//-------------------------------------------------------------------------
/*
Copyright (C) 2010-2019 EDuke32 developers and contributors
Copyright (C) 2019 Nuke.YKT

This file is part of NBlood.

NBlood is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License version 2
as published by the Free Software Foundation.

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., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
*/
//-------------------------------------------------------------------------

#include "ns.h"	// Must come before everything else!

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <random>
#include "build.h"
#include "common_game.h"

#include "actor.h"
#include "db.h"
#include "gameutil.h"
#include "globals.h"
#include "tile.h"
#include "trig.h"

BEGIN_BLD_NS

POINT2D baseWall[kMaxWalls];
POINT3D baseSprite[kMaxSprites];
int baseFloor[kMaxSectors];
int baseCeil[kMaxSectors];
int velFloor[kMaxSectors];
int velCeil[kMaxSectors];
short gUpperLink[kMaxSectors];
short gLowerLink[kMaxSectors];
HITINFO gHitInfo;

bool AreSectorsNeighbors(int sect1, int sect2)
{
    dassert(sect1 >= 0 && sect1 < kMaxSectors);
    dassert(sect2 >= 0 && sect2 < kMaxSectors);
    if (sector[sect1].wallnum < sector[sect2].wallnum)
    {
        for (int i = 0; i < sector[sect1].wallnum; i++)
        {
            if (wall[sector[sect1].wallptr+i].nextsector == sect2)
            {
                return 1;
            }
        }
    }
    else
    {
        for (int i = 0; i < sector[sect2].wallnum; i++)
        {
            if (wall[sector[sect2].wallptr+i].nextsector == sect1)
            {
                return 1;
            }
        }
    }
    return 0;
}

bool FindSector(int nX, int nY, int nZ, int *nSector)
{
    int32_t nZFloor, nZCeil;
    dassert(*nSector >= 0 && *nSector < kMaxSectors);
    if (inside(nX, nY, *nSector))
    {
        getzsofslope(*nSector, nX, nY, &nZCeil, &nZFloor);
        if (nZ >= nZCeil && nZ <= nZFloor)
        {
            return 1;
        }
    }
    walltype *pWall = &wall[sector[*nSector].wallptr];
    for (int i = sector[*nSector].wallnum; i > 0; i--, pWall++)
    {
        int nOSector = pWall->nextsector;
        if (nOSector >= 0 && inside(nX, nY, nOSector))
        {
            getzsofslope(nOSector, nX, nY, &nZCeil, &nZFloor);
            if (nZ >= nZCeil && nZ <= nZFloor)
            {
                *nSector = nOSector;
                return 1;
            }
        }
    }
    for (int i = 0; i < numsectors; i++)
    {
        if (inside(nX, nY, i))
        {
            getzsofslope(i, nX, nY, &nZCeil, &nZFloor);
            if (nZ >= nZCeil && nZ <= nZFloor)
            {
                *nSector = i;
                return 1;
            }
        }
    }
    return 0;
}

bool FindSector(int nX, int nY, int *nSector)
{
    dassert(*nSector >= 0 && *nSector < kMaxSectors);
    if (inside(nX, nY, *nSector))
    {
        return 1;
    }
    walltype *pWall = &wall[sector[*nSector].wallptr];
    for (int i = sector[*nSector].wallnum; i > 0; i--, pWall++)
    {
        int nOSector = pWall->nextsector;
        if (nOSector >= 0 && inside(nX, nY, nOSector))
        {
            *nSector = nOSector;
            return 1;
        }
    }
    for (int i = 0; i < numsectors; i++)
    {
        if (inside(nX, nY, i))
        {
            *nSector = i;
            return 1;
        }
    }
    return 0;
}

void CalcFrameRate(void)
{
    static int ticks[64];
    static int index;
    if (ticks[index] != gFrameClock)
    {
        gFrameRate = (120*64)/((int)gFrameClock-ticks[index]);
        ticks[index] = (int)gFrameClock;
    }
    index = (index+1) & 63;
}

bool CheckProximity(spritetype *pSprite, int nX, int nY, int nZ, int nSector, int nDist)
{
    dassert(pSprite != NULL);
    int oX = klabs(nX-pSprite->x)>>4;
    if (oX >= nDist) return 0;

    int oY = klabs(nY-pSprite->y)>>4;
    if (oY >= nDist) return 0;

