Render precip through blockmap instead of during BSP

There can be very many precipmobjs in a sector. During BSP
rendering, for each sector reached by BSP (the entire
visible level at least), all the precipmobjs would be
iterated and their distance from the camera calculated, to
determine whether they are within draw distance.

The issue with the old approach is that there really are
too many precipmobjs in each sector. By iterating the
blockmap within a certain range instead, precipmobjs
out of view are not iterated at all, saving some time.

Caveat: drawdist_precip is no longer respected as an
exact value, since it must round to the precision of the
blockmap.

List of potentially scary changes:

- Removes snext/sprev for precipmobj_t
- Removes preciplist for sector_t

- Adds bnext/bprev for precipmobj_t
  - mobj_t and precipmobj_t field offsets are symmetrical

- Modified P_SetPrecipitationThingPosition and P_SetThingPosition
  - The syntax in these functions is kind of wacky

src/hardware/hw_main.c

@@ -69,6 +69,7 @@ struct hwdriver_s hwdriver;
 static void HWR_AddSprites(sector_t *sec);
 static void HWR_ProjectSprite(mobj_t *thing);
 #ifdef HWPRECIP
+static void HWR_AddPrecipitationSprites(void);
 static void HWR_ProjectPrecipitationSprite(precipmobj_t *thing);
 #endif
 static void HWR_ProjectBoundingBox(mobj_t *thing);
@@ -5052,9 +5053,6 @@ static UINT8 sectorlight;
 static void HWR_AddSprites(sector_t *sec)
 {
 	mobj_t *thing;
-#ifdef HWPRECIP
-	precipmobj_t *precipthing;
-#endif
 	fixed_t limit_dist;
 
 	// BSP is traversed by subsector.
@@ -5085,19 +5083,45 @@ static void HWR_AddSprites(sector_t *sec)
 			HWR_ProjectBoundingBox(thing);
 		}
 	}
+}
 
 #ifdef HWPRECIP
+// --------------------------------------------------------------------------
+// HWR_AddPrecipitationSprites
+// This renders through the blockmap instead of BSP to avoid
+// iterating a huge amount of precipitation sprites in sectors
+// that are beyond drawdist.
+// --------------------------------------------------------------------------
+static void HWR_AddPrecipitationSprites(void)
+{
+	const fixed_t drawdist = cv_drawdist_precip.value * mapobjectscale;
+
+	INT32 xl, xh, yl, yh, bx, by;
+	precipmobj_t *th;
+
 	// no, no infinite draw distance for precipitation. this option at zero is supposed to turn it off
-	if ((limit_dist = (fixed_t)cv_drawdist_precip.value * mapobjectscale))
+	if (drawdist == 0)
 	{
-		for (precipthing = sec->preciplist; precipthing; precipthing = precipthing->snext)
+		return;
+	}
+
+	R_GetRenderBlockMapDimensions(drawdist, &xl, &xh, &yl, &yh);
+
+	for (bx = xl; bx <= xh; bx++)
+	{
+		for (by = yl; by <= yh; by++)
 		{
-			if (R_PrecipThingVisible(precipthing, limit_dist))
-				HWR_ProjectPrecipitationSprite(precipthing);
+			for (th = precipblocklinks[(by * bmapwidth) + bx]; th; th = th->bnext)
+			{
+				if (R_PrecipThingVisible(th))
+				{
+					HWR_ProjectPrecipitationSprite(th);
+				}
+			}
 		}
 	}
-#endif
 }
+#endif
 
 // --------------------------------------------------------------------------
 // HWR_ProjectSprite
@@ -6315,6 +6339,10 @@ static void HWR_RenderViewpoint(player_t *player, boolean drawSkyTexture, boolea
 
 	HWR_RenderBSPNode((INT32)numnodes-1);
 
