r_things.c

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    if (tz < MINZ)
	return;
    
    xscale = FixedDiv(projection, tz);
	
    gxt = -FixedMul(tr_x,viewsin); 
    gyt = FixedMul(tr_y,viewcos); 
    tx = -(gyt+gxt); 

    // too far off the side?
    if (abs(tx)>(tz<<2))
	return;
    
    // decide which patch to use for sprite relative to player
#ifdef RANGECHECK
    if ((unsigned)thing->sprite >= numsprites)
	I_Error ("R_ProjectSprite: invalid sprite number %i ",
		 thing->sprite);
#endif
    sprdef = &sprites[thing->sprite];
#ifdef RANGECHECK
    if ( (thing->frame&FF_FRAMEMASK) >= sprdef->numframes )
	I_Error ("R_ProjectSprite: invalid sprite frame %i : %i ",
		 thing->sprite, thing->frame);
#endif
    sprframe = &sprdef->spriteframes[ thing->frame & FF_FRAMEMASK];

    if (sprframe->rotate)
    {
	// choose a different rotation based on player view
	ang = R_PointToAngle (thing->x, thing->y);
	rot = (ang-thing->angle+(unsigned)(ANG45/2)*9)>>29;
	lump = sprframe->lump[rot];
	flip = (boolean)sprframe->flip[rot];
    }
    else
    {
	// use single rotation for all views
	lump = sprframe->lump[0];
	flip = (boolean)sprframe->flip[0];
    }
    
    // calculate edges of the shape
    tx -= spriteoffset[lump];	
    x1 = (centerxfrac + FixedMul (tx,xscale) ) >>FRACBITS;

    // off the right side?
    if (x1 > viewwidth)
	return;
    
    tx +=  spritewidth[lump];
    x2 = ((centerxfrac + FixedMul (tx,xscale) ) >>FRACBITS) - 1;

    // off the left side
    if (x2 < 0)
	return;
    
    // store information in a vissprite
    vis = R_NewVisSprite ();
    vis->mobjflags = thing->flags;
    vis->scale = xscale<<detailshift;
    vis->gx = thing->x;
    vis->gy = thing->y;
    vis->gz = thing->z;
    vis->gzt = thing->z + spritetopoffset[lump];
    vis->texturemid = vis->gzt - viewz;
    vis->x1 = x1 < 0 ? 0 : x1;
    vis->x2 = x2 >= viewwidth ? viewwidth-1 : x2;	
    iscale = FixedDiv (FRACUNIT, xscale);

    if (flip)
    {
	vis->startfrac = spritewidth[lump]-1;
	vis->xiscale = -iscale;
    }
    else
    {
	vis->startfrac = 0;
	vis->xiscale = iscale;
    }

    if (vis->x1 > x1)
	vis->startfrac += vis->xiscale*(vis->x1-x1);
    vis->patch = lump;
    
    // get light level
    if (thing->flags & MF_SHADOW)
    {
	// shadow draw
	vis->colormap = NULL;
    }
    else if (fixedcolormap)
    {
	// fixed map
	vis->colormap = fixedcolormap;
    }
    else if (thing->frame & FF_FULLBRIGHT)
    {
	// full bright
	vis->colormap = colormaps;
    }
    
    else
    {
	// diminished light
	index = xscale>>(LIGHTSCALESHIFT-detailshift);

	if (index >= MAXLIGHTSCALE) 
	    index = MAXLIGHTSCALE-1;

	vis->colormap = spritelights[index];
    }	
}




//
// R_AddSprites
// During BSP traversal, this adds sprites by sector.
//
void R_AddSprites (sector_t* sec)
{
    mobj_t*		thing;
    int			lightnum;

    // BSP is traversed by subsector.
    // A sector might have been split into several
    //  subsectors during BSP building.
    // Thus we check whether its already added.
    if (sec->validcount == validcount)
	return;		

    // Well, now it will be done.
    sec->validcount = validcount;
	
    lightnum = (sec->lightlevel >> LIGHTSEGSHIFT)+extralight;

    if (lightnum < 0)		
	spritelights = scalelight[0];
    else if (lightnum >= LIGHTLEVELS)
	spritelights = scalelight[LIGHTLEVELS-1];
    else
	spritelights = scalelight[lightnum];

    // Handle all things in sector.
    for (thing = sec->thinglist ; thing ; thing = thing->snext)
	R_ProjectSprite (thing);
}


//
// R_DrawPSprite
//
void R_DrawPSprite (pspdef_t* psp)
{
    fixed_t		tx;
    int			x1;
    int			x2;
    spritedef_t*	sprdef;
    spriteframe_t*	sprframe;
    int			lump;
    boolean		flip;
    vissprite_t*	vis;
    vissprite_t		avis;
    
