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40 lines
1.2 KiB
40 lines
1.2 KiB
3 years ago
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/**
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* @module ol/geom/flat/length
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*/
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/**
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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 {number} Length.
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*/
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export function lineStringLength(flatCoordinates, offset, end, stride) {
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let x1 = flatCoordinates[offset];
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let y1 = flatCoordinates[offset + 1];
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let length = 0;
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for (let i = offset + stride; i < end; i += stride) {
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const x2 = flatCoordinates[i];
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const y2 = flatCoordinates[i + 1];
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length += Math.sqrt((x2 - x1) * (x2 - x1) + (y2 - y1) * (y2 - y1));
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x1 = x2;
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y1 = y2;
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}
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return length;
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}
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/**
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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 {number} Perimeter.
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*/
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export function linearRingLength(flatCoordinates, offset, end, stride) {
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let perimeter = lineStringLength(flatCoordinates, offset, end, stride);
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const dx = flatCoordinates[end - stride] - flatCoordinates[offset];
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const dy = flatCoordinates[end - stride + 1] - flatCoordinates[offset + 1];
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perimeter += Math.sqrt(dx * dx + dy * dy);
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return perimeter;
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}
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