- do some better sorting of slope sprites.

Splitting by translucent floor plane is essential, splitting by wall not that much - sorting by center point should be sufficient here.

source/core/rendering/scene/hw_drawinfo.h

@@ -110,6 +110,7 @@ struct HWDrawInfo
 	TArray<HWPortal *> Portals;
 	tspritetype tsprite[MAXSPRITESONSCREEN];
 	int spritesortcnt;
+	TArray<FFlatVertex> SlopeSpriteVertices;	// we need to cache these in system memory in case of translucency splits.
 
 	// This is needed by the BSP traverser.
 	bool multithread;

source/core/rendering/scene/hw_drawlist.cpp

@@ -32,6 +32,8 @@
 #include "hw_renderstate.h"
 #include "hw_drawinfo.h"
 
+#define MIN_EQ (0.0005f)
+
 FMemArena RenderDataAllocator(1024*1024);	// Use large blocks to reduce allocation time.
 
 void ResetRenderDataAllocator()
@@ -385,7 +387,51 @@ void HWDrawList::SortSpriteIntoPlane(SortNode * head, SortNode * sort)
 //
 //
 //==========================================================================
-#define MIN_EQ (0.0005f)
+void HWDrawList::SortSlopeIntoPlane(HWDrawInfo* di, SortNode* head, SortNode* sort)
+{
+	HWFlat* fh = flats[drawitems[head->itemindex].index];
+	HWFlat* ss = flats[drawitems[sort->itemindex].index];
+
+	bool ceiling = fh->z > SortZ;
+	auto svp = &di->SlopeSpriteVertices[ss->slopeindex];
+
+	float hiz = -FLT_MAX;
+	float loz = FLT_MAX;
+	for (int i = 0; i < ss->slopecount; i++)
+	{
+		if (svp[i].z < loz) loz = svp[i].z;
+		if (svp[i].z > hiz) hiz = svp[i].z;
+	}
+
+	if ((hiz > fh->z && loz < fh->z))
+	{
+		// We have to split this sprite
+		auto s = NewFlat(true);
+		*s = *ss;
+
+		SortNode* sort2 = SortNodes.GetNew();
+		memset(sort2, 0, sizeof(SortNode));
+		sort2->itemindex = drawitems.Size() - 1;
+
+		head->AddToLeft(sort);
+		head->AddToRight(sort2);
+	}
+	else if ((loz < fh->z && !ceiling) || (hiz > fh->z && ceiling))	// completely on the left side
+	{
+		head->AddToLeft(sort);
+	}
+	else
+	{
+		head->AddToRight(sort);
+	}
+}
+
+
+//==========================================================================
+//
+//
+//
+//==========================================================================
 
 // Lines start-end and fdiv must intersect.
 inline double CalcIntersectionVertex(HWWall *w1, HWWall * w2)
@@ -579,6 +625,55 @@ void HWDrawList::SortSpriteIntoWall(HWDrawInfo *di, SortNode * head,SortNode * s
 	}
 }
 
+static TArray<float> onside; // static to avoid reallocation.
+void HWDrawList::SortSlopeIntoWall(HWDrawInfo* di, SortNode* head, SortNode* sort)
+{
+	HWWall* wh = walls[drawitems[head->itemindex].index];
+	HWFlat* ss = flats[drawitems[sort->itemindex].index];
+
+	auto svp = &di->SlopeSpriteVertices[ss->slopeindex];
+
+	onside.Resize(ss->slopecount);
+	float hiz = -FLT_MAX;
+	float loz = FLT_MAX;
+	for (int i = 0; i < ss->slopecount; i++)
+	{
+		onside[i] = wh->PointOnSide(svp[i].x, svp[i].y);
+		if (onside[i] < loz) loz = onside[i];
+		if (onside[i] > hiz) hiz = onside[i];
+	}
+
+
+	if (fabs(loz) < MIN_EQ && fabs(hiz) < MIN_EQ)
+	{
+		head->AddToEqual(sort);
+	}
+	else if (loz < MIN_EQ && hiz < MIN_EQ)
+	{
+		head->AddToLeft(sort);
+	}
+	else if (hiz > -MIN_EQ && loz > -MIN_EQ)
+	{
+		head->AddToRight(sort);
+	}
+	else
+	{
+		const bool drawWithXYBillboard = false;//
+
+		// [Nash] has +ROLLSPRITE
+		const bool rotated = false;//
+
+		// Proper splitting should not be necessary here and can be added once a map shows up that needs it.
+		if (fabs(hiz) > fabs(loz))
+		{
+			head->AddToRight(sort);
+		}
+		else
+		{
+			head->AddToLeft(sort);
+		}
+	}
+}
 
