path: root/apps/plugins/doom/r_things.c

/* Emacs style mode select   -*- C++ -*-
 *-----------------------------------------------------------------------------
 *
 *
 *  PrBoom a Doom port merged with LxDoom and LSDLDoom
 *  based on BOOM, a modified and improved DOOM engine
 *  Copyright (C) 1999 by
 *  id Software, Chi Hoang, Lee Killough, Jim Flynn, Rand Phares, Ty Halderman
 *  Copyright (C) 1999-2000 by
 *  Jess Haas, Nicolas Kalkhof, Colin Phipps, Florian Schulze
 *
 *  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.
 *
 * DESCRIPTION:
 *  Refresh of things, i.e. objects represented by sprites.
 *
 *-----------------------------------------------------------------------------*/

#include "doomdef.h"
#include "m_swap.h"

#include "doomstat.h"
#include "w_wad.h"
#include "r_main.h"
#include "r_bsp.h"
#include "r_segs.h"
#include "r_draw.h"
#include "r_things.h"
#include "i_system.h"
//#include "lprintf.h"
#include "rockmacros.h"

#define MINZ    (FRACUNIT*4)
#define BASEYCENTER   100

typedef struct {
   int x1;
   int x2;
   int column;
   int topclip;
   int bottomclip;
}
maskdraw_t;

//
// Sprite rotation 0 is facing the viewer,
//  rotation 1 is one angle turn CLOCKWISE around the axis.
// This is not the same as the angle,
//  which increases counter clockwise (protractor).
// There was a lot of stuff grabbed wrong, so I changed it...
//
fixed_t  pspritescale;
fixed_t  pspriteiscale;
// proff 11/06/98: Added for high-res
fixed_t pspriteyscale;

static lighttable_t** spritelights;

// constant arrays
//  used for psprite clipping and initializing clipping
short  negonearray[MAX_SCREENWIDTH];
short  screenheightarray[MAX_SCREENWIDTH];


//
// INITIALIZATION FUNCTIONS
//

// variables used to look up and range check thing_t sprites patches

spritedef_t* sprites;
int  numsprites;

#define MAX_SPRITE_FRAMES 29          /* Macroized -- killough 1/25/98 */

static spriteframe_t sprtemp[MAX_SPRITE_FRAMES];
static int maxframe;

//
// R_InstallSpriteLump
// Local function for R_InitSprites.
//

static void R_InstallSpriteLump(int lump, unsigned frame,
                                unsigned rotation, boolean flipped)
{

   if (frame >= MAX_SPRITE_FRAMES || rotation > 8)
      I_Error("R_InstallSpriteLump: Bad frame characters in lump %i", lump);

   if ((int)frame > maxframe)
      maxframe = frame;

   if (rotation == 0)
   {    // the lump should be used for all rotations
      int r;
      for (r=0 ; r<8 ; r++)
         if (sprtemp[frame].lump[r]==-1)
         {
            sprtemp[frame].lump[r] = lump - firstspritelump;
            sprtemp[frame].flip[r] = (byte) flipped;
            sprtemp[frame].rotate = false; //jff 4/24/98 if any subbed, rotless
         }
      return;
   }

   // the lump is only used for one rotation

   if (sprtemp[frame].lump[--rotation] == -1)
   {
      sprtemp[frame].lump[rotation] = lump - firstspritelump;
      sprtemp[frame].flip[rotation] = (byte) flipped;
      sprtemp[frame].rotate = true; //jff 4/24/98 only change if rot used
   }
}

//
// R_InitSpriteDefs
// Pass a null terminated list of sprite names
// (4 chars exactly) to be used.
//
// Builds the sprite rotation matrixes to account
// for horizontally flipped sprites.
//
// Will report an error if the lumps are inconsistent.
// Only called at startup.
//
// Sprite lump names are 4 characters for the actor,
//  a letter for the frame, and a number for the rotation.
//
// A sprite that is flippable will have an additional
//  letter/number appended.
//
// The rotation character can be 0 to signify no rotations.
//
// 1/25/98, 1/31/98 killough : Rewritten for performance
//
// Empirically verified to have excellent hash
// properties across standard Doom sprites:

