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Setting up a gradient Like Palette

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ayatollah

Joined: 04 Sep 2005
Posts: 15

Posted: Thu Oct 20, 2005 5:31 am Post subject: Setting up a gradient Like Palette

Hi

I am trying to setup a 32Bit Palette to use as Texture which generally works just fine using:

Code:

   sceGuClutMode(GU_PSM_8888,0,0xff,0); // 32-bit palette
   sceGuClutLoad((256/8),clut256); // upload 32*8 entries (256)
   sceGuTexMode(GU_PSM_T8,0,0,0); // 8-bit image

now the (for me) tricky part.. I am trying to compute the Color Palette and I found varous sources on the net.. All of them deal with VGA Mode where it appears that one needs to call:

Code:

outp(0x3C8,col);
outp(0x3C9,R);
outp(0x3C9,G);
outp(0x3C9,B);

and this loop does the trick:

Code:

for (x=1; x<=32; x++) {
setrgb(x, 0, 0, x*2-1); /* Blue part */
setrgb(x+32, x*2-1, 0, 63);
setrgb(x+64, 63, x*2-1, 63);
setrgb(x+96, 63, 63, 63);

setrgb(x+128, 63, 63, 63);
setrgb(x+160, 63, 63, 63-(x*2-1));
setrgb(x+192, 63, 63-(x*2-1), 0);
setrgb(x+224, 63-(x*2-1), 0, 0); /* Red part */

}

I found in the CLUT Sample of the SDK a Routine that does set up the Plaette like

Code:

unsigned int* clut = (unsigned int*)(((unsigned int)clut256)|0x40000000);
   for (i = 0; i < 256; ++i)
   {
      unsigned int j = (i + offset)&0xff;
      *(clut++) = (j << 24)|(j << 16)|(j << 8)|(j);
   }

Now if I use this, it gives me a GREYScale Palette only..
I tried to do:

Code:

for (i=1; i<=32; i++)
{
*clut+i = (0xff << 24) | ((i*2-1) << 16) | (0 << 8) | 0;
*clut+i+32 = (0xff << 24) | (63 << 16) | (0 << 8) | (i*2-1);
*clut+i+64 = (0xff << 24) | (63 << 16) | ((i*2-1) << 8) | 63;
*clut+i+96 = (0xff << 24) | (63 << 16) | (63 << 8) | 63;

*clut+i+128 = (0xff << 24) | (63 << 16) | (63 << 8) | 63;
*clut+i+160 = (0xff << 24) | (63-(i*2-1) << 16) | (63 << 8) | 63;
*clut+i+192 = (0xff << 24) | (0 << 16) | (63-(i*2-1) << 8) | 63;
*clut+i+224 = (0xff << 24) | (0 << 16) | (0 << 8) | 63-(i*2-1); */
}
}

but obviously that does not work. It gives the Error Message:

error: invalid lvalue in assignment

Anyhow.. I am really bad at pointers and not really sure how to get this done.. Is there anybody out that that can help me?? I am aware that this is a general C problem and the topic will most likely be closed but maybe somebody can shed some light ?!??!

THANK YOU SO MUCH!

Saotome

Joined: 03 Apr 2004
Posts: 182

Posted: Thu Oct 20, 2005 5:44 am Post subject:

look at the CLUT sample again. especialy this line:

Code:

*(clut++) = (j << 24)|(j << 16)|(j << 8)|(j);

then look at your code, here for example:

Code:

*clut+i+32 = ...

if you still don't see it, try this ;)

Code:

*(clut+i+32) = ...

_________________
infj

ayatollah

Joined: 04 Sep 2005
Posts: 15

Posted: Thu Oct 20, 2005 7:41 am Post subject:

ouch... Thanx.. it works like a charm now !!!!

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