Рефактор.

shaders/tracked.gdshader

@@ -1,4 +1,7 @@
 shader_type canvas_item;
+
+#include "res://shaders/tools.gdshaderinc"
+
 uniform vec4 ColorFig:source_color;
 uniform vec2 point_1;
 uniform vec2 point_2;
@@ -14,10 +17,6 @@ const float DSS = 0.002525;
 const float radius = 0.125;
 uniform float speed:  hint_range(0.0, 1024.0) = 0.0;
 
-float smooth_px(float r, float R, float dss)
-{
-	return 1.0 - smoothstep(R - dss, R + dss, r);
-}
 
 float line(vec2 p1, vec2 p2, float width, vec2 uv)
 {