    int oZ = klabs(nZ-pSprite->z)>>8;
    if (oZ >= nDist) return 0;

    if (approxDist(oX, oY) >= nDist) return 0;

    int bottom, top;
    GetSpriteExtents(pSprite, &top, &bottom);
    if (cansee(pSprite->x, pSprite->y, pSprite->z, pSprite->sectnum, nX, nY, nZ, nSector))
        return 1;
    if (cansee(pSprite->x, pSprite->y, bottom, pSprite->sectnum, nX, nY, nZ, nSector))
        return 1;
    if (cansee(pSprite->x, pSprite->y, top, pSprite->sectnum, nX, nY, nZ, nSector))
        return 1;
    return 0;
}

bool CheckProximityPoint(int nX1, int nY1, int nZ1, int nX2, int nY2, int nZ2, int nDist)
{
    int oX = klabs(nX2-nX1)>>4;
    if (oX >= nDist)
        return 0;
    int oY = klabs(nY2-nY1)>>4;
    if (oY >= nDist)
        return 0;
    int oZ = klabs(nZ2-nZ1)>>4;
    if (oZ >= nDist)
        return 0;
    if (approxDist(oX, oY) >= nDist) return 0;
    return 1;
}

bool CheckProximityWall(int nWall, int x, int y, int nDist)
{
    int x1 = wall[nWall].x;
    int y1 = wall[nWall].y;
    int x2 = wall[wall[nWall].point2].x;
    int y2 = wall[wall[nWall].point2].y;
    nDist <<= 4;
    if (x1 < x2)
    {
        if (x <= x1 - nDist || x >= x2 + nDist)
        {
            return 0;
        }
    }
    else
    {
        if (x <= x2 - nDist || x >= x1 + nDist)
        {
            return 0;
        }
        if (x1 == x2)
        {
            int px1 = x - x1;
            int py1 = y - y1;
            int px2 = x - x2;
            int py2 = y - y2;
            int dist1 = px1 * px1 + py1 * py1;
            int dist2 = px2 * px2 + py2 * py2;
            if (y1 < y2)
            {
                if (y <= y1 - nDist || y >= y2 + nDist)
                {
                    return 0;
                }
                if (y < y1)
                {
                    return dist1 < nDist * nDist;
                }
                if (y > y2)
                {
                    return dist2 < nDist * nDist;
                }
            }
            else
            {
                if (y <= y2 - nDist || y >= y1 + nDist)
                {
                    return 0;
                }
                if (y < y2)
                {
                    return dist2 < nDist * nDist;
                }
                if (y > y1)
                {
                    return dist1 < nDist * nDist;
                }
            }
            return 1;
        }
    }
    if (y1 < y2)
    {
        if (y <= y1 - nDist || y >= y2 + nDist)
        {
            return 0;
        }
    }
    else
    {
        if (y <= y2 - nDist || y >= y1 + nDist)
        {
            return 0;
        }
        if (y1 == y2)
        {
            int px1 = x - x1;
            int py1 = y - y1;
            int px2 = x - x2;
            int py2 = y - y2;
            int check1 = px1 * px1 + py1 * py1;
            int check2 = px2 * px2 + py2 * py2;
            if (x1 < x2)
            {
                if (x <= x1 - nDist || x >= x2 + nDist)
                {
                    return 0;
                }
                if (x < x1)
                {
                    return check1 < nDist * nDist;
                }
                if (x > x2)
                {
                    return check2 < nDist * nDist;
                }
            }
            else
            {
                if (x <= x2 - nDist || x >= x1 + nDist)
                {
                    return 0;
                }
                if (x < x2)
                {
                    return check2 < nDist * nDist;
                }
                if (x > x1)
                {
                    return check1 < nDist * nDist;
                }
            }
        }
    }

    int dx = x2 - x1;
    int dy = y2 - y1;
    int px = x - x2;
    int py = y - y2;
    int side = px * dx + dy * py;
    if (side >= 0)
    {
        return px * px + py * py < nDist * nDist;
    }
    px = x - x1;
    py = y - y1;
    side = px * dx + dy * py;
    if (side <= 0)
    {
        return px * px + py * py < nDist * nDist;
    }
    int check1 = px * dy - dx * py;
    int check2 = dy * dy + dx * dx;
    return check1 * check1 < check2 * nDist * nDist;
}

