// d_scan.c
//
// Portable C scan-level rasterization code, all pixel depths.

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

unsigned char *r_turb_pbase, *r_turb_pdest;
fixed16_t r_turb_s, r_turb_t, r_turb_sstep, r_turb_tstep;
int *r_turb_turb;
int r_turb_spancount;

void D_DrawTurbulent8Span(void);


/*
=============
D_WarpScreen

// this performs a slight compression of the screen at the same time as
// the sine warp, to keep the edges from wrapping
=============
*/
void D_WarpScreen(void)
{
    int w, h;
    int u, v;
    byte *dest;
    int *turb;
    int *col;
    byte **row;
    byte *rowptr[1024];
    int column[1280];
    float wratio, hratio;

    w = r_refdef.vrect.width;
    h = r_refdef.vrect.height;

    wratio = w / (float) scr_vrect.width;
    hratio = h / (float) scr_vrect.height;

    for (v = 0; v < scr_vrect.height + AMP2 * 2; v++) {
	rowptr[v] = d_viewbuffer + (r_refdef.vrect.y * screenwidth) +
	    (screenwidth *
	     (int) ((float) v * hratio * h / (h + AMP2 * 2)));
    }

    for (u = 0; u < scr_vrect.width + AMP2 * 2; u++) {
	column[u] = r_refdef.vrect.x +
	    (int) ((float) u * wratio * w / (w + AMP2 * 2));
    }

    turb = intsintable + ((int) (cl.time * SPEED) & (CYCLE - 1));
    dest = vid.buffer + scr_vrect.y * vid.rowbytes + scr_vrect.x;

    for (v = 0; v < scr_vrect.height; v++, dest += vid.rowbytes) {
	col = &column[turb[v]];
	row = &rowptr[v];
	for (u = 0; u < scr_vrect.width; u += 4) {
	    dest[u + 0] = row[turb[u + 0]][col[u + 0]];
	    dest[u + 1] = row[turb[u + 1]][col[u + 1]];
	    dest[u + 2] = row[turb[u + 2]][col[u + 2]];
	    dest[u + 3] = row[turb[u + 3]][col[u + 3]];
	}
    }
}


/*
=============
D_DrawTurbulent8Span
=============
*/
void D_DrawTurbulent8Span(void)
{
    int sturb, tturb;

    do {
	sturb =
	    ((r_turb_s +
	      r_turb_turb[(r_turb_t >> 16) & (CYCLE - 1)]) >> 16) & 63;
	tturb =
	    ((r_turb_t +
	      r_turb_turb[(r_turb_s >> 16) & (CYCLE - 1)]) >> 16) & 63;
	*r_turb_pdest++ = *(r_turb_pbase + (tturb << 6) + sturb);
	r_turb_s += r_turb_sstep;
	r_turb_t += r_turb_tstep;
    } while (--r_turb_spancount > 0);
}

/*
=============
Turbulent8
=============
*/
void Turbulent8(espan_t * pspan)
{
    int count;
    fixed16_t snext, tnext;
    float sdivz, tdivz, zi, z, du, dv, spancountminus1;
    float sdivz16stepu, tdivz16stepu, zi16stepu;

    r_turb_turb = sintable + ((int) (cl.time * SPEED) & (CYCLE - 1));

    r_turb_sstep = 0;		// keep compiler happy
    r_turb_tstep = 0;		// ditto

    r_turb_pbase = (unsigned char *) cacheblock;

    sdivz16stepu = d_sdivzstepu * 16;
    tdivz16stepu = d_tdivzstepu * 16;
    zi16stepu = d_zistepu * 16;

    do {
	r_turb_pdest = (unsigned char *) ((byte *) d_viewbuffer +
					  (screenwidth * pspan->v) +
					  pspan->u);

	count = pspan->count;

