From 40b76dc9b0cd8d59c0f2c597cc4a690cb78ab89e Mon Sep 17 00:00:00 2001
From: Magnus Norddahl <dpjudas@users.noreply.github.com>
Date: Sat, 11 Jun 2016 18:41:56 +0200
Subject: [PATCH] Apply gamma when using true color output on Linux and Mac

---
 src/posix/cocoa/i_video.mm |  5 +--
 src/posix/sdl/sdlvideo.cpp | 12 +------
 src/v_video.cpp            | 67 ++++++++++++++++++++++++++++++++++++--
 src/v_video.h              |  1 +
 4 files changed, 68 insertions(+), 17 deletions(-)

diff --git a/src/posix/cocoa/i_video.mm b/src/posix/cocoa/i_video.mm
index 425fe5887..ddfccaa57 100644
--- a/src/posix/cocoa/i_video.mm
+++ b/src/posix/cocoa/i_video.mm
@@ -869,10 +869,7 @@ void CocoaFrameBuffer::Update()
 
 	if (IsBgra())
 	{
-		for (int y = 0; y < Height; y++)
-		{
-			memcpy((uint32_t*)m_pixelBuffer + y * Width, (uint32_t*)MemBuffer + y * Pitch, Width * BYTES_PER_PIXEL);
-		}
+		CopyWithGammaBgra(m_pixelBuffer, Width * BYTES_PER_PIXEL, m_gammaTable[0], m_gammaTable[1], m_gammaTable[2], m_flashColor, m_flashAmount);
 	}
 	else
 	{
diff --git a/src/posix/sdl/sdlvideo.cpp b/src/posix/sdl/sdlvideo.cpp
index 26121aa71..56b883978 100644
--- a/src/posix/sdl/sdlvideo.cpp
+++ b/src/posix/sdl/sdlvideo.cpp
@@ -497,17 +497,7 @@ void SDLFB::Update ()
 
 	if (Bgra)
 	{
-		if (pitch == Pitch * 4)
-		{
-			memcpy(pixels, MemBuffer, Width*Height*4);
-		}
-		else
-		{
-			for (int y = 0; y < Height; ++y)
-			{
-				memcpy((BYTE *)pixels + y*pitch, MemBuffer + y*Pitch*4, Width*4);
-			}
-		}
+		CopyWithGammaBgra(pixels, pitch, GammaTable[0], GammaTable[1], GammaTable[2], Flash, FlashAmount);
 	}
 	else if (NotPaletted)
 	{
diff --git a/src/v_video.cpp b/src/v_video.cpp
index bc99edbf1..e58638121 100644
--- a/src/v_video.cpp
+++ b/src/v_video.cpp
@@ -742,13 +742,12 @@ void DCanvas::CalcGamma (float gamma, BYTE gammalookup[256])
 	// I found this formula on the web at
 	// <http://panda.mostang.com/sane/sane-gamma.html>,
 	// but that page no longer exits.
-
 	double invgamma = 1.f / gamma;
 	int i;
 
 	for (i = 0; i < 256; i++)
 	{
-		gammalookup[i] = (BYTE)(255.0 * pow (i / 255.0, invgamma));
+		gammalookup[i] = (BYTE)(255.0 * pow (i / 255.0, invgamma) + 0.5);
 	}
 }
 
@@ -876,6 +875,70 @@ DFrameBuffer::DFrameBuffer (int width, int height, bool bgra)
 	Accel2D = false;
 }
 
+//==========================================================================
+//
+// DFrameBuffer :: PostprocessBgra
+//
+// Copies data to destination buffer while performing gamma and flash.
+// This is only needed if a target cannot do this with shaders.
+//
+//==========================================================================
+
+void DFrameBuffer::CopyWithGammaBgra(void *output, int pitch, const BYTE *gammared, const BYTE *gammagreen, const BYTE *gammablue, PalEntry flash, int flash_amount)
+{
+	const BYTE *gammatables[3] = { gammared, gammagreen, gammablue };
+
+	if (flash_amount > 0)
+	{
+		uint16_t inv_flash_amount = 256 - flash_amount;
+		uint16_t flash_red = flash.r * flash_amount;
+		uint16_t flash_green = flash.g * flash_amount;
+		uint16_t flash_blue = flash.b * flash_amount;
+		
+		for (int y = 0; y < Height; y++)
+		{
+			BYTE *dest = (BYTE*)output + y * pitch;
+			BYTE *src = MemBuffer + y * Pitch * 4;
+			for (int x = 0;  x < Width; x++)
+			{
+				uint16_t fg_red = src[2];
+				uint16_t fg_green = src[1];
+				uint16_t fg_blue = src[0];
+				uint16_t red = (fg_red * inv_flash_amount + flash_red) >> 8;
+				uint16_t green = (fg_green * inv_flash_amount + flash_green) >> 8;
+				uint16_t blue = (fg_blue * inv_flash_amount + flash_blue) >> 8;
+
+				dest[0] = gammatables[2][blue];
+				dest[1] = gammatables[1][green];
+				dest[2] = gammatables[0][red];
+				dest[3] = 0xff;
+
+				dest += 4;
+				src += 4;
+			}
+		}
+	}
+	else
+	{
+		for (int y = 0; y < Height; y++)
+		{
+			BYTE *dest = (BYTE*)output + y * pitch;
+			BYTE *src = MemBuffer + y * Pitch * 4;
+			for (int x = 0;  x < Width; x++)
+			{
+				dest[0] = gammatables[2][src[0]];
+				dest[1] = gammatables[1][src[1]];
+				dest[2] = gammatables[0][src[2]];
+				dest[3] = 0xff;
+
+				dest += 4;
+				src += 4;
+			}
+		}
+	}
+}
+
+
 //==========================================================================
 //
 // DFrameBuffer :: DrawRateStuff
diff --git a/src/v_video.h b/src/v_video.h
index 120beff9a..19213bd26 100644
--- a/src/v_video.h
+++ b/src/v_video.h
@@ -420,6 +420,7 @@ public:
 protected:
 	void DrawRateStuff ();
 	void CopyFromBuff (BYTE *src, int srcPitch, int width, int height, BYTE *dest);
+	void CopyWithGammaBgra(void *output, int pitch, const BYTE *gammared, const BYTE *gammagreen, const BYTE *gammablue, PalEntry flash, int flash_amount);
 
 	DFrameBuffer () {}