Curveness can be negative value

src/chart/graph/circularLayoutHelper.js

@@ -40,7 +40,7 @@ define(function (require) {
             var cp1;
             var x12 = (p1[0] + p2[0]) / 2;
             var y12 = (p1[1] + p2[1]) / 2;
-            if (curveness > 0) {
+            if (+curveness) {
                 curveness *= 3;
                 cp1 = [
                     cx * curveness + x12 * (1 - curveness),

src/chart/graph/forceLayout.js

@@ -89,7 +89,7 @@ define(function (require) {
                             points[1] = points[1] || [];
                             vec2.copy(points[0], p1);
                             vec2.copy(points[1], p2);
-                            if (e.curveness > 0) {
+                            if (+e.curveness) {
                                 points[2] = [
                                     (p1[0] + p2[0]) / 2 - (p1[1] - p2[1]) * e.curveness,
                                     (p1[1] + p2[1]) / 2 - (p2[0] - p1[0]) * e.curveness

src/chart/graph/simpleLayoutEdge.js

@@ -6,7 +6,7 @@ define(function (require) {
             var p1 = vec2.clone(edge.node1.getLayout());
             var p2 = vec2.clone(edge.node2.getLayout());
             var points = [p1, p2];
-            if (curveness > 0) {
+            if (+curveness) {
                 points.push([
                     (p1[0] + p2[0]) / 2 - (p1[1] - p2[1]) * curveness,
                     (p1[1] + p2[1]) / 2 - (p2[0] - p1[0]) * curveness

src/chart/lines/linesLayout.js

@@ -29,7 +29,7 @@ define(function (require) {
                     pts[1] = coordSys.dataToPoint(coords[1]);
 
                     var curveness = itemModel.get('lineStyle.normal.curveness');
-                    if (curveness > 0) {
+                    if (+curveness) {
                         pts[2] = [
                             (pts[0][0] + pts[1][0]) / 2 - (pts[0][1] - pts[1][1]) * curveness,
                             (pts[0][1] + pts[1][1]) / 2 - (pts[1][0] - pts[0][0]) * curveness