	// calculate the initial s/z, t/z, 1/z, s, and t and clamp
	du = (float) pspan->u;
	dv = (float) pspan->v;

	sdivz = d_sdivzorigin + dv * d_sdivzstepv + du * d_sdivzstepu;
	tdivz = d_tdivzorigin + dv * d_tdivzstepv + du * d_tdivzstepu;
	zi = d_ziorigin + dv * d_zistepv + du * d_zistepu;
	z = (float) 0x10000 / zi;	// prescale to 16.16 fixed-point

	r_turb_s = (int) (sdivz * z) + sadjust;
	if (r_turb_s > bbextents)
	    r_turb_s = bbextents;
	else if (r_turb_s < 0)
	    r_turb_s = 0;

	r_turb_t = (int) (tdivz * z) + tadjust;
	if (r_turb_t > bbextentt)
	    r_turb_t = bbextentt;
	else if (r_turb_t < 0)
	    r_turb_t = 0;

	do {
	    // calculate s and t at the far end of the span
	    if (count >= 16)
		r_turb_spancount = 16;
	    else
		r_turb_spancount = count;

	    count -= r_turb_spancount;

	    if (count) {
		// calculate s/z, t/z, zi->fixed s and t at far end of span,
		// calculate s and t steps across span by shifting
		sdivz += sdivz16stepu;
		tdivz += tdivz16stepu;
		zi += zi16stepu;
		z = (float) 0x10000 / zi;	// prescale to 16.16 fixed-point

		snext = (int) (sdivz * z) + sadjust;
		if (snext > bbextents)
		    snext = bbextents;
		else if (snext < 16)
		    snext = 16;	// prevent round-off error on <0 steps from
		//  from causing overstepping & running off the
		//  edge of the texture

		tnext = (int) (tdivz * z) + tadjust;
		if (tnext > bbextentt)
		    tnext = bbextentt;
		else if (tnext < 16)
		    tnext = 16;	// guard against round-off error on <0 steps

		r_turb_sstep = (snext - r_turb_s) >> 4;
		r_turb_tstep = (tnext - r_turb_t) >> 4;
	    } else {
		// calculate s/z, t/z, zi->fixed s and t at last pixel in span (so
		// can't step off polygon), clamp, calculate s and t steps across
		// span by division, biasing steps low so we don't run off the
		// texture
		spancountminus1 = (float) (r_turb_spancount - 1);
		sdivz += d_sdivzstepu * spancountminus1;
		tdivz += d_tdivzstepu * spancountminus1;
		zi += d_zistepu * spancountminus1;
		z = (float) 0x10000 / zi;	// prescale to 16.16 fixed-point
		snext = (int) (sdivz * z) + sadjust;
		if (snext > bbextents)
		    snext = bbextents;
		else if (snext < 16)
		    snext = 16;	// prevent round-off error on <0 steps from
		//  from causing overstepping & running off the
		//  edge of the texture

		tnext = (int) (tdivz * z) + tadjust;
		if (tnext > bbextentt)
		    tnext = bbextentt;
		else if (tnext < 16)
		    tnext = 16;	// guard against round-off error on <0 steps

		if (r_turb_spancount > 1) {
		    r_turb_sstep =
			(snext - r_turb_s) / (r_turb_spancount - 1);
		    r_turb_tstep =
			(tnext - r_turb_t) / (r_turb_spancount - 1);
		}
	    }

	    r_turb_s = r_turb_s & ((CYCLE << 16) - 1);
	    r_turb_t = r_turb_t & ((CYCLE << 16) - 1);

	    D_DrawTurbulent8Span();

	    r_turb_s = snext;
	    r_turb_t = tnext;

	} while (count > 0);

    } while ((pspan = pspan->pnext) != NULL);
}


/*
=============
D_DrawSpans8
=============
*/
void D_DrawSpans8(espan_t * pspan)
{
    int count, spancount;
    unsigned char *pbase, *pdest;
    fixed16_t s, t, snext, tnext, sstep, tstep;
    float sdivz, tdivz, zi, z, du, dv, spancountminus1;
    float sdivz8stepu, tdivz8stepu, zi8stepu;

    sstep = 0;			// keep compiler happy
    tstep = 0;			// ditto

    pbase = (unsigned char *) cacheblock;

    sdivz8stepu = d_sdivzstepu * 8;
    tdivz8stepu = d_tdivzstepu * 8;
    zi8stepu = d_zistepu * 8;

    do {
	pdest = (unsigned char *) ((byte *) d_viewbuffer +
				   (screenwidth * pspan->v) + pspan->u);

	count = pspan->count;

