From e1eb54ecdad3420c3c9508cd78e258ba87621684 Mon Sep 17 00:00:00 2001
From: Christoph Oelckers <coelckers@users.noreply.github.com>
Date: Thu, 4 Aug 2022 23:47:47 +0200
Subject: [PATCH] - replaced sectordist with a floating point variant with
 better precision.

---
 source/build/include/build.h |  1 -
 source/build/src/clip.cpp    | 26 +++++++++++++++++---------
 source/build/src/engine.cpp  | 35 ++---------------------------------
 3 files changed, 19 insertions(+), 43 deletions(-)

diff --git a/source/build/include/build.h b/source/build/include/build.h
index 756e7f41eec..a6fe2f90d5e 100644
--- a/source/build/include/build.h
+++ b/source/build/include/build.h
@@ -172,7 +172,6 @@ inline void updatesectorz(int32_t const x, int32_t const y, int32_t const z, sec
 void updatesectorneighbor(int32_t const x, int32_t const y, int * const sectnum, int32_t maxDistance = MAXUPDATESECTORDIST) ATTRIBUTE((nonnull(3)));
 
 
-int32_t getsectordist(vec2_t const in, int const sectnum, vec2_t * const out = nullptr);
 extern const int16_t *chsecptr_onextwall;
 
 inline int32_t krand(void)
diff --git a/source/build/src/clip.cpp b/source/build/src/clip.cpp
index 78ab897fb33..6cc4e975ae6 100644
--- a/source/build/src/clip.cpp
+++ b/source/build/src/clip.cpp
@@ -413,11 +413,11 @@ static void clipupdatesector(vec2_t const pos, int * const sectnum, int walldist
     if (inside_p(pos.X, pos.Y, *sectnum))
         return;
 
-    int16_t nsecs = min<int16_t>(getsectordist(pos, *sectnum), INT16_MAX);
+    double nsecs = SquareDistToSector(pos.X * inttoworld, pos.Y * inttoworld, &sector[*sectnum]);
 
-    if (nsecs > (walldist + 8))
+    double wd = (walldist + 8) * inttoworld; wd *= wd;
+    if (nsecs > wd)
     {
-        Printf("%s(): initial position (%d, %d) not within initial sector %d; shortest distance %d.\n", __func__, pos.X, pos.Y, *sectnum, nsecs);
         walldist = 0x7fff;
     }
 
@@ -1057,9 +1057,13 @@ void getzrange(const vec3_t& pos, sectortype* sect, int32_t* ceilz, CollisionBas
     vec2_t closest = pos.vec2;
     int sectnum = ::sectnum(sect);
     if (enginecompatibility_mode == ENGINECOMPATIBILITY_NONE)
-        getsectordist(closest, sectnum, &closest);
-    else
-        getzsofslopeptr(sect,closest.X,closest.Y,ceilz,florz);
+    {
+        DVector2 v;
+        SquareDistToSector(closest.X * inttoworld, closest.Y * inttoworld, &sector[sectnum], &v);
+        closest = { int(v.X * worldtoint), int(v.Y * worldtoint) };
+    }
+
+    getzsofslopeptr(sect,closest.X,closest.Y,ceilz,florz);
     ceilhit.setSector(sect);
     florhit.setSector(sect);
 
@@ -1119,9 +1123,13 @@ void getzrange(const vec3_t& pos, sectortype* sect, int32_t* ceilz, CollisionBas
                 int32_t daz = 0, daz2 = 0;
                 closest = pos.vec2;
                 if (enginecompatibility_mode == ENGINECOMPATIBILITY_NONE)
-                    getsectordist(closest, nextsectno, &closest);
-                else
-                    getzsofslopeptr(nextsect, closest.X,closest.Y, &daz,&daz2);
+                {
+                    DVector2 v;
+                    SquareDistToSector(closest.X * inttoworld, closest.Y * inttoworld, &sector[nextsectno], &v);
+                    closest = { int(v.X * worldtoint), int(v.Y * worldtoint) };
+                }
+
+                getzsofslopeptr(nextsect, closest.X,closest.Y, &daz,&daz2);
 
                 {
                     if (daz > *ceilz)
diff --git a/source/build/src/engine.cpp b/source/build/src/engine.cpp
index 27b409e9b42..71272b3e3f2 100644
--- a/source/build/src/engine.cpp
+++ b/source/build/src/engine.cpp
@@ -471,42 +471,11 @@ int32_t getwalldist(vec2_t const in, int const wallnum, vec2_t * const out)
 }
 
 
-int32_t getsectordist(vec2_t const in, int const sectnum, vec2_t * const out /*= nullptr*/)
-{
-    if (inside_p(in.X, in.Y, sectnum))
-    {
-        if (out)
-            *out = in;
-        return 0;
-    }
-
-    int32_t distance = INT32_MAX;
-
-    vec2_t     closest = {};
-
-    for (auto& wal : wallsofsector(sectnum))
-    {
-        vec2_t p;
-        int32_t const walldist = getwalldist(in, wallnum(&wal), &p);
-
-        if (walldist < distance)
-        {
-            distance = walldist;
-            closest = p;
-        }
-    }
-
-    if (out)
-        *out = closest;
-
-    return distance;
-}
-
-
 template<class Inside>
 void updatesectorneighborz(int32_t const x, int32_t const y, int32_t const z, int* const sectnum, int32_t maxDistance, Inside checker)
 {
     int const initialsectnum = *sectnum;
+    double maxDist = maxDistance * inttoworld; maxDist *= maxDist;
 
     if ((validSectorIndex(initialsectnum)))
     {
@@ -526,7 +495,7 @@ void updatesectorneighborz(int32_t const x, int32_t const y, int32_t const z, in
 
             for (auto& wal : wallsofsector(listsectnum))
             {
-                if (wal.nextsector >= 0 && (iter == 0 || getsectordist({ x, y }, wal.nextsector) <= maxDistance))
+                if (wal.nextsector >= 0 && (iter == 0 || SquareDistToSector(x * inttoworld, y * inttoworld, wal.nextSector()) <= maxDist))
                     search.Add(wal.nextsector);
             }
             iter++;