lcd1x_sharp.fsh

/*
	lcd1x_sharp shader
	
	This is an attempt to make a shader with a non-blurry LCD effect.
	It combines the existing shader code:
	
	- Nearest neighbour scaling, taken from zfast_lcd
	  [Original code copyright (C) 2017 Greg Hogan (SoltanGris42)]
	
	- lcd3x 'grille effect', but without colour seperation
	  [Original code by Gigaherz, released into the public domain]
	  [Code here derived from PPSSPP version of lcd3x made by LunaMoo]
	
	Code mashed together 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.
	
	*** Requires rendering resolution to be set to 1xPSP
	
	*** Surprisingly, looks reasonably good on low resolution (720p/768p)
	    displays...
*/

//=== Config
#define BRIGHTEN_SCANLINES 16.0 // "Brighten Scanlines" - default: 16.0, min: 1.0, max: 32.0, step: 0.5
										  // (brightness of horizontal lines)
#define BRIGHTEN_LCD 4.0        // "Brighten LCD"       - default:  4.0, min: 1.0, max: 12.0, step: 0.1
										  // (brightness of vertical lines)

//================
#ifdef GL_ES
precision mediump float;
precision mediump int;
// For android, use this instead...
//precision highp float;
//precision highp int;
//
#endif

//================
#define PI 3.141592654

//================
uniform sampler2D sampler0;
uniform vec2 u_texelDelta;
varying vec2 v_texcoord0;

// Have to use standard names to ensure compatibility with
// Vulkan backend...
varying vec2 v_texcoord1; // TextureSize

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

//================
void main()
{
	// Generate LCD grid effect
	// > Note the 0.25 pixel offset -> required to ensure that
	//   scanlines occur *between* pixels
	vec2 angle = 2.0 * PI * ((v_texcoord0.xy * v_texcoord1.xy) - 0.25); // v_texcoord1 == TextureSize
	
	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
	vec2 centerCoord = floor(v_texcoord0.xy * v_texcoord1.xy) + vec2(0.5, 0.5); // v_texcoord1 == TextureSize
	vec3 colour = texture2D(sampler0, u_texelDelta.xy * centerCoord).rgb;
	
	// Apply LCD grid effect
	colour.rgb = yfactor * xfactor * colour.rgb;
	
	gl_FragColor = vec4(colour.rgb, 1.0);
}