// 
//---------------------------------------------------------------------------
//
// Copyright(C) 2000-2016 Christoph Oelckers
// All rights reserved.
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 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 Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with this program.  If not, see http://www.gnu.org/licenses/
//
//--------------------------------------------------------------------------
//

#include "texturemanager.h"
#include "hw_dynlightdata.h"
#include "hw_material.h"
#include "hw_cvars.h"
#include "hw_clock.h"
//#include "hw_lighting.h"
//#include "hwrenderer/scene/hw_drawinfo.h"
//#include "hwrenderer/scene/hw_drawstructs.h"
//#include "hwrenderer/scene/hw_portal.h"
#include "hw_lightbuffer.h"
#include "hw_renderstate.h"
#include "hw_skydome.h"
#include "hw_drawstructs.h"
#include "render.h"
#include "cmdlib.h"

#include "v_video.h"
#include "flatvertices.h"
#include "glbackend/glbackend.h"


//==========================================================================
//
// General purpose wall rendering function
// everything goes through here
//
//==========================================================================

void HWWall::RenderWall(HWDrawInfo *di, FRenderState &state, int textured)
{
	assert(vertcount > 0);
	state.SetLightIndex(dynlightindex);
	state.Draw(DT_TriangleFan, vertindex, vertcount);
	vertexcount += vertcount;
}

//==========================================================================
//
// 
//
//==========================================================================

void HWWall::RenderFogBoundary(HWDrawInfo *di, FRenderState &state)
{
#if 0
	if (gl_fogmode && !di->isFullbrightScene())
	{
		int rel = rellight + getExtraLight();
		state.EnableDrawBufferAttachments(false);
		di->SetFog(state, lightlevel, rel, false, &Colormap, false);
		state.SetEffect(EFF_FOGBOUNDARY);
		state.AlphaFunc(Alpha_GEqual, 0.f);
		state.SetDepthBias(-1, -128);
		RenderWall(di, state, HWWall::RWF_BLANK);
		state.ClearDepthBias();
		state.SetEffect(EFF_NONE);
		state.EnableDrawBufferAttachments(true);
	}
#endif
}


//==========================================================================
//
// 
//
//==========================================================================
void HWWall::RenderMirrorSurface(HWDrawInfo *di, FRenderState &state)
{
#if 0
	if (!TexMan.mirrorTexture.isValid()) return;

	state.SetDepthFunc(DF_LEqual);

	// we use texture coordinates and texture matrix to pass the normal stuff to the shader so that the default vertex buffer format can be used as is.
	state.EnableTextureMatrix(true);

	// Use sphere mapping for this
	state.SetEffect(EFF_SPHEREMAP);
	di->SetColor(state, lightlevel, 0, di->isFullbrightScene(), Colormap, 0.1f);
	di->SetFog(state, lightlevel, 0, di->isFullbrightScene(), &Colormap, true);
	state.SetRenderStyle(STYLE_Add);
	state.AlphaFunc(Alpha_Greater, 0);

	auto tex = TexMan.GetGameTexture(TexMan.mirrorTexture, false);
	state.SetMaterial(tex, UF_None, 0, CLAMP_NONE, 0, -1); // do not upscale the mirror texture.

	flags &= ~HWWall::HWF_GLOW;
	RenderWall(di, state, HWWall::RWF_BLANK);

	state.EnableTextureMatrix(false);
	state.SetEffect(EFF_NONE);
	state.AlphaFunc(Alpha_GEqual, gl_mask_sprite_threshold);

	state.SetDepthFunc(DF_Less);

	// This is drawn in the translucent pass which is done after the decal pass
	// As a result the decals have to be drawn here, right after the wall they are on,
	// because the depth buffer won't get set by translucent items.
	if (seg->sidedef->AttachedDecals)
	{
		DrawDecalsForMirror(di, state, di->Decals[1]);
	}
	state.SetRenderStyle(STYLE_Translucent);
#endif
}

//==========================================================================
//
// 
//
//==========================================================================

void HWWall::RenderTexturedWall(HWDrawInfo *di, FRenderState &state, int rflags)
{
#if 0
	int tmode = state.GetTextureMode();

	state.SetMaterial(texture, UF_Texture, 0, flags & 3, 0, -1);

	
	int32_t size = xs_CRoundToInt(texture->GetDisplayHeight());
	int32_t size2;
	for (size2 = 1; size2 < size; size2 += size2) {}
	if (size == size2)
		state.SetNpotEmulation(0.f, 0.f);
	else
	{
		float xOffset = 1.f / texture->GetDisplayWidth();
		state.SetNpotEmulation((1.f * size2) / size, xOffset);
	}


	float absalpha = fabsf(alpha);
	if (type != RENDERWALL_M2SNF) di->SetFog(state, lightlevel, rel, di->isFullbrightScene(), &Colormap, RenderStyle == STYLE_Add);
	di->SetColor(state, lightlevel, rel, di->isFullbrightScene(), Colormap, absalpha);
	RenderWall(di, state, rflags);

	state.SetNpotEmulation(0.f, 0.f);
	state.SetObjectColor(0xffffffff);
	state.SetObjectColor2(0);
	state.SetAddColor(0);
	state.SetTextureMode(tmode);
	state.EnableGlow(false);
	state.EnableGradient(false);
	state.ApplyTextureManipulation(nullptr);
#endif
}