#define R_SpriteNameHash(s) ((unsigned)((s)[0]-((s)[1]*3-(s)[3]*2-(s)[2])*2))

void R_InitSpriteDefs(const char * const * namelist)
{
   size_t numentries = lastspritelump-firstspritelump+1;
   struct {
      int index, next;
   }
   *hash;
   int i;

   if (!numentries || !*namelist)
      return;

   // count the number of sprite names
   for (i=0; namelist[i]; i++)
      ;

   numsprites = i;

   sprites = Z_Malloc(numsprites *sizeof(*sprites), PU_STATIC, NULL);

   // Create hash table based on just the first four letters of each sprite
   // killough 1/31/98

   hash = malloc(sizeof(*hash)*numentries); // allocate hash table

   for (i=0; (size_t)i<numentries; i++)             // initialize hash table as empty
      hash[i].index = -1;

   for (i=0; (size_t)i<numentries; i++)             // Prepend each sprite to hash chain
   {                                      // prepend so that later ones win
      int j = R_SpriteNameHash(lumpinfo[i+firstspritelump].name) % numentries;
      hash[i].next = hash[j].index;
      hash[j].index = i;
   }

   // scan all the lump names for each of the names,
   //  noting the highest frame letter.

   for (i=0 ; i<numsprites ; i++)
   {
      const char *spritename = namelist[i];
      int j = hash[R_SpriteNameHash(spritename) % numentries].index;

      if (j >= 0)
      {
         memset(sprtemp, -1, sizeof(sprtemp));
         maxframe = -1;
         do
         {
            register lumpinfo_t *lump = lumpinfo + j + firstspritelump;

            // Fast portable comparison -- killough
            // (using int pointer cast is nonportable):

            if (!((lump->name[0] ^ spritename[0]) |
                  (lump->name[1] ^ spritename[1]) |
                  (lump->name[2] ^ spritename[2]) |
                  (lump->name[3] ^ spritename[3])))
            {
               R_InstallSpriteLump(j+firstspritelump,
                                   lump->name[4] - 'A',
                                   lump->name[5] - '0',
                                   false);
               if (lump->name[6])
                  R_InstallSpriteLump(j+firstspritelump,
                                      lump->name[6] - 'A',
                                      lump->name[7] - '0',
                                      true);
            }
         }
         while ((j = hash[j].next) >= 0)
            ;

         // check the frames that were found for completeness
         if ((sprites[i].numframes = ++maxframe))  // killough 1/31/98
         {
            int frame;
            for (frame = 0; frame < maxframe; frame++)
               switch ((int) sprtemp[frame].rotate)
               {
               case -1:
                  // no rotations were found for that frame at all
                  I_Error ("R_InitSprites: No patches found "
                           "for %.8s frame %c", namelist[i], frame+'A');
                  break;

               case 0:
                  // only the first rotation is needed
                  break;

               case 1:
                  // must have all 8 frames
                  {
                     int rotation;
                     for (rotation=0 ; rotation<8 ; rotation++)
                        if (sprtemp[frame].lump[rotation] == -1)
                           I_Error ("R_InitSprites: Sprite %.8s frame %c "
                                    "is missing rotations",
                                    namelist[i], frame+'A');
                     break;
                  }
               }
            // allocate space for the frames present and copy sprtemp to it
            sprites[i].spriteframes =
               Z_Malloc (maxframe * sizeof(spriteframe_t), PU_STATIC, NULL);
            memcpy (sprites[i].spriteframes, sprtemp,
                    maxframe*sizeof(spriteframe_t));
         }
      }
   }
   free(hash);             // free hash table
}

//
// GAME FUNCTIONS
//

static vissprite_t *vissprites, **vissprite_ptrs;  // killough
static size_t num_vissprite, num_vissprite_alloc, num_vissprite_ptrs;


