fix Path animateShow missing z (#2581)

Author: deyihu

packages/maptalks/src/geometry/Path.ts

@@ -193,6 +193,7 @@ export class Path extends Geometry {
             this._animLenSoFar += segLen;
         }
         this._animIdx = i - 1;
+        //is end
         if (this._animIdx >= l - 1) {
             this.setCoordinates(coordinates);
             return coordinates[coordinates.length - 1];
@@ -211,9 +212,12 @@ export class Path extends Geometry {
 
         const c1 = coordinates[idx], c2 = coordinates[idx + 1];
         const cx = c1.x + (c2.x - c1.x) * r,
-            cy = c1.y + (c2.y - c1.y) * r;
+            cy = c1.y + (c2.y - c1.y) * r,
+            cz = (c1.z || 0) + ((c2.z || 0) - (c1.z || 0)) * r;
         this._tempCoord.x = cx;
         this._tempCoord.y = cy;
+        this._tempCoord.z = cz;
+
         // const targetCoord = projection.unproject(lastCoord, this._tempCoord);
         const targetCoord = this._tempCoord;
         const isPolygon = !!this.getShell;

packages/maptalks/test/geometry/LineStringSpec.js

@@ -635,6 +635,34 @@ describe('Geometry.LineString', function () {
             });
             layer.addGeometry(line);
         });
+
+        it('fix missing z,the coordinates should carray z', function (done) {
+            const c1 = map.getCenter();
+            const c2 = c1.add(0.001, 0);
+            c1.z = 10;
+            c2.z = 20;
+            var line = new maptalks.LineString([c1, c2], {
+                symbol: [{
+                    'lineColor': '#1bbc9b',
+                    'lineWidth': 6,
+                    'lineJoin': 'round', //miter, round, bevel
+                    'lineCap': 'round', //butt, round, square
+                    'lineDasharray': null, //dasharray, e.g. [10, 5, 5]
+                    'lineOpacity ': 1
+                }]
+            });
+            layer.addGeometry(line);
+
+            setTimeout(() => {
+                const player = line.animateShow({ duration: 3000 }, ((frame, current) => {
+                    expect(current).to.be.a('object');
+                    expect(current.z).to.be.a('number');
+                    expect(current.z).to.be.within(10, 20);
+                    player.cancel();
+                    done();
+                }));
+            }, 100);
+        });
     });
 
     it('#2167 line draw altitude wall ', function (done) {