From 60c5eb372b7ff2c34e265845eb029a30baf0bf93 Mon Sep 17 00:00:00 2001
From: TehRealSalt <tehrealsalt@gmail.com>
Date: Sun, 16 Sep 2018 23:28:10 -0400
Subject: [PATCH] New color brightness formula

Gets more accurate looking results
---
 src/hardware/hw_md2.c | 17 ++++++++++++++---
 src/k_kart.c          | 15 +++++++++++++--
 2 files changed, 27 insertions(+), 5 deletions(-)

diff --git a/src/hardware/hw_md2.c b/src/hardware/hw_md2.c
index 2446b023b..f87f187ad 100644
--- a/src/hardware/hw_md2.c
+++ b/src/hardware/hw_md2.c
@@ -948,6 +948,15 @@ spritemd2found:
 	fclose(f);
 }
 
+// Define for getting accurate color brightness readings according to how the human eye sees them.
+// https://en.wikipedia.org/wiki/Relative_luminance
+// 0.2126 to red
+// 0.7152 to green
+// 0.0722 to blue
+// (See this same define in k_kart.c!)
+#define SETBRIGHTNESS(brightness,r,g,b) \
+	brightness = (UINT8)(((1063*((UINT16)r)/5000) + (3576*((UINT16)g)/5000) + (361*((UINT16)b)/5000)) / 3)
+	
 static void HWR_CreateBlendedTexture(GLPatch_t *gpatch, GLPatch_t *blendgpatch, GLMipmap_t *grmip, INT32 skinnum, skincolors_t color)
 {
 	UINT8 i;
@@ -1028,11 +1037,11 @@ static void HWR_CreateBlendedTexture(GLPatch_t *gpatch, GLPatch_t *blendgpatch,
 			{
 				UINT32 tempcolor;
 				UINT16 imagebright, blendbright, finalbright, colorbright;
-				imagebright = (image->s.red+image->s.green+image->s.blue)/3;
-				blendbright = (blendimage->s.red+blendimage->s.green+blendimage->s.blue)/3;
+				SETBRIGHTNESS(imagebright,image->s.red,image->s.green,image->s.blue);
+				SETBRIGHTNESS(blendbright,blendimage->s.red,blendimage->s.green,blendimage->s.blue);
 				// slightly dumb average between the blend image color and base image colour, usually one or the other will be fully opaque anyway
 				finalbright = (imagebright*(255-blendimage->s.alpha))/255 + (blendbright*blendimage->s.alpha)/255;
-				colorbright = (blendcolor.s.red+blendcolor.s.green+blendcolor.s.blue)/3;
+				SETBRIGHTNESS(colorbright,blendcolor.s.red,blendcolor.s.green,blendcolor.s.blue);
 
 				tempcolor = (finalbright*blendcolor.s.red)/colorbright;
 				tempcolor = min(255, tempcolor);
@@ -1090,6 +1099,8 @@ static void HWR_CreateBlendedTexture(GLPatch_t *gpatch, GLPatch_t *blendgpatch,
 	return;
 }
 
+#undef SETBRIGHTNESS
+
 static void HWR_GetBlendedTexture(GLPatch_t *gpatch, GLPatch_t *blendgpatch, INT32 skinnum, const UINT8 *colormap, skincolors_t color)
 {
 	// mostly copied from HWR_GetMappedPatch, hence the similarities and comment
diff --git a/src/k_kart.c b/src/k_kart.c
index 9966b5573..65f427890 100644
--- a/src/k_kart.c
+++ b/src/k_kart.c
@@ -255,6 +255,15 @@ UINT8 colortranslations[MAXSKINCOLORS][16] = {
 
 //#define SALLYALTRAINBOW // Sal's edited version of the below, which keeps a colors' lightness, and looks better with hue-shifted colors like Ruby & Dream. Not strictly *better*, just different...
 
+// Define for getting accurate color brightness readings according to how the human eye sees them.
+// https://en.wikipedia.org/wiki/Relative_luminance
+// 0.2126 to red
+// 0.7152 to green
+// 0.0722 to blue
+// (See this same define in hw_md2.c!)
+#define SETBRIGHTNESS(brightness,r,g,b) \
+	brightness = (UINT8)(((1063*((UINT16)r)/5000) + (3576*((UINT16)g)/5000) + (361*((UINT16)b)/5000)) / 3)
+
 /** \brief	Generates the rainbow colourmaps that are used when a player has the invincibility power
 
 	\param	dest_colormap	colormap to populate
@@ -275,7 +284,7 @@ void K_RainbowColormap(UINT8 *dest_colormap, UINT8 skincolor)
 	for (i = 0; i < 16; i++)
 	{
 		color = V_GetColor(colortranslations[skincolor][i]);
-		colorbrightnesses[i] = (UINT8)(((UINT16)color.s.red + (UINT16)color.s.green + (UINT16)color.s.blue)/3);
+		SETBRIGHTNESS(colorbrightnesses[i], color.s.red, color.s.green, color.s.blue);
 	}
 #endif
 
@@ -288,7 +297,7 @@ void K_RainbowColormap(UINT8 *dest_colormap, UINT8 skincolor)
 			continue;
 		}
 		color = V_GetColor(i);
-		brightness = (UINT8)(((UINT16)color.s.red + (UINT16)color.s.green + (UINT16)color.s.blue)/3);
+		SETBRIGHTNESS(brightness, color.s.red, color.s.green, color.s.blue);
 #ifdef SALLYALTRAINBOW
 		brightness = 15-(brightness/16); // Yes, 15.
 		dest_colormap[i] = colortranslations[skincolor][brightness];
@@ -307,6 +316,8 @@ void K_RainbowColormap(UINT8 *dest_colormap, UINT8 skincolor)
 	}
 }
 
+#undef SETBRIGHTNESS
+
 /**	\brief	Generates a translation colormap for Kart, to replace R_GenerateTranslationColormap in r_draw.c
 
 	\param	dest_colormap	colormap to populate