int GetWallAngle(int nWall)
{
    int nWall2 = wall[nWall].point2;
    return getangle(wall[nWall2].x - wall[nWall].x, wall[nWall2].y - wall[nWall].y);
}

void GetWallNormal(int nWall, int *pX, int *pY)
{
    dassert(nWall >= 0 && nWall < kMaxWalls);
    int nWall2 = wall[nWall].point2;
    int dX = -(wall[nWall2].y - wall[nWall].y);
    dX >>= 4;
    int dY = wall[nWall2].x - wall[nWall].x;
    dY >>= 4;
    int nLength = ksqrt(dX*dX+dY*dY);
    if (nLength <= 0)
        nLength = 1;
    *pX = divscale16(dX, nLength);
    *pY = divscale16(dY, nLength);
}

bool IntersectRay(int wx, int wy, int wdx, int wdy, int x1, int y1, int z1, int x2, int y2, int z2, int *ix, int *iy, int *iz)
{
    int dX = x1 - x2;
    int dY = y1 - y2;
    int dZ = z1 - z2;
    int side = wdx * dY - wdy * dX;
    int dX2 = x1 - wx;
    int dY2 = y1 - wy;
    int check1 = dX2 * dY - dY2 * dX;
    int check2 = wdx * dY2 - wdy * dX2;
    if (side >= 0)
    {
        if (!side)
            return 0;
        if (check1 < 0)
            return 0;
        if (check2 < 0 || check2 >= side)
            return 0;
    }
    else
    {
        if (check1 > 0)
            return 0;
        if (check2 > 0 || check2 <= side)
            return 0;
    }
    int nScale = divscale16(check2, side);
    *ix = x1 + mulscale16(dX, nScale);
    *iy = y1 + mulscale16(dY, nScale);
    *iz = z1 + mulscale16(dZ, nScale);
    return 1;
}

int HitScan(spritetype *pSprite, int z, int dx, int dy, int dz, unsigned int nMask, int nRange)
{
    dassert(pSprite != NULL);
    dassert(dx != 0 || dy != 0);
    gHitInfo.hitsect = -1;
    gHitInfo.hitwall = -1;
    gHitInfo.hitsprite = -1;
    int x = pSprite->x;
    int y = pSprite->y;
    int nSector = pSprite->sectnum;
    int bakCstat = pSprite->cstat;
    pSprite->cstat &= ~256;
    if (nRange)
    {
        hitscangoal.x = x + mulscale30(nRange << 4, Cos(pSprite->ang));
        hitscangoal.y = y + mulscale30(nRange << 4, Sin(pSprite->ang));
    }
    else
    {
        hitscangoal.x = hitscangoal.y = 0x1ffffff;
    }
    vec3_t pos = { x, y, z };
    hitdata_t hitData;
    hitData.pos.z = gHitInfo.hitz;
    hitscan(&pos, nSector, dx, dy, dz << 4, &hitData, nMask);
    gHitInfo.hitsect = hitData.sect;
    gHitInfo.hitwall = hitData.wall;
    gHitInfo.hitsprite = hitData.sprite;
    gHitInfo.hitx = hitData.pos.x;
    gHitInfo.hity = hitData.pos.y;
    gHitInfo.hitz = hitData.pos.z;
    hitscangoal.x = hitscangoal.y = 0x1ffffff;
    pSprite->cstat = bakCstat;
    if (gHitInfo.hitsprite >= kMaxSprites || gHitInfo.hitwall >= kMaxWalls || gHitInfo.hitsect >= kMaxSectors)
        return -1;
    if (gHitInfo.hitsprite >= 0)
        return 3;
    if (gHitInfo.hitwall >= 0)
    {
        if (wall[gHitInfo.hitwall].nextsector == -1)
            return 0;
        int nZCeil, nZFloor;
        getzsofslope(wall[gHitInfo.hitwall].nextsector, gHitInfo.hitx, gHitInfo.hity, &nZCeil, &nZFloor);
        if (gHitInfo.hitz <= nZCeil || gHitInfo.hitz >= nZFloor)
            return 0;
        return 4;
    }
    if (gHitInfo.hitsect >= 0)
        return 1 + (z < gHitInfo.hitz);
    return -1;
}