//
// R_InitSprites
// Called at program start.
//
void R_InitSprites(const char * const *namelist)
{
   int  i;

   for (i=0 ; i<MAX_SCREENWIDTH ; i++)
      negonearray[i] = -1;
   R_InitSpriteDefs (namelist);
}

void R_ClearSprites (void)
{
   num_vissprite = 0;            // killough
}

//
// R_NewVisSprite
//

vissprite_t *R_NewVisSprite(void)
{
   if (num_vissprite >= num_vissprite_alloc)             // killough
   {
      num_vissprite_alloc = num_vissprite_alloc ? num_vissprite_alloc*2 : 128;
      vissprites = realloc(vissprites,num_vissprite_alloc*sizeof(*vissprites));
   }
   return vissprites + num_vissprite++;
}

//
// R_DrawMaskedColumn
// Used for sprites and masked mid textures.
// Masked means: partly transparent, i.e. stored
//  in posts/runs of opaque pixels.
//

short*  mfloorclip;
short*  mceilingclip;
fixed_t  spryscale;
fixed_t  sprtopscreen;

void R_DrawMaskedColumn(const column_t *column)
{
   int     topscreen;
   int     bottomscreen;
   fixed_t basetexturemid = dc_texturemid;

   dc_texheight = 0; // killough 11/98
   while (column->topdelta != 0xff)
   {
      // calculate unclipped screen coordinates for post
      topscreen = sprtopscreen + spryscale*column->topdelta;
      bottomscreen = topscreen + spryscale*column->length;

      dc_yl = (topscreen+FRACUNIT-1)>>FRACBITS;
      dc_yh = (bottomscreen-1)>>FRACBITS;

      if (dc_yh >= mfloorclip[dc_x])
         dc_yh = mfloorclip[dc_x]-1;

      if (dc_yl <= mceilingclip[dc_x])
         dc_yl = mceilingclip[dc_x]+1;

      // killough 3/2/98, 3/27/98: Failsafe against overflow/crash:
      if (dc_yl <= dc_yh && dc_yh < viewheight)
      {
         dc_source = (byte *)column + 3;
         dc_texturemid = basetexturemid - (column->topdelta<<FRACBITS);

         // Drawn by either R_DrawColumn
         //  or (SHADOW) R_DrawFuzzColumn.
         colfunc ();
      }
      column = (const column_t *)(  (byte *)column + column->length + 4);
   }
   dc_texturemid = basetexturemid;
}

//
// R_DrawVisSprite
//  mfloorclip and mceilingclip should also be set.
//
// CPhipps - new wad lump handling, *'s to const*'s
void R_DrawVisSprite(vissprite_t *vis, int x1, int x2)
{
   (void)x1;
   (void)x2;
   const column_t *column;
   int      texturecolumn;
   fixed_t  frac;
   const patch_t *patch = W_CacheLumpNum (vis->patch+firstspritelump);

   dc_colormap = vis->colormap;

   // killough 4/11/98: rearrange and handle translucent sprites
   // mixed with translucent/non-translucenct 2s normals

   if (!dc_colormap)   // NULL colormap = shadow draw
      colfunc = R_DrawFuzzColumn;    // killough 3/14/98
   else
      if (vis->mobjflags & MF_TRANSLATION)
      {
         colfunc = R_DrawTranslatedColumn;
         dc_translation = translationtables - 256 +
                          ((vis->mobjflags & MF_TRANSLATION) >> (MF_TRANSSHIFT-8) );
      }
      else
         if (vis->mobjflags & MF_TRANSLUCENT && general_translucency) // phares
         {
            colfunc = R_DrawTLColumn;
            tranmap = main_tranmap;       // killough 4/11/98
         }
         else
            colfunc = R_DrawColumn;         // killough 3/14/98, 4/11/98


   // proff 11/06/98: Changed for high-res
   dc_iscale = FixedDiv (FRACUNIT, vis->scale);
   dc_texturemid = vis->texturemid;
   frac = vis->startfrac;
   spryscale = vis->scale;
   sprtopscreen = centeryfrac - FixedMul(dc_texturemid,spryscale);

   for (dc_x=vis->x1 ; dc_x<=vis->x2 ; dc_x++, frac += vis->xiscale)
   {
      texturecolumn = frac>>FRACBITS;

