Inspect linestring validity before drawing

src/ol/render/webgl/imagereplay/index.js

@@ -1052,6 +1052,8 @@ ol.render.webgl.LineStringReplay.prototype.drawCoordinates_ = function(flatCoord
   //We rotate those points, thus every point is RTE corrected only once.
   var p0, p1, p2, tempP;
 
+  if (this.isValid_(flatCoordinates, offset, end, stride, closed)) {
+
     for (i = offset, ii = end; i < ii; i += stride) {
 
       var n = numVertices / 7;
@@ -1208,6 +1210,7 @@ ol.render.webgl.LineStringReplay.prototype.drawCoordinates_ = function(flatCoord
       this.indices_[numIndices++] = lastIndex - 1;
       this.indices_[numIndices++] = lastIndex;
     }
+  }
 };
 
 /**
@@ -1249,6 +1252,39 @@ ol.render.webgl.LineStringReplay.prototype.isClosed_ = function(flatCoordinates,
   return false;
 };
 
+/**
+ * Check if the linestring can be drawn (i. e. valid).
+ * @param {Array.<number>} flatCoordinates Flat coordinates.
+ * @param {number} offset Offset.
+ * @param {number} end End.
+ * @param {number} stride Stride.
+ * @param {boolean} closed The linestring is a boundary.
+ * @return {boolean} The linestring can be drawn.
+ * @private
+ */
+ol.render.webgl.LineStringReplay.prototype.isValid_ = function(flatCoordinates, offset, end, stride,
+    closed) {
+  var uniqueCoords = [[flatCoordinates[offset], flatCoordinates[offset + 1]]];
+  var minUnique = closed ? 3 : 2;
+  var i, ii, j;
+  for (i = offset + stride, ii = end; i < ii; i += stride) {
+    var currentCoords = [flatCoordinates[i], flatCoordinates[i + 1]];
+    for (j = 0; j < uniqueCoords.length; ++j) {
+      if (ol.array.equals(currentCoords, uniqueCoords[j])) {
+        j = -1;
+        break;
+      }
+    }
+    if (j > -1) {
+      uniqueCoords.push(currentCoords);
+    }
+    if (uniqueCoords.length >= minUnique) {
+      return true;
+    }
+  }
+  return false;
+};
+
 
 /**
  * @inheritDoc