//==========================================================================
//
// 
//
//==========================================================================

void HWWall::RenderTranslucentWall(HWDrawInfo *di, FRenderState &state)
{
#if 0
	state.SetRenderStyle(RenderStyle);
	if (!texture->GetTranslucency()) state.AlphaFunc(Alpha_GEqual, gl_mask_threshold);
	else state.AlphaFunc(Alpha_GEqual, 0.f);
	RenderTexturedWall(di, state, HWWall::RWF_TEXTURED);
	state.SetRenderStyle(STYLE_Translucent);
#endif
}

//==========================================================================
//
// 
//
//==========================================================================
void HWWall::DrawWall(HWDrawInfo *di, FRenderState &state, bool translucent)
{
	/*
	if (screen->BuffersArePersistent())
	{
		if (di->Level->HasDynamicLights && !di->isFullbrightScene() && texture != nullptr)
		{
			SetupLights(di, lightdata);
		}
		MakeVertices(di, !!(flags & HWWall::HWF_TRANSLUCENT));
	}
	*/

	state.SetNormal(glseg.Normal());
	if (!translucent)
	{
		RenderTexturedWall(di, state, HWWall::RWF_TEXTURED);
	}
	else
	{
		switch (type)
		{
		case RENDERWALL_MIRRORSURFACE:
			RenderMirrorSurface(di, state);
			break;

		case RENDERWALL_FOGBOUNDARY:
			RenderFogBoundary(di, state);
			break;

		default:
			RenderTranslucentWall(di, state);
			break;
		}
	}
}

//==========================================================================
//
// Collect lights for shader
//
//==========================================================================
#if 0
void HWWall::SetupLights(HWDrawInfo *di, FDynLightData &lightdata)
{
	lightdata.Clear();

	if (RenderStyle == STYLE_Add && !di->Level->lightadditivesurfaces) return;	// no lights on additively blended surfaces.

	// check for wall types which cannot have dynamic lights on them (portal types never get here so they don't need to be checked.)
	switch (type)
	{
	case RENDERWALL_FOGBOUNDARY:
	case RENDERWALL_MIRRORSURFACE:
	case RENDERWALL_COLOR:
		return;
	}

	float vtx[]={glseg.x1,zbottom[0],glseg.y1, glseg.x1,ztop[0],glseg.y1, glseg.x2,ztop[1],glseg.y2, glseg.x2,zbottom[1],glseg.y2};
	Plane p;


	auto normal = glseg.Normal();
	p.Set(normal, -normal.X * glseg.x1 - normal.Z * glseg.y1);

	FLightNode *node;
	if (seg->sidedef == NULL)
	{
		node = NULL;
	}
	else if (!(seg->sidedef->Flags & WALLF_POLYOBJ))
	{
		node = seg->sidedef->lighthead;
	}
	else if (sub)
	{
		// Polobject segs cannot be checked per sidedef so use the subsector instead.
		node = sub->section->lighthead;
	}
	else node = NULL;

	// Iterate through all dynamic lights which touch this wall and render them
	while (node)
	{
		if (node->lightsource->IsActive())
		{
			iter_dlight++;

			DVector3 posrel = node->lightsource->PosRelative(seg->frontsector->PortalGroup);
			float x = posrel.X;
			float y = posrel.Y;
			float z = posrel.Z;
			float dist = fabsf(p.DistToPoint(x, z, y));
			float radius = node->lightsource->GetRadius();
			float scale = 1.0f / ((2.f * radius) - dist);
			FVector3 fn, pos;

			if (radius > 0.f && dist < radius)
			{
				FVector3 nearPt, up, right;

				pos = { x, z, y };
				fn = p.Normal();

				fn.GetRightUp(right, up);

				FVector3 tmpVec = fn * dist;
				nearPt = pos + tmpVec;

				FVector3 t1;
				int outcnt[4]={0,0,0,0};
				texcoord tcs[4];

