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Title; Sprite Extend
Author; David De Vorchik
Distribution; *Acorn only*
History;
        24-Jul-92 DDV Created
         4-Aug-92 DDV Added some notes



INTRODUCTION
------------

This document oultines the changes made to Sprite Extend between the Green
and Blue releases.  The changes are documented at programmer level, along
with important information about coding changes and bug fixes. 

The main changes to the module since the green release is support for the
new sprite format and the ability to render into and from 16 or 32 bit per
pixel depth tiles.  Some sprite operations were recoded to be more optimal
and reliable.



SpriteReason_PutSpriteScaled / Transformed
------------------------------------------
  in:   as before
  out:  as before

These calls are designed for the old-style sprite format, and will only
work with it.  They support input depths upto eight bit per pixel, anything
above will be faulted.

They will render into higher depth modes, ones with 16 or 32 bit per pixel.

ColourTrans and Sprite Extend conspire by using a backwards compatibility
hack, this is when rendering to a mode that has a depth > 8 bit per pixel,
ColourTrans generates an VIDC 1 8 bit per pixel translation table the format
is "bgrt" with two bits per gun and tint.

SpriteExtend then notices that the depth is > 8 and has code optimised to
expand these values out to represent the sprite correctly on the display
device, although the quality is limited in effect to a VIDC 1 mode.


To do
-----
  + Fix the put sprite transformed bug (offset by lh margin)
  + Sort out so handles new header format correctly
