/usr/share/movit/luma_mix_effect.frag is in libmovit8 1.6.1-1.
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 | // Implicit uniforms:
// uniform float PREFIX(progress_mul_w_plus_one);
// uniform bool PREFIX(bool_inverse);
vec4 FUNCNAME(vec2 tc) {
vec4 first = INPUT1(tc);
vec4 second = INPUT2(tc);
// We treat the luma as going from 0 to w, where w is the transition width
// (wider means the boundary between transitioned and non-transitioned
// will be harder, while w=0 is essentially just a straight fade).
// We need to map this 0..w range in the luma image to a (clamped) 0..1
// range for how far this pixel has come in a fade. At the very
// beginning, we can visualize it like this, where every pixel is in
// the state 0.0 (100% first image, 0% second image):
//
// 0 w
// luma: |---------------------|
// mix: |----|
// 0 1
//
// Then as we progress, eventually the luma range should move to the right
// so that more pixels start moving towards higher mix value:
//
// 0 w
// luma: |---------------------|
// mix: |----|
// 0 1
//
// and at the very end, all pixels should be in the state 1.0 (0% first image,
// 100% second image):
//
// 0 w
// luma: |---------------------|
// mix: |----|
// 0 1
//
// So clearly, it should move (w+1) units to the right, and apart from that
// just stay a simple mapping.
float w = PREFIX(transition_width);
float luma = INPUT3(tc).x;
if (PREFIX(bool_inverse)) {
luma = 1.0 - luma;
}
float m = clamp((luma * w - w) + PREFIX(progress_mul_w_plus_one), 0.0, 1.0);
return mix(first, second, m);
}
|