				// do a quick check whether the light touches this polygon
				for(int i=0;i<4;i++)
				{
					t1 = FVector3(&vtx[i*3]);
					FVector3 nearToVert = t1 - nearPt;
					tcs[i].u = ((nearToVert | right) * scale) + 0.5f;
					tcs[i].v = ((nearToVert | up) * scale) + 0.5f;

					if (tcs[i].u<0) outcnt[0]++;
					if (tcs[i].u>1) outcnt[1]++;
					if (tcs[i].v<0) outcnt[2]++;
					if (tcs[i].v>1) outcnt[3]++;

				}
				if (outcnt[0]!=4 && outcnt[1]!=4 && outcnt[2]!=4 && outcnt[3]!=4) 
				{
					draw_dlight += GetLight(lightdata, seg->frontsector->PortalGroup, p, node->lightsource, true);
				}
			}
		}
		node = node->nextLight;
	}
	dynlightindex = screen->mLights->UploadLights(lightdata);
}
#endif

//==========================================================================
//
// 
//
//==========================================================================
void HWWall::PutWall(HWDrawInfo *di, bool translucent)
{
	if (translucent || (texture && texture->GetTranslucency() && type == RENDERWALL_M2S))
	{
		flags |= HWF_TRANSLUCENT;
		//ViewDistance = (di->Viewpoint.Pos - (seg->linedef->v1->fPos() + seg->linedef->Delta() / 2)).XY().LengthSquared();
	}
	
	/*
	if (!screen->BuffersArePersistent())
	{
		if (di->Level->HasDynamicLights && !di->isFullbrightScene() && texture != nullptr)
		{
			SetupLights(di, lightdata);
		}
		MakeVertices(di, translucent);
	}

	bool hasDecals = type != RENDERWALL_M2S && seg->sidedef->AttachedDecals;
	if (hasDecals)
	{
		// If we want to use the light infos for the decal we cannot delay the creation until the render pass.
		if (screen->BuffersArePersistent())
		{
			if (di->Level->HasDynamicLights && !di->isFullbrightScene() && texture != nullptr)
			{
				SetupLights(di, lightdata);
			}
		}
		ProcessDecals(di);
	}
	*/

#if 0
	di->AddWall(this);
#else
	// route it through the GLInterface for now for easier testing
	int palid = TRANSLATION(Translation_Remap + curbasepal, globalpal);
	GLInterface.SetFade(globalfloorpal);
	GLInterface.SetTexture(texture, TRANSLATION(Translation_Remap + curbasepal, palette), 0);

	GLInterface.SetShade(shade, numshades);

	int h = texture->GetTexelHeight();
	int h2 = 1 << sizeToBits(h);
	if (h != h2)
	{
		float xOffset = 1.f / texture->GetTexelWidth();
		GLInterface.SetNpotEmulation(float(h2) / h, xOffset);
	}
	else
	{
		GLInterface.SetNpotEmulation(0.f, 0.f);
	}
	GLInterface.SetTextureMode(TM_OPAQUE);
	GLInterface.SetVisibility(visibility);

	// The shade rgb from the tint is ignored here.
	float pc[4];
	pc[0] = (float)globalr * (1.f / 255.f);
	pc[1] = (float)globalg * (1.f / 255.f);
	pc[2] = (float)globalb * (1.f / 255.f);
	pc[3] = alpha;
	GLInterface.SetColor(pc[0], pc[1], pc[2], pc[3]);

	auto data = screen->mVertexData->AllocVertices(4);
	auto vt = data.first;
	vt[0].SetTexCoord(tcs[LOLFT].u, tcs[LOLFT].v);
	vt[0].SetVertex(glseg.x1, zbottom[0], glseg.y1);
	vt[1].SetTexCoord(tcs[UPLFT].u, tcs[UPLFT].v);
	vt[1].SetVertex(glseg.x1, ztop[0], glseg.y1);
	vt[2].SetTexCoord(tcs[UPRGT].u, tcs[UPRGT].v);
	vt[2].SetVertex(glseg.x2, ztop[1], glseg.y2);
	vt[3].SetTexCoord(tcs[LORGT].u, tcs[LORGT].v);
	vt[3].SetVertex(glseg.x2, zbottom[1], glseg.y2);

	GLInterface.Draw(DT_TriangleFan, data.second, 4);

	GLInterface.SetNpotEmulation(0.f, 0.f);
	GLInterface.SetTextureMode(TM_NORMAL);

#endif
	// make sure that following parts of the same linedef do not get this one's vertex and lighting info.
	vertcount = 0;	
	dynlightindex = -1;
	flags &= ~HWF_TRANSLUCENT;
}

//==========================================================================
//
// will be done later.
//
//==========================================================================

void HWWall::PutPortal(HWDrawInfo *di, int ptype, int plane)
{
#if 0
	HWPortal * portal = nullptr;

