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Move ol.geom.flatLinearRingIsClockwise into ol.geom.flat

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This commit is contained in:
Tom Payne
2013-11-12 12:44:13 +01:00
parent 857c28a88b
commit 0aa0cfd54b
3 changed files with 29 additions and 29 deletions
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25
src/ol/geom/flatgeom.js
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@@ -173,6 +173,31 @@ ol.geom.flat.linearRingContainsXY =
};
/**
* @param {Array.<number>} flatCoordinates Flat coordinates.
* @param {number} offset Offset.
* @param {number} end End.
* @param {number} stride Stride.
* @return {boolean} Is clockwise.
*/
ol.geom.flat.linearRingIsClockwise =
function(flatCoordinates, offset, end, stride) {
// http://tinyurl.com/clockwise-method
// https://github.com/OSGeo/gdal/blob/trunk/gdal/ogr/ogrlinearring.cpp
var edge = 0;
var x1 = flatCoordinates[end - stride];
var y1 = flatCoordinates[end - stride + 1];
for (; offset < end; offset += stride) {
var x2 = flatCoordinates[offset];
var y2 = flatCoordinates[offset + 1];
edge += (x2 - x1) * (y2 + y1);
x1 = x2;
y1 = y2;
}
return edge > 0;
};
/**
* @param {Array.<number>} flatCoordinates Flat coordinates.
* @param {number} offset Offset.