| Re: [AD] Font drawing bug |
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On 8 Aug 2008, at 19:44, Milan Mimica wrote:
On linux, memset() is usually a much more expensive operation than
malloc(),
because it's at memset() that the memory is actually allocated by
the kernel.
Immaterial in this case, since at some point you will use the memory
allocated to the sprite anyway. Either immediately (by clearing it
explicitly) or afterwards.
Say you have a C++ class which contains several bitmaps which are
created in
constructor, but not filled until some method is called.
You mean, not until some method that is not part of the
initialisation? Otherwise it wouldn't matter.
Or when you load sprites and you don't need the bitmap to be cleared.
That's the situation I was thinking of where you don't care about the
bitmap being cleared or not.
The only situation where you want the bitmap to be cleared is when
you draw your
own sprite from the code.
When you do your own manipulation of the bitmap. Slight difference in
emphasis.
In a sense it's the reverse of the previous point: unless you load
some data into the bitmap anyway, you'll want to have it cleared. You
could argue that in a game, the normal operation is to load data from
disk so you don't care. Besides, it's easy to tell the user to clear
the bitmap before using it if they want to use it.
In a sense it's the difference between using malloc() and calloc().
Which actually raises a question: what does Allegro 4.2 do when you
allocate a bitmap? Is it guarenteed to be initialised to all 0? I
have a recollection of this not being the case at some point in the
distant past (it might have been with Allegro 3.11), which has lead
me to the habit of always clearing it myself after create_bitmap().
Evert