 //==========================================================================
 //
@@ -588,8 +683,8 @@ void HWDrawList::SortSpriteIntoWall(HWDrawInfo *di, SortNode * head,SortNode * s
 
 inline int HWDrawList::CompareSprites(SortNode * a,SortNode * b)
 {
-	HWSprite * s1= sprites[drawitems[a->itemindex].index];
+	HWFlatOrSprite* s1 = drawitems[a->itemindex].rendertype == DrawType_SPRITE ? (HWFlatOrSprite*)sprites[drawitems[a->itemindex].index] : flats[drawitems[a->itemindex].index];
-	HWSprite * s2= sprites[drawitems[b->itemindex].index];
+	HWFlatOrSprite* s2 = drawitems[b->itemindex].rendertype == DrawType_SPRITE ? (HWFlatOrSprite*)sprites[drawitems[b->itemindex].index] : flats[drawitems[b->itemindex].index];
 
 	if (s1->depth < s2->depth) return 1;
 	if (s1->depth > s2->depth) return -1;
@@ -659,6 +754,10 @@ SortNode * HWDrawList::DoSort(HWDrawInfo *di, SortNode * head)
 			case DrawType_SPRITE:
 				SortSpriteIntoPlane(head,node);
 				break;
+
+			case DrawType_SLOPE:
+				SortSlopeIntoPlane(di, head, node);
+				break;
 			}
 			node=next;
 		}
@@ -685,6 +784,10 @@ SortNode * HWDrawList::DoSort(HWDrawInfo *di, SortNode * head)
 					SortSpriteIntoWall(di, head, node);
 					break;
 
+				case DrawType_SLOPE:
+					SortSlopeIntoWall(di, head, node);
+					break;
+
 				case DrawType_FLAT: break;
 				}
 				node=next;
@@ -873,10 +976,10 @@ HWWall *HWDrawList::NewWall()
 //
 //
 //==========================================================================
-HWFlat *HWDrawList::NewFlat()
+HWFlat *HWDrawList::NewFlat(bool slopespr)
 {
 	auto flat = (HWFlat*)RenderDataAllocator.Alloc(sizeof(HWFlat));
-	drawitems.Push(HWDrawItem(DrawType_FLAT,flats.Push(flat)));
+	drawitems.Push(HWDrawItem(slopespr? DrawType_SLOPE : DrawType_FLAT,flats.Push(flat)));
 	return flat;
 }
 
@@ -901,6 +1004,7 @@ void HWDrawList::DoDraw(HWDrawInfo *di, FRenderState &state, bool translucent, i
 {
 	switch(drawitems[i].rendertype)
 	{
+	case DrawType_SLOPE:
 	case DrawType_FLAT:
 		{
 			HWFlat * f= flats[drawitems[i].index];

source/core/rendering/scene/hw_drawlist.h

@@ -24,6 +24,7 @@ enum HWDrawItemType
 	DrawType_WALL,
 	DrawType_FLAT,
 	DrawType_SPRITE,
+	DrawType_SLOPE,
 };
 
 struct HWDrawItem
@@ -89,7 +90,7 @@ public:
 	}
 
 	HWWall *NewWall();
-	HWFlat *NewFlat();
+	HWFlat *NewFlat(bool slopespr = false);
 	HWSprite *NewSprite();
 	void Reset();
 	void SortWallsHorz(HWDrawInfo* di);
@@ -103,8 +104,10 @@ public:
 	void SortPlaneIntoPlane(SortNode * head,SortNode * sort);
 	void SortWallIntoPlane(HWDrawInfo* di, SortNode * head,SortNode * sort);
 	void SortSpriteIntoPlane(SortNode * head,SortNode * sort);
+	void SortSlopeIntoPlane(HWDrawInfo* di, SortNode* head, SortNode* sort);
 	void SortWallIntoWall(HWDrawInfo *di, SortNode * head,SortNode * sort);
 	void SortSpriteIntoWall(HWDrawInfo *di, SortNode * head,SortNode * sort);
+	void SortSlopeIntoWall(HWDrawInfo* di, SortNode* head, SortNode* sort);
 	int CompareSprites(SortNode * a,SortNode * b);
 	SortNode * SortSpriteList(SortNode * head);
 	SortNode * DoSort(HWDrawInfo *di, SortNode * head);

source/core/rendering/scene/hw_drawlistadd.cpp

@@ -94,17 +94,19 @@ void HWDrawInfo::AddMirrorSurface(HWWall *w)
 void HWDrawInfo::AddFlat(HWFlat *flat)
 {
 	int list;;
+	bool slopespr = false;
 
