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 falling covered the entire page.