	MakeVertices(di, false);
	switch (ptype)
	{
		// portals don't go into the draw list.
		// Instead they are added to the portal manager
	case PORTALTYPE_HORIZON:
		horizon = portalState.UniqueHorizons.Get(horizon);
		portal = di->FindPortal(horizon);
		if (!portal)
		{
			portal = new HWHorizonPortal(&portalState, horizon, di->Viewpoint);
			di->Portals.Push(portal);
		}
		portal->AddLine(this);
		break;

	case PORTALTYPE_SKYBOX:
		portal = di->FindPortal(secportal);
		if (!portal)
		{
			// either a regular skybox or an Eternity-style horizon
			if (secportal->mType != PORTS_SKYVIEWPOINT) portal = new HWEEHorizonPortal(&portalState, secportal);
			else
			{
				portal = new HWSkyboxPortal(&portalState, secportal);
				di->Portals.Push(portal);
			}
		}
		portal->AddLine(this);
		break;

	case PORTALTYPE_SECTORSTACK:
		portal = di->FindPortal(this->portal);
		if (!portal)
		{
			portal = new HWSectorStackPortal(&portalState, this->portal);
			di->Portals.Push(portal);
		}
		portal->AddLine(this);
		break;

	case PORTALTYPE_PLANEMIRROR:
		if (portalState.PlaneMirrorMode * planemirror->fC() <= 0)
		{
			planemirror = portalState.UniquePlaneMirrors.Get(planemirror);
			portal = di->FindPortal(planemirror);
			if (!portal)
			{
				portal = new HWPlaneMirrorPortal(&portalState, planemirror);
				di->Portals.Push(portal);
			}
			portal->AddLine(this);
		}
		break;

	case PORTALTYPE_MIRROR:
		portal = di->FindPortal(seg->linedef);
		if (!portal)
		{
			portal = new HWMirrorPortal(&portalState, seg->linedef);
			di->Portals.Push(portal);
		}
		portal->AddLine(this);
		if (gl_mirror_envmap)
		{
			// draw a reflective layer over the mirror
			di->AddMirrorSurface(this);
		}
		break;

	case PORTALTYPE_LINETOLINE:
		if (!lineportal)
			return;
		portal = di->FindPortal(lineportal);
		if (!portal)
		{
			line_t *otherside = lineportal->lines[0]->mDestination;
			if (otherside != nullptr && otherside->portalindex < di->Level->linePortals.Size())
			{
				di->ProcessActorsInPortal(otherside->getPortal()->mGroup, di->in_area);
			}
			portal = new HWLineToLinePortal(&portalState, lineportal);
			di->Portals.Push(portal);
		}
		portal->AddLine(this);
		break;

	case PORTALTYPE_SKY:
		sky = portalState.UniqueSkies.Get(sky);
		portal = di->FindPortal(sky);
		if (!portal)
		{
			portal = new HWSkyPortal(screen->mSkyData, &portalState, sky);
			di->Portals.Push(portal);
		}
		portal->AddLine(this);
		break;
	}
	vertcount = 0;

	if (plane != -1 && portal)
	{
		portal->planesused |= (1<<plane);
	}
#endif
}

//==========================================================================
//
// Build does not have horizon effects.
//
//==========================================================================
bool HWWall::DoHorizon(HWDrawInfo* di, walltype* seg, sectortype* fs, DVector2& v1, DVector2& v2)
{
#if 0
	HWHorizonInfo hi;
	lightlist_t * light;

	// ZDoom doesn't support slopes in a horizon sector so I won't either!
	ztop[1] = ztop[0] = fs->GetPlaneTexZ(sector_t::ceiling);
	zbottom[1] = zbottom[0] = fs->GetPlaneTexZ(sector_t::floor);

    auto vpz = di->Viewpoint.Pos.Z;
	if (vpz < fs->GetPlaneTexZ(sector_t::ceiling))
	{
		if (vpz > fs->GetPlaneTexZ(sector_t::floor))
			zbottom[1] = zbottom[0] = vpz;

		if (fs->GetTexture(sector_t::ceiling) == skyflatnum)
		{
			SkyPlane(di, fs, sector_t::ceiling, false);
		}
		else
		{
			hi.plane.GetFromSector(fs, sector_t::ceiling);
			hi.lightlevel = hw_ClampLight(fs->GetCeilingLight());
			hi.colormap = fs->Colormap;
			hi.specialcolor = fs->SpecialColors[sector_t::ceiling];

			if (di->isFullbrightScene()) hi.colormap.Clear();
			horizon = &hi;
			PutPortal(di, PORTALTYPE_HORIZON, -1);
		}
		ztop[1] = ztop[0] = zbottom[0];
	} 

