Jean-Luc Dery (dery++at++cae.ca)
Fri, 6 Oct 1995 09:18:19 -0400
I send a mail yesterday on the z buffer read using the rectcopy with a shift to
the alpha in the normal buffer. As I said, I can write to any RGB value of the
normal bit plane but can't write on the alpha bits. This takes place in a
Performer application with a RE2.
Here is, again but corrected, what i'm doing:
...
pixmode( PM_SIZE, 32 );
pixmode( PM_INPUT_TYPE, PM_UNSIGNED_BYTE );
pixmode( PM_INPUT_FORMAT, PM_ABGR );
pixmode( PM_OUTPUT_TYPE, PM_UNSIGNED_BYTE );
pixmode( PM_OUTPUT_FORMAT, PM_ABGR );
pixmode( PM_SHIFT, 8 );
zbuffer( FALSE );
readsource( SRC_ZBUFFER );
RGBWritemask( 0x00, 0x00, 0x00 );
rectcopy( ... );
RGBwritemask( 0xFF, 0xFF, 0xFF );
zbuffer( TRUE );
...
The results I get is like
AABBGGRR ZBUF AABBGGRR
0xFF------ 0x------00 => 0xFF------
If I query the graphics set up at the end of the pipe ConfigFunc, I get
getgdesc( GD_BITS_NORM_DBL_RED ) = 12
getgdesc( GD_BITS_NORM_DBL_ALPHA ) = 12
getgdesc( GD_BITS_NORM_ZBUFFER ) = 32
getgconfig( GC_DOUBLE ) = 1
getgconfig( GC_BITS_RED ) = 8
getgconfig( GC_BITS_ALPHA ) = 0 <---------------
getgconfig( GC_BITS_ZBUFFER ) = 4294967272
The setup I'm in doesn't seem to configure any available alpha bit planes.
Another thing is that when I read the z buffer with a lrectread, all the lower
8 bits are at 00.
One more thing, in the RGBsize man page, under the BUGS notice, I read the
following:
On the IRIS-4D RealityEngine models when the number of planes configured
for each single-color component is 8, the framebuffer consist of no alpha
bit planes.
On the IRIS-4D RealityEngine models the framebuffer cannot be configured
to consist of 32 Z buffer planes (or 32 depth planes in the multisample
buffer) and 8 color planes for each of the RGB color buffers
simultaneously.
Does this apply in my case, with a RE2; am I in a dead end ???
Thanks for any help.
--
___________________________________________________________________
____ ___ __
Jean-Luc Dery / \ /_ /__) \__/
System engineer __/___/ /___ / \ /
CAE Electronics Ltd.
GRAPHICS SOFTWARE TECHNOLOGY Phone: (514)341-6780 x2275
e-mail: dery++at++cae.ca FAX: (514)340-5496
___________________________________________________________________
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