Alpha masking goodness in Flash Player 8
A while back when we started implementing the cache as bitmap functionality in the Flash Player I was tasked to make masks work with it. The initial implementation was simply doing edge based masking and behaved like you think Flash should behave. What is edge based masking? It means that the vectors of the mask and masquee are intersected before they are drawn to obtain the cutout which is a vector shape in itself. That's why alpha masking was not easily possible technically in previous Flash Player versions since there is no pixel level interaction at this level between mask and masquee. Now, and so it happened a few times during this release, I stared at the code and told myself: Alpha masks are now trivial to implement with the bitmap caching! A couple of hours later it was done.

So how do you make it work? Mask and masquee have to be both movie clips and need to have the cacheAsBitmap flag set. Now you can simply do a setMask() and that is it. The only sad part about this is that due to time constraints there was simply no time to add this to the authoring tool for easy access. But, the good news is that designers will only need one line of code to make it work. Hence the example I posted here. Softwipe goodness! You can't tell me that this is not beautiful! This movie has only one line of code, the rest are simple tweens on the timeline:

mc1.setMask(mc2)

eddy444, Так и после компиляции не работает. Каким образом маску накладывать?

А чем тебе не нравится описанный вариант с одной строкой кода?
Вместо того чтобы цеплять слою "физическую" маску просто напиши слоем выше в пустом кадре одну строку. Чем неудобно?

градиен хочется повернуть подвигать маску и т.д. и т.п.