/*
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;
}


/*
=================
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;

	for (x = 0; x < SKYSIZE; x += 4) {
	    unsigned bsky, bmask;

	    ofs = baseofs + ((x + xshift) & SKYMASK);
	    memcpy(&bsky, &bottomsky[ofs], sizeof(bsky));
	    memcpy(&bmask, &bottommask[ofs], sizeof(bmask));
	    *pnewsky = (pnewsky[128 / sizeof(unsigned)] & bmask) | bsky;
	    pnewsky++;
	}
	pnewsky += 128 / sizeof(unsigned);
    }

    r_skymade = 1;
}


/*
=================
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;

	for (x = 0; x < SKYSIZE; x += 4) {
	    unsigned bsky, bmask;

	    ofs = baseofs + ((x + xshift) & SKYMASK);
	    memcpy(&bsky, &bottomsky[ofs], sizeof(bsky));
	    memcpy(&bmask, &bottommask[ofs], sizeof(bmask));
	    *pd = (pnewsky[128 / sizeof(unsigned)] & bmask) | bsky;
	    pnewsky++;
	    pd++;
	}
	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;
}