zfast_lcd+natural_vision.dsd

// zfast_lcd+natural_vision - A very simple LCD shader meant to be used at 1080p
// 
// - Original 'zfast_lcd' code copyright (C) 2017 Greg Hogan (SoltanGris42)
// 
// - 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.
// 
// Notes: This shader applies 'Natural Vision' colour enhancement, then applies
//        a simple grid effect, darkening the borders of 'virtual' pixels at
//        the native NDS resolution to imitate an LCD screen.
//        You can change the darkness/thickness of the borders.
//        The shader is compatible with both 'native' and 'high resolution' 3D
//        rendering modes.
// 
// *** Integer screen scaling is recommended for best results
=============================================

<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 BORDERMULT
#define BORDERMULT 14.0
#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

uniform sampler2D u_texture;
uniform vec4 u_texture_size;

varying vec2 v_texture_coordinate;

const float NDS_SCREEN_HEIGHT = 192.0;

// 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()
{
	// Generate grid pattern (in native NDS coordinate space)
	// - Have to divide by the current scale factor...
	//   There can only be two values here:
	//   > 'High-Resolution 3D Rendering' OFF - scale factor == 1
	//   > 'High-Resolution 3D Rendering' ON  - scale factor == 2
	//   But it's easiest to assume the general case...
	//    scale_factor == texture_height / NDS_SCREEN_HEIGHT
	vec2 texcoordInPixels = v_texture_coordinate.xy * u_texture_size.zw * (NDS_SCREEN_HEIGHT * u_texture_size.y);
	vec2 centerCoord = floor(texcoordInPixels.xy) + vec2(0.5, 0.5);
	vec2 distFromCenter = abs(centerCoord - texcoordInPixels);
	
	float Y = max(distFromCenter.x, distFromCenter.y);
	
	Y = Y * Y;
	float YY = Y * Y;
	float YYY = YY * Y;
	
	float LineWeight = YY - 2.7 * YYY;
	LineWeight = 1.0 - BORDERMULT * LineWeight;
	
	// Get colour sample and apply colour enhancement
	vec3 screen = pow(texture2D(u_texture, v_texture_coordinate.xy).rgb, vec3(NATVIS_GIN));
	screen = RGBtoYIQ * screen;
	screen = vec3(pow(screen.x, NATVIS_Y), screen.y * NATVIS_I, screen.z * NATVIS_Q);
	screen = clamp(screen, YIQ_lo, YIQ_hi);
	screen = YIQtoRGB * screen;
	screen = pow(screen, vec3(1.0 / NATVIS_GOUT));
	
	// Add grid lines
	gl_FragColor = vec4(screen * LineWeight, 1.0);
}

</fragment>