ref: 73fca33b06e2ebb61473d295fdd39f8bbf57e4dd
dir: /qw/d_sprite.c/
// d_sprite.c: software top-level rasterization driver module for drawing sprites
#include <u.h>
#include <libc.h>
#include <stdio.h>
#include "quakedef.h"
static int sprite_height;
static int minindex, maxindex;
static sspan_t *sprite_spans;
/*
=====================
D_SpriteDrawSpans
=====================
*/
void D_SpriteDrawSpans (sspan_t *pspan)
{
int count, spancount, izistep;
int izi;
byte *pbase, *pdest;
fixed16_t s, t, snext, tnext, sstep, tstep;
float sdivz, tdivz, zi, z, du, dv, spancountminus1;
float sdivz8stepu, tdivz8stepu, zi8stepu;
byte btemp;
short *pz;
sstep = 0; // keep compiler happy
tstep = 0; // ditto
pbase = cacheblock;
sdivz8stepu = d_sdivzstepu * 8;
tdivz8stepu = d_tdivzstepu * 8;
zi8stepu = d_zistepu * 8;
// we count on FP exceptions being turned off to avoid range problems
izistep = (int)(d_zistepu * 0x8000 * 0x10000);
do
{
pdest = (byte *)d_viewbuffer + (screenwidth * pspan->v) + pspan->u;
pz = d_pzbuffer + (d_zwidth * pspan->v) + pspan->u;
count = pspan->count;
if (count <= 0)
goto NextSpan;
// 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
// we count on FP exceptions being turned off to avoid range problems
izi = (int)(zi * 0x8000 * 0x10000);
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
{
btemp = *(pbase + (s >> 16) + (t >> 16) * cachewidth);
if (btemp != 255)
{
if (*pz <= (izi >> 16))
{
*pz = izi >> 16;
*pdest = btemp;
}
}
izi += izistep;
pdest++;
pz++;
s += sstep;
t += tstep;
} while (--spancount > 0);
s = snext;
t = tnext;
} while (count > 0);
NextSpan:
pspan++;
} while (pspan->count != DS_SPAN_LIST_END);
}
/*
=====================
D_SpriteScanLeftEdge
=====================
*/
void D_SpriteScanLeftEdge (void)
{
int i, v, itop, ibottom, lmaxindex;
emitpoint_t *pvert, *pnext;
sspan_t *pspan;
float du, dv, vtop, vbottom, slope;
fixed16_t u, u_step;
pspan = sprite_spans;
i = minindex;
if (i == 0)
i = r_spritedesc.nump;
lmaxindex = maxindex;
if (lmaxindex == 0)
lmaxindex = r_spritedesc.nump;
vtop = ceil (r_spritedesc.pverts[i].v);
do
{
pvert = &r_spritedesc.pverts[i];
pnext = pvert - 1;
vbottom = ceil (pnext->v);
if (vtop < vbottom)
{
du = pnext->u - pvert->u;
dv = pnext->v - pvert->v;
slope = du / dv;
u_step = (int)(slope * 0x10000);
// adjust u to ceil the integer portion
u = (int)((pvert->u + (slope * (vtop - pvert->v))) * 0x10000) +
(0x10000 - 1);
itop = (int)vtop;
ibottom = (int)vbottom;
for (v=itop ; v<ibottom ; v++)
{
pspan->u = u >> 16;
pspan->v = v;
u += u_step;
pspan++;
}
}
vtop = vbottom;
i--;
if (i == 0)
i = r_spritedesc.nump;
} while (i != lmaxindex);
}
/*
=====================
D_SpriteScanRightEdge
=====================
*/
void D_SpriteScanRightEdge (void)
{
int i, v, itop, ibottom;
emitpoint_t *pvert, *pnext;
sspan_t *pspan;
float du, dv, vtop, vbottom, slope, uvert, unext, vvert, vnext;
fixed16_t u, u_step;
pspan = sprite_spans;
i = minindex;
vvert = r_spritedesc.pverts[i].v;
if (vvert < r_refdef.fvrecty_adj)
vvert = r_refdef.fvrecty_adj;
if (vvert > r_refdef.fvrectbottom_adj)
vvert = r_refdef.fvrectbottom_adj;
vtop = ceil (vvert);
do
{
pvert = &r_spritedesc.pverts[i];
pnext = pvert + 1;
vnext = pnext->v;
if (vnext < r_refdef.fvrecty_adj)
vnext = r_refdef.fvrecty_adj;