	if (vpz > fs->GetPlaneTexZ(sector_t::floor))
	{
		zbottom[1] = zbottom[0] = fs->GetPlaneTexZ(sector_t::floor);
		if (fs->GetTexture(sector_t::floor) == skyflatnum)
		{
			SkyPlane(di, fs, sector_t::floor, false);
		}
		else
		{
			hi.plane.GetFromSector(fs, sector_t::floor);
			hi.lightlevel = hw_ClampLight(fs->GetFloorLight());
			hi.colormap = fs->Colormap;
			hi.specialcolor = fs->SpecialColors[sector_t::floor];

			horizon = &hi;
			PutPortal(di, PORTALTYPE_HORIZON, -1);
		}
	}
#endif
	return true;
}

static float sectorVisibility(sectortype *sec)
{
	// Beware of wraparound madness...
	int v = sec->visibility;
	return v ? ((uint8_t)(v + 16)) / 16.f : 1.f;
}

//==========================================================================
//
// Build math sucks. This would be easier if NPOT was handled properly.
// Panning is calculated in NPOT dimensions only, the next largest one
// to the texture height applies, so the panning needs to be scaled accordingly.
//
//==========================================================================

static float GetYPanning(float curypanning, FGameTexture* tex/*, bool aligned*/)
{
	// get next largest POT size.
	int th = tex->GetTexelHeight();
	int pow2size = 1 << sizeToBits(th);
	if (pow2size < th) pow2size *= 2;

	/* crap for lack of NPOT emulation. Should not be needed anymore
	if (aligned)
	{
		float yoffs = (pow2size - th) * (255.0f / pow2size);
		if (curypanning > 256 - yoffs)
			curypanning -= yoffs;
	}
	*/

	// scale the panning factor and scale to texture coordinates.
	return pow2size * curypanning / (256.0f * th);
}

//==========================================================================
//
// 
//
//==========================================================================

bool HWWall::SetWallCoordinates(walltype * seg, float topleft, float topright, float bottomleft, float bottomright)
{
	//
	//
	// set up coordinates for the left side of the polygon
	//
	// check left side for intersections
	if (topleft >= bottomleft)
	{
		// normal case
		ztop[0] = topleft;
		zbottom[0] = bottomleft;
	}
	else
	{
		// ceiling below floor - clip to the visible part of the wall
		float dch = topright - topleft;
		float dfh = bottomright - bottomleft;
		float inter_x = (bottomleft - topleft) / (dch - dfh);
		float inter_y = topleft + inter_x * dch;

		glseg.x1 = glseg.x1 + inter_x * (glseg.x2 - glseg.x1);
		glseg.y1 = glseg.y1 + inter_x * (glseg.y2 - glseg.y1);
		glseg.fracleft = inter_x;

		zbottom[0] = ztop[0] = inter_y;
	}

	//
	//
	// set up coordinates for the right side of the polygon
	//
	// check left side for intersections
	if (topright >= bottomright)
	{
		// normal case
		ztop[1] = topright;
		zbottom[1] = bottomright;
	}
	else
	{
		// ceiling below floor - clip to the visible part of the wall
		float dch = topright - topleft;
		float dfh = bottomright - bottomleft;
		float inter_x = (bottomleft - topleft) / (dch - dfh);

		float inter_y = topleft + inter_x * dch;

		glseg.x2 = glseg.x1 + inter_x * (glseg.x2 - glseg.x1);
		glseg.y2 = glseg.y1 + inter_x * (glseg.y2 - glseg.y1);
		glseg.fracright = inter_x;

		zbottom[1] = ztop[1] = inter_y;
	}

	return true;
}

//==========================================================================
//
// Do some tweaks with the texture coordinates to reduce visual glitches
//
//==========================================================================

void HWWall::CheckTexturePosition()
{
	float sub;

	if (texture->isHardwareCanvas()) return;

	// clamp texture coordinates to a reasonable range.
	// Extremely large values can cause visual problems
	if (tcs[UPLFT].v > tcs[LOLFT].v || tcs[UPRGT].v > tcs[LORGT].v)
	{
		if (tcs[UPLFT].v < tcs[UPRGT].v)
		{
			sub = float(xs_FloorToInt(tcs[UPLFT].v));
		}
		else
		{
			sub = float(xs_FloorToInt(tcs[UPRGT].v));
		}
		tcs[UPLFT].v -= sub;
		tcs[UPRGT].v -= sub;
		tcs[LOLFT].v -= sub;
		tcs[LORGT].v -= sub;

