Add ol.geom.closest

src/ol/geom/closestgeom.js

@@ -0,0 +1,194 @@
+// FIXME find better names for these functions
+
+goog.provide('ol.geom.closest');
+
+goog.require('goog.asserts');
+goog.require('ol.geom.flat');
+
+
+/**
+ * @param {Array.<number>} flatCoordinates Flat coordinates.
+ * @param {number} offset Offset.
+ * @param {number} end End.
+ * @param {number} stride Stride.
+ * @param {number} maxSquaredDelta Max squared delta.
+ * @return {number} Max squared delta.
+ */
+ol.geom.closest.getMaxSquaredDelta =
+    function(flatCoordinates, offset, end, stride, maxSquaredDelta) {
+  var x1 = flatCoordinates[offset];
+  var y1 = flatCoordinates[offset + 1];
+  for (offset += stride; offset < end; offset += stride) {
+    var x2 = flatCoordinates[offset];
+    var y2 = flatCoordinates[offset + 1];
+    var squaredDelta = ol.geom.flat.squaredDistance(x1, y1, x2, y2);
+    if (squaredDelta > maxSquaredDelta) {
+      maxSquaredDelta = squaredDelta;
+    }
+    x1 = x2;
+    y1 = y2;
+  }
+  return maxSquaredDelta;
+};
+
+
+/**
+ * @param {Array.<number>} flatCoordinates Flat coordinates.
+ * @param {number} offset Offset.
+ * @param {Array.<number>} ends Ends.
+ * @param {number} stride Stride.
+ * @param {number} maxSquaredDelta Max squared delta.
+ * @return {number} Max squared delta.
+ */
+ol.geom.closest.getsMaxSquaredDelta =
+    function(flatCoordinates, offset, ends, stride, maxSquaredDelta) {
+  var i, ii;
+  for (i = 0, ii = ends.length; i < ii; ++i) {
+    var end = ends[i];
+    maxSquaredDelta = ol.geom.closest.getMaxSquaredDelta(
+        flatCoordinates, offset, end, stride, maxSquaredDelta);
+    offset = end;
+  }
+  return maxSquaredDelta;
+};
+
+
+/**
+ * @param {Array.<number>} flatCoordinates Flat coordinates.
+ * @param {number} offset Offset.
+ * @param {Array.<Array.<number>>} endss Endss.
+ * @param {number} stride Stride.
+ * @param {number} maxSquaredDelta Max squared delta.
+ * @return {number} Max squared delta.
+ */
+ol.geom.closest.getssMaxSquaredDelta =
+    function(flatCoordinates, offset, endss, stride, maxSquaredDelta) {
+  var i, ii;
+  for (i = 0, ii = endss.length; i < ii; ++i) {
+    var ends = endss[i];
+    maxSquaredDelta = ol.geom.closest.getsMaxSquaredDelta(
+        flatCoordinates, offset, ends, stride, maxSquaredDelta);
+    offset = ends[ends.length - 1];
+  }
+  return maxSquaredDelta;
+};
+
+
+/**
+ * @param {Array.<number>} flatCoordinates Flat coordinates.
+ * @param {number} offset Offset.
+ * @param {number} end End.
+ * @param {number} stride Stride.
+ * @param {number} maxDelta Max delta.
+ * @param {boolean} isRing Is ring.
+ * @param {number} x X.
+ * @param {number} y Y.
+ * @param {Array.<number>} closestPoint Closest point.
+ * @param {number} minSquaredDistance Minimum squared distance.
+ * @return {number} Minimum squared distance.
+ */
+ol.geom.closest.getClosestPoint = function(flatCoordinates, offset, end, stride,
+    maxDelta, isRing, x, y, closestPoint, minSquaredDistance) {
+  if (offset == end) {
+    return minSquaredDistance;
+  }
+  var squaredDistance;
+  if (maxDelta === 0) {
+    // All points are identical, so just test the first point.