    // decide which patch to use
#ifdef RANGECHECK
    if ( (unsigned)psp->state->sprite >= numsprites)
	I_Error ("R_ProjectSprite: invalid sprite number %i ",
		 psp->state->sprite);
#endif
    sprdef = &sprites[psp->state->sprite];
#ifdef RANGECHECK
    if ( (psp->state->frame & FF_FRAMEMASK)  >= sprdef->numframes)
	I_Error ("R_ProjectSprite: invalid sprite frame %i : %i ",
		 psp->state->sprite, psp->state->frame);
#endif
    sprframe = &sprdef->spriteframes[ psp->state->frame & FF_FRAMEMASK ];

    lump = sprframe->lump[0];
    flip = (boolean)sprframe->flip[0];
    
    // calculate edges of the shape
    tx = psp->sx-160*FRACUNIT;
	
    tx -= spriteoffset[lump];	
    x1 = (centerxfrac + FixedMul (tx,pspritescale) ) >>FRACBITS;

    // off the right side
    if (x1 > viewwidth)
	return;		

    tx +=  spritewidth[lump];
    x2 = ((centerxfrac + FixedMul (tx, pspritescale) ) >>FRACBITS) - 1;

    // off the left side
    if (x2 < 0)
	return;
    
    // store information in a vissprite
    vis = &avis;
    vis->mobjflags = 0;
    vis->texturemid = (BASEYCENTER<<FRACBITS)+FRACUNIT/2-(psp->sy-spritetopoffset[lump]);
    vis->x1 = x1 < 0 ? 0 : x1;
    vis->x2 = x2 >= viewwidth ? viewwidth-1 : x2;	
    vis->scale = pspritescale<<detailshift;
    
    if (flip)
    {
	vis->xiscale = -pspriteiscale;
	vis->startfrac = spritewidth[lump]-1;
    }
    else
    {
	vis->xiscale = pspriteiscale;
	vis->startfrac = 0;
    }
    
    if (vis->x1 > x1)
	vis->startfrac += vis->xiscale*(vis->x1-x1);

    vis->patch = lump;

    if (viewplayer->powers[pw_invisibility] > 4*32
	|| viewplayer->powers[pw_invisibility] & 8)
    {
	// shadow draw
	vis->colormap = NULL;
    }
    else if (fixedcolormap)
    {
	// fixed color
	vis->colormap = fixedcolormap;
    }
    else if (psp->state->frame & FF_FULLBRIGHT)
    {
	// full bright
	vis->colormap = colormaps;
    }
    else
    {
	// local light
	vis->colormap = spritelights[MAXLIGHTSCALE-1];
    }
	
    R_DrawVisSprite (vis, vis->x1, vis->x2);
}



//
// R_DrawPlayerSprites
//
void R_DrawPlayerSprites (void)
{
    int		i;
    int		lightnum;
    pspdef_t*	psp;
    
    // get light level
    lightnum =
	(viewplayer->mo->subsector->sector->lightlevel >> LIGHTSEGSHIFT) 
	+extralight;

    if (lightnum < 0)		
	spritelights = scalelight[0];
    else if (lightnum >= LIGHTLEVELS)
	spritelights = scalelight[LIGHTLEVELS-1];
    else
	spritelights = scalelight[lightnum];
    
    // clip to screen bounds
    mfloorclip = screenheightarray;
    mceilingclip = negonearray;
    
    // add all active psprites
    for (i=0, psp=viewplayer->psprites;
	 i<NUMPSPRITES;
	 i++,psp++)
    {
	if (psp->state)
	    R_DrawPSprite (psp);
    }
}




//
// R_SortVisSprites
//
vissprite_t	vsprsortedhead;


void R_SortVisSprites (void)
{
    int			i;
    int			count;
    vissprite_t*	ds;
    vissprite_t*	best;
    vissprite_t		unsorted;
    fixed_t		bestscale;

    count = vissprite_p - vissprites;
	
    unsorted.next = unsorted.prev = &unsorted;

    if (!count)
	return;
		
    for (ds=vissprites ; ds<vissprite_p ; ds++)
    {
	ds->next = ds+1;
	ds->prev = ds-1;
    }
    
    vissprites[0].prev = &unsorted;
    unsorted.next = &vissprites[0];
    (vissprite_p-1)->next = &unsorted;
    unsorted.prev = vissprite_p-1;
    
