Linearly interpolate extra dimensions in ol.geom.flat.closestPoint

src/ol/geom/closestgeom.js

@@ -95,14 +95,16 @@ ol.geom.closest.getClosestPoint = function(flatCoordinates, offset, end, stride,
   if (offset == end) {
     return minSquaredDistance;
   }
-  var squaredDistance;
+  var i, 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];
+      for (i = 0; i < stride; ++i) {
+        closestPoint[i] = flatCoordinates[offset + i];
+      }
+      closestPoint.length = stride;
       return squaredDistance;
     } else {
       return minSquaredDistance;
@@ -112,15 +114,16 @@ ol.geom.closest.getClosestPoint = function(flatCoordinates, offset, end, stride,
   var tmpPoint = goog.isDef(opt_tmpPoint) ? opt_tmpPoint : [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], tmpPoint);
+    ol.geom.flat.closestPoint(
+        flatCoordinates, index - stride, index, stride, x, y, tmpPoint);
     squaredDistance = ol.geom.flat.squaredDistance(
         x, y, tmpPoint[0], tmpPoint[1]);
     if (squaredDistance < minSquaredDistance) {
       minSquaredDistance = squaredDistance;
-      closestPoint[0] = tmpPoint[0];
-      closestPoint[1] = tmpPoint[1];
+      for (i = 0; i < stride; ++i) {
+        closestPoint[i] = tmpPoint[i];
+      }
+      closestPoint.length = stride;
       index += stride;
     } else {
       // Skip ahead multiple points, because we know that all the skipped
@@ -140,15 +143,16 @@ ol.geom.closest.getClosestPoint = function(flatCoordinates, offset, end, stride,
   }
   if (isRing) {
     // Check the closing segment.
-    ol.geom.flat.closestPoint(x, y,
-        flatCoordinates[end - stride], flatCoordinates[end - stride + 1],
-        flatCoordinates[offset], flatCoordinates[offset + 1], tmpPoint);
+    ol.geom.flat.closestPoint(
+        flatCoordinates, end - stride, offset, stride, x, y, tmpPoint);
     squaredDistance = ol.geom.flat.squaredDistance(
         x, y, tmpPoint[0], tmpPoint[1]);
     if (squaredDistance < minSquaredDistance) {
       minSquaredDistance = squaredDistance;
-      closestPoint[0] = tmpPoint[0];
-      closestPoint[1] = tmpPoint[1];
+      for (i = 0; i < stride; ++i) {
+        closestPoint[i] = tmpPoint[i];
+      }
+      closestPoint.length = stride;
     }
   }
   return minSquaredDistance;

src/ol/geom/flatgeom.js

@@ -2,39 +2,50 @@ goog.provide('ol.geom.flat');
 
 goog.require('goog.array');
 goog.require('goog.asserts');
+goog.require('goog.math');
 goog.require('goog.vec.Mat4');
 
 
 /**
- * Returns the point on the line segment (x1, y1) to (x2, y2) that is closest to
- * the point (x, y).
+ * Returns the point on the 2D line segment flatCoordinates[offset1] to
+ * flatCoordinates[offset2] that is closest to the point (x, y).  Extra
+ * dimensions are linearly interpolated.
+ * @param {Array.<number>} flatCoordinates Flat coordinates.
+ * @param {number} offset1 Offset 1.
+ * @param {number} offset2 Offset 2.
+ * @param {number} stride Stride.
  * @param {number} x X.
  * @param {number} y Y.
- * @param {number} x1 X1.
- * @param {number} y1 Y1.
- * @param {number} x2 X2.
- * @param {number} y2 Y2.
  * @param {Array.<number>} closestPoint Closest point.
  */
-ol.geom.flat.closestPoint = function(x, y, x1, y1, x2, y2, closestPoint) {
-  var dx = x2 - x1;
-  var dy = y2 - y1;
+ol.geom.flat.closestPoint =
+    function(flatCoordinates, offset1, offset2, stride, x, y, closestPoint) {
+  var x1 = flatCoordinates[offset1];
+  var y1 = flatCoordinates[offset1 + 1];
+  var dx = flatCoordinates[offset2] - x1;
+  var dy = flatCoordinates[offset2 + 1] - y1;
+  var i, offset;
   if (dx === 0 && dy === 0) {
-    closestPoint[0] = x1;
-    closestPoint[1] = y1;
+    offset = offset1;
   } else {
     var t = ((x - x1) * dx + (y - y1) * dy) / (dx * dx + dy * dy);
     if (t > 1) {
-      closestPoint[0] = x2;
-      closestPoint[1] = y2;
+      offset = offset2;
     } else if (t > 0) {
-      closestPoint[0] = x1 + dx * t;
-      closestPoint[1] = y1 + dy * t;
+      for (i = 0; i < stride; ++i) {
+        closestPoint[i] = goog.math.lerp(flatCoordinates[offset1 + i],
+            flatCoordinates[offset2 + i], t);
+      }
+      closestPoint.length = stride;
+      return;
     } else {
-      closestPoint[0] = x1;
-      closestPoint[1] = y1;
+      offset = offset1;
     }
   }
+  for (i = 0; i < stride; ++i) {
+    closestPoint[i] = flatCoordinates[offset + i];
+  }
+  closestPoint.length = stride;
 };
 
 

test/spec/ol/geom/closestgeom.test.js

@@ -113,6 +113,33 @@ describe('ol.geom.closest', function() {
 
   });
 
+  describe('with multi-dimensional data', function() {
+
+    var flatCoordinates = [0, 0, 10, -10, 2, 2, 30, -20];
+    var stride = 4;
+
+    describe('ol.geom.closest.getClosestPoint', function() {
+
+      it('interpolates M coordinates', function() {
+        var maxDelta = Math.sqrt(ol.geom.closest.getMaxSquaredDelta(
+            flatCoordinates, 0, flatCoordinates.length, stride, 0));
+        expect(maxDelta).to.roughlyEqual(Math.sqrt(8), 1e-9);
+        var closestPoint = [NaN, NaN];
+        expect(ol.geom.closest.getClosestPoint(
+            flatCoordinates, 0, flatCoordinates.length, stride,
+            maxDelta, false, 1, 1, closestPoint, Infinity)).
+            to.roughlyEqual(0, 1e-9);
+        expect(closestPoint).to.have.length(stride);
+        expect(closestPoint[0]).to.be(1);
+        expect(closestPoint[1]).to.be(1);
+        expect(closestPoint[2]).to.be(20);
+        expect(closestPoint[3]).to.be(-15);
+      });
+
+    });
+
+  });
+
 });