picom: transparency for feishin

src/.config/picom/shaders/transparency-sonixd.glsl

@@ -0,0 +1,54 @@
+// transparency for sonixd and feishin (music player). use "default dark" theme
+
+// https://github.com/ikz87/picom-shaders
+
+#version 330
+// rgb value for the maximum transparency
+uniform vec3 median_color = vec3(0.063);
+// maximum derivation from the median_color of each color channel (rgb)
+uniform vec3 max_derivation = vec3(0.40);
+// e.g. (1,0,0)±(0.2,0.2,0.2) -> gradient from #c00 to #f00 to #f33 with #f00 being the least opaque
+// (0,0,0)±(0.25,0.25,0,25) -> gradient from #000 to #444 with #000 being at min_opacity
+// opacity for the median_color
+uniform float min_opacity = 0.1;
+// exponent for the gradient (e.g. 1 for linear, 2 for quadratic, etc)
+uniform int power = 2;
+// use mean for a different effect
+float get_float (vec3 c) {
+    // maximum
+    return max(max(c.r,c.g),c.b);
+    // mean
+    // return (v.r + v.g + v.b)/3;
+}
+// tweak the above variables and functions for your needs
+
+// texture coordinate of the fragment
+in vec2 texcoord;
+// texture of the window
+uniform sampler2D tex;
+// Default window post-processing:
+// 1) invert color
+// 2) opacity / transparency
+// 3) max-brightness clamping
+// 4) rounded corners
+vec4 default_post_processing(vec4 c);
+
+
+// Default window shader:
+// 1) fetch the specified pixel
+// 2) apply default post-processing
+vec4 window_shader() {
+    vec4 c = texelFetch(tex, ivec2(texcoord), 0);
+
+    // get the each colorchannels derivation from the median_color channels and normalize them
+    vec3 normalized_derivation = abs(c.rgb - median_color)/max_derivation;
+    // only add transparency, if the pixel is not already transparent
+    if (c.a == 1 && get_float(normalized_derivation) < 1) {
+        // apply the gradient curvature
+        normalized_derivation = vec3(1)-pow(vec3(1)-normalized_derivation, vec3(power));
+        // apply transparency to rgb and alpha, because glx uses premultiplied alpha
+        c *= min_opacity + get_float(normalized_derivation) * (1-min_opacity);
+    }
+
+    return default_post_processing( c );
+}

src/.local/bin/picomstart.sh

@@ -1,4 +1,5 @@
 #!/bin/sh
 # misc opts so i don't have to use absolute path in picom config
 
-picom --window-shader-fg-rule "$HOME/.config/picom/shaders/transparency.glsl:class_g = 'qutebrowser'"
+picom  --window-shader-fg-rule "$HOME/.config/picom/shaders/transparency-sonixd.glsl:class_g = 'feishin'" \
+	--window-shader-fg-rule "$HOME/.config/picom/shaders/transparency.glsl:class_g = 'qutebrowser'" \