		if ((tcs[UPLFT].v == 0.f && tcs[UPRGT].v == 0.f && tcs[LOLFT].v <= 1.f && tcs[LORGT].v <= 1.f) ||
			(tcs[UPLFT].v >= 0.f && tcs[UPRGT].v >= 0.f && tcs[LOLFT].v == 1.f && tcs[LORGT].v == 1.f))
		{
			flags |= HWF_CLAMPY;
		}
	}
	else
	{
		if (tcs[LOLFT].v < tcs[LORGT].v)
		{
			sub = float(xs_FloorToInt(tcs[LOLFT].v));
		}
		else
		{
			sub = float(xs_FloorToInt(tcs[LORGT].v));
		}
		tcs[UPLFT].v -= sub;
		tcs[UPRGT].v -= sub;
		tcs[LOLFT].v -= sub;
		tcs[LORGT].v -= sub;

		if ((tcs[LOLFT].v == 0.f && tcs[LORGT].v == 0.f && tcs[UPLFT].v <= 1.f && tcs[UPRGT].v <= 1.f) ||
			(tcs[LOLFT].v >= 0.f && tcs[LORGT].v >= 0.f && tcs[UPLFT].v == 1.f && tcs[UPRGT].v == 1.f))
		{
			flags |= HWF_CLAMPY;
		}
	}
}


//==========================================================================
//
// Common part of wall drawers
//
//==========================================================================

void HWWall::DoTexture(HWDrawInfo* di, walltype* wal, walltype* refwall, float refheight, float topleft, float topright, float bottomleft, float bottomright)
{
	auto glsave = glseg;
	float ypanning = wal->ypan_ ? GetYPanning(wal->ypan_, texture) : 0;
	SetWallCoordinates(wal, topleft, topright, bottomleft, bottomright);

	bool xflipped = (wal->cstat & CSTAT_WALL_XFLIP);
	float leftdist = xflipped ? 1.f - glseg.fracleft : glseg.fracleft;
	float rightdist = xflipped ? 1.f - glseg.fracright : glseg.fracright;

	float tw = texture->GetTexelWidth();
	float th = texture->GetTexelHeight();
	tcs[LOLFT].u = tcs[UPLFT].u = ((leftdist * 8.f * wal->xrepeat) + wal->xpan_) / tw;
	tcs[LORGT].u = tcs[UPRGT].u = ((rightdist * 8.f * wal->xrepeat) + wal->xpan_) / tw;
	 
	auto setv = [=](float hl, float hr, float frac) -> float
	{
		float h = hl + (hr - hl) * frac;
		h = ((float)(refheight - (h * 256)) / ((th * 2048.0f) / (float)(wal->yrepeat))) + ypanning;
		if (wal->cstat & CSTAT_WALL_YFLIP) h = 1.f - h;
		return h;
	};

	tcs[UPLFT].v = setv(topleft, topright, glseg.fracleft);
	tcs[LOLFT].v = setv(bottomleft, bottomright, glseg.fracleft);
	tcs[UPRGT].v = setv(topleft, topright, glseg.fracright);
	tcs[LORGT].v = setv(bottomleft, bottomright, glseg.fracright);
	CheckTexturePosition();
	bool trans = type == RENDERWALL_M2S && (wal->cstat & CSTAT_WALL_TRANSLUCENT);
	if (trans)
	{
		SetRenderStyleFromBlend(!!(wal->cstat & CSTAT_WALL_TRANSLUCENT), 0, !!(wal->cstat & CSTAT_WALL_TRANS_FLIP));
		alpha = GetAlphaFromBlend((wal->cstat & CSTAT_WALL_TRANS_FLIP) ? DAMETH_TRANS2 : DAMETH_TRANS1, 0);
	}
	PutWall(di, trans);
	glseg = glsave;
}

//==========================================================================
//
//  Handle one sided walls
//
//==========================================================================

void HWWall::DoOneSidedTexture(HWDrawInfo* di, walltype* wal, sectortype* frontsector, sectortype* backsector,
	float topleft, float topright, float bottomleft, float bottomright)
{
	// get the alignment reference position.
	int refheight;

	if ((wal->cstat & CSTAT_WALL_1WAY) && backsector)
	{
		if ((!(wal->cstat & CSTAT_WALL_BOTTOM_SWAP) && (wal->cstat & CSTAT_WALL_1WAY)) ||
			((wal->cstat & CSTAT_WALL_BOTTOM_SWAP) && (wall[wal->nextwall].cstat & CSTAT_WALL_ALIGN_BOTTOM)))
			refheight = frontsector->ceilingz;
		else
			refheight = backsector->floorz;
	}
	else
	{
		refheight = (wal->cstat & CSTAT_WALL_ALIGN_BOTTOM) ? frontsector->floorz : frontsector->ceilingz;
	}

	type = RENDERWALL_M1S;
	DoTexture(di, wal, wal, refheight, topleft, topright, bottomleft, bottomright);
}

