/*
Copyright (C) 1996-1997 Id Software, Inc.

This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License
as published by the Free Software Foundation; either version 2
of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  

See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.

*/
// r_sky.c

#include "quakedef.h"
#include "r_local.h"
#include "d_local.h"


int   iskyspeed = 8;
int   iskyspeed2 = 2;
float skyspeed, skyspeed2;

float   skytime;

byte    *r_skysource;

int r_skymade;
int r_skydirect;    // not used?


// TODO: clean up these routines

byte  bottomsky[128*131];
byte  bottommask[128*131];
byte  newsky[128*256];  // newsky and topsky both pack in here, 128 bytes
              //  of newsky on the left of each scan, 128 bytes
              //  of topsky on the right, because the low-level
              //  drawers need 256-byte scan widths


/*
=============
R_InitSky

A sky texture is 256*128, with the right side being a masked overlay
==============
*/
void R_InitSky (texture_t *mt)
{
  int     i, j;
  byte    *src;

  src = (byte *)mt + mt->offsets[0];

  for (i=0 ; i<128 ; i++)
  {
    for (j=0 ; j<128 ; j++)
    {
      newsky[(i*256) + j + 128] = src[i*256 + j + 128];
    }
  }

  for (i=0 ; i<128 ; i++)
  {
    for (j=0 ; j<131 ; j++)
    {
      if (src[i*256 + (j & 0x7F)])
      {
        bottomsky[(i*131) + j] = src[i*256 + (j & 0x7F)];
        bottommask[(i*131) + j] = 0;
      }
      else
      {
        bottomsky[(i*131) + j] = 0;
        bottommask[(i*131) + j] = 0xff;
      }
    }
  }
  
  r_skysource = newsky;
}


#ifndef M68KASM
/*
=================
R_MakeSky
=================
*/
void R_MakeSky (void)
{
  int     x, y;
  int     ofs, baseofs;
  int     xshift, yshift;
  unsigned  *pnewsky;
  static int  xlast = -1, ylast = -1;

  xshift = skytime*skyspeed;
  yshift = skytime*skyspeed;

  if ((xshift == xlast) && (yshift == ylast))
    return;

  xlast = xshift;
  ylast = yshift;
  
  pnewsky = (unsigned *)&newsky[0];

  for (y=0 ; y<SKYSIZE ; y++)
  {
    baseofs = ((y+yshift) & SKYMASK) * 131;

// FIXME: clean this up
#if UNALIGNED_OK

    for (x=0 ; x<SKYSIZE ; x += 4)
    {
      ofs = baseofs + ((x+xshift) & SKYMASK);

    // PORT: unaligned dword access to bottommask and bottomsky

      *pnewsky = (*(pnewsky + (128 / sizeof (unsigned))) &
            *(unsigned *)&bottommask[ofs]) |
            *(unsigned *)&bottomsky[ofs];
      pnewsky++;
    }

#else

    for (x=0 ; x<SKYSIZE ; x++)
    {
      ofs = baseofs + ((x+xshift) & SKYMASK);

      *(byte *)pnewsky = (*((byte *)pnewsky + 128) &
            *(byte *)&bottommask[ofs]) |
            *(byte *)&bottomsky[ofs];
      pnewsky = (unsigned *)((byte *)pnewsky + 1);
    }

#endif

    pnewsky += 128 / sizeof (unsigned);
  }

  r_skymade = 1;
}
#endif


/*
=================
R_GenSkyTile
=================
*/
void R_GenSkyTile (void *pdest)
{
  int     x, y;
  int     ofs, baseofs;
  int     xshift, yshift;
  unsigned  *pnewsky;
  unsigned  *pd;

  xshift = skytime*skyspeed;
  yshift = skytime*skyspeed;

  pnewsky = (unsigned *)&newsky[0];
  pd = (unsigned *)pdest;

  for (y=0 ; y<SKYSIZE ; y++)
  {
    baseofs = ((y+yshift) & SKYMASK) * 131;

// FIXME: clean this up
#if UNALIGNED_OK

    for (x=0 ; x<SKYSIZE ; x += 4)
    {
      ofs = baseofs + ((x+xshift) & SKYMASK);

    // PORT: unaligned dword access to bottommask and bottomsky

      *pd = (*(pnewsky + (128 / sizeof (unsigned))) &
           *(unsigned *)&bottommask[ofs]) |
           *(unsigned *)&bottomsky[ofs];
      pnewsky++;
      pd++;
    }

#else

    for (x=0 ; x<SKYSIZE ; x++)
    {
      ofs = baseofs + ((x+xshift) & SKYMASK);

      *(byte *)pd = (*((byte *)pnewsky + 128) &
            *(byte *)&bottommask[ofs]) |
            *(byte *)&bottomsky[ofs];
      pnewsky = (unsigned *)((byte *)pnewsky + 1);
      pd = (unsigned *)((byte *)pd + 1);
    }

#endif

    pnewsky += 128 / sizeof (unsigned);
  }
}


/*
=================
R_GenSkyTile16
=================
*/
void R_GenSkyTile16 (void *pdest)
{
  int       x, y;
  int       ofs, baseofs;
  int       xshift, yshift;
  byte      *pnewsky;
  unsigned short  *pd;

  xshift = skytime * skyspeed;
  yshift = skytime * skyspeed;

  pnewsky = (byte *)&newsky[0];
  pd = (unsigned short *)pdest;

  for (y=0 ; y<SKYSIZE ; y++)
  {
    baseofs = ((y+yshift) & SKYMASK) * 131;

// FIXME: clean this up
// FIXME: do faster unaligned version?
    for (x=0 ; x<SKYSIZE ; x++)
    {
      ofs = baseofs + ((x+xshift) & SKYMASK);

      *pd = d_8to16table[(*(pnewsky + 128) &
          *(byte *)&bottommask[ofs]) |
          *(byte *)&bottomsky[ofs]];
      pnewsky++;
      pd++;
    }

    pnewsky += TILE_SIZE;
  }
}


/*
=============
R_SetSkyFrame
==============
*/
void R_SetSkyFrame (void)
{
  int   g, s1, s2;
  float temp;

  skyspeed = iskyspeed;
  skyspeed2 = iskyspeed2;

  g = GreatestCommonDivisor (iskyspeed, iskyspeed2);
  s1 = iskyspeed / g;
  s2 = iskyspeed2 / g;
  temp = SKYSIZE * s1 * s2;

  skytime = cl.time - ((int)(cl.time / temp) * temp);
  

  r_skymade = 0;
}