int VectorScan(spritetype *pSprite, int nOffset, int nZOffset, int dx, int dy, int dz, int nRange, int ac)
{
    int nNum = 256;
    dassert(pSprite != NULL);
    gHitInfo.hitsect = -1;
    gHitInfo.hitwall = -1;
    gHitInfo.hitsprite = -1;
    int x1 = pSprite->x+mulscale30(nOffset, Cos(pSprite->ang+512));
    int y1 = pSprite->y+mulscale30(nOffset, Sin(pSprite->ang+512));
    int z1 = pSprite->z+nZOffset;
    int bakCstat = pSprite->cstat;
    pSprite->cstat &= ~256;
    int nSector = pSprite->sectnum;
    if (nRange)
    {
        hitscangoal.x = x1+mulscale30(nRange<<4, Cos(pSprite->ang));
        hitscangoal.y = y1+mulscale30(nRange<<4, Sin(pSprite->ang));
    }
    else
    {
        hitscangoal.x = hitscangoal.y = 0x1fffffff;
    }
    vec3_t pos = { x1, y1, z1 };
    hitdata_t hitData;
    hitData.pos.z = gHitInfo.hitz;
    hitscan(&pos, nSector, dx, dy, dz << 4, &hitData, CLIPMASK1);
    gHitInfo.hitsect = hitData.sect;
    gHitInfo.hitwall = hitData.wall;
    gHitInfo.hitsprite = hitData.sprite;
    gHitInfo.hitx = hitData.pos.x;
    gHitInfo.hity = hitData.pos.y;
    gHitInfo.hitz = hitData.pos.z;
    hitscangoal.x = hitscangoal.y = 0x1ffffff;
    pSprite->cstat = bakCstat;
    while (nNum--)
    {
        if (gHitInfo.hitsprite >= kMaxSprites || gHitInfo.hitwall >= kMaxWalls || gHitInfo.hitsect >= kMaxSectors)
            return -1;
        if (nRange && approxDist(gHitInfo.hitx - pSprite->x, gHitInfo.hity - pSprite->y) > nRange)
            return -1;
        if (gHitInfo.hitsprite >= 0)
        {
            spritetype *pOther = &sprite[gHitInfo.hitsprite];
            if ((pOther->flags & 8) && !(ac & 1))
                return 3;
            if ((pOther->cstat & 0x30) != 0)
                return 3;
            int nPicnum = pOther->picnum;
            if (tilesiz[nPicnum].x == 0 || tilesiz[nPicnum].y == 0)
                return 3;
            int height = (tilesiz[nPicnum].y*pOther->yrepeat)<<2;
            int otherZ = pOther->z;
            if (pOther->cstat & 0x80)
                otherZ += height / 2;
            int nOffset = picanm[nPicnum].yofs;
            if (nOffset)
                otherZ -= (nOffset*pOther->yrepeat)<<2;
            dassert(height > 0);
            int height2 = scale(otherZ-gHitInfo.hitz, tilesiz[nPicnum].y, height);
            if (!(pOther->cstat & 8))
                height2 = tilesiz[nPicnum].y-height2;
            if (height2 >= 0 && height2 < tilesiz[nPicnum].y)
            {
                int width = (tilesiz[nPicnum].x*pOther->xrepeat)>>2;
                width = (width*3)/4;
                int check1 = ((y1 - pOther->y)*dx - (x1 - pOther->x)*dy) / ksqrt(dx*dx+dy*dy);
                dassert(width > 0);
                int width2 = scale(check1, tilesiz[nPicnum].x, width);
                int nOffset = picanm[nPicnum].xofs;
                width2 += nOffset + tilesiz[nPicnum].x / 2;
                if (width2 >= 0 && width2 < tilesiz[nPicnum].x)
                {
                    auto pData = tileLoadTile(nPicnum);
                    if (pData[width2*tilesiz[nPicnum].y+height2] != (char)255)
                        return 3;
                }
            }
            int bakCstat = pOther->cstat;
            pOther->cstat &= ~256;
            gHitInfo.hitsect = -1;
            gHitInfo.hitwall = -1;
            gHitInfo.hitsprite = -1;
            x1 = gHitInfo.hitx;
            y1 = gHitInfo.hity;
            z1 = gHitInfo.hitz;
            pos = { x1, y1, z1 };
            hitData.pos.z = gHitInfo.hitz;
            hitscan(&pos, pOther->sectnum,
                dx, dy, dz << 4, &hitData, CLIPMASK1);
            gHitInfo.hitsect = hitData.sect;
            gHitInfo.hitwall = hitData.wall;
            gHitInfo.hitsprite = hitData.sprite;
            gHitInfo.hitx = hitData.pos.x;
            gHitInfo.hity = hitData.pos.y;
            gHitInfo.hitz = hitData.pos.z;
            pOther->cstat = bakCstat;
            continue;
        }
        if (gHitInfo.hitwall >= 0)
        {
            walltype *pWall = &wall[gHitInfo.hitwall];
            if (pWall->nextsector == -1)
                return 0;
            sectortype *pSector = &sector[gHitInfo.hitsect];
            sectortype *pSectorNext = &sector[pWall->nextsector];
            int nZCeil, nZFloor;
            getzsofslope(pWall->nextsector, gHitInfo.hitx, gHitInfo.hity, &nZCeil, &nZFloor);
            if (gHitInfo.hitz <= nZCeil)
                return 0;
            if (gHitInfo.hitz >= nZFloor)
            {
                if (!(pSector->floorstat&1) || !(pSectorNext->floorstat&1))
                    return 0;
                return 2;
            }
            if (!(pWall->cstat & 0x30))
                return 0;
            int nOffset;
            if (pWall->cstat & 4)
                nOffset = ClipHigh(pSector->floorz, pSectorNext->floorz);
            else
                nOffset = ClipLow(pSector->ceilingz, pSectorNext->ceilingz);
            nOffset = (gHitInfo.hitz - nOffset) >> 8;
            if (pWall->cstat & 256)
                nOffset = -nOffset;