//==========================================================================
//
//
//
//==========================================================================

void HWWall::DoUpperTexture(HWDrawInfo* di, walltype* wal, sectortype* frontsector, sectortype* backsector,
	float topleft, float topright, float bottomleft, float bottomright)
{
	// get the alignment reference position.
	int refheight = (wal->cstat & CSTAT_WALL_ALIGN_BOTTOM) ? frontsector->floorz : frontsector->ceilingz;

	type = RENDERWALL_BOTTOM;
	DoTexture(di, wal, wal, refheight, topleft, topright, bottomleft, bottomright);
}

//==========================================================================
//
//
//
//==========================================================================

void HWWall::DoLowerTexture(HWDrawInfo* di, walltype* wal, sectortype* frontsector, sectortype* backsector,
	float topleft, float topright, float bottomleft, float bottomright)
{
	// get the alignment reference position.
	int refheight;
	auto refwall = (wall->cstat & CSTAT_WALL_BOTTOM_SWAP) ? &wall[wal->nextwall] : wal;

	if ((wal->cstat & CSTAT_WALL_1WAY) && backsector)
	{
		if ((!(wal->cstat & CSTAT_WALL_BOTTOM_SWAP) && (wal->cstat & CSTAT_WALL_1WAY)) ||
			((wal->cstat & CSTAT_WALL_BOTTOM_SWAP) && (wall[wal->nextwall].cstat & CSTAT_WALL_ALIGN_BOTTOM)))
			refheight = frontsector->ceilingz;
		else
			refheight = backsector->floorz;
	}
	else
	{
		refheight = (wal->cstat & CSTAT_WALL_ALIGN_BOTTOM) ? frontsector->floorz : frontsector->ceilingz;
	}

	shade = refwall->shade;
	palette = refwall->pal;
	type = RENDERWALL_BOTTOM;
	DoTexture(di, wal, refwall, refheight, topleft, topright, bottomleft, bottomright);
}

//==========================================================================
//
// 
//
//==========================================================================

void HWWall::DoMidTexture(HWDrawInfo* di, walltype* wal,
	sectortype* front, sectortype* back,
	float fch1, float fch2, float ffh1, float ffh2,
	float bch1, float bch2, float bfh1, float bfh2)
{
	float topleft,bottomleft,topright,bottomright;
	float refheight = (wal->cstat & CSTAT_WALL_ALIGN_BOTTOM) ? frontsector->ceilingz : backsector->ceilingz;

	topleft = std::min(bch1,fch1);
	topright = std::min(bch2,fch2);
	bottomleft = std::max(bfh1,ffh1);
	bottomright = std::max(bfh2,ffh2);
	if (topleft<=bottomleft && topright<=bottomright) return;
	type = seg->cstat & CSTAT_WALL_1WAY ? RENDERWALL_M1S : RENDERWALL_M2S;

	// todo: transparency.

	DoTexture(di, wal, wal, refheight, topleft, topright, bottomleft, bottomright);
	RenderStyle = STYLE_Normal;
	alpha = 1.f;
}


//==========================================================================
//
// 
//
//==========================================================================
void HWWall::Process(HWDrawInfo *di, walltype *wal, sectortype* frontsector, sectortype* backsector)
{
	auto backwall = wall->nextwall >= 0 && wall->nextwall < numwalls? &wall[wal->nextwall] : nullptr;
	auto p2wall = &wall[wal->point2];

	float fch1;
	float ffh1;
	float fch2;
	float ffh2;

	FVector2 v1(WallStartX(wal), WallStartY(wal));
	FVector2 v2(WallEndX(wal), WallEndY(wal));

	PlanesAtPoint(frontsector, wal->x, wal->y, &fch1, &ffh1);
	PlanesAtPoint(frontsector, p2wall->x, p2wall->y, &fch2, &ffh2);

#ifdef _DEBUG
	if (wal - wall == 14454)
	{
		int a = 0;
	}
	if (fabs(v1.X) == 400 && fabs(v1.Y) == 3968)
	{
		int a = 0;
	}
#endif

	// note: we always have a valid sidedef and linedef reference when getting here.

	this->seg = wal;
	this->frontsector = frontsector;
	this->backsector = backsector;
	vertindex = 0;
	vertcount = 0;