+    squaredDistance = ol.geom.flat.squaredDistance(
+        x, y, flatCoordinates[offset], flatCoordinates[offset + 1]);
+    if (squaredDistance < minSquaredDistance) {
+      closestPoint[0] = flatCoordinates[offset];
+      closestPoint[1] = flatCoordinates[offset + 1];
+      return squaredDistance;
+    } else {
+      return minSquaredDistance;
+    }
+  }
+  goog.asserts.assert(maxDelta > 0);
+  var point = [NaN, NaN];
+  var index = offset + stride;
+  while (index < end) {
+    ol.geom.flat.closestPoint(x, y,
+        flatCoordinates[index - stride], flatCoordinates[index - stride + 1],
+        flatCoordinates[index], flatCoordinates[index + 1], point);
+    squaredDistance = ol.geom.flat.squaredDistance(x, y, point[0], point[1]);
+    if (squaredDistance < minSquaredDistance) {
+      minSquaredDistance = squaredDistance;
+      closestPoint[0] = point[0];
+      closestPoint[1] = point[1];
+      index += stride;
+    } else {
+      index += stride * Math.max(
+          ((Math.sqrt(squaredDistance) -
+            Math.sqrt(minSquaredDistance)) / maxDelta) | 0, 1);
+    }
+  }
+  if (isRing) {
+    // check the closing segment
+    ol.geom.flat.closestPoint(x, y,
+        flatCoordinates[end - stride], flatCoordinates[end - stride + 1],
+        flatCoordinates[offset], flatCoordinates[offset + 1], point);
+    squaredDistance = ol.geom.flat.squaredDistance(x, y, point[0], point[1]);
+    if (squaredDistance < minSquaredDistance) {
+      minSquaredDistance = squaredDistance;
+      closestPoint[0] = point[0];
+      closestPoint[1] = point[1];
+    }
+  }
+  return minSquaredDistance;
+};
+
+
+/**
+ * @param {Array.<number>} flatCoordinates Flat coordinates.
+ * @param {number} offset Offset.
+ * @param {Array.<number>} ends Ends.
+ * @param {number} stride Stride.
+ * @param {number} maxDelta Max delta.
+ * @param {boolean} isRing Is ring.
+ * @param {number} x X.
+ * @param {number} y Y.
+ * @param {Array.<number>} closestPoint Closest point.
+ * @param {number} minSquaredDistance Minimum squared distance.
+ * @return {number} Minimum squared distance.
+ */
+ol.geom.closest.getsClosestPoint = function(flatCoordinates, offset, ends,
+    stride, maxDelta, isRing, x, y, closestPoint, minSquaredDistance) {
+  var i, ii;
+  for (i = 0, ii = ends.length; i < ii; ++i) {
+    var end = ends[i];
+    minSquaredDistance = ol.geom.closest.getClosestPoint(
+        flatCoordinates, offset, end, stride,
+        maxDelta, isRing, x, y, closestPoint, minSquaredDistance);
+    offset = end;
+  }
+  return minSquaredDistance;
+};
+
+
+/**
+ * @param {Array.<number>} flatCoordinates Flat coordinates.
+ * @param {number} offset Offset.
+ * @param {Array.<Array.<number>>} endss Endss.
+ * @param {number} stride Stride.
+ * @param {number} maxDelta Max delta.
+ * @param {boolean} isRing Is ring.
+ * @param {number} x X.
+ * @param {number} y Y.
+ * @param {Array.<number>} closestPoint Closest point.
+ * @param {number} minSquaredDistance Minimum squared distance.
+ * @return {number} Minimum squared distance.
+ */
+ol.geom.closest.getssClosestPoint = function(flatCoordinates, offset, endss,
+    stride, maxDelta, isRing, x, y, closestPoint, minSquaredDistance) {
+  var i, ii;
+  for (i = 0, ii = endss.length; i < ii; ++i) {
+    var ends = endss[i];
+    minSquaredDistance = ol.geom.closest.getsClosestPoint(
+        flatCoordinates, offset, ends, stride,
+        maxDelta, isRing, x, y, closestPoint, minSquaredDistance);
+    offset = ends[ends.length - 1];
+  }
+  return minSquaredDistance;
+};