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Use binary search in ol.geom.flat.lineStringCoordinateAtM

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This commit is contained in:
Tom Payne
2014-02-25 19:13:38 +01:00
parent 1c21316d20
commit c0f9b1de19
1 changed files with 28 additions and 18 deletions
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46
src/ol/geom/flatgeom.js
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@@ -341,26 +341,36 @@ ol.geom.flat.lineStringCoordinateAtM =
}
}
// FIXME use O(1) search
for (offset += stride; offset < end; offset += stride) {
var m1 = flatCoordinates[offset + stride - 1];
if (m < m1) {
var m0 = flatCoordinates[offset - 1];
var t = (m - m0) / (m1 - m0);
coordinate = [];
var i;
for (i = 0; i < stride - 1; ++i) {
coordinate.push((1 - t) * flatCoordinates[offset - stride + i] +
t * flatCoordinates[offset + i]);
}
coordinate.push(m);
goog.asserts.assert(coordinate.length == stride);
return coordinate;
} else if (m == m1) {
return flatCoordinates.slice(offset, offset + stride);
if (m == flatCoordinates[offset + stride - 1]) {
return flatCoordinates.slice(offset, offset + stride);
}
var lo = offset / stride;
var hi = end / stride;
while (lo < hi) {
var mid = (lo + hi) >> 1;
if (m < flatCoordinates[(mid + 1) * stride - 1]) {
hi = mid;
} else {
lo = mid + 1;
}
}
goog.asserts.fail();
return null;
var m0 = flatCoordinates[lo * stride - 1];
if (m == m0) {
return flatCoordinates.slice((lo - 1) * stride, (lo - 1) * stride + stride);
}
var m1 = flatCoordinates[(lo + 1) * stride - 1];
goog.asserts.assert(m0 < m);
goog.asserts.assert(m <= m1);
var t = (m - m0) / (m1 - m0);
coordinate = [];
var i;
for (i = 0; i < stride - 1; ++i) {
coordinate.push((1 - t) * flatCoordinates[(lo - 1) * stride + i] +
t * flatCoordinates[lo * stride + i]);
}
coordinate.push(m);
goog.asserts.assert(coordinate.length == stride);
return coordinate;
};