From 42b4ec310f8070a7fe9e4ef97b09e6284340e6f5 Mon Sep 17 00:00:00 2001
From: ehofman <ehofman>
Date: Sat, 17 May 2003 12:43:47 +0000
Subject: [PATCH] Add a gamma correction function

---
 simgear/screen/Makefile.am |  4 +--
 simgear/screen/colors.hxx  | 50 ++++++++++++++++++++++++++++++++++++++
 2 files changed, 52 insertions(+), 2 deletions(-)
 create mode 100644 simgear/screen/colors.hxx

diff --git a/simgear/screen/Makefile.am b/simgear/screen/Makefile.am
index 20ccf043..c5c05dcc 100644
--- a/simgear/screen/Makefile.am
+++ b/simgear/screen/Makefile.am
@@ -12,10 +12,10 @@ IMAGE_SERVER_INCL =
 IMAGE_SERVER_SRCS = 
 endif
 
-noinst_HEADERS = \
-        colours.h
+noinst_HEADERS = colours.h
 
 include_HEADERS = \
+	colors.hxx \
 	texture.hxx \
 	$(IMAGE_SERVER_INCL) \
 	screen-dump.hxx \
diff --git a/simgear/screen/colors.hxx b/simgear/screen/colors.hxx
new file mode 100644
index 00000000..13c6ef3f
--- /dev/null
+++ b/simgear/screen/colors.hxx
@@ -0,0 +1,50 @@
+// colours.h 
+//
+// -- This header file contains color related functions
+//
+// Copyright (C) 2003  FlightGear Flight Simulator
+//
+// This program is free software; you can redistribute it and/or
+// modify it under the terms of the GNU General Public License as
+// published by the Free Software Foundation; either version 2 of the
+// License, or (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful, but
+// WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+// General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program; if not, write to the Free Software
+// Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+//
+// $Id$
+
+
+#ifndef _SG_COLORS_HXX
+#define _SG_COLORS_HXX 1
+
+#include <math.h>
+
+#if defined( macintosh )
+const float system_gamma = 1.4;
+
+#elif defined (sgi)
+const float system_gamma = 1.7;
+
+#else	// others
+const float system_gamma = 2.5;
+#endif
+
+
+// simple architecture independant gamma correction function.
+inline void gamma_correct(float *color,
+                          float reff = 2.5, float system = system_gamma)
+{
+   color[0] = pow(color[0], reff/system);
+   color[1] = pow(color[1], reff/system);
+   color[2] = pow(color[2], reff/system);
+};
+
+#endif // _SG_COLORS_HXX
+
-- 
2.39.5