***************************************************************************
*                                                                         *
*                                   DBW_Render                            *
*                              RISC OS version 2.00                       *
*                                                                         *
*                                  General Guide                          *
*                                Neil Coffey 1992                        *
*                                                                         *
***************************************************************************


  Contents:

     !ArcFS                      - Read only version of archive filing
                                   system for reading compressed example
                                   files
     !DBWRender                  - The ray tracer itself
     Docs                        - Ray tracer documentation
     Examples                    - An archive containing four example
                                   pictures complete with the script files
                                   used to create them
     Library                     - Contains the utilities DBWLink, DBWPCX
                                   and DBWSprite
     SourceCode                  - The source code to the original
                                   DBW_Render

  The RISC OS version of DBW_Render is a multi-tasking application. Once
  it is installed, ray tracing is started by dragging a directory contain-
  ing a command script file on to the window, and clicking on 'Ray Trace'.

  The script is a list of commands telling the ray tracer where to place
  the objects in the scene. A separate documentation file, 'Script',
  details the various commands. The script file is created in !Edit and
  should be saved with the name 'DAT' inside the directory (see examples).

  During ray tracing, the program produces another file, TMP, inside the
  directory. This is a file containing the raw picture information, and is
  in the format:

      2 bytes:   X resolution
      2 bytes:   Y resolution

  and then:

      2 bytes:   scan line number
    160 bytes:   320 4-bit red intensities
    160 bytes:   320 4-bit green intensities
    160 bytes:   320 4-bit blue intensities

  The utility DBWSprite is then used to convert a TMP file into a sprite
  file. A full image consists of 200 lines of 320 pixels. DBWSprite uses
  this to create a dithered mode 15 sprite.

  The scan line region to be traced is set up in the main window before
  tracing. The whole screen is scan lines 0-200; the first half would be
  0-100; the second quarter would be 50-100.

  The program DBWLink can be used to join such files together to create one
  whole image. This allows you to share the computation across two or more
  machines.

  The program DBWPCX converts DBW_Render files into PCX files which can then
  be exported to PCs.


  Neil Coffey
  August 1992