if (vnext > r_refdef.fvrectbottom_adj)
vnext = r_refdef.fvrectbottom_adj;
vbottom = ceil (vnext);
if (vtop < vbottom)
{
uvert = pvert->u;
if (uvert < r_refdef.fvrectx_adj)
uvert = r_refdef.fvrectx_adj;
if (uvert > r_refdef.fvrectright_adj)
uvert = r_refdef.fvrectright_adj;
unext = pnext->u;
if (unext < r_refdef.fvrectx_adj)
unext = r_refdef.fvrectx_adj;
if (unext > r_refdef.fvrectright_adj)
unext = r_refdef.fvrectright_adj;
du = unext - uvert;
dv = vnext - vvert;
slope = du / dv;
u_step = (int)(slope * 0x10000);
// adjust u to ceil the integer portion
u = (int)((uvert + (slope * (vtop - vvert))) * 0x10000) +
(0x10000 - 1);
itop = (int)vtop;
ibottom = (int)vbottom;
for (v=itop ; v<ibottom ; v++)
{
pspan->count = (u >> 16) - pspan->u;
u += u_step;
pspan++;
}
}
vtop = vbottom;
vvert = vnext;
i++;
if (i == r_spritedesc.nump)
i = 0;
} while (i != maxindex);
pspan->count = DS_SPAN_LIST_END; // mark the end of the span list
}
/*
=====================
D_SpriteCalculateGradients
=====================
*/
void D_SpriteCalculateGradients (void)
{
vec3_t p_normal, p_saxis, p_taxis, p_temp1;
float distinv;
TransformVector (r_spritedesc.vpn, p_normal);
TransformVector (r_spritedesc.vright, p_saxis);
TransformVector (r_spritedesc.vup, p_taxis);
VectorInverse (p_taxis);
distinv = 1.0 / (-DotProduct (modelorg, r_spritedesc.vpn));
d_sdivzstepu = p_saxis[0] * xscaleinv;
d_tdivzstepu = p_taxis[0] * xscaleinv;
d_sdivzstepv = -p_saxis[1] * yscaleinv;
d_tdivzstepv = -p_taxis[1] * yscaleinv;
d_zistepu = p_normal[0] * xscaleinv * distinv;
d_zistepv = -p_normal[1] * yscaleinv * distinv;
d_sdivzorigin = p_saxis[2] - xcenter * d_sdivzstepu -
ycenter * d_sdivzstepv;
d_tdivzorigin = p_taxis[2] - xcenter * d_tdivzstepu -
ycenter * d_tdivzstepv;
d_ziorigin = p_normal[2] * distinv - xcenter * d_zistepu -
ycenter * d_zistepv;
TransformVector (modelorg, p_temp1);
sadjust = ((fixed16_t)(DotProduct (p_temp1, p_saxis) * 0x10000 + 0.5)) -
(-(cachewidth >> 1) << 16);
tadjust = ((fixed16_t)(DotProduct (p_temp1, p_taxis) * 0x10000 + 0.5)) -
(-(sprite_height >> 1) << 16);
// -1 (-epsilon) so we never wander off the edge of the texture
bbextents = (cachewidth << 16) - 1;
bbextentt = (sprite_height << 16) - 1;
}
/*
=====================
D_DrawSprite
=====================
*/
void D_DrawSprite (void)
{
int i, nump;
float ymin, ymax;
emitpoint_t *pverts;
sspan_t spans[MAXHEIGHT+1];
sprite_spans = spans;
// find the top and bottom vertices, and make sure there's at least one scan to
// draw
ymin = 999999.9;
ymax = -999999.9;
pverts = r_spritedesc.pverts;
for (i=0 ; i<r_spritedesc.nump ; i++)
{
if (pverts->v < ymin)
{
ymin = pverts->v;
minindex = i;
}
if (pverts->v > ymax)
{
ymax = pverts->v;
maxindex = i;
}
pverts++;
}
ymin = ceil (ymin);
ymax = ceil (ymax);
if (ymin >= ymax)
return; // doesn't cross any scans at all
cachewidth = r_spritedesc.pspriteframe->width;
sprite_height = r_spritedesc.pspriteframe->height;
cacheblock = (byte *)&r_spritedesc.pspriteframe->pixels[0];
// copy the first vertex to the last vertex, so we don't have to deal with
// wrapping
nump = r_spritedesc.nump;
pverts = r_spritedesc.pverts;
pverts[nump] = pverts[0];
D_SpriteCalculateGradients ();
D_SpriteScanLeftEdge ();
D_SpriteScanRightEdge ();
D_SpriteDrawSpans (sprite_spans);
}