ref: a2c587e7d7a8b72a7ef9afcd119d8cfb20076b54
dir: /d_sprite.c/
#include "quakedef.h"
static int sprite_height;
static int minindex, maxindex;
static sspan_t *sprite_spans;
/*
=====================
D_SpriteDrawSpans
=====================
*/
static void
D_SpriteDrawSpans(sspan_t *pspan, texvars_t *tv, byte alpha)
{
int count, spancount, izistep;
int izi;
pixel_t *pbase, *pdest, btemp;
fixed16_t s, t, snext, tnext, sstep, tstep;
float sdivz, tdivz, zi, z, du, dv, spancountminus1;
float sdivz8stepu, tdivz8stepu, zi8stepu;
uzint *pz;
sstep = 0; // keep compiler happy
tstep = 0; // ditto
pbase = tv->p;
sdivz8stepu = tv->s.divz.stepu * 8;
tdivz8stepu = tv->t.divz.stepu * 8;
zi8stepu = tv->z.stepu * 8;
// we count on FP exceptions being turned off to avoid range problems
izistep = (int)(tv->z.stepu * 0x8000 * 0x10000);
assert(pspan->v >= 0);
do
{
pdest = dvars.fb + dvars.w * pspan->v + pspan->u;
pz = dvars.zb + dvars.w * 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 = tv->s.divz.origin + dv*tv->s.divz.stepv + du*tv->s.divz.stepu;
tdivz = tv->t.divz.origin + dv*tv->t.divz.stepv + du*tv->t.divz.stepu;
zi = tv->z.origin + dv*tv->z.stepv + du*tv->z.stepu;
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) + tv->s.adjust;
s = clamp(s, 0, tv->s.bbextent);
t = (int)(tdivz * z) + tv->t.adjust;
t = clamp(t, 0, tv->t.bbextent);
do
{
// calculate s and t at the far end of the span
spancount = min(count, 8);
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) + tv->s.adjust;
snext = clamp(snext, 8, tv->s.bbextent);
// prevent round-off error on <0 steps from
// from causing overstepping & running off the
// edge of the texture
tnext = (int)(tdivz * z) + tv->t.adjust;
tnext = clamp(tnext, 8, tv->t.bbextent); // 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 += tv->s.divz.stepu * spancountminus1;
tdivz += tv->t.divz.stepu * spancountminus1;
zi += tv->z.stepu * spancountminus1;
z = (float)0x10000 / zi; // prescale to 16.16 fixed-point
snext = (int)(sdivz * z) + tv->s.adjust;
snext = clamp(snext, 8, tv->s.bbextent);
// prevent round-off error on <0 steps from
// from causing overstepping & running off the
// edge of the texture
tnext = (int)(tdivz * z) + tv->t.adjust;
tnext = clamp(tnext, 8, tv->t.bbextent); // 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) * tv->w);
if(opaque(btemp) && *pz <= izi){
if(r_drawflags & DRAW_BLEND){
*pdest = blendalpha(btemp, *pdest, alpha);
}else{
*pz = izi;
*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
=====================
*/
static 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
=====================
*/
static 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
=====================
*/
static void
D_SpriteCalculateGradients(view_t *v, texvars_t *tv)
{
vec3_t p_normal, p_saxis, p_taxis, p_temp1;
float distinv;
TransformVector (r_spritedesc.vpn, p_normal, v);
TransformVector (r_spritedesc.vright, p_saxis, v);
TransformVector (r_spritedesc.vup, p_taxis, v);
VectorInverse (p_taxis);
distinv = 1.0 / (-DotProduct (v->modelorg, r_spritedesc.vpn));
tv->s.divz.stepu = p_saxis[0] * xscaleinv;
tv->t.divz.stepu = p_taxis[0] * xscaleinv;
tv->s.divz.stepv = -p_saxis[1] * yscaleinv;
tv->t.divz.stepv = -p_taxis[1] * yscaleinv;
tv->z.stepu = p_normal[0] * xscaleinv * distinv;
tv->z.stepv = -p_normal[1] * yscaleinv * distinv;
tv->s.divz.origin = p_saxis[2] - xcenter*tv->s.divz.stepu - ycenter*tv->s.divz.stepv;
tv->t.divz.origin = p_taxis[2] - xcenter*tv->t.divz.stepu - ycenter*tv->t.divz.stepv;
tv->z.origin = p_normal[2]*distinv - xcenter*tv->z.stepu - ycenter*tv->z.stepv;
TransformVector (v->modelorg, p_temp1, v);
tv->s.adjust = ((fixed16_t)(DotProduct (p_temp1, p_saxis) * 0x10000 + 0.5)) - (-(tv->w >> 1) << 16);
tv->t.adjust = ((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
tv->s.bbextent = (tv->w << 16) - 1;
tv->t.bbextent = (sprite_height << 16) - 1;
}
/*
=====================
D_DrawSprite
=====================
*/
void
D_DrawSprite(view_t *v)
{
int i, nump;
float ymin, ymax;
emitpoint_t *pverts;
static sspan_t spans[MAXHEIGHT+1];
texvars_t tv;
sprite_spans = spans;
// find the top and bottom vertices, and make sure there's at least one scan to
// draw
ymin = Q_MAXFLOAT;
ymax = -Q_MAXFLOAT;
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
tv.w = r_spritedesc.pspriteframe->width;
tv.p = r_spritedesc.pspriteframe->pixels;
sprite_height = r_spritedesc.pspriteframe->height;
// 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(v, &tv);
D_SpriteScanLeftEdge();
D_SpriteScanRightEdge();
D_SpriteDrawSpans(sprite_spans, &tv, currententity->alpha);
}