            int nPicnum = pWall->overpicnum;
            int nSizX = tilesiz[nPicnum].x;
            int nSizY = tilesiz[nPicnum].y;
            if (!nSizX || !nSizY)
                return 0;

            int potX = nSizX == (1<<(picsiz[nPicnum]&15));
            int potY = nSizY == (1<<(picsiz[nPicnum]>>4));

            nOffset = (nOffset*pWall->yrepeat) / 8;
            nOffset += (nSizY*pWall->ypanning) / 256;
            int nLength = approxDist(pWall->x - wall[pWall->point2].x, pWall->y - wall[pWall->point2].y);
            int nHOffset;
            if (pWall->cstat & 8)
                nHOffset = approxDist(gHitInfo.hitx - wall[pWall->point2].x, gHitInfo.hity - wall[pWall->point2].y);
            else
                nHOffset = approxDist(gHitInfo.hitx - pWall->x, gHitInfo.hity - pWall->y);

            nHOffset = pWall->xpanning + ((nHOffset*pWall->xrepeat) << 3) / nLength;
            if (potX)
                nHOffset &= nSizX - 1;
            else
                nHOffset %= nSizX;
            if (potY)
                nOffset &= nSizY - 1;
            else
                nOffset %= nSizY;
            auto pData = tileLoadTile(nPicnum);
            int nPixel;
            if (potY)
                nPixel = (nHOffset<<(picsiz[nPicnum]>>4)) + nOffset;
            else
                nPixel = nHOffset*nSizY + nOffset;