+#ifdef HWPRECIP
+	HWR_AddPrecipitationSprites();
+#endif
+
 #ifndef NEWCLIP
 	// Make a viewangle int so we can render things based on mouselook
 	viewangle = localaiming[viewssnum];

src/p_local.h

@@ -510,6 +510,7 @@ extern INT32 bmapheight; // in mapblocks
 extern fixed_t bmaporgx;
 extern fixed_t bmaporgy; // origin of block map
 extern mobj_t **blocklinks; // for thing chains
+extern precipmobj_t **precipblocklinks; // special blockmap for precip rendering
 
 extern struct minimapinfo
 {

src/p_maputl.c

@@ -1006,15 +1006,45 @@ void P_UnsetThingPosition(mobj_t *thing)
 
 void P_UnsetPrecipThingPosition(precipmobj_t *thing)
 {
-	precipmobj_t **sprev = thing->sprev;
-	precipmobj_t  *snext = thing->snext;
-	if ((*sprev = snext) != NULL)  // unlink from sector list
-		snext->sprev = sprev;
+	precipmobj_t **bprev = thing->bprev;
+	precipmobj_t  *bnext = thing->bnext;
+
+	if (bprev && (*bprev = bnext) != NULL)  // unlink from block map
+		bnext->bprev = bprev;
 
 	precipsector_list = thing->touching_sectorlist;
 	thing->touching_sectorlist = NULL; //to be restored by P_SetPrecipThingPosition
 }
 
+static void P_LinkToBlockMap(mobj_t *thing, mobj_t **bmap)
+{
+	const INT32 blockx = (unsigned)(thing->x - bmaporgx) >> MAPBLOCKSHIFT;
+	const INT32 blocky = (unsigned)(thing->y - bmaporgy) >> MAPBLOCKSHIFT;
+
+	if (blockx >= 0 && blockx < bmapwidth
+		&& blocky >= 0 && blocky < bmapheight)
+	{
+		// killough 8/11/98: simpler scheme using
+		// pointer-to-pointer prev pointers --
+		// allows head nodes to be treated like everything else
+
+		mobj_t **link = &bmap[(blocky * bmapwidth) + blockx];
+		mobj_t *bnext = *link;
+
+		thing->bnext = bnext;
+
+		if (bnext != NULL)
+			bnext->bprev = &thing->bnext;
+
+		thing->bprev = link;
+		*link = thing;
+	}
+	else // thing is off the map
+	{
+		thing->bnext = NULL, thing->bprev = NULL;
+	}
+}
+
 //
 // P_SetThingPosition
 // Links a thing into both a block and a subsector
@@ -1071,24 +1101,7 @@ void P_SetThingPosition(mobj_t *thing)
 	if (!(thing->flags & MF_NOBLOCKMAP))
 	{
 		// inert things don't need to be in blockmap
-		const INT32 blockx = (unsigned)(thing->x - bmaporgx)>>MAPBLOCKSHIFT;
-		const INT32 blocky = (unsigned)(thing->y - bmaporgy)>>MAPBLOCKSHIFT;
-		if (blockx >= 0 && blockx < bmapwidth
-			&& blocky >= 0 && blocky < bmapheight)
-		{
-			// killough 8/11/98: simpler scheme using
-			// pointer-to-pointer prev pointers --
-			// allows head nodes to be treated like everything else
-
-			mobj_t **link = &blocklinks[blocky*bmapwidth + blockx];
-			mobj_t *bnext = *link;
-			if ((thing->bnext = bnext) != NULL)
-				bnext->bprev = &thing->bnext;
-			thing->bprev = link;
-			*link = thing;
-		}
-		else // thing is off the map
-			thing->bnext = NULL, thing->bprev = NULL;
+		P_LinkToBlockMap(thing, blocklinks);
 	}
 
