Fix issue where vignette aspect ratio is different between offscreen and direct rendering
Fix issue where vignette aspect ratio is different between offscreen and direct rendering

NicolasBuecher/Babylon.js,RaananW/Babylon.js,sebavan/Babylon.js,jbousquie/Babylon.js,Kesshi/Babylon.js,sebavan/Babylon.js,BabylonJS/Babylon.js,jbousquie/Babylon.js,Kesshi/Babylon.js,NicolasBuecher/Babylon.js,NicolasBuecher/Babylon.js,sebavan/Babylon.js,BabylonJS/Babylon.js,jbousquie/Babylon.js,RaananW/Babylon.js,BabylonJS/Babylon.js,Kesshi/Babylon.js,RaananW/Babylon.js