From 99a29e9d57b3d8314bb0dedf804e68a6a2e782b2 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Miloslav=20=C4=8C=C3=AD=C5=BE?= <tastyfish@seznam.cz>
Date: Wed, 12 Sep 2018 15:39:28 +0200
Subject: [PATCH] Improve horizon

---
 raycastlib.h | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/raycastlib.h b/raycastlib.h
index bcd2e32..c5e59f2 100644
--- a/raycastlib.h
+++ b/raycastlib.h
@@ -815,7 +815,7 @@ void _columnFunction(HitResult *hits, uint16_t hitCount, uint16_t x, Ray ray)
     int_maybe32_t z1ScreenCeilNoClamp = 0; 
     int_maybe32_t z2ScreenCeil = 0;
     int_maybe32_t wallScreenHeightCeilNoClamp = 0;
-    int_maybe32_t zBottomCeil;
+    int_maybe32_t zBottomCeil = y2;
     int8_t skipCeilingWall = 1;
 
     if (_ceilFunction != 0)
@@ -959,13 +959,17 @@ void _columnFunction(HitResult *hits, uint16_t hitCount, uint16_t x, Ray ray)
   Unit horizon = (y2 < _middleRow || _ceilFunction == 0) ? _middleRow : y2;
   horizon = clamp(horizon,0,_camera.resolution.y);
 
-  for (int_maybe32_t i = y; i >= horizon + (horizon > y2 ? 0 : 1); --i)
+  horizon += horizon > y2 ? 0 : 1; // bug workaround
+
+  for (int_maybe32_t i = y; i >= horizon; --i)
   {
     p.position.y = i;
     p.depth = (_fogStartYBottom - i) * _floorDepthStep + floorCameraDiff;
     _pixelFunction(&p);
   }
 
+  y = horizon < y ? horizon : y;
+
   // draw ceiling until horizon
 
   p.isFloor = 0;
@@ -974,10 +978,7 @@ void _columnFunction(HitResult *hits, uint16_t hitCount, uint16_t x, Ray ray)
     _ceilFunction != 0 ?
     absVal(worldZPrevCeil) * VERTICAL_DEPTH_MULTIPLY : UNITS_PER_SQUARE;
 
-  horizon = y > _middleRow ? _middleRow : y;
-  horizon = clamp(horizon,0,_camResYLimit);
-
-  for (int_maybe32_t i = y2; i < horizon; ++i)
+  for (int_maybe32_t i = y2; i < y; ++i)
   {
     p.position.y = i;
     p.depth = (i - _fogStartYTop) * _floorDepthStep + ceilCameraDiff;