From 184ff91453fea23b4b79168092f1fd3fe77d8576 Mon Sep 17 00:00:00 2001
From: fabiensanglard <fabien.sanglard@gmail.com>
Date: Fri, 27 Apr 2018 23:50:00 +0300
Subject: [PATCH] Added Unreal kernel filtering.

---
 src/client/refresh/soft/sw_main.c |  2 ++
 src/client/refresh/soft/sw_scan.c | 58 +++++++++++++++++++++++++++----
 2 files changed, 53 insertions(+), 7 deletions(-)

diff --git a/src/client/refresh/soft/sw_main.c b/src/client/refresh/soft/sw_main.c
index 7b3e59f25..98713a2ba 100644
--- a/src/client/refresh/soft/sw_main.c
+++ b/src/client/refresh/soft/sw_main.c
@@ -124,6 +124,7 @@ cvar_t	*sw_surfcacheoverride;
 cvar_t	*sw_waterwarp;
 static cvar_t	*sw_overbrightbits;
 cvar_t	*sw_custom_particles;
+cvar_t	*sw_texture_filtering;
 
 cvar_t	*r_drawworld;
 static cvar_t	*r_drawentities;
@@ -272,6 +273,7 @@ R_Register (void)
 	sw_waterwarp = ri.Cvar_Get ("sw_waterwarp", "1", 0);
 	sw_overbrightbits = ri.Cvar_Get("sw_overbrightbits", "1.0", CVAR_ARCHIVE);
 	sw_custom_particles = ri.Cvar_Get("sw_custom_particles", "0", CVAR_ARCHIVE);
+	sw_texture_filtering = ri.Cvar_Get("sw_texture_filtering", "0", CVAR_ARCHIVE);
 	r_mode = ri.Cvar_Get( "r_mode", "0", CVAR_ARCHIVE );
 
 	r_lefthand = ri.Cvar_Get( "hand", "0", CVAR_USERINFO | CVAR_ARCHIVE );
diff --git a/src/client/refresh/soft/sw_scan.c b/src/client/refresh/soft/sw_scan.c
index ebc9b2efd..5b2420d69 100644
--- a/src/client/refresh/soft/sw_scan.c
+++ b/src/client/refresh/soft/sw_scan.c
@@ -382,6 +382,19 @@ void NonTurbulent8 (espan_t *pspan)
 //PGM
 //====================
 
+// Enable custom filtering
+extern cvar_t	*sw_texture_filtering;
+static int filtering_kernel[2][2][2] = {
+	{
+		{16384,	0},
+		{49152,	32768}
+	},
+	{
+		{32768,	49152},
+		{0,	16384}
+	}
+};
+
 /*
 =============
 D_DrawSpans16
@@ -505,15 +518,46 @@ void D_DrawSpans16 (espan_t *pspan)
 				}
 			}
 
-			do
+			// Drawing phrase
+			if (sw_texture_filtering->value == 0.0f)
+			{
+				do
+				{
+					*pdest++ = *(pbase + (s >> 16) + (t >> 16) * cachewidth);
+					s += sstep;
+					t += tstep;
+				} while (--spancount > 0);
+
+				s = snext;
+				t = tnext;
+			}
+			else if (sw_texture_filtering->value == 1.0f)
 			{
-				*pdest++ = *(pbase + (s >> 16) + (t >> 16) * cachewidth);
-				s += sstep;
-				t += tstep;
-			} while (--spancount > 0);
+				do
+				{
+					int idiths = s;
+					int iditht = t;
+
+					int X = (pspan->u + spancount) & 1;
+					int Y = (pspan->v)&1;
+
+					//Using the kernel
+					idiths += filtering_kernel[X][Y][0];
+					iditht += filtering_kernel[X][Y][1];
+
+					idiths = idiths >> 16;
+					idiths = idiths ? idiths -1 : idiths;
 
-			s = snext;
-			t = tnext;
+
+					iditht = iditht >> 16;
+					iditht = iditht ? iditht -1 : iditht;
+
+
+					*pdest++ = *(pbase + idiths + iditht * cachewidth);
+					s += sstep;
+					t += tstep;
+				} while (--spancount > 0);
+			}
 
 		} while (count > 0);