# Flash Game, erase or add

**URL:** <https://forum.kirupa.com/t/flash-game-erase-or-add/285042>\
**Category:** flash\
**Created:** [March 26, 2009, 2:01pm UTC](https://forum.kirupa.com/t/flash-game-erase-or-add/285042 "2009-03-26T14:01:53Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![jnsjohansson](https://avatars.discourse-cdn.com/v4/letter/j/94ad74/32.png) [@jnsjohansson](https://forum.kirupa.com/u/jnsjohansson)\
**Post date:** [March 26, 2009, 2:01pm UTC](https://forum.kirupa.com/t/flash-game-erase-or-add/285042/1 "2009-03-26T14:01:53Z")

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Yoyo, allright I’m working on a big project right now and I’m a bit puzzled about the logic of the coding.

Basically you have 2 bitmaps, and you erase parts of the top to reveal the bottom.

I could achieve the same effect by drawing the bottom bitmap over the top bitmap.

So, either I erase parts of the top. Or I paint parts of the bottom on the top, making the illusion i “erase”.

Which would be best, coding-wise, performance-wise etc. which would give me the most flexibility in terms of “seeing where i erased”, hitTests etc.