javascript - Three.js Mirror reflection issue -

i using three.js mirror class reflect ring mesh in scene , reflection has strange artifacts in it.

this relevant code:

verticalmirror = new three.mirror( renderer, camera, { clipbias: 0.003, texturewidth: 512, textureheight: 512, color:0xdddddd} );  var verticalmirrormesh = new three.mesh( new three.planebuffergeometry( 300, 300 ), verticalmirror.material ); verticalmirrormesh.add( verticalmirror ); verticalmirrormesh.position.y = 0; verticalmirrormesh.position.z = -10; editor.scene.add( verticalmirrormesh );  function render () {    renderer.clear();    verticalmirror.render();    renderer.render(scene, camera); } 

in center reflection looks more or less ok, on sides it's stretched edges of mirror. please see images below.

i've researched other posts on mirroring in three.js , seem follow suggesting. still doing wrong? advice appreciated.

thank you, anton.