self portrait
webgl
webcam
shader
webcam can't be loaded under unsecure web
http://104.248.51.221:8080/class1/homework/index.html
then i changed webcam to video, it works
http://104.248.51.221:8080/class1/homework/index2.html
http://yn818.itp.io:8080/class1/homework/index2.html
