Add a inverse flag to LumaMixEffect.

[movit] / luma_mix_effect.frag

diff --git a/luma_mix_effect.frag b/luma_mix_effect.frag
index bf0833eec8d0c834c3b9048f32b3edd359ff8255..709d19262047d2371cd1933f3f3c88cfdb1ef27c 100644 (file)
--- a/luma_mix_effect.frag
+++ b/luma_mix_effect.frag
@@ -1,4 +1,5 @@
 uniform float PREFIX(progress_mul_w_plus_one);
+uniform bool PREFIX(inverse);
 
 vec4 FUNCNAME(vec2 tc) {
        vec4 first = INPUT1(tc);
@@ -36,8 +37,11 @@ vec4 FUNCNAME(vec2 tc) {
        // 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 * w;
-       float m = clamp((luma - w) + PREFIX(progress_mul_w_plus_one), 0.0, 1.0);
+       float luma = INPUT3(tc).x;
+       if (PREFIX(inverse)) {
+               luma = 1.0f - luma;
+       }
+       float m = clamp((luma * w - w) + PREFIX(progress_mul_w_plus_one), 0.0, 1.0);
 
        return mix(first, second, m);
 }