#ifdef RANGECHECK

      if (texturecolumn < 0 || texturecolumn >= SHORT(patch->width))
         I_Error ("R_DrawSpriteRange: Bad texturecolumn");
#endif

      column = (const column_t *)((const byte *) patch +
                                  LONG(patch->columnofs[texturecolumn]));
      R_DrawMaskedColumn (column);
   }
   colfunc = R_DrawColumn;         // killough 3/14/98
   W_UnlockLumpNum(vis->patch+firstspritelump); // cph - release lump
}

//
// R_ProjectSprite
// Generates a vissprite for a thing if it might be visible.
//

void R_ProjectSprite (mobj_t* thing)
{
   fixed_t   gzt;               // killough 3/27/98
   fixed_t   tx;
   fixed_t   xscale;
   int       x1;
   int       x2;
   spritedef_t   *sprdef;
   spriteframe_t *sprframe;
   int       lump;
   boolean   flip;
   vissprite_t *vis;
#ifndef GL_DOOM

   fixed_t   iscale;
#endif

   int heightsec;      // killough 3/27/98

   // transform the origin point
   fixed_t tr_x = thing->x - viewx;
   fixed_t tr_y = thing->y - viewy;

   fixed_t gxt = FixedMul(tr_x,viewcos);
   fixed_t gyt = -FixedMul(tr_y,viewsin);

   fixed_t tz = gxt-gyt;

   // thing is behind view plane?
   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 (D_abs(tx)>(tz<<2))
      return;

   // decide which patch to use for sprite relative to player
#ifdef RANGECHECK

   if ((unsigned) thing->sprite >= (unsigned)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
      angle_t ang = R_PointToAngle(thing->x, thing->y);
      unsigned 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
    * cph 2003/08/1 - fraggle points out that this offset must be flipped if the
    * sprite is flipped; e.g. FreeDoom imp is messed up by this. */
   tx -= flip ? spritewidth[lump] - spriteoffset[lump] : 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;

   gzt = thing->z + spritetopoffset[lump];

   // killough 4/9/98: clip things which are out of view due to height
   if (thing->z > viewz + FixedDiv(centeryfrac, xscale) ||
         gzt      < viewz - FixedDiv(centeryfrac-viewheight, xscale))
      return;

   // killough 3/27/98: exclude things totally separated
   // from the viewer, by either water or fake ceilings
   // killough 4/11/98: improve sprite clipping for underwater/fake ceilings

   heightsec = thing->subsector->sector->heightsec;

   if (heightsec != -1)   // only clip things which are in special sectors
   {
      int phs = viewplayer->mo->subsector->sector->heightsec;
      if (phs != -1 && viewz < sectors[phs].floorheight ?
            thing->z >= sectors[heightsec].floorheight :
            gzt < sectors[heightsec].floorheight)
         return;
      if (phs != -1 && viewz > sectors[phs].ceilingheight ?
            gzt < sectors[heightsec].ceilingheight &&
            viewz >= sectors[heightsec].ceilingheight :
            thing->z >= sectors[heightsec].ceilingheight)
         return;
   }

   // store information in a vissprite
   vis = R_NewVisSprite ();

   // killough 3/27/98: save sector for special clipping later
   vis->heightsec = heightsec;

   vis->mobjflags = thing->flags;
   // proff 11/06/98: Changed for high-res
   vis->scale = FixedDiv(projectiony, tz);
   vis->gx = thing->x;
   vis->gy = thing->y;
   vis->gz = thing->z;
   vis->gzt = gzt;                          // killough 3/27/98
   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)
      vis->colormap = NULL;             // shadow draw
   else if (fixedcolormap)
      vis->colormap = fixedcolormap;      // fixed map
   else if (thing->frame & FF_FULLBRIGHT)
      vis->colormap = fullcolormap;     // full bright  // killough 3/20/98
   else
   {      // diminished light
      int index = xscale>>LIGHTSCALESHIFT;
      if (index >= MAXLIGHTSCALE)
         index = MAXLIGHTSCALE-1;
      vis->colormap = spritelights[index];
   }
}

