEqual([[5, 6]]);
expect(vertices.coordinates).toEqual([-9, -18]);
expect(vertices.remove(first)).toEqual([[1, 2]]);
expect(vertices.coordinates).toEqual([]);
});
});
describe('#coordinates', function() {
it('is not reassigned', function() {
var vertices = new ol.geom.SharedVertices();
var first = vertices.add([[1, 2], [3, 4]]);
@@ -181,12 +194,6 @@ describe('ol.geom.SharedVertices', function() {
var second = vertices.add([[5, 6]]);
expect(vertices.coordinates).toBe(coordinates);
vertices.remove(first);
expect(vertices.coordinates).toBe(coordinates);
vertices.remove(second);
expect(vertices.coordinates).toBe(coordinates);
});
});