WebGLRenderer: render LineStrip or LinePieces with indexed buffer geometry

src/renderers/WebGLRenderer.js

@@ -2730,7 +2730,7 @@ THREE.WebGLRenderer = function ( parameters ) {
 
 					}
 
-					_gl.drawElements( _gl.LINES, index.array.length, type, 0 ); // 2 bytes per Uint16Array
+					_gl.drawElements( mode, index.array.length, type, 0 ); // 2 bytes per Uint16Array
 
 					_this.info.render.calls ++;
 					_this.info.render.vertices += index.array.length; // not really true, here vertices can be shared
@@ -2756,7 +2756,7 @@ THREE.WebGLRenderer = function ( parameters ) {
 
 						// render indexed lines
 
-						_gl.drawElements( _gl.LINES, offsets[ i ].count, type, offsets[ i ].start * size ); // 2 bytes per Uint16Array
+						_gl.drawElements( mode, offsets[ i ].count, type, offsets[ i ].start * size ); // 2 bytes per Uint16Array
 
 						_this.info.render.calls ++;
 						_this.info.render.vertices += offsets[ i ].count; // not really true, here vertices can be shared