lcd1x+nds_color+natural_vision.dsd

// lcd1x+nds_color+natural_vision - Simple LCD 'scanline' shader, based on lcd3x
// 
// - Original lcd3x code by Gigaherz, released into the public domain
// 
// - Original 'nds_color' code written by hunterk, modified by Pokefan531 and
//   released into the public domain
// 
// - 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.
// 
// lcd1x+natural_vision differs from lcd3x in the following manner:
// 
// > Omits LCD-style colour separation
// 
// > Has 'correctly' aligned scanlines
// 
// > Automatically supports 'high resolution 3d rendering' ON or OFF
// 
// > Applies NDS colour correction followed by 'Natural Vision'
//   colour enhancement
=============================================

<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 BRIGHTEN_SCANLINES
#define BRIGHTEN_SCANLINES 16.0
#endif
#ifndef BRIGHTEN_LCD
#define BRIGHTEN_LCD 4.0
#endif
#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

#define PI 3.141592654

uniform sampler2D u_texture;
uniform vec4 u_texture_size;

varying vec2 v_texture_coordinate;

const float NDS_SCREEN_HEIGHT = 192.0;
const float INV_BRIGHTEN_SCANLINES_INC = 1.0 / (BRIGHTEN_SCANLINES + 1.0);
const float INV_BRIGHTEN_LCD_INC = 1.0 / (BRIGHTEN_LCD + 1.0);

// NDS Colour defines
#define NDS_LUM 0.89
#define NDS_R 0.87
#define NDS_G 0.645
#define NDS_B 0.73
#define NDS_RG 0.10
#define NDS_RB 0.10
#define NDS_GR 0.255
#define NDS_GB 0.17
#define NDS_BR -0.125
#define NDS_BG 0.255

const mat3 NDSColourMatrix = mat3(NDS_R,  NDS_RG, NDS_RB,
											 NDS_GR, NDS_G,  NDS_GB,
											 NDS_BR, NDS_BG, NDS_B);

// 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()
{
	// Note to self: uniform vec4 u_texture_size(1.0/w, 1.0/h, w, h)
	
	// Generate LCD grid effect
	// > Note the 0.25 pixel offset -> required to ensure that
	//   scanlines occur *between* pixels
	// > Divide pixel coordinate by current scale factor (texture_height / NDS_SCREEN_HEIGHT)
	vec2 angle = 2.0 * PI * (((v_texture_coordinate.xy * u_texture_size.zw) * NDS_SCREEN_HEIGHT * u_texture_size.y) - 0.25);
	
	float yfactor = (BRIGHTEN_SCANLINES + sin(angle.y)) * INV_BRIGHTEN_SCANLINES_INC;
	float xfactor = (BRIGHTEN_LCD + sin(angle.x)) * INV_BRIGHTEN_LCD_INC;
	
	// Get colour sample and apply apply colour correction + enhancement
	vec3 colour = pow(texture2D(u_texture, v_texture_coordinate.xy).rgb, vec3(NATVIS_GIN));
	// > NDS colour
	colour = clamp(colour * NDS_LUM, 0.0, 1.0);
	colour = NDSColourMatrix * colour;
	// > Natural vision
	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));
	
	// Apply LCD grid effect
	colour.rgb = yfactor * xfactor * colour.rgb;
	
	gl_FragColor = vec4(colour.rgb, 1.0);
}

</fragment>