How to set up sky brushes for light emission

ArghRad is an alternative to Qrad3, first released on the 7th of April, 1998. Version 2.0 was released on the 2nd of March, 1999.

It features phong shading, emitting light from brush entities, more realistic directional sunlight, special checking in order to prevent light "bleeding" through solids etc.

Hammer/J.A.C.K./Sledge and Trenchbroom users: this will require a modified FGD file. Add keyvalues manually until then, or edit your own.

Version 2.00: March 2, 1999
   * program: added phong shading
   * program: added _sun_surface feature
   * program: rewrote sunlight code to be more efficient
   * program: rewrote anti-light-bleed code to improve quality
   * program: fixed qrad3 black-band & splotchy sky/liquid light bugs
   * program: fixed qrad3 surface #0 bounced light bug
   * program: improved command-line option output
   * program: removed some now-unused qrad3 code
   * text: added new feature info, made minor tweaks elsewhere
   * text: added John Fitzgibbons to acknowledgments
Version 1.50: November 2, 1998
   * program: added direct-lighting of unvised maps
   * program: added FreeDirectLights() to reclaim memory
   * program: added light-bleed checking and -nostopbleed
   * program: tweaked speed and memory use in some areas
   * program: added -radmin cutoff
   * program: rewrote texture handling code to be more efficient
   * text: added new feature info, made minor tweaks elsewhere
   * text: added Mr Elusive to acknowledgments
Version 1.03b:  September 17, 1998
   * program: fixed -moddir to read all pak#.pak
Version 1.03:  September 17, 1998
   * program: fixed ambient & minlight bug from original qrad3
   * program: tweaked -gamedir/-moddir to not require final backslash
   * text: _sun_angle clarification
Version 1.02:  August 24, 1998
   * program: fixed spotlight _focus lighting bug
   * program: fixed bad _ambient lighting in worldspawn
   * text: added -nominlimit info
   * text: added Michael Meadows to acknowledgments, added webpage URL
Version 1.01:  April 30, 1998
   * program: eliminated crashes with multiple suns using _sun aiming
   * program: fixed -chop* and -nobmodlight settings messages
   * program: fixed the spelling of "square" in verbose mode
   * text: corrected Rich Tollerton's name in acknowledgments
   * text: negative light clarification
No version change:  April 8, 1998
   * text: -gamedir/-moddir correction
No version change:  April 7, 1998
   * text: sunlight correction
Version 1.0:  April 7, 1998
   * first release

The download was found at the download page of BSP, under the Mapping Tools section. I was unable to retrieve it from the original ArghRad site (on the Web Archive), which has been down for a long time.