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nuclear@12
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1 /*
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nuclear@12
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2 Printblobs - typography display hack
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3 Copyright (C) 2013 John Tsiombikas <nuclear@member.fsf.org>
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4
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5 This program is free software: you can redistribute it and/or modify
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6 it under the terms of the GNU General Public License as published by
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7 the Free Software Foundation, either version 3 of the License, or
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8 (at your option) any later version.
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9
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10 This program is distributed in the hope that it will be useful,
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11 but WITHOUT ANY WARRANTY; without even the implied warranty of
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12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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13 GNU General Public License for more details.
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14
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15 You should have received a copy of the GNU General Public License
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16 along with this program. If not, see <http://www.gnu.org/licenses/>.
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nuclear@12
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17 */
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nuclear@0
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18 uniform sampler2D framebuf, dither_tex;
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nuclear@0
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19 uniform int dither_levels, dither_size;
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20
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21 uniform float tfadein;
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22
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23 vec4 fetch_pixel(vec2 texcoord)
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24 {
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25 float x = step(0.5, mod(texcoord.y, 0.5) / 0.5);
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26 float offs = mix(1.0 - tfadein, tfadein - 1.0, x);
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27 vec2 tc = texcoord + vec2(offs, 0.0);
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28
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29 return (1.0 - step(1.0, tc.x)) * step(0.0, tc.x) * texture2D(framebuf, tc);
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30 }
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nuclear@11
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31
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nuclear@0
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32 void main()
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nuclear@0
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33 {
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34 float levels = float(dither_levels);
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35
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36 //vec4 pixel = texture2D(framebuf, gl_TexCoord[0].xy);
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37 vec4 pixel = fetch_pixel(gl_TexCoord[0].xy);
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nuclear@0
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38 float lum = dot(pixel.xyz, vec3(0.2126, 0.7152, 0.0722));
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39 float coord_shift = floor(lum * levels) / levels;
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40
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nuclear@0
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41 vec2 dsz2 = vec2(float(dither_size), float(dither_size));
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nuclear@0
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42
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43 vec2 coord = mod(gl_FragCoord.xy, dsz2) / float(dither_size);
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44 coord.y = coord.y / levels + coord_shift;
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45 float val = texture2D(dither_tex, coord).x;
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46
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47 const vec3 dark_col = vec3(0.043, 0.286, 0.337);
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48 const vec3 bright_col = vec3(0.965, 0.778, 0.555);
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49
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50 gl_FragColor = vec4(mix(dark_col, bright_col, val), 1.0);
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nuclear@0
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51 }
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