1 uniform sampler2D framebuf, dither_tex;

2 uniform int dither_levels, dither_size;

3

4 uniform float tfadein;

5

6 vec4 fetch_pixel(vec2 texcoord)

7 {

8 float x = step(0.5, mod(texcoord.y, 0.5) / 0.5);

9 float offs = mix(1.0 - tfadein, tfadein - 1.0, x);

10 vec2 tc = texcoord + vec2(offs, 0.0);

11

12 return (1.0 - step(1.0, tc.x)) * step(0.0, tc.x) * texture2D(framebuf, tc);

13 }

14

15 void main()

16 {

17 float levels = float(dither_levels);

18

19 //vec4 pixel = texture2D(framebuf, gl_TexCoord[0].xy);

20 vec4 pixel = fetch_pixel(gl_TexCoord[0].xy);

21 float lum = dot(pixel.xyz, vec3(0.2126, 0.7152, 0.0722));

22 float coord_shift = floor(lum * levels) / levels;

23

24 vec2 dsz2 = vec2(float(dither_size), float(dither_size));

25

26 vec2 coord = mod(gl_FragCoord.xy, dsz2) / float(dither_size);

27 coord.y = coord.y / levels + coord_shift;

28 float val = texture2D(dither_tex, coord).x;

29

30 const vec3 dark_col = vec3(0.043, 0.286, 0.337);

31 const vec3 bright_col = vec3(0.965, 0.778, 0.555);

32

33 gl_FragColor = vec4(mix(dark_col, bright_col, val), 1.0);

34 }