            if (pData[nPixel] == (char)255)
            {
                int bakCstat = pWall->cstat;
                pWall->cstat &= ~64;
                int bakCstat2 = wall[pWall->nextwall].cstat;
                wall[pWall->nextwall].cstat &= ~64;
                gHitInfo.hitsect = -1;
                gHitInfo.hitwall = -1;
                gHitInfo.hitsprite = -1;
                x1 = gHitInfo.hitx;
                y1 = gHitInfo.hity;
                z1 = gHitInfo.hitz;
                pos = { x1, y1, z1 };
                hitData.pos.z = gHitInfo.hitz;
                hitscan(&pos, pWall->nextsector,
                    dx, dy, dz << 4, &hitData, CLIPMASK1);
                gHitInfo.hitsect = hitData.sect;
                gHitInfo.hitwall = hitData.wall;
                gHitInfo.hitsprite = hitData.sprite;
                gHitInfo.hitx = hitData.pos.x;
                gHitInfo.hity = hitData.pos.y;
                gHitInfo.hitz = hitData.pos.z;
                pWall->cstat = bakCstat;
                wall[pWall->nextwall].cstat = bakCstat2;
                continue;
            }
            return 4;
        }
        if (gHitInfo.hitsect >= 0)
        {
            if (dz > 0)
            {
                if (gUpperLink[gHitInfo.hitsect] < 0)
                    return 2;
                int nSprite = gUpperLink[gHitInfo.hitsect];
                int nLink = sprite[nSprite].owner & 0xfff;
                gHitInfo.hitsect = -1;
                gHitInfo.hitwall = -1;
                gHitInfo.hitsprite = -1;
                x1 = gHitInfo.hitx + sprite[nLink].x - sprite[nSprite].x;
                y1 = gHitInfo.hity + sprite[nLink].y - sprite[nSprite].y;
                z1 = gHitInfo.hitz + sprite[nLink].z - sprite[nSprite].z;
                pos = { x1, y1, z1 };
                hitData.pos.z = gHitInfo.hitz;
                hitscan(&pos, sprite[nLink].sectnum, dx, dy, dz<<4, &hitData, CLIPMASK1);
                gHitInfo.hitsect = hitData.sect;
                gHitInfo.hitwall = hitData.wall;
                gHitInfo.hitsprite = hitData.sprite;
                gHitInfo.hitx = hitData.pos.x;
                gHitInfo.hity = hitData.pos.y;
                gHitInfo.hitz = hitData.pos.z;
                continue;
            }
            else
            {
                if (gLowerLink[gHitInfo.hitsect] < 0)
                    return 1;
                int nSprite = gLowerLink[gHitInfo.hitsect];
                int nLink = sprite[nSprite].owner & 0xfff;
                gHitInfo.hitsect = -1;
                gHitInfo.hitwall = -1;
                gHitInfo.hitsprite = -1;
                x1 = gHitInfo.hitx + sprite[nLink].x - sprite[nSprite].x;
                y1 = gHitInfo.hity + sprite[nLink].y - sprite[nSprite].y;
                z1 = gHitInfo.hitz + sprite[nLink].z - sprite[nSprite].z;
                pos = { x1, y1, z1 };
                hitData.pos.z = gHitInfo.hitz;
                hitscan(&pos, sprite[nLink].sectnum, dx, dy, dz<<4, &hitData, CLIPMASK1);
                gHitInfo.hitsect = hitData.sect;
                gHitInfo.hitwall = hitData.wall;
                gHitInfo.hitsprite = hitData.sprite;
                gHitInfo.hitx = hitData.pos.x;
                gHitInfo.hity = hitData.pos.y;
                gHitInfo.hitz = hitData.pos.z;
                continue;
            }
        }
        return -1;
    }
    return -1;
}

void GetZRange(spritetype *pSprite, int *ceilZ, int *ceilHit, int *floorZ, int *floorHit, int nDist, unsigned int nMask, unsigned int nClipParallax)
{
    dassert(pSprite != NULL);
    int bakCstat = pSprite->cstat;
    int32_t nTemp1, nTemp2;
    pSprite->cstat &= ~257;
    getzrange_old(pSprite->x, pSprite->y, pSprite->z, pSprite->sectnum, (int32_t*)ceilZ, (int32_t*)ceilHit, (int32_t*)floorZ, (int32_t*)floorHit, nDist, nMask);
    if (((*floorHit) & 0xc000) == 0x4000)
    {
        int nSector = (*floorHit) & 0x3fff;
        if ((nClipParallax & PARALLAXCLIP_FLOOR) == 0 && (sector[nSector].floorstat & 1))
            *floorZ = 0x7fffffff;
        if (sector[nSector].extra > 0)
        {
            XSECTOR *pXSector = &xsector[sector[nSector].extra];
            *floorZ += pXSector->Depth << 10;
        }
        if (gUpperLink[nSector] >= 0)
        {
            int nSprite = gUpperLink[nSector];
            int nLink = sprite[nSprite].owner & 0xfff;
            getzrange_old(pSprite->x+sprite[nLink].x-sprite[nSprite].x, pSprite->y+sprite[nLink].y-sprite[nSprite].y,
                pSprite->z+sprite[nLink].z-sprite[nSprite].z, sprite[nLink].sectnum, &nTemp1, &nTemp2, (int32_t*)floorZ, (int32_t*)floorHit,
                nDist, nMask);
            *floorZ -= sprite[nLink].z - sprite[nSprite].z;
        }
    }
    if (((*ceilHit) & 0xc000) == 0x4000)
    {
        int nSector = (*ceilHit) & 0x3fff;
        if ((nClipParallax & PARALLAXCLIP_CEILING) == 0 && (sector[nSector].ceilingstat & 1))
            *ceilZ = 0x80000000;
        if (gLowerLink[nSector] >= 0)
        {
            int nSprite = gLowerLink[nSector];
            int nLink = sprite[nSprite].owner & 0xfff;
            getzrange_old(pSprite->x+sprite[nLink].x-sprite[nSprite].x, pSprite->y+sprite[nLink].y-sprite[nSprite].y,
                pSprite->z+sprite[nLink].z-sprite[nSprite].z, sprite[nLink].sectnum, (int32_t*)ceilZ, (int32_t*)ceilHit, &nTemp1, &nTemp2,
                nDist, nMask);
            *ceilZ -= sprite[nLink].z - sprite[nSprite].z;
        }
    }
    pSprite->cstat = bakCstat;
}

