Mail Archives: djgpp/1997/03/03/04:31:21
I have several questions about Allegro, mostly out of curiosity...
* Why, when using a SVGA mode e.g. GFX_AUTODETECT 640x480, does a
fade_in(palette) or a fade_out() seem to do 4 fades in series instead of
just 1? Fades work as expected in GFX_MODEX. Is it a bug or a "feature"?
* Is the video manipulation ultimately done with super-fast nearptrs or far
pointers? Near pointers are thought not to work on some DPMI hosts,
so an optimal Allegro would detect the DPMI host, if it is a known safe
one i.e. cwsdpmi use nearptrs, else use farptrs for safety...
* What functions in allegro are typically inlined?
* Which graphics functions use inline asm for optimisation?
* Was Allegro compiled with -m486?
* Compiled sprites seem to have four compiled routines in them. Why?
(My guesses were: one for the screen, one for a sub bitmap of the screen,
one for memory bitmaps, and one for a sub bitmap of a memory bitmap.)
* Do you know where UniVBE 5.1 can be obtained?
It seems to be the most up-to-date version that DOESN'T cripple itself
after 21 days.
* When an allegro program that uses sound starts, there is a popping noise.
The noise also happens at exit. I have learned to dread this pop, since
usually if it happens when I'm not expecting it, I find myself staring at
a stack dump a few seconds later. What is it?
* There is a definite link between using allegro and GCC making funny noises
during compile. For instance, using RHIDE and Allegro, I ran a program,
and it hit a breakpoint. I inspected a few variables, then changed some
source and ran Make. GCC was called, and five seconds into the compile a
bunch of queer repeating and *LOUD* sound effects started coming from my SB!
It has happened a total of 3 times now. All 3 times after an allegro
program a) used sound and b) never got to allegro_exit.
I also have a suggestion: to create a new bitmap/sprite type, say
MODEX_BITMAP. These would be like memory bitmaps but with a planar
structure. They would answer TRUE to is_planar_bitmap and is_memory_bitmap.
They might be made from a regular bitmap using a get_modex_bitmap function.
This way, it might be possible to do blitting (and dare we hope, sprite
and rle-sprite) operations from memory to the ModeX screen faster than
usual (though not as fast as with latch registers, which I assume only
works between two parts of video ram.)
Also, using an S3, and lacking a non-crippled UniVBE supporting Vesa 2.0,
is it possible to get a "modex" mode 320x240 that is not limited to 256 k?
--
.*. Where feelings are concerned, answers are rarely simple [GeneDeWeese]
-() < When I go to the theater, I always go straight to the "bag and mix"
`*' bulk candy section...because variety is the spice of life... [me]
Paul Derbyshire ao950 AT freenet DOT carleton DOT ca, http://chat.carleton.ca/~pderbysh
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