/usr/share/movit/dither_effect.frag is in libmovit4 1.3.1-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 | // Implicit uniforms:
// uniform sampler2D PREFIX(dither_tex);
// uniform vec2 PREFIX(tc_scale);
// uniform float PREFIX(round_fac), PREFIX(inv_round_fac);
// See footer.frag for details about this if statement.
#ifndef YCBCR_ALSO_OUTPUT_RGBA
#define YCBCR_ALSO_OUTPUT_RGBA 0
#endif
#if YCBCR_ALSO_OUTPUT_RGBA
// There are two values to dither; otherwise, exactly the same as the algorithm below
// (so comments are not duplicated).
vec4[2] FUNCNAME(vec2 tc) {
vec4[2] result = INPUT(tc);
float d = tex2D(PREFIX(dither_tex), tc * PREFIX(tc_scale)).x;
result[0].rgb += vec3(d);
result[1].rgb += vec3(d);
#if NEED_EXPLICIT_ROUND
result[0] = round(result[0] * vec4(PREFIX(round_fac))) * vec4(PREFIX(inv_round_fac));
result[1] = round(result[1] * vec4(PREFIX(round_fac))) * vec4(PREFIX(inv_round_fac));
#endif
return result;
}
#else
vec4 FUNCNAME(vec2 tc) {
vec4 result = INPUT(tc);
float d = tex2D(PREFIX(dither_tex), tc * PREFIX(tc_scale)).x;
// Don't dither alpha; the case of alpha=255 (1.0) is very important to us,
// and if there's any inaccuracy earlier in the chain so that it becomes e.g.
// 254.8, it's better to just get it rounded off than to dither and have it
// possibly get down to 254. This is not the case for the color components.
result.rgb += vec3(d);
// NEED_EXPLICIT_ROUND will be #defined to 1 if the GPU has inaccurate
// fp32 -> int8 framebuffer rounding, and 0 otherwise.
#if NEED_EXPLICIT_ROUND
result = round(result * vec4(PREFIX(round_fac))) * vec4(PREFIX(inv_round_fac));
#endif
return result;
}
#endif
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