nginx开启.b3dm压缩

开启.b3dm压缩。可优化cesium加载模型卡慢问题。

方式：

appl

        gzip  on;

        gzip_min_length 1k;

        gzip_buffers 4 16k;

        gzip_comp_level 3;

        # gzip_types text/plain text/css application/xml application/javascript application/x-javascript text/javascript;

   gzip_types text/plain application/x-javascript text/css text/javascript application/x-httpd-php image/jpeg image/gif image/png application/octet-stream;

# application/octet-stream开启b3dm文件压缩