                       Documentation for !RGB_Spr V1.00
                       ---------------------------------

******************** Incredibly boring Copyright Notice *******************
                                                                           
      All program code is the exclusive copyright of Roger C. Attrill.    
           The program source and documentation for !RGB_Spr are          
freely distributable and should not be charged for under ANY circumstances.
                                                                            
****************************************************************************

Installing RGB_Spr (Requires RISC OS)
---------------------------------------

Simply start up the Desktop and double-click on the !RGB_Spr application
directory. This will install an icon on the RHS of the icon bar, ready to
run. clicking menu brings up the usual info and quit selections. Dragging
RGB files onto the icon will convert them into sprites.

So what does !RGB_Spr do ?
---------------------------                                     

Having written a program which used the code I found it useful to have
a small stand alone program to convert a 24-bit/pixel RGB description
file into a sprite.

The RGB file is a common format used by ray tracers such as MTV,QRT - and
the one I'm working on. It consists of a first line of the form

<xresolution> <yresolution>

eg  

512 256

!RGB_Spr will accept a destination mode and a short descriptor

eg

512 256 15 A message goes here

The rest of the file consists of <xresolution>*<yresolution> triplets of
bytes which correspond to the red, green, and blue intensities of each
pixel. The order is from left to right, and top to bottom of the picture.

!RGB_Spr will take this format (Drag the file onto the bar icon) and
convert it into a sprite of the given size and in the given mode. If no
mode is given then the best mode for the resolutions is chosen from
modes 13,15 or 21.
 
The image is created using floyd steinberg dithering to give the best
possible result for a 256 colour display. The default palette for a 256
colour mode is used.

Once the image has been created, the if desktop is in a 256 colour mode,
the image will be displayed. By clicking menu inside the image you have
the options to get sprite info, magnify the image, or save the image - as
a sprite - to a file.

An RGB file can be easily created using a short BASIC program - an example
should be included in this archive. By their nature RGB files tend to be
rather big - a hard disk is needed to create a full screen mode 21 RGB file.



Where to find me to report bugs or improvements to !RGB_Spr
-----------------------------------------------------------

Snail Mail                                   JANET e-mail
----------                                   ------------
Roger C. Attrill,                            ra2@doc.ic.ac.uk
Department of Computing,
Huxley Building,
Imperial College of Science and Technology,
Exhibition Road,
London SW7 2BZ.
