Index: hg_sdf.glsl
===================================================================
--- hg_sdf.glsl	(revision 8705)
+++ hg_sdf.glsl	(working copy)
@@ -4,17 +4,57 @@
 //
 //     GLSL LIBRARY FOR BUILDING SIGNED DISTANCE BOUNDS
 //
-//     version 2021-01-29
+//     version 2021-07-19
 //
-//     Check https://mercury.sexy/hg_sdf for updates
+//     Check https://mercury.sexy/hg_sdf/ for updates
 //     and usage examples. Send feedback to spheretracing@mercury.sexy.
 //
-//     Brought to you by MERCURY https://mercury.sexy
+//     Brought to you by MERCURY https://mercury.sexy/
 //
 //
 //
-// Released as Creative Commons Attribution-NonCommercial (CC BY-NC)
+// Released dual-licensed under
+//   Creative Commons Attribution-NonCommercial (CC BY-NC)
+// or
+//   MIT License
+// at your choice.
 //
+// SPDX-License-Identifier: MIT OR CC-BY-NC-4.0
+//
+// /////
+//
+// CC-BY-NC-4.0
+// https://creativecommons.org/licenses/by-nc/4.0/legalcode
+// https://creativecommons.org/licenses/by-nc/4.0/
+//
+// /////
+//
+// /////
+//
+// MIT License
+//
+// Copyright (c) 2011-2021 Mercury Demogroup
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in all
+// copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+// SOFTWARE.
+//
+// /////
+//
 ////////////////////////////////////////////////////////////////
 //
 // How to use this: