50 lines
1.3 KiB
JavaScript
50 lines
1.3 KiB
JavaScript
goog.provide('ol.geom.flat.straightchunk');
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/**
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* @param {number} maxAngle Maximum acceptable angle delta between segments.
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* @param {Array.<number>} flatCoordinates Flat coordinates.
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* @param {number} offset Offset.
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* @param {number} end End.
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* @param {number} stride Stride.
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* @return {Array.<number>} Start and end of the first suitable chunk of the
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* given `flatCoordinates`.
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*/
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ol.geom.flat.straightchunk.lineString = function(maxAngle, flatCoordinates, offset, end, stride) {
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var chunkStart = offset;
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var chunkEnd = offset;
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var chunkM = 0;
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var m = 0;
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var start = offset;
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var acos, i, m12, m23, x1, y1, x12, y12, x23, y23;
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for (i = offset; i < end; i += stride) {
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var x2 = flatCoordinates[i];
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var y2 = flatCoordinates[i + 1];
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if (x1 !== undefined) {
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x23 = x2 - x1;
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y23 = y2 - y1;
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m23 = Math.sqrt(x23 * x23 + y23 * y23);
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if (x12 !== undefined) {
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m += m12;
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acos = Math.acos((x12 * x23 + y12 * y23) / (m12 * m23));
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if (acos > maxAngle) {
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if (m > chunkM) {
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chunkM = m;
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chunkStart = start;
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chunkEnd = i;
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}
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m = 0;
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start = i - stride;
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}
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}
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m12 = m23;
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x12 = x23;
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y12 = y23;
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}
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x1 = x2;
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y1 = y2;
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}
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m += m23;
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return m > chunkM ? [start, i] : [chunkStart, chunkEnd];
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};
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