The Humus demos don't have an explicit copyright license on the
shaders, but the C++ code that loads them has this for its license
text:

/* * * * * * * * * * * * * Author's note * * * * * * * * * * * *\
*   _       _   _       _   _       _   _       _     _ _ _ _   *
*  |_|     |_| |_|     |_| |_|_   _|_| |_|     |_|  _|_|_|_|_|  *
*  |_|_ _ _|_| |_|     |_| |_|_|_|_|_| |_|     |_| |_|_ _ _     *
*  |_|_|_|_|_| |_|     |_| |_| |_| |_| |_|     |_|   |_|_|_|_   *
*  |_|     |_| |_|_ _ _|_| |_|     |_| |_|_ _ _|_|  _ _ _ _|_|  *
*  |_|     |_|   |_|_|_|   |_|     |_|   |_|_|_|   |_|_|_|_|    *
*                                                               *
*                     http://www.humus.name                     *
*                                                                *
* This file is a part of the work done by Humus. You are free to   *
* use the code in any way you like, modified, unmodified or copied   *
* into your own work. However, I expect you to respect these points:  *
*  - If you use this file and its contents unmodified, or use a major *
*    part of this file, please credit the author and leave this note. *
*  - For use in anything commercial, please request my approval.     *
*  - Share your work and ideas too as much as you can.             *
*                                                                *
\* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */


/***********      .---.         .-"-.      *******************\
* -------- *     /   ._.       / <B4> ` \     * ---------------- *
* Author's *     \_  (__\      \_<B0>v<B0>_/     * humus@rogers.com *
*   note   *     //   \\       //   \\     * ICQ #47010716    *
* -------- *    ((     ))     ((     ))    * ---------------- *
*          ****--""---""-------""---""--****                  ********\
* This file is a part of the work done by Humus. You are free to use  *
* the code in any way you like, modified, unmodified or copy'n'pasted *
* into your own work. However, I expect you to respect these points:  *
*  @ If you use this file and its contents unmodified, or use a major *
*    part of this file, please credit the author and leave this note. *
*  @ For use in anything commercial, please request my approval.      *
*  @ Share your work and ideas too as much as you can.                *
\*********************************************************************/