void GetZRangeAtXYZ(int x, int y, int z, int nSector, int *ceilZ, int *ceilHit, int *floorZ, int *floorHit, int nDist, unsigned int nMask, unsigned int nClipParallax)
{
    int32_t nTemp1, nTemp2;
    getzrange_old(x, y, z, nSector, (int32_t*)ceilZ, (int32_t*)ceilHit, (int32_t*)floorZ, (int32_t*)floorHit, nDist, nMask);
    if (((*floorHit) & 0xc000) == 0x4000)
    {
        int nSector = (*floorHit) & 0x3fff;
        if ((nClipParallax & PARALLAXCLIP_FLOOR) == 0 && (sector[nSector].floorstat & 1))
            *floorZ = 0x7fffffff;
        if (sector[nSector].extra > 0)
        {
            XSECTOR *pXSector = &xsector[sector[nSector].extra];
            *floorZ += pXSector->Depth << 10;
        }
        if (gUpperLink[nSector] >= 0)
        {
            int nSprite = gUpperLink[nSector];
            int nLink = sprite[nSprite].owner & 0xfff;
            getzrange_old(x+sprite[nLink].x-sprite[nSprite].x, y+sprite[nLink].y-sprite[nSprite].y,
                z+sprite[nLink].z-sprite[nSprite].z, sprite[nLink].sectnum, &nTemp1, &nTemp2, (int32_t*)floorZ, (int32_t*)floorHit,
                nDist, nMask);
            *floorZ -= sprite[nLink].z - sprite[nSprite].z;
        }
    }
    if (((*ceilHit) & 0xc000) == 0x4000)
    {
        int nSector = (*ceilHit) & 0x3fff;
        if ((nClipParallax & PARALLAXCLIP_CEILING) == 0 && (sector[nSector].ceilingstat & 1))
            *ceilZ = 0x80000000;
        if (gLowerLink[nSector] >= 0)
        {
            int nSprite = gLowerLink[nSector];
            int nLink = sprite[nSprite].owner & 0xfff;
            getzrange_old(x+sprite[nLink].x-sprite[nSprite].x, y+sprite[nLink].y-sprite[nSprite].y,
                z+sprite[nLink].z-sprite[nSprite].z, sprite[nLink].sectnum, (int32_t*)ceilZ, (int32_t*)ceilHit, &nTemp1, &nTemp2,
                nDist, nMask);
            *ceilZ -= sprite[nLink].z - sprite[nSprite].z;
        }
    }
}

int GetDistToLine(int x1, int y1, int x2, int y2, int x3, int y3)
{
    int check = (y1-y3)*(x3-x2);
    int check2 = (x1-x2)*(y3-y2);
    if (check2 > check)
        return -1;
    int v8 = dmulscale(x1-x2,x3-x2,y1-y3,y3-y2,4);
    int vv = dmulscale(x3-x2,x3-x2,y3-y2,y3-y2,4);
    int t1, t2;
    if (v8 <= 0)
    {
        t1 = x2;
        t2 = y2;
    }
    else if (vv > v8)
    {
        t1 = x2+scale(x3-x2,v8,vv);
        t2 = y2+scale(y3-y2,v8,vv);
    }
    else
    {
        t1 = x3;
        t2 = y3;
    }
    return approxDist(t1-x1, t2-y1);
}

