refactor: make the whole thing more generic

modules/home-manager/desktops/hyprland/hypr/shaders/vibrance.frag

@@ -0,0 +1,39 @@
+// vibrance for hyprland
+
+precision mediump float;
+varying vec2 v_texcoord;
+uniform sampler2D tex;
+
+// see https://github.com/CeeJayDK/SweetFX/blob/a792aee788c6203385a858ebdea82a77f81c67f0/Shaders/Vibrance.fx#L20-L30
+const vec3 VIB_RGB_BALANCE = vec3(1.0, 1.0, 1.0);
+const float VIB_VIBRANCE = 0.15;
+
+
+const vec3 VIB_coeffVibrance = VIB_RGB_BALANCE * -VIB_VIBRANCE;
+
+void main() {
+
+    vec4 pixColor = texture2D(tex, v_texcoord);
+
+    // RGB
+    vec3 color = vec3(pixColor[0], pixColor[1], pixColor[2]);
+
+
+    // vec3 VIB_coefLuma = vec3(0.333333, 0.333334, 0.333333); // was for `if VIB_LUMA == 1`
+    vec3 VIB_coefLuma = vec3(0.212656, 0.715158, 0.072186); // try both and see which one looks nicer.
+
+    float luma = dot(VIB_coefLuma, color);
+
+    float max_color = max(color[0], max(color[1], color[2]));
+    float min_color = min(color[0], min(color[1], color[2]));
+
+    float color_saturation = max_color - min_color;
+
+    vec3 p_col = vec3(vec3(vec3(vec3(sign(VIB_coeffVibrance) * color_saturation) - 1.0) * VIB_coeffVibrance) + 1.0);
+
+    pixColor[0] = mix(luma, color[0], p_col[0]);
+    pixColor[1] = mix(luma, color[1], p_col[1]);
+    pixColor[2] = mix(luma, color[2], p_col[2]);
+
+    gl_FragColor = pixColor;
+}