//
// R_AddSprites
// During BSP traversal, this adds sprites by sector.
//
// killough 9/18/98: add lightlevel as parameter, fixing underwater lighting
void R_AddSprites(subsector_t* subsec, int lightlevel)
{
   sector_t* sec=subsec->sector;
   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 = (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, 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 >= (unsigned)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 : %li",
               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;
   // killough 12/98: fix psprite positioning problem
   vis->texturemid = (BASEYCENTER<<FRACBITS) /* +  FRACUNIT/2 */ -
                     (psp->sy-spritetopoffset[lump]);
   vis->x1 = x1 < 0 ? 0 : x1;
   vis->x2 = x2 >= viewwidth ? viewwidth-1 : x2;
   // proff 11/06/98: Added for high-res
   vis->scale = pspriteyscale;

   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)
      vis->colormap = NULL;                    // shadow draw
   else if (fixedcolormap)
      vis->colormap = fixedcolormap;           // fixed color
   else if (psp->state->frame & FF_FULLBRIGHT)
      vis->colormap = fullcolormap;            // full bright // killough 3/20/98
   else
      vis->colormap = spritelights[MAXLIGHTSCALE-1];  // local light

   R_DrawVisSprite(vis, vis->x1, vis->x2);
}

//
// R_DrawPlayerSprites
//

void R_DrawPlayerSprites(void)
{
   int i, 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
//
// Rewritten by Lee Killough to avoid using unnecessary
// linked lists, and to use faster sorting algorithm.
//

#define bcopyp(d, s, n) memcpy(d, s, (n) * sizeof(void *))

// killough 9/2/98: merge sort

static void msort(vissprite_t **s, vissprite_t **t, int n)
{
   if (n >= 16)
   {
      int n1 = n/2, n2 = n - n1;
      vissprite_t **s1 = s, **s2 = s + n1, **d = t;

      msort(s1, t, n1);
      msort(s2, t, n2);

      while ((*s1)->scale > (*s2)->scale ?
             (*d++ = *s1++, --n1) : (*d++ = *s2++, --n2))
         ;

      if (n2)
         bcopyp(d, s2, n2);
      else
         bcopyp(d, s1, n1);

      bcopyp(s, t, n);
   }
   else
   {
      int i;
      for (i = 1; i < n; i++)
      {
         vissprite_t *temp = s[i];
         if (s[i-1]->scale < temp->scale)
         {
            int j = i;
            while ((s[j] = s[j-1])->scale < temp->scale && --j)
               ;
            s[j] = temp;
         }
      }
   }
}

void R_SortVisSprites (void)
{
   if (num_vissprite)
   {
      int i = num_vissprite;

      // If we need to allocate more pointers for the vissprites,
      // allocate as many as were allocated for sprites -- killough
      // killough 9/22/98: allocate twice as many

      if (num_vissprite_ptrs < num_vissprite*2)
      {
         free(vissprite_ptrs);  // better than realloc -- no preserving needed
         vissprite_ptrs = malloc((num_vissprite_ptrs = num_vissprite_alloc*2)
                                 * sizeof *vissprite_ptrs);
      }

      while (--i>=0)
         vissprite_ptrs[i] = vissprites+i;

      // killough 9/22/98: replace qsort with merge sort, since the keys
      // are roughly in order to begin with, due to BSP rendering.

      msort(vissprite_ptrs, vissprite_ptrs + num_vissprite, num_vissprite);
   }
}

//
// R_DrawSprite
//

void R_DrawSprite (vissprite_t* spr)
{
   drawseg_t *ds;
   short   clipbot[MAX_SCREENWIDTH];       // killough 2/8/98:
   short   cliptop[MAX_SCREENWIDTH];       // change to MAX_*
   int     x;
   int     r1;
   int     r2;
   fixed_t scale;
   fixed_t lowscale;

   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.