	// calculate the initial s/z, t/z, 1/z, s, and t and clamp
	du = (float) pspan->u;
	dv = (float) pspan->v;

	sdivz = d_sdivzorigin + dv * d_sdivzstepv + du * d_sdivzstepu;
	tdivz = d_tdivzorigin + dv * d_tdivzstepv + du * d_tdivzstepu;
	zi = d_ziorigin + dv * d_zistepv + du * d_zistepu;
	z = (float) 0x10000 / zi;	// prescale to 16.16 fixed-point

	s = (int) (sdivz * z) + sadjust;
	if (s > bbextents)
	    s = bbextents;
	else if (s < 0)
	    s = 0;

	t = (int) (tdivz * z) + tadjust;
	if (t > bbextentt)
	    t = bbextentt;
	else if (t < 0)
	    t = 0;

	do {
	    // calculate s and t at the far end of the span
	    if (count >= 8)
		spancount = 8;
	    else
		spancount = count;

	    count -= spancount;

	    if (count) {
		// calculate s/z, t/z, zi->fixed s and t at far end of span,
		// calculate s and t steps across span by shifting
		sdivz += sdivz8stepu;
		tdivz += tdivz8stepu;
		zi += zi8stepu;
		z = (float) 0x10000 / zi;	// prescale to 16.16 fixed-point

		snext = (int) (sdivz * z) + sadjust;
		if (snext > bbextents)
		    snext = bbextents;
		else if (snext < 8)
		    snext = 8;	// prevent round-off error on <0 steps from
		//  from causing overstepping & running off the
		//  edge of the texture

		tnext = (int) (tdivz * z) + tadjust;
		if (tnext > bbextentt)
		    tnext = bbextentt;
		else if (tnext < 8)
		    tnext = 8;	// guard against round-off error on <0 steps

		sstep = (snext - s) >> 3;
		tstep = (tnext - t) >> 3;
	    } else {
		// calculate s/z, t/z, zi->fixed s and t at last pixel in span (so
		// can't step off polygon), clamp, calculate s and t steps across
		// span by division, biasing steps low so we don't run off the
		// texture
		spancountminus1 = (float) (spancount - 1);
		sdivz += d_sdivzstepu * spancountminus1;
		tdivz += d_tdivzstepu * spancountminus1;
		zi += d_zistepu * spancountminus1;
		z = (float) 0x10000 / zi;	// prescale to 16.16 fixed-point
		snext = (int) (sdivz * z) + sadjust;
		if (snext > bbextents)
		    snext = bbextents;
		else if (snext < 8)
		    snext = 8;	// prevent round-off error on <0 steps from
		//  from causing overstepping & running off the
		//  edge of the texture

		tnext = (int) (tdivz * z) + tadjust;
		if (tnext > bbextentt)
		    tnext = bbextentt;
		else if (tnext < 8)
		    tnext = 8;	// guard against round-off error on <0 steps

		if (spancount > 1) {
		    sstep = (snext - s) / (spancount - 1);
		    tstep = (tnext - t) / (spancount - 1);
		}
	    }

	    do {
		*pdest++ = *(pbase + (s >> 16) + (t >> 16) * cachewidth);
		s += sstep;
		t += tstep;
	    } while (--spancount > 0);

	    s = snext;
	    t = tnext;

	} while (count > 0);

    } while ((pspan = pspan->pnext) != NULL);
}

/*
=============
D_DrawZSpans
=============
*/
void D_DrawZSpans(espan_t * pspan)
{
    int count, doublecount, izistep;
    int izi;
    short *pdest;
    unsigned ltemp;
    double zi;
    float du, dv;

// FIXME: check for clamping/range problems
// we count on FP exceptions being turned off to avoid range problems
    izistep = (int) (d_zistepu * 0x8000 * 0x10000);

    do {
	pdest = d_pzbuffer + (d_zwidth * pspan->v) + pspan->u;

	count = pspan->count;

	// calculate the initial 1/z
	du = (float) pspan->u;
	dv = (float) pspan->v;

	zi = d_ziorigin + dv * d_zistepv + du * d_zistepu;
	// we count on FP exceptions being turned off to avoid range problems
	izi = (int) (zi * 0x8000 * 0x10000);

	if ((long) pdest & 0x02) {
	    *pdest++ = (short) (izi >> 16);
	    izi += izistep;
	    count--;
	}

	if ((doublecount = count >> 1) > 0) {
	    do {
		ltemp = izi >> 16;
		izi += izistep;
		ltemp |= izi & 0xFFFF0000;
		izi += izistep;
		*(int *) pdest = ltemp;
		pdest += 2;
	    } while (--doublecount > 0);
	}

	if (count & 1)
	    *pdest = (short) (izi >> 16);

    } while ((pspan = pspan->pnext) != NULL);
}
