Add standalone natural_vision shader

README.md

@@ -24,6 +24,12 @@ A port of the 'sharp-bilinear'/'sharp-bilinear-simple' shader from RetroArch. Cr
 
 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
+## *Extras*
+
+### 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.
+
+### Natural Vision
+
+A stand-alone 'Natural Vision' colour (saturation) enhancement shader, which may be combined (as a first pass) with other shaders not included in this repository.

natural_vision.dfx

@@ -0,0 +1,38 @@
+// natural_vision shader
+=============================================
+<options>
+name=Natural Vision
+textures=1
+</options>
+
+<fheader>
+#if GL_ES
+#ifdef GL_FRAGMENT_PRECISION_HIGH
+precision highp float;
+#else
+precision mediump float;
+#endif
+#endif
+// Configuration
+#define NATVIS_GIN 1.91  // "NaturalVision Gamma In"
+                         // - default: 1.91, min: 0.0, max: 10.0, step: 0.01
+#define NATVIS_GOUT 1.91 // "NaturalVision Gamma Out"
+                         // - default: 1.91, min: 0.0, max: 10.0, step: 0.01
+#define NATVIS_Y 1.1     // "NaturalVision Luminance"
+                         // - default: 1.1, min: 0.0, max: 10.0, step: 0.01
+#define NATVIS_I 1.1     // "NaturalVision Orange-Cyan"
+                         // - default: 1.1, min: 0.0, max: 10.0, step: 0.01
+#define NATVIS_Q 1.1     // "NaturalVision Magenta-Green"
+                         // - default: 1.1, min: 0.0, max: 10.0, step: 0.01
+</fheader>
+
+<texture:0>
+input=framebuffer
+min_filter=GL_NEAREST
+mag_filter=GL_NEAREST
+</texture>
+
+<pass>
+shader=natural_vision.dsd
+sampler:u_texture=0
+</pass>

natural_vision.dsd

@@ -0,0 +1,78 @@
+// natural_vision - Applies 'Natural Vision' colour enhancement
+// 
+// - Original 'natural_vision' code written by ShadX, modified by
+//   Hyllian and Sp00kyFox, 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>
+
+#ifndef NATVIS_GIN
+#define NATVIS_GIN 1.91
+#endif
+#ifndef NATVIS_GOUT
+#define NATVIS_GOUT 1.91
+#endif
+#ifndef NATVIS_Y
+#define NATVIS_Y 1.1
+#endif
+#ifndef NATVIS_I
+#define NATVIS_I 1.1
+#endif
+#ifndef NATVIS_Q
+#define NATVIS_Q 1.1
+#endif
+
+uniform sampler2D u_texture;
+uniform vec4 u_texture_size;
+
+varying vec2 v_texture_coordinate;
+
+// Natural Vision helpers
+const mat3 RGBtoYIQ = mat3(0.299,  0.595716,  0.211456, 
+									0.587, -0.274453, -0.522591, 
+									0.114, -0.321263,  0.311135);
+
+const mat3 YIQtoRGB = mat3(1.0, 1.0, 1.0,
+									0.95629572,-0.27212210,-1.10698902,
+									0.62102442,-0.64738060, 1.70461500);
+
+const vec3 YIQ_lo = vec3(0.0, -0.595716, -0.522591);
+const vec3 YIQ_hi = vec3(1.0,  0.595716,  0.522591);
+
+void main()
+{
+	// Get colour sample and apply colour enhancement
+	vec3 colour = pow(texture2D(u_texture, v_texture_coordinate.xy).rgb, vec3(NATVIS_GIN));
+	colour = RGBtoYIQ * colour;
+	colour = vec3(pow(colour.x, NATVIS_Y), colour.y * NATVIS_I, colour.z * NATVIS_Q);
+	colour = clamp(colour, YIQ_lo, YIQ_hi);
+	colour = YIQtoRGB * colour;
+	colour = pow(colour, vec3(1.0 / NATVIS_GOUT));
+
+	gl_FragColor = vec4(colour.rgb, 1.0);
+}
+
+</fragment>