From 3d47652d080c63da259d23f04b27b9f9ef36eed9 Mon Sep 17 00:00:00 2001
From: Christoph Oelckers <coelckers@users.noreply.github.com>
Date: Tue, 31 Dec 2019 22:53:03 +0100
Subject: [PATCH] - had a look at Exhumed's shade tables and implemented the
 necessary adjustments for the 3 with abnormal gradients.

---
 source/exhumed/src/light.cpp   | 25 ++++++-------------------
 source/glbackend/glbackend.cpp |  2 ++
 source/glbackend/glbackend.h   |  3 +--
 3 files changed, 9 insertions(+), 21 deletions(-)

diff --git a/source/exhumed/src/light.cpp b/source/exhumed/src/light.cpp
index 4d82b7d03..aa0508c3b 100644
--- a/source/exhumed/src/light.cpp
+++ b/source/exhumed/src/light.cpp
@@ -22,6 +22,7 @@ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 #include "view.h"
 #include "cd.h"
 #include "lighting.h"
+#include "../glbackend/glbackend.h"
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
@@ -101,25 +102,11 @@ int LoadPaletteLookups()
         bGreenPal = 0;
 
 #ifdef USE_OPENGL
-		/*
-        // Very rough approximation...
-        palookupfogfactor[kPalNormal] = 1.f;
-        palookupfogfactor[kPalNoDim] = 0.f;
-        palookupfogfactor[kPalTorch] = 0.36f;
-        palookupfogfactor[kPalNoTorch] = 0.15f;
-        palookupfogfactor[kPalBrite] = 2.f;
-        palookupfogfactor[kPalRedBrite] = 0.36f;
-        palookupfog[kPalRedBrite] = { 248, 32, 0, 0 };
-        hicsetpalettetint(kPalRedBrite, 255, 255, 255, 248, 32, 0, 0);
-        palookupfog[kPalGreenBrite] = { 248, 32, 0, 0 };
-        palookupfogfactor[kPalGreenBrite] = 0.f;
-        hicsetpalettetint(kPalGreenBrite, 100, 200, 100, 0, 0, 0, 0);
-        palookupfogfactor[kPalNormal2] = 1.f;
-        palookupfogfactor[kPalNoDim2] = 0.f;
-        palookupfogfactor[kPalTorch2] = 0.36f;
-        palookupfogfactor[kPalNoTorch2] = 0.15f;
-        palookupfogfactor[kPalBrite2] = 2.f;
-		*/
+        // These 3 tables do not have normal gradients. The others work without adjustment.
+        // Other changes than altering the fog gradient are not necessary.
+        shadediv[kPalTorch] = shadediv[kPalTorch2] = 1 / 20.f;
+        shadediv[kPalNoTorch] = shadediv[kPalNoTorch2] = 0.25f;
+        shadediv[kPalBrite] = shadediv[kPalBrite] = 1 / 128.f;
 #endif
 
     }
diff --git a/source/glbackend/glbackend.cpp b/source/glbackend/glbackend.cpp
index 84143e76f..b346eb7dc 100644
--- a/source/glbackend/glbackend.cpp
+++ b/source/glbackend/glbackend.cpp
@@ -50,6 +50,7 @@
 #include "gl_renderer.h"
 
 extern int xdim, ydim;
+float shadediv[MAXPALOOKUPS];
 
 FileReader GetResource(const char* fn)
 {
@@ -511,6 +512,7 @@ void GLInstance::SetPalette(int index)
 void GLInstance::SetPalswap(int index)
 {
 	palmanager.BindPalswap(index);
+	renderState.ShadeDiv = shadediv[index] == 0 ? 1.f / (renderState.NumShades) : shadediv[index];
 }
 
 void GLInstance::DrawImGui(ImDrawData* data)
diff --git a/source/glbackend/glbackend.h b/source/glbackend/glbackend.h
index f4c62fa7f..cd6ec21f6 100644
--- a/source/glbackend/glbackend.h
+++ b/source/glbackend/glbackend.h
@@ -174,6 +174,7 @@ enum ETexType
 
 struct ImDrawData;
 struct palette_t;
+extern float shadediv[256];
 
 class GLInstance
 {
@@ -334,8 +335,6 @@ public:
 	{
 		renderState.Shade = shade;
 		renderState.NumShades = numshades;
-		renderState.ShadeDiv = 1.f / (numshades-2);
-
 	}
 
 	void SetVisibility(float visibility, float fviewingrange)