From 5a64307ad12253d5f4a492bf5201d2552d68b6a9 Mon Sep 17 00:00:00 2001
From: raa-eruanna <eruanna@drdteam.org>
Date: Wed, 7 Sep 2016 03:34:08 -0400
Subject: [PATCH] Changes the tonemap generation algorithm.

---
 src/gl/renderer/gl_postprocess.cpp | 39 +++++++++++++++++++++++++++++-
 src/gl/renderer/gl_renderer.h      |  2 ++
 2 files changed, 40 insertions(+), 1 deletion(-)

diff --git a/src/gl/renderer/gl_postprocess.cpp b/src/gl/renderer/gl_postprocess.cpp
index e6ca7faad6..d7eac80071 100644
--- a/src/gl/renderer/gl_postprocess.cpp
+++ b/src/gl/renderer/gl_postprocess.cpp
@@ -257,7 +257,7 @@ void FGLRenderer::BindTonemapPalette(int texunit)
 			{
 				for (int b = 0; b < 64; b++)
 				{
-					PalEntry color = GPalette.BaseColors[ColorMatcher.Pick((r << 2) | (r >> 4), (g << 2) | (g >> 4), (b << 2) | (b >> 4))];
+					PalEntry color = GPalette.BaseColors[(BYTE)PTM_BestColor((uint32 *)GPalette.BaseColors, (r << 2) | (r >> 4), (g << 2) | (g >> 4), (b << 2) | (b >> 4), 0, 256)];
 					int index = ((r * 64 + g) * 64 + b) * 4;
 					lut[index] = color.r;
 					lut[index + 1] = color.g;
@@ -472,3 +472,40 @@ void FGLRenderer::ClearBorders()
 	}
 	glDisable(GL_SCISSOR_TEST);
 }
+
+
+// [SP] Re-implemented BestColor for more precision rather than speed. This function is only ever called once until the game palette is changed.
+
+int FGLRenderer::PTM_BestColor (const uint32 *pal_in, int r, int g, int b, int first, int num)
+{
+	const PalEntry *pal = (const PalEntry *)pal_in;
+	static double powtable[256];
+	static bool firstTime = true;
+
+	double fbestdist, fdist;
+	int bestcolor;
+
+	if (firstTime)
+	{
+		firstTime = false;
+		for (int x = 0; x < 256; x++) powtable[x] = pow((double)x/255,1.2);
+	}
+
+	for (int color = first; color < num; color++)
+	{
+		double x = powtable[abs(r-pal[color].r)];
+		double y = powtable[abs(g-pal[color].g)];
+		double z = powtable[abs(b-pal[color].b)];
+		fdist = x + y + z;
+		if (color == first || fdist < fbestdist)
+		{
+			if (fdist == 0)
+				return color;
+
+			fbestdist = fdist;
+			bestcolor = color;
+		}
+	}
+	return bestcolor;
+}
+
diff --git a/src/gl/renderer/gl_renderer.h b/src/gl/renderer/gl_renderer.h
index 120f6a4490..f652b4765c 100644
--- a/src/gl/renderer/gl_renderer.h
+++ b/src/gl/renderer/gl_renderer.h
@@ -189,6 +189,8 @@ public:
 	void FillSimplePoly(FTexture *texture, FVector2 *points, int npoints,
 		double originx, double originy, double scalex, double scaley,
 		DAngle rotation, FDynamicColormap *colormap, int lightlevel);
+
+	int PTM_BestColor (const uint32 *pal_in, int r, int g, int b, int first, int num);
 };
 
 // Global functions. Make them members of GLRenderer later?