Per application color saturation support (#21)

* Initial implementation without fullscreen support

* Limit saturation to 2

* Fixed saturation not working for fullscreen applications like CSGO

* Fixed saturation ignoring border radius

* Updated README and sway.5 man page

* Rebased from Master

* Added command to README

* Fixed nitpicks

1 files changed, 12 insertions, 1 deletions

diff --git a/sway/desktop/shaders/tex_rgba.frag b/sway/desktop/shaders/tex_rgba.frag
index 95f58987..2a9dbccb 100644
--- a/sway/desktop/shaders/tex_rgba.frag
+++ b/sway/desktop/shaders/tex_rgba.frag
@@ -7,9 +7,20 @@ uniform vec2 size;
 uniform vec2 position;
 uniform float radius;
 uniform bool has_titlebar;
+uniform float saturation;
+const vec3 saturation_weight = vec3(0.2125, 0.7154, 0.0721);
 
 void main() {
-    gl_FragColor = texture2D(tex, v_texcoord) * alpha;
+    // Saturation
+    if (saturation != 1.0) {
+        vec4 pixColor = texture2D(tex, v_texcoord);
+        vec3 irgb = pixColor.rgb;
+        vec3 target = vec3(dot(irgb, saturation_weight));
+        gl_FragColor = vec4(mix(target, irgb, saturation), pixColor.a) * alpha;
+    } else {
+        gl_FragColor = texture2D(tex, v_texcoord) * alpha;
+    }
+
     if (!has_titlebar || gl_FragCoord.y - position.y > radius) {
         vec2 corner_distance = min(gl_FragCoord.xy - position, size + position - gl_FragCoord.xy);
         if (max(corner_distance.x, corner_distance.y) < radius) {