Add standalone nds_color shader

README.md

@@ -21,3 +21,7 @@ A port of the 'sharp-bilinear'/'sharp-bilinear-simple' shader from RetroArch. Cr
 ## zFast LCD
 
 A port of the 'zfast_lcd' shader from RetroArch. Creates an LCD effect by adding a subtle grid lattice to the screen. REQUIRES a high resolution display (at least 1080p). Works best with integer screen scaling, but fine without.
+
+## NDS Color
+
+A stand-alone DS Phat colour correction shader, which may be combined (as a first pass) with other shaders not included in this repository.

nds_color.dfx

@@ -0,0 +1,27 @@
+// nds_color shader
+=============================================
+<options>
+name=NDS Color
+textures=1
+</options>
+
+<fheader>
+#if GL_ES
+#ifdef GL_FRAGMENT_PRECISION_HIGH
+precision highp float;
+#else
+precision mediump float;
+#endif
+#endif
+</fheader>
+
+<texture:0>
+input=framebuffer
+min_filter=GL_NEAREST
+mag_filter=GL_NEAREST
+</texture>
+
+<pass>
+shader=nds_color.dsd
+sampler:u_texture=0
+</pass>

nds_color.dsd

@@ -0,0 +1,67 @@
+// nds_color - Applies NDS colour correction, designed to mimic the
+//             display characteristics of an NDS Phat
+// 
+// - Original 'nds_color' code written by hunterk, modified by Pokefan531 and
+//   released into the public domain
+// 
+// 'Ported' (i.e. copy/paste) to DraStic format by jdgleaver
+// 
+// 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.
+=============================================
+
+<vertex>
+
+attribute vec2 a_vertex_coordinate;
+attribute vec2 a_texture_coordinate;
+uniform vec4 u_texture_size;
+
+varying vec2 v_texture_coordinate;
+
+void main()
+{
+	v_texture_coordinate = a_texture_coordinate;
+	gl_Position = vec4(a_vertex_coordinate.xy, 0.0, 1.0);
+}
+
+</vertex>
+
+<fragment>
+
+// Colour defines...
+#define target_gamma 1.91
+#define display_gamma 1.91
+#define lum 0.89
+#define r 0.87
+#define g 0.645
+#define b 0.73
+#define rg 0.10
+#define rb 0.10
+#define gr 0.255
+#define gb 0.17
+#define br -0.125
+#define bg 0.255
+
+uniform sampler2D u_texture;
+uniform vec4 u_texture_size;
+
+varying vec2 v_texture_coordinate;
+
+void main()
+{
+	// Get colour sample and apply colour correction
+	vec3 colour = pow(texture2D(u_texture, v_texture_coordinate.xy).rgb, vec3(target_gamma));
+	colour = clamp(colour * lum, 0.0, 1.0);
+	colour = pow(
+		mat3(r,  rg, rb,
+			  gr, g,  gb,
+			  br, bg, b) * colour,
+		vec3(1.0 / display_gamma)
+	);
+
+	gl_FragColor = vec4(colour.rgb, 1.0);
+}
+
+</fragment>