Path: chuka.playstation.co.uk!news
From: "Rikki Prince" <rprince@dircon.co.uk>
Newsgroups: scee.yaroze.programming.2d_graphics
Subject: pmode in GsIMAGE
Date: Sun, 28 Feb 1999 01:28:05 -0000
Organization: PlayStation Net Yaroze (SCEE)
Lines: 47
Message-ID: <7ba63i$9po27@chuka.playstation.co.uk>
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I'm currently trying to write a function which will set up a sprite, just by
passing as few  as possible parameters i.e. only the absolutely needed ones
are passed: TIM address, pointer to sprite etc. However, one thing that I
cannot currently get to work is getting the function to work out within
itself whether the TIM is 4bit CLUT, 8bit CLUT or otherwise. From the look
of the GsIMAGE structure in the library reference manual, I should be able
to read the pmode member and work out whether it is 4bit, 8 bit or
otherwise. However, when I put this in a switch statement, it doesn't work.
I've also tried it in an if/else if/else setup, and it still doesn't work.
I've just realised I should have put this earlier in the message, but the
problem I'm having is (constructing sentences and messages!! lol) trying to
set the width of the sprite in the GsSPRITE structure, as when the TIM is
4bit, you need to *4, and when it's 8bit you need to *2 (something I picked
up from the Ira Rainey tutorial). As this is going to be a function I'll
need to use for different TIMs, and therefore not specific, I need it to
work out for itself whether the TIM is 4/8/16 bit etc. I've got it partly
working, by putting in  if((tim.pmode>>3)&0x01) sprite->w=tim.pw*2;  the
'if' part of which I took from the texture load in Peter Passmore's 3d
tutorial, but I believe (well, guess) this bit manipulation tests whether
it's one of 8 or 4 bit, not either individually, which is what I want!

Basically in conclusion, I need some help on how I can test to see if the
sprite is 4bit/8bit/otherwise, so I can set the width accordingly, something
which seems not to work normally, and only with bits shifts and clever
tricky stuff which the 286 in me 'ead don't seem to be able to cope with.

Thanks in advance to anyone who can decipher what I've said in the preceding
message, and decides to help this poor little beginner :-)

Rikki


PS here's my switch statement which doesn't work, if anyone is interested.

switch (tim.pmode)
  {
  case 0 :sprite->w=tim.pw*4; /* If sprite is 4 bit, make width 4 times
bigger */
    break;
  case 1 :sprite->w=tim.pw*2; /* If sprite is 8 bit, make width 2 times
bigger */
    break;
  default :sprite->w=tim.pw*2; /* Else set it to width got from tim info */
    break;
  }