    // pull the vissprites out by scale
    //best = 0;		// shut up the compiler warning
    vsprsortedhead.next = vsprsortedhead.prev = &vsprsortedhead;
    for (i=0 ; i<count ; i++)
    {
	bestscale = MAXINT;
	for (ds=unsorted.next ; ds!= &unsorted ; ds=ds->next)
	{
	    if (ds->scale < bestscale)
	    {
		bestscale = ds->scale;
		best = ds;
	    }
	}
	best->next->prev = best->prev;
	best->prev->next = best->next;
	best->next = &vsprsortedhead;
	best->prev = vsprsortedhead.prev;
	vsprsortedhead.prev->next = best;
	vsprsortedhead.prev = best;
    }
}



//
// R_DrawSprite
//
void R_DrawSprite (vissprite_t* spr)
{
    drawseg_t*		ds;
    short		clipbot[SCREENWIDTH];
    short		cliptop[SCREENWIDTH];
    int			x;
    int			r1;
    int			r2;
    fixed_t		scale;
    fixed_t		lowscale;
    int			silhouette;
		
    for (x = spr->x1 ; x<=spr->x2 ; x++)
	clipbot[x] = cliptop[x] = -2;
    
    // Scan drawsegs from end to start for obscuring segs.
    // The first drawseg that has a greater scale
    //  is the clip seg.
    for (ds=ds_p-1 ; ds >= drawsegs ; ds--)
    {
	// determine if the drawseg obscures the sprite
	if (ds->x1 > spr->x2
	    || ds->x2 < spr->x1
	    || (!ds->silhouette
		&& !ds->maskedtexturecol) )
	{
	    // does not cover sprite
	    continue;
	}
			
	r1 = ds->x1 < spr->x1 ? spr->x1 : ds->x1;
	r2 = ds->x2 > spr->x2 ? spr->x2 : ds->x2;

	if (ds->scale1 > ds->scale2)
	{
	    lowscale = ds->scale2;
	    scale = ds->scale1;
	}
	else
	{
	    lowscale = ds->scale1;
	    scale = ds->scale2;
	}
		
	if (scale < spr->scale
	    || ( lowscale < spr->scale
		 && !R_PointOnSegSide (spr->gx, spr->gy, ds->curline) ) )
	{
	    // masked mid texture?
	    if (ds->maskedtexturecol)	
		R_RenderMaskedSegRange (ds, r1, r2);
	    // seg is behind sprite
	    continue;			
	}

	
	// clip this piece of the sprite
	silhouette = ds->silhouette;
	
	if (spr->gz >= ds->bsilheight)
	    silhouette &= ~SIL_BOTTOM;

	if (spr->gzt <= ds->tsilheight)
	    silhouette &= ~SIL_TOP;
			
	if (silhouette == 1)
	{
	    // bottom sil
	    for (x=r1 ; x<=r2 ; x++)
		if (clipbot[x] == -2)
		    clipbot[x] = ds->sprbottomclip[x];
	}
	else if (silhouette == 2)
	{
	    // top sil
	    for (x=r1 ; x<=r2 ; x++)
		if (cliptop[x] == -2)
		    cliptop[x] = ds->sprtopclip[x];
	}
	else if (silhouette == 3)
	{
	    // both
	    for (x=r1 ; x<=r2 ; x++)
	    {
		if (clipbot[x] == -2)
		    clipbot[x] = ds->sprbottomclip[x];
		if (cliptop[x] == -2)
		    cliptop[x] = ds->sprtopclip[x];
	    }
	}
		
    }
    
    // all clipping has been performed, so draw the sprite

    // check for unclipped columns
    for (x = spr->x1 ; x<=spr->x2 ; x++)
    {
	if (clipbot[x] == -2)		
	    clipbot[x] = viewheight;

	if (cliptop[x] == -2)
	    cliptop[x] = -1;
    }
		
    mfloorclip = clipbot;
    mceilingclip = cliptop;
    R_DrawVisSprite (spr, spr->x1, spr->x2);
}




//
// R_DrawMasked
//
void R_DrawMasked (void)
{
    vissprite_t*	spr;
    drawseg_t*		ds;
	
    R_SortVisSprites ();

    if (vissprite_p > vissprites)
    {
	// draw all vissprites back to front
	for (spr = vsprsortedhead.next ;
	     spr != &vsprsortedhead ;
	     spr=spr->next)
	{
	    
	    R_DrawSprite (spr);
	}
    }
    
    // render any remaining masked mid textures
    for (ds=ds_p-1 ; ds >= drawsegs ; ds--)
	if (ds->maskedtexturecol)
	    R_RenderMaskedSegRange (ds, ds->x1, ds->x2);
    
    // draw the psprites on top of everything
    //  but does not draw on side views
    if (!viewangleoffset)		
	R_DrawPlayerSprites ();
}