three.js - Renderer clear color not working : black background instead? -

a picture being worth thausand words :

i have black background replaced fog color (the violet color). here code :

var fogcolor = 0xeab5ef  //...  renderer = new three.webglrenderer(); renderer.setclearcolor(fogcolor); element = renderer.domelement; container = glframe; container.appendchild(element); effect = new three.stereoeffect(renderer);  // ... camera = new three.perspectivecamera(90, window.innerwidth / window.innerheight, 0.001, 800);  // ... scene.fog = new three.fogexp2(fogcolor, .0029) 

on dom side, every parent of canvas , has background:transparent

any ideas why happens ?

have tried renderer.setclearcolor(fogcolor,1);?

it might black because alpha value zero