[threejs] Don't mark buffer objects for an update if they are zero length. Fixes #1345.

spine-ts/build/spine-all.js

@@ -9865,11 +9865,11 @@ var spine;
 				this.indicesLength += indicesLength;
 			};
 			MeshBatcher.prototype.end = function () {
-				this.vertexBuffer.needsUpdate = true;
+				this.vertexBuffer.needsUpdate = this.verticesLength > 0;
 				this.vertexBuffer.updateRange.offset = 0;
 				this.vertexBuffer.updateRange.count = this.verticesLength;
 				var geo = this.geometry;
-				geo.getIndex().needsUpdate = true;
+				geo.getIndex().needsUpdate = this.indicesLength > 0;
 				geo.getIndex().updateRange.offset = 0;
 				geo.getIndex().updateRange.count = this.indicesLength;
 				geo.drawRange.start = 0;

spine-ts/build/spine-threejs.js

@@ -6995,11 +6995,11 @@ var spine;
 				this.indicesLength += indicesLength;
 			};
 			MeshBatcher.prototype.end = function () {
-				this.vertexBuffer.needsUpdate = true;
+				this.vertexBuffer.needsUpdate = this.verticesLength > 0;
 				this.vertexBuffer.updateRange.offset = 0;
 				this.vertexBuffer.updateRange.count = this.verticesLength;
 				var geo = this.geometry;
-				geo.getIndex().needsUpdate = true;
+				geo.getIndex().needsUpdate = this.indicesLength > 0;
 				geo.getIndex().updateRange.offset = 0;
 				geo.getIndex().updateRange.count = this.indicesLength;
 				geo.drawRange.start = 0;

spine-ts/threejs/src/MeshBatcher.ts

@@ -98,11 +98,11 @@ module spine.threejs {
 		}
 
 		end () {
-			this.vertexBuffer.needsUpdate = true;
+			this.vertexBuffer.needsUpdate = this.verticesLength > 0;
 			this.vertexBuffer.updateRange.offset = 0;
 			this.vertexBuffer.updateRange.count = this.verticesLength;
 			let geo = (<THREE.BufferGeometry>this.geometry);
-			geo.getIndex().needsUpdate = true;
+			geo.getIndex().needsUpdate = this.indicesLength > 0;
 			geo.getIndex().updateRange.offset = 0;
 			geo.getIndex().updateRange.count = this.indicesLength;
 			geo.drawRange.start = 0;