html5 canvas漫天飞雪动画效果代码基于html5 canvas制作的漫天飞雪动画效果代码，很棒的下雪效果代码。蓝色天空背景，白色的雪花飘落布满整个网页。-html5 canvas sky snow animation code based on html5 canvas sky snow animation production code, great snow effect of the code. Blue sky background with white snowflakes