可能楼主没注意看,snow system是用的snowflake.dds,里面还有一个说明文件
The snowflake.dds was created by loading a plain white bitmap image "block.bmp"
into the DX Tex tool. Then we loaded snowball.bmp into its alpha channel. This
results the snow flake (provided alpha blending is enabled) to be a round white ball.
The black image border will not be displayed.