- Adding transparency :

We previously used the "trans" parameter in normal sprites to make the clouds transparent. However, when defining an animation, you may want to define the transparency within the animation itself. This is done by adding some other code at the end of the line :
[mcode]
[Begin Action WTF Trans]
10,2,0,0,5      ;Normal sprite
10,2,0,0,5,,A   ;Additive transparency (identical to trans=add)
10,2,0,0,5,,A1   ;Additive transparency with background dimmed to 50% brightness (identical to trans=add1)
10,2,0,0,5,,S   ;Substractive transparency (identical to trans=sub)
[/mcode]
notice the two ",,". These are made because the code between the commas is made to flip the sprites, as we have seen in the precedent paragraph.

If you're using WinMugen or Linux Mugen (but not DOS Mugen), you can also define the transparency better as if you were using "trans = AddAlpha". This is done by using ASxxxDyyy, with "xxx" being the source, and "yyy" the destination, both values being between 0 and 256. If you want to make an animation fade out, you would use a code like this :
[mcode]
[Begin Action 16];Fading Out
16,0, 0,0, 4,,A
...
16,13, 0,0, 4,,A
16,14, 0,0, 4,,A
16,15, 0,0, 4,,AS200D256
16,16, 0,0, 4,,AS160D256
16,17, 0,0, 4,,AS120D256
16,18, 0,0, 4,,AS80D256
16,19, 0,0, 4,,AS40D256
16,-1, 0,0, 40,,AS40D256
[/mcode]
The last line means that you're using and empty sprite.