 	// Allows you to 'step' on a new linedef exec when the previous
@@ -1143,18 +1156,15 @@ void P_SetUnderlayPosition(mobj_t *thing)
 
 void P_SetPrecipitationThingPosition(precipmobj_t *thing)
 {
-	subsector_t *ss = thing->subsector = R_PointInSubsector(thing->x, thing->y);
-
-	precipmobj_t **link = &ss->sector->preciplist;
-	precipmobj_t *snext = *link;
-	if ((thing->snext = snext) != NULL)
-		snext->sprev = &thing->snext;
-	thing->sprev = link;
-	*link = thing;
+	thing->subsector = R_PointInSubsector(thing->x, thing->y);
 
 	P_CreatePrecipSecNodeList(thing, thing->x, thing->y);
 	thing->touching_sectorlist = precipsector_list; // Attach to Thing's precipmobj_t
 	precipsector_list = NULL; // clear for next time
+
+	// NOTE: this works because bnext/bprev are at the same
+	// offsets in precipmobj_t and mobj_t
+	P_LinkToBlockMap((mobj_t*)thing, (mobj_t**)precipblocklinks);
 }
 
 //

src/p_mobj.h

@@ -291,9 +291,10 @@ struct mobj_t
 	mobjtype_t type;
 	const mobjinfo_t *info; // &mobjinfo[mobj->type]
 
-	// More list: links in sector (if needed)
-	mobj_t *snext;
-	mobj_t **sprev; // killough 8/11/98: change to ptr-to-ptr
+	// Interaction info, by BLOCKMAP.
+	// Links in blocks (if needed).
+	mobj_t *bnext;
+	mobj_t **bprev; // killough 8/11/98: change to ptr-to-ptr
 
 	// More drawing info: to determine current sprite.
 	angle_t angle, pitch, roll; // orientation
@@ -347,10 +348,9 @@ struct mobj_t
 	//  using an internal color lookup table for re-indexing.
 	UINT16 color; // This replaces MF_TRANSLATION. Use 0 for default (no translation).
 
-	// Interaction info, by BLOCKMAP.
-	// Links in blocks (if needed).
-	mobj_t *bnext;
-	mobj_t **bprev; // killough 8/11/98: change to ptr-to-ptr
+	// More list: links in sector (if needed)
+	mobj_t *snext;
+	mobj_t **sprev; // killough 8/11/98: change to ptr-to-ptr
 
 	// Additional pointers for NiGHTS hoops
 	mobj_t *hnext;
@@ -448,9 +448,10 @@ struct precipmobj_t
 	mobjtype_t type;
 	const mobjinfo_t *info; // &mobjinfo[mobj->type]
 
-	// More list: links in sector (if needed)
-	precipmobj_t *snext;
-	precipmobj_t **sprev; // killough 8/11/98: change to ptr-to-ptr
+	// Links in blocks (if needed).
+	// The blockmap is only used by precip to render.
+	precipmobj_t *bnext;
+	precipmobj_t **bprev; // killough 8/11/98: change to ptr-to-ptr
 
 	// More drawing info: to determine current sprite.
 	angle_t angle, pitch, roll; // orientation

src/p_setup.c

@@ -160,6 +160,7 @@ INT32 *blockmaplump; // Big blockmap
 fixed_t bmaporgx, bmaporgy;
 // for thing chains
 mobj_t **blocklinks;
+precipmobj_t **precipblocklinks;
 
 // REJECT
 // For fast sight rejection.
@@ -881,7 +882,6 @@ static void P_InitializeSector(sector_t *ss)
 
 	ss->floorspeed = ss->ceilspeed = 0;
 
-	ss->preciplist = NULL;
 	ss->touching_preciplist = NULL;
 
 	ss->f_slope = NULL;
@@ -3546,6 +3546,10 @@ static boolean P_LoadBlockMap(UINT8 *data, size_t count)
 	// haleyjd 2/22/06: setup polyobject blockmap
 	count = sizeof(*polyblocklinks) * bmapwidth * bmapheight;
 	polyblocklinks = Z_Calloc(count, PU_LEVEL, NULL);
+
+	count = sizeof (*precipblocklinks)* bmapwidth*bmapheight;
+	precipblocklinks = Z_Calloc(count, PU_LEVEL, NULL);
+
 	return true;
 }
 