unsigned int ClipMove(int *x, int *y, int *z, int *nSector, int xv, int yv, int wd, int cd, int fd, unsigned int nMask)
{
    int bakX = *x;
    int bakY = *y;
    int bakZ = *z;
    short bakSect = *nSector;
    unsigned int nRes = clipmove_old((int32_t*)x, (int32_t*)y, (int32_t*)z, &bakSect, xv<<14, yv<<14, wd, cd, fd, nMask);
    if (bakSect == -1)
    {
        *x = bakX; *y = bakY; *z = bakZ;
    }
    else
    {
        *nSector = bakSect;
    }
    return nRes;
}

int GetClosestSectors(int nSector, int x, int y, int nDist, short *pSectors, char *pSectBit)
{
    char sectbits[(kMaxSectors+7)>>3];
    dassert(pSectors != NULL);
    memset(sectbits, 0, sizeof(sectbits));
    pSectors[0] = nSector;
    SetBitString(sectbits, nSector);
    int n = 1;
    int i = 0;
    if (pSectBit)
    {
        memset(pSectBit, 0, (kMaxSectors+7)>>3);
        SetBitString(pSectBit, nSector);
    }
    while (i < n)
    {
        int nCurSector = pSectors[i];
        int nStartWall = sector[nCurSector].wallptr;
        int nEndWall = nStartWall + sector[nCurSector].wallnum;
        walltype *pWall = &wall[nStartWall];
        for (int j = nStartWall; j < nEndWall; j++, pWall++)
        {
            int nNextSector = pWall->nextsector;
            if (nNextSector < 0)
                continue;
            if (TestBitString(sectbits, nNextSector))
                continue;
            SetBitString(sectbits, nNextSector);
            int dx = klabs(wall[pWall->point2].x - x)>>4;
            int dy = klabs(wall[pWall->point2].y - y)>>4;
            if (dx < nDist && dy < nDist)
            {
                if (approxDist(dx, dy) < nDist)
                {
                    if (pSectBit)
                        SetBitString(pSectBit, nNextSector);
                    pSectors[n++] = nNextSector;
                }
            }
        }
        i++;
    }
    pSectors[n] = -1;
    return n;
}

int GetClosestSpriteSectors(int nSector, int x, int y, int nDist, short *pSectors, char *pSectBit, short *a8)
{
    char sectbits[(kMaxSectors+7)>>3];
    dassert(pSectors != NULL);
    memset(sectbits, 0, sizeof(sectbits));
    pSectors[0] = nSector;
    SetBitString(sectbits, nSector);
    int n = 1, m = 0;
    int i = 0;
    if (pSectBit)
    {
        memset(pSectBit, 0, (kMaxSectors+7)>>3);
        SetBitString(pSectBit, nSector);
    }
    while (i < n)
    {
        int nCurSector = pSectors[i];
        int nStartWall = sector[nCurSector].wallptr;
        int nEndWall = nStartWall + sector[nCurSector].wallnum;
        walltype *pWall = &wall[nStartWall];
        for (int j = nStartWall; j < nEndWall; j++, pWall++)
        {
            int nNextSector = pWall->nextsector;
            if (nNextSector < 0)
                continue;
            if (TestBitString(sectbits, nNextSector))
                continue;
            SetBitString(sectbits, nNextSector);
            if (CheckProximityWall(wall[j].point2, x, y, nDist))
            {
                if (pSectBit)
                    SetBitString(pSectBit, nNextSector);
                pSectors[n++] = nNextSector;
                if (a8 && pWall->extra > 0)
                {
                    XWALL *pXWall = &xwall[pWall->extra];
                    if (pXWall->triggerVector && !pXWall->isTriggered && !pXWall->state)
                        a8[m++] = j;
                }
            }
        }
        i++;
    }
    pSectors[n] = -1;
    if (a8)
    {
        a8[m] = -1;
    }
    return n;
}

int picWidth(short nPic, short repeat) {
    return ClipLow((tilesiz[nPic].y * repeat) >> 2, 0);
}

int picHeight(short nPic, short repeat) {
    return ClipLow((tilesiz[nPic].y * repeat) << 2, 0);
}

// by NoOne: used for better randomness in single player
int STD_Random(int a, int b) {
    std::default_random_engine stdRandom;
    stdRandom.seed(std::random_device()());
    std::uniform_int_distribution<int> dist_a_b(a, b);
    return dist_a_b(stdRandom);
}

END_BLD_NS