 	if (flat->RenderStyle != LegacyRenderStyles[STYLE_Translucent] || flat->alpha < 1.f - FLT_EPSILON || checkTranslucentReplacement(flat->texture->GetID(), flat->palette))
 	{
 		// translucent portals go into the translucent border list.
 		list = flat->Sprite? GLDL_TRANSLUCENT : GLDL_TRANSLUCENTBORDER;
+		slopespr = (flat->Sprite && flat->Sprite->clipdist & TSPR_SLOPESPRITE);
 	}
 	else
 	{
 		list = flat->Sprite ? GLDL_MASKEDFLATS : GLDL_PLAINFLATS;
 	}
-	auto newflat = drawlists[list].NewFlat();
+	auto newflat = drawlists[list].NewFlat(slopespr);
 	*newflat = *flat;
 }
 

source/core/rendering/scene/hw_drawstructs.h

@@ -248,20 +248,32 @@ public:
 
 };
 
+//==========================================================================
+//
+// Common fields needed by the sprite sorter.
+//
+//==========================================================================
+
+class HWFlatOrSprite
+{
+public:
+	float depth;
+	tspritetype* Sprite; // for flat sprites.
+};
+
 //==========================================================================
 //
 // One flat plane in the draw list
 //
 //==========================================================================
 
-class HWFlat
+class HWFlat : public HWFlatOrSprite
 {
 public:
-	int section;
+	sectortype* sec;
-	sectortype * sec;
+	FGameTexture* texture;
-	tspritetype* Sprite; // for flat sprites.
-	FGameTexture *texture;
 
+	int section;
 	float z; // the z position of the flat (only valid for non-sloped planes)
 
 	PalEntry fade;
@@ -271,10 +283,12 @@ public:
 	FRenderStyle RenderStyle;
 	int iboindex;
 	bool stack;
+	uint8_t plane;
+	short slopecount;
 	FVector2 geoofs;
 	//int vboheight;
 
-	int plane;
+	int slopeindex;
 	int vertindex, vertcount;	// this should later use a static vertex buffer, but that'd hinder the development phase, so for now vertex data gets created on the fly.
 	void MakeVertices(HWDrawInfo* di);
 
@@ -298,11 +312,10 @@ public:
 //==========================================================================
 
 
-class HWSprite
+class HWSprite : public HWFlatOrSprite
 {
 public:
 
-	tspritetype* Sprite;
 	PalEntry fade;
 	int shade, palette;
 	float visibility;
@@ -312,7 +325,6 @@ public:
 	voxmodel_t* voxel;
 
 	int index;
-	float depth;
 	int vertexindex;
 
 	float x,y,z;	// needed for sorting!

source/core/rendering/scene/hw_flats.cpp

@@ -165,15 +165,27 @@ void HWFlat::MakeVertices(HWDrawInfo* di)
 				if (minofs < 0 && maxofs <= -ONPLANE_THRESHOLD && minofs >= ONPLANE_THRESHOLD) z -= minofs;
 			}
 		}
+		unsigned svi = di->SlopeSpriteVertices.Reserve(4);
+		auto svp = &di->SlopeSpriteVertices[svi];
+
+		auto& vpt = di->Viewpoint;
+		depth = (float)((Sprite->pos.X * (1/16.f) - vpt.Pos.X) * vpt.TanCos + (Sprite->pos.Y * (1 / -16.f) - vpt.Pos.Y) * vpt.TanSin);
+
+		for (unsigned j = 0; j < 4; j++)
+		{
+			svp->SetVertex(pos[j].X * (1 / 16.f), z + ofsz[j] * (1 / -256.f), pos[j].Y * (1 / -16.f));
+			if (!canvas) svp->SetTexCoord(j == 1 || j == 2 ? 1.f - x : x, j == 2 || j == 3 ? 1.f - y : y);
+			else svp->SetTexCoord(j == 1 || j == 2 ? 1.f - x : x, j == 2 || j == 3 ? y : 1.f - y);
+			svp++;
+		}
+
 		for (unsigned i = 0; i < 6; i++)
 		{
 			const static unsigned indices[] = { 0, 1, 2, 0, 2, 3 };
-			int j = indices[i];
+			*vp++ = di->SlopeSpriteVertices[svi + indices[i]];
-			vp->SetVertex(pos[j].X * (1 / 16.f), z + ofsz[j] * (1 / -256.f), pos[j].Y * (1 / -16.f));
-			if (!canvas) vp->SetTexCoord(j == 1 || j == 2 ? 1.f - x : x, j == 2 || j == 3 ? 1.f - y : y);
-			else vp->SetTexCoord(j == 1 || j == 2 ? 1.f - x : x, j == 2 || j == 3 ? y : 1.f - y);
-			vp++;
 		}
+		slopeindex = svi;
+		slopecount = 4;
 		vertindex = ret.second;
 		vertcount = 6;
 	}