@@ -3799,6 +3803,9 @@ static void P_CreateBlockMap(void)
 		// haleyjd 2/22/06: setup polyobject blockmap
 		count = sizeof(*polyblocklinks) * bmapwidth * bmapheight;
 		polyblocklinks = Z_Calloc(count, PU_LEVEL, NULL);
+
+		count = sizeof (*precipblocklinks)* bmapwidth*bmapheight;
+		precipblocklinks = Z_Calloc(count, PU_LEVEL, NULL);
 	}
 }
 

src/r_defs.h

@@ -524,7 +524,6 @@ struct sector_t
 	fixed_t floorspeed, ceilspeed;
 
 	// list of precipitation mobjs in sector
-	precipmobj_t *preciplist;
 	mprecipsecnode_t *touching_preciplist;
 
 	// Eternity engine slope

src/r_main.c

@@ -493,6 +493,33 @@ boolean R_DoCulling(line_t *cullheight, line_t *viewcullheight, fixed_t vz, fixe
 	return false;
 }
 
+// Returns search dimensions within a blockmap, in the direction of viewangle and out to a certain distance.
+void R_GetRenderBlockMapDimensions(fixed_t drawdist, INT32 *xl, INT32 *xh, INT32 *yl, INT32 *yh)
+{
+	const angle_t left = viewangle - clipangle[viewssnum];
+	const angle_t right = viewangle + clipangle[viewssnum];
+
+	const fixed_t vxleft = viewx + FixedMul(drawdist, FCOS(left));
+	const fixed_t vyleft = viewy + FixedMul(drawdist, FSIN(left));
+
+	const fixed_t vxright = viewx + FixedMul(drawdist, FCOS(right));
+	const fixed_t vyright = viewy + FixedMul(drawdist, FSIN(right));
+
+	// Try to narrow the search to within only the field of view
+	*xl = (unsigned)(min(viewx, min(vxleft, vxright)) - bmaporgx)>>MAPBLOCKSHIFT;
+	*xh = (unsigned)(max(viewx, max(vxleft, vxright)) - bmaporgx)>>MAPBLOCKSHIFT;
+	*yl = (unsigned)(min(viewy, min(vyleft, vyright)) - bmaporgy)>>MAPBLOCKSHIFT;
+	*yh = (unsigned)(max(viewy, max(vyleft, vyright)) - bmaporgy)>>MAPBLOCKSHIFT;
+
+	if (*xh >= bmapwidth)
+		*xh = bmapwidth - 1;
+
+	if (*yh >= bmapheight)
+		*yh = bmapheight - 1;
+
+	BMBOUNDFIX(*xl, *xh, *yl, *yh);
+}
+
 //
 // R_InitTextureMapping
 //
@@ -1485,6 +1512,7 @@ static void R_RenderViewpoint(maskcount_t* mask)
 	curdrawsegs = ds_p;
 
 	R_RenderBSPNode((INT32)numnodes - 1);
+	R_AddPrecipitationSprites();
 
 	Mask_Post(mask);
 }
@@ -1556,7 +1584,6 @@ void R_RenderPlayerView(void)
 	ps_bsptime = I_GetPreciseTime();
 	R_RenderViewpoint(&masks[nummasks - 1]);
 	ps_bsptime = I_GetPreciseTime() - ps_bsptime;
-	ps_numsprites = visspritecount;
 #ifdef TIMING
 	RDMSR(0x10, &mycount);
 	mytotal += mycount; // 64bit add

src/r_main.h

@@ -87,6 +87,8 @@ subsector_t *R_PointInSubsectorOrNull(fixed_t x, fixed_t y);
 
 boolean R_DoCulling(line_t *cullheight, line_t *viewcullheight, fixed_t vz, fixed_t bottomh, fixed_t toph);
 
