From 230a4aefccf1e5a6a86385a38c48d20c1af30656 Mon Sep 17 00:00:00 2001
From: Bradley Bell <btb@icculus.org>
Date: Wed, 12 May 2004 22:06:02 +0000
Subject: [PATCH] added function to create blend tables

---
 2d/palette.c      | 21 ++++++++++++++++++++-
 ChangeLog         |  3 +++
 include/palette.h |  3 ++-
 3 files changed, 25 insertions(+), 2 deletions(-)

diff --git a/2d/palette.c b/2d/palette.c
index 30ed0e68a..aedfdf7db 100644
--- a/2d/palette.c
+++ b/2d/palette.c
@@ -1,4 +1,4 @@
-/* $Id: palette.c,v 1.10 2003-06-10 17:50:50 btb Exp $ */
+/* $Id: palette.c,v 1.11 2004-05-12 22:06:02 btb Exp $ */
 /*
 THE COMPUTER CODE CONTAINED HEREIN IS THE SOLE PROPERTY OF PARALLAX
 SOFTWARE CORPORATION ("PARALLAX").  PARALLAX, IN DISTRIBUTING THE CODE TO
@@ -402,3 +402,22 @@ void gr_make_cthru_table(ubyte * table, ubyte r, ubyte g, ubyte b )
 	}
 }
 
+void gr_make_blend_table(ubyte *blend_table, ubyte r, ubyte g, ubyte b)
+{
+	int i, j;
+	float alpha;
+	ubyte r1, g1, b1;
+
+	for (j = 0; j < GR_FADE_LEVELS; j++)
+	{
+		alpha = 1.0 - (float)j / ((float)GR_FADE_LEVELS - 1);
+		for (i = 0; i < 255; i++)
+		{
+			r1 = (ubyte)((1.0 - alpha) * (float)gr_palette[i * 3 + 0] + (alpha * (float)r));
+			g1 = (ubyte)((1.0 - alpha) * (float)gr_palette[i * 3 + 1] + (alpha * (float)g));
+			b1 = (ubyte)((1.0 - alpha) * (float)gr_palette[i * 3 + 2] + (alpha * (float)b));
+			blend_table[i + j * 256] = gr_find_closest_color(r1, g1, b1);
+		}
+		blend_table[i + j * 256] = 255; // leave white alone
+	}
+}
diff --git a/ChangeLog b/ChangeLog
index f64b0e375..1a23665e0 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,8 @@
 2004-05-12  Bradley Bell  <btb@icculus.org>
 
+	* 2d/palette.c, include/palette.h: added function to create blend
+	tables
+
 	* maths/rand.c, maths/tables.c, maths/vecmat.c: formatting
 
 2004-05-11  Bradley Bell  <btb@icculus.org>
diff --git a/include/palette.h b/include/palette.h
index f1f8e6641..c105bb38c 100644
--- a/include/palette.h
+++ b/include/palette.h
@@ -1,4 +1,4 @@
-/* $Id: palette.h,v 1.3 2002-10-11 03:37:58 btb Exp $ */
+/* $Id: palette.h,v 1.4 2004-05-12 22:06:02 btb Exp $ */
 /*
 THE COMPUTER CODE CONTAINED HEREIN IS THE SOLE PROPERTY OF PARALLAX
 SOFTWARE CORPORATION ("PARALLAX").  PARALLAX, IN DISTRIBUTING THE CODE TO
@@ -67,6 +67,7 @@ extern int gr_palette_fade_out(ubyte *pal, int nsteps, int allow_keys );
 extern int gr_palette_fade_in(ubyte *pal,int nsteps, int allow_keys );
 extern void gr_palette_load( ubyte * pal );
 extern void gr_make_cthru_table(ubyte * table, ubyte r, ubyte g, ubyte b );
+extern void gr_make_blend_table(ubyte *blend_table, ubyte r, ubyte g, ubyte b);
 extern int gr_find_closest_color_current( int r, int g, int b );
 extern void gr_palette_read(ubyte * palette);
 extern void init_computed_colors(void);