From 271c6dc1298f07eb34338f886fe2dbdcfdc04ceb Mon Sep 17 00:00:00 2001
From: Vicki Pfau <vi@endrift.com>
Date: Mon, 16 Sep 2024 03:51:08 -0700
Subject: [PATCH] Res: Update gba-colors shader (closes #2976)

---
 res/shaders/gba-color.shader/gba-color.fs | 35 +++++++----------------
 res/shaders/gba-color.shader/gba-color.vs | 34 ++++++++++++++++++++++
 res/shaders/gba-color.shader/manifest.ini |  8 ++++++
 3 files changed, 53 insertions(+), 24 deletions(-)
 create mode 100644 res/shaders/gba-color.shader/gba-color.vs

diff --git a/res/shaders/gba-color.shader/gba-color.fs b/res/shaders/gba-color.shader/gba-color.fs
index 09177ddfe..461228c20 100644
--- a/res/shaders/gba-color.shader/gba-color.fs
+++ b/res/shaders/gba-color.shader/gba-color.fs
@@ -1,34 +1,21 @@
+// Shader that replicates the LCD Colorspace from Gameboy Advance --
 varying vec2 texCoord;
+varying mat4 profile;
 uniform sampler2D tex;
 uniform vec2 texSize;
 
 uniform float darken_screen;
-const float target_gamma = 2.2;
-const float display_gamma = 2.5;
-const float sat = 1.0;
-const float lum = 0.99;
-const float contrast = 1.0;
-const vec3 bl = vec3(0.0, 0.0, 0.0);
-const vec3 r = vec3(0.84, 0.09, 0.15);
-const vec3 g = vec3(0.18, 0.67, 0.10);
-const vec3 b = vec3(0.0, 0.26, 0.73);
+const float target_gamma = 2.0;
+const float display_gamma = 2.0;
 
 void main() {
+	// bring out our stored luminance value
+	float lum = profile[3].w;
+
+	// our adjustments need to happen in linear gamma
 	vec4 screen = pow(texture2D(tex, texCoord), vec4(target_gamma + darken_screen)).rgba;
-	vec4 avglum = vec4(0.5);
-	screen = mix(screen, avglum, (1.0 - contrast));
- 
-	mat4 color = mat4(	r.r,	r.g,	r.b,	0.0,
-				g.r,	g.g,	g.b,	0.0,
-				b.r,	b.g,	b.b,	0.0,
-				bl.r,	bl.g,	bl.b,	1.0);
-			  
-	mat4 adjust = mat4(	(1.0 - sat) * 0.3086 + sat,	(1.0 - sat) * 0.3086,		(1.0 - sat) * 0.3086,		1.0,
-				(1.0 - sat) * 0.6094,		(1.0 - sat) * 0.6094 + sat,	(1.0 - sat) * 0.6094,		1.0,
-				(1.0 - sat) * 0.0820,		(1.0 - sat) * 0.0820,		(1.0 - sat) * 0.0820 + sat,	1.0,
-				0.0,				0.0,				0.0,				1.0);
-	color *= adjust;
+
 	screen = clamp(screen * lum, 0.0, 1.0);
-	screen = color * screen;
-	gl_FragColor = pow(screen, vec4(1.0 / display_gamma + (darken_screen * 0.125)));
+	screen = profile * screen;
+	gl_FragColor = pow(screen, vec4(1.0 / display_gamma));
 }
diff --git a/res/shaders/gba-color.shader/gba-color.vs b/res/shaders/gba-color.shader/gba-color.vs
new file mode 100644
index 000000000..bbf406278
--- /dev/null
+++ b/res/shaders/gba-color.shader/gba-color.vs
@@ -0,0 +1,34 @@
+uniform int color_mode;
+attribute vec4 position;
+varying vec2 texCoord;
+varying mat4 profile;
+
+const mat4 GBA_sRGB = mat4(
+	0.80, 0.135, 0.195, 0.0,  //red channel
+	0.275, 0.64, 0.155, 0.0,  //green channel
+	-0.075, 0.225, 0.65, 0.0,  //blue channel
+	0.0,  0.0,  0.0,  0.93   //alpha channel
+); 
+
+const mat4 GBA_DCI = mat4(
+	0.685, 0.16, 0.20, 0.0,  //red channel
+	0.34, 0.629, 0.19, 0.0,  //green channel
+	-0.025, 0.211, 0.61, 0.0,  //blue channel
+	0.0,  0.0,  0.0,  0.975  //alpha channel
+); 
+
+const mat4 GBA_Rec2020 = mat4(
+	0.555, 0.1825, 0.20, 0.0,  //red channel
+	0.395, 0.61, 0.195, 0.0,  //green channel
+	0.05, 0.2075, 0.605, 0.0,  //blue channel
+	0.0,   0.0,  0.0,   1.0  //alpha channel
+); 
+
+void main() {
+	if (color_mode == 1) profile = GBA_sRGB;
+	else if (color_mode == 2) profile = GBA_DCI;
+	else if (color_mode == 3) profile = GBA_Rec2020;
+
+	gl_Position = position;
+	texCoord = (position.st + vec2(1.0, 1.0)) * vec2(0.5, 0.5);
+}
diff --git a/res/shaders/gba-color.shader/manifest.ini b/res/shaders/gba-color.shader/manifest.ini
index 8f9735aa3..ed16900cd 100644
--- a/res/shaders/gba-color.shader/manifest.ini
+++ b/res/shaders/gba-color.shader/manifest.ini
@@ -6,6 +6,7 @@ passes=1
 
 [pass.0]
 fragmentShader=gba-color.fs
+vertexShader=gba-color.vs
 blend=1
 width=-1
 height=-1
@@ -14,3 +15,10 @@ height=-1
 type=float
 default=0.5
 readableName=Darken Screen
+
+[pass.0.uniform.color_mode]
+type=int
+default=1
+min=1
+max=3
+readableName=Color Profile (1=sRGB, 2=DCI, 3=Rec2020)