nuclear@12: /*
nuclear@12: Printblobs - typography display hack
nuclear@12: Copyright (C) 2013  John Tsiombikas <nuclear@member.fsf.org>
nuclear@12: 
nuclear@12: This program is free software: you can redistribute it and/or modify
nuclear@12: it under the terms of the GNU General Public License as published by
nuclear@12: the Free Software Foundation, either version 3 of the License, or
nuclear@12: (at your option) any later version.
nuclear@12: 
nuclear@12: This program is distributed in the hope that it will be useful,
nuclear@12: but WITHOUT ANY WARRANTY; without even the implied warranty of
nuclear@12: MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
nuclear@12: GNU General Public License for more details.
nuclear@12: 
nuclear@12: You should have received a copy of the GNU General Public License
nuclear@12: along with this program.  If not, see <http://www.gnu.org/licenses/>.
nuclear@12: */
nuclear@0: uniform sampler2D framebuf, dither_tex;
nuclear@0: uniform int dither_levels, dither_size;
nuclear@0: 
nuclear@11: uniform float tfadein;
nuclear@11: 
nuclear@11: vec4 fetch_pixel(vec2 texcoord)
nuclear@11: {
nuclear@11: 	float x = step(0.5, mod(texcoord.y, 0.5) / 0.5);
nuclear@11: 	float offs = mix(1.0 - tfadein, tfadein - 1.0, x);
nuclear@11: 	vec2 tc = texcoord + vec2(offs, 0.0);
nuclear@11: 
nuclear@11: 	return (1.0 - step(1.0, tc.x)) * step(0.0, tc.x) * texture2D(framebuf, tc);
nuclear@11: }
nuclear@11: 
nuclear@0: void main()
nuclear@0: {
nuclear@0: 	float levels = float(dither_levels);
nuclear@0: 
nuclear@11: 	//vec4 pixel = texture2D(framebuf, gl_TexCoord[0].xy);
nuclear@11: 	vec4 pixel = fetch_pixel(gl_TexCoord[0].xy);
nuclear@0: 	float lum = dot(pixel.xyz, vec3(0.2126, 0.7152, 0.0722));
nuclear@0: 	float coord_shift = floor(lum * levels) / levels;
nuclear@0: 
nuclear@0: 	vec2 dsz2 = vec2(float(dither_size), float(dither_size));
nuclear@0: 
nuclear@0: 	vec2 coord = mod(gl_FragCoord.xy, dsz2) / float(dither_size);
nuclear@0: 	coord.y = coord.y / levels + coord_shift;
nuclear@0: 	float val = texture2D(dither_tex, coord).x;
nuclear@0: 
nuclear@0: 	const vec3 dark_col = vec3(0.043, 0.286, 0.337);
nuclear@0: 	const vec3 bright_col = vec3(0.965, 0.778, 0.555);
nuclear@0: 
nuclear@0: 	gl_FragColor = vec4(mix(dark_col, bright_col, val), 1.0);
nuclear@0: }