   // Modified by Lee Killough:
   // (pointer check was originally nonportable
   // and buggy, by going past LEFT end of array):

   //    for (ds=ds_p-1 ; ds >= drawsegs ; ds--)    old buggy code

   for (ds=ds_p ; ds-- > drawsegs ; )  // new -- killough
   {      // determine if the drawseg obscures the sprite
      if (ds->x1 > spr->x2 || ds->x2 < spr->x1 ||
            (!ds->silhouette && !ds->maskedtexturecol))
         continue;      // does not cover sprite

      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)))
      {
         if (ds->maskedtexturecol)       // masked mid texture?
            R_RenderMaskedSegRange(ds, r1, r2);
         continue;               // seg is behind sprite
      }

      // clip this piece of the sprite
      // killough 3/27/98: optimized and made much shorter

      if (ds->silhouette&SIL_BOTTOM && spr->gz < ds->bsilheight) //bottom sil
         for (x=r1 ; x<=r2 ; x++)
            if (clipbot[x] == -2)
               clipbot[x] = ds->sprbottomclip[x];

      if (ds->silhouette&SIL_TOP && spr->gzt > ds->tsilheight)   // top sil
         for (x=r1 ; x<=r2 ; x++)
            if (cliptop[x] == -2)
               cliptop[x] = ds->sprtopclip[x];
   }

   // killough 3/27/98:
   // Clip the sprite against deep water and/or fake ceilings.
   // killough 4/9/98: optimize by adding mh
   // killough 4/11/98: improve sprite clipping for underwater/fake ceilings
   // killough 11/98: fix disappearing sprites

   if (spr->heightsec != -1)  // only things in specially marked sectors
   {
      fixed_t h,mh;
      int phs = viewplayer->mo->subsector->sector->heightsec;
      if ((mh = sectors[spr->heightsec].floorheight) > spr->gz &&
            (h = centeryfrac - FixedMul(mh-=viewz, spr->scale)) >= 0 &&
            (h >>= FRACBITS) < viewheight)
      {
         if (mh <= 0 || (phs != -1 && viewz > sectors[phs].floorheight))
         {                          // clip bottom
            for (x=spr->x1 ; x<=spr->x2 ; x++)
               if (clipbot[x] == -2 || h < clipbot[x])
                  clipbot[x] = h;
         }
         else                        // clip top
            if (phs != -1 && viewz <= sectors[phs].floorheight) // killough 11/98
               for (x=spr->x1 ; x<=spr->x2 ; x++)
                  if (cliptop[x] == -2 || h > cliptop[x])
                     cliptop[x] = h;
      }

      if ((mh = sectors[spr->heightsec].ceilingheight) < spr->gzt &&
            (h = centeryfrac - FixedMul(mh-viewz, spr->scale)) >= 0 &&
            (h >>= FRACBITS) < viewheight)
      {
         if (phs != -1 && viewz >= sectors[phs].ceilingheight)
         {                         // clip bottom
            for (x=spr->x1 ; x<=spr->x2 ; x++)
               if (clipbot[x] == -2 || h < clipbot[x])
                  clipbot[x] = h;
         }
         else                       // clip top
            for (x=spr->x1 ; x<=spr->x2 ; x++)
               if (cliptop[x] == -2 || h > cliptop[x])
                  cliptop[x] = h;
      }
   }
   // killough 3/27/98: end special clipping for deep water / fake ceilings

   // 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)
{
   int i;
   drawseg_t *ds;

   R_SortVisSprites();

   // draw all vissprites back to front

   //   rendered_vissprites = num_vissprite;
   for (i = num_vissprite ;--i>=0; )
      R_DrawSprite(vissprite_ptrs[i]);         // killough

   // render any remaining masked mid textures

   // Modified by Lee Killough:
   // (pointer check was originally nonportable
   // and buggy, by going past LEFT end of array):

   //    for (ds=ds_p-1 ; ds >= drawsegs ; ds--)    old buggy code

   for (ds=ds_p ; ds-- > drawsegs ; )  // new -- killough
      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 ();
}