From 13baf03ffbec87e988eb06dda40f0a44b2d4881a Mon Sep 17 00:00:00 2001
From: kaetemi <kaetemi@gmail.com>
Date: Mon, 30 Mar 2015 11:22:25 +0200
Subject: [PATCH] Apply bayer dither to TGA16 export for smoother lightmaps

---
 code/nel/tools/3d/tga_2_dds/tga2dds.cpp | 27 +++++++++++++++++++++++++
 1 file changed, 27 insertions(+)

diff --git a/code/nel/tools/3d/tga_2_dds/tga2dds.cpp b/code/nel/tools/3d/tga_2_dds/tga2dds.cpp
index 292280349..19fd70d32 100644
--- a/code/nel/tools/3d/tga_2_dds/tga2dds.cpp
+++ b/code/nel/tools/3d/tga_2_dds/tga2dds.cpp
@@ -359,6 +359,13 @@ void dividSize (CBitmap &bitmap)
 	}
 }
 
+const int bayerDiv8[4][4] = {
+	0, 4, 1, 5,
+	6, 2, 7, 3,
+	1, 5, 0, 4,
+	7, 3, 6, 2,
+};
+
 // ***************************************************************************
 int main(int argc, char **argv)
 {
@@ -601,6 +608,26 @@ int main(int argc, char **argv)
 		Reduce--;
 	}
 
+	if (algo == TGA16)
+	{
+		// Apply bayer dither
+		CObjectVector<uint8> &rgba = picSrc.getPixels(0);
+		const uint32 w = picSrc.getWidth(0);
+		uint32 x = 0;
+		uint32 y = 0;
+		for (uint32 i = 0; i < rgba.size(); i += 4)
+		{
+			NLMISC::CRGBA &c = reinterpret_cast<NLMISC::CRGBA &>(rgba[i]);
+			c.R = (uint8)std::min(255, (int)c.R + bayerDiv8[x % 4][y % 4]);
+			c.G = (uint8)std::min(255, (int)c.G + bayerDiv8[x % 4][y % 4]);
+			c.B = (uint8)std::min(255, (int)c.B + bayerDiv8[x % 4][y % 4]);
+			++x;
+			x %= w;
+			if (x == 0)
+				++y;
+		}
+	}
+
 	// 8 or 16 bits TGA or PNG ?
 	if ((algo == TGA16) || (algo == TGA8) || (algo == PNG16) || (algo == PNG8))
 	{