	//vertexes[0] = v1;
	//vertexes[1] = v2;

	glseg.x1 = v1.X;
	glseg.y1 = v1.Y;
	glseg.x2 = v2.X;
	glseg.y2 = v2.Y;
	glseg.fracleft = 0;
	glseg.fracright = 1;
	flags = 0;
	dynlightindex = -1;
	shade = wal->shade;
	palette = wal->pal;
	floorpal = frontsector->floorpal;
	visibility = sectorVisibility(frontsector);

	alpha = 1.0f;
	RenderStyle = STYLE_Normal;
	texture = NULL;

	/*
	if (wal->linedef->special == Line_Horizon)
	{
		SkyNormal(di, frontsector, v1, v2);
		DoHorizon(di, wal, frontsector, v1, v2);
		return;
	}
	*/

	bool isportal = false;// wal->linedef->isVisualPortal() && wal->sidedef == wal->linedef->sidedef[0];

	if (!backsector || !backwall)
	{
		// sector's sky
		SkyNormal(di, frontsector, v1, v2);

		/*
		if (isportal)
		{
			lineportal = wal->linedef->getPortal()->mGroup;
			ztop[0] = zceil[0];
			ztop[1] = zceil[1];
			zbottom[0] = zfloor[0];
			zbottom[1] = zfloor[1];
			PutPortal(di, PORTALTYPE_LINETOLINE, -1);
		}
		else
		*/
		{
			// normal texture

			int tilenum = (wal->cstat & CSTAT_WALL_1WAY) ? wal->overpicnum : wal->picnum;
			tileUpdatePicnum(&tilenum, int(wal-wall) + 16384, wall->cstat);
			texture = tileGetTexture(tilenum);
			if (texture && texture->isValid())
			{
				DoOneSidedTexture(di, wal, frontsector, backsector, fch1, fch2, ffh1, ffh2);
			}
		}
	}
	else // two sided
	{
		float bfh1;
		float bfh2;
		float bch1;
		float bch2;
		PlanesAtPoint(backsector, wal->x, wal->y, &bch1, &bfh1);
		PlanesAtPoint(backsector, p2wall->x, p2wall->y, &bch2, &bfh2);

		float zalign = 0.f;

		SkyTop(di, wal, frontsector, backsector, v1, v2);
		SkyBottom(di, wal, frontsector, backsector, v1, v2);

		// upper texture
		if (!(frontsector->ceilingstat & backsector->ceilingstat & CSTAT_SECTOR_SKY))
		{
			float bch1a = bch1;
			float bch2a = bch2;
			if (ffh1 > bch1 && ffh2 > bch2)
			{
				// the back sector's floor obstructs part of this wall
				bch2a = ffh2;
				bch1a = ffh1;
			}

			if (bch1a < fch1 || bch2a < fch2)
			{
				int tilenum = wal->picnum;
				tileUpdatePicnum(&tilenum, int(wal - wall) + 16384, wall->cstat);
				texture = tileGetTexture(tilenum);
				if (texture && texture->isValid())
				{
					DoUpperTexture(di, wal, frontsector, backsector, fch1, fch2, bch1a, bch2a);
				}
			}
		}

		/*
		if (isportal)
		{
			lineportal = wal->linedef->getPortal()->mGroup;
			ztop[0] = bch1;
			ztop[1] = bch2;
			zbottom[0] = bfh1;
			zbottom[1] = bfh2;
			PutPortal(di, PORTALTYPE_LINETOLINE, -1);
		}
		else*/

		if (wall->cstat & (CSTAT_WALL_MASKED | CSTAT_WALL_1WAY))
		{
			int tilenum = wal->overpicnum;
			tileUpdatePicnum(&tilenum, int(wal - wall) + 16384, wall->cstat);
			texture = tileGetTexture(tilenum);
			if (texture && texture->isValid())
			{
				DoMidTexture(di, wal, frontsector, backsector, fch1, fch2, ffh1, ffh2, bch1, bch2, bfh1, bfh2);
			}
		}

		// lower texture
		if (!(frontsector->floorstat & backsector->floorstat & CSTAT_SECTOR_SKY))
		{
			if (fch1 < bfh1 && fch2 < bfh2)
			{
				// the back sector's ceiling obstructs part of this wall.
				bfh1 = fch1;
				bfh2 = fch2;
			}

			if (bfh1 > ffh1 || bfh2 > ffh2)
			{
				auto w = (wal->cstat & CSTAT_WALL_BOTTOM_SWAP) ? backwall : wal;
				int tilenum = w->picnum;
				tileUpdatePicnum(&tilenum, int(wal - wall) + 16384, w->cstat);
				texture = tileGetTexture(tilenum);
				if (texture && texture->isValid())
				{
					DoLowerTexture(di, wal, frontsector, backsector, bfh1, bfh2, ffh1, ffh2);
				}
			}
		}
	}
}