lcd1x.dsd

// lcd1x - Simple LCD 'scanline' shader, based on lcd3x
// 
// Original code by Gigaherz, 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 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
=============================================

<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

#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);

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
	vec3 colour = texture2D(u_texture, v_texture_coordinate.xy).rgb;
	
	// Apply LCD grid effect
	colour.rgb = yfactor * xfactor * colour.rgb;
	
	gl_FragColor = vec4(colour.rgb, 1.0);
}

</fragment>