+void R_GetRenderBlockMapDimensions(fixed_t drawdist, INT32 *xl, INT32 *xh, INT32 *yl, INT32 *yh);
+
 // Render stats
 
 extern precise_t ps_prevframetime;// time when previous frame was rendered

src/r_things.c

@@ -2639,7 +2639,6 @@ weatherthink:
 void R_AddSprites(sector_t *sec, INT32 lightlevel)
 {
 	mobj_t *thing;
-	precipmobj_t *precipthing; // Tails 08-25-2002
 	INT32 lightnum;
 	fixed_t limit_dist;
 
@@ -2696,14 +2695,45 @@ void R_AddSprites(sector_t *sec, INT32 lightlevel)
 			}
 		}
 	}
+}
+
+// R_AddPrecipitationSprites
+// This renders through the blockmap instead of BSP to avoid
+// iterating a huge amount of precipitation sprites in sectors
+// that are beyond drawdist.
+//
+void R_AddPrecipitationSprites(void)
+{
+	const fixed_t drawdist = cv_drawdist_precip.value * mapobjectscale;
+
+	INT32 xl, xh, yl, yh, bx, by;
+	precipmobj_t *th;
 
 	// no, no infinite draw distance for precipitation. this option at zero is supposed to turn it off
-	if ((limit_dist = (fixed_t)cv_drawdist_precip.value * mapobjectscale) && !portalskipprecipmobjs)
+	if (drawdist == 0)
 	{
-		for (precipthing = sec->preciplist; precipthing; precipthing = precipthing->snext)
+		return;
+	}
+
+	// do not render in skybox
+	if (portalskipprecipmobjs)
+	{
+		return;
+	}
+
+	R_GetRenderBlockMapDimensions(drawdist, &xl, &xh, &yl, &yh);
+
+	for (bx = xl; bx <= xh; bx++)
+	{
+		for (by = yl; by <= yh; by++)
 		{
-			if (R_PrecipThingVisible(precipthing, limit_dist))
-				R_ProjectPrecipitationSprite(precipthing);
+			for (th = precipblocklinks[(by * bmapwidth) + bx]; th; th = th->bnext)
+			{
+				if (R_PrecipThingVisible(th))
+				{
+					R_ProjectPrecipitationSprite(th);
+				}
+			}
 		}
 	}
 }
@@ -3641,17 +3671,12 @@ boolean R_ThingWithinDist (mobj_t *thing, fixed_t limit_dist)
 }
 
 /* Check if precipitation may be drawn from our current view. */
-boolean R_PrecipThingVisible (precipmobj_t *precipthing,
-		fixed_t limit_dist)
+boolean R_PrecipThingVisible (precipmobj_t *precipthing)
 {
-	fixed_t approx_dist;
-
 	if (( precipthing->precipflags & PCF_INVISIBLE ))
 		return false;
 
-	approx_dist = P_AproxDistance(viewx-precipthing->x, viewy-precipthing->y);
-
-	return ( approx_dist <= limit_dist );
+	return true;
 }
 
 boolean R_ThingHorizontallyFlipped(mobj_t *thing)

src/r_things.h

@@ -67,6 +67,7 @@ fixed_t R_GetShadowZ(mobj_t *thing, pslope_t **shadowslope);
 
 //SoM: 6/5/2000: Light sprites correctly!
 void R_AddSprites(sector_t *sec, INT32 lightlevel);
+void R_AddPrecipitationSprites(void);
 void R_InitSprites(void);
 void R_ClearSprites(void);
 
@@ -78,8 +79,7 @@ boolean R_ThingVisible (mobj_t *thing);
 boolean R_ThingWithinDist (mobj_t *thing,
 		fixed_t        draw_dist);
 
-boolean R_PrecipThingVisible (precipmobj_t *precipthing,
-		fixed_t precip_draw_dist);
+boolean R_PrecipThingVisible (precipmobj_t *precipthing);
 
 boolean R_ThingHorizontallyFlipped (mobj_t *thing);
 boolean R_ThingVerticallyFlipped (mobj_t *thing);