Add Lynx documentation to sp65

git-svn-id: svn://svn.cc65.org/cc65/trunk@5916 b7a2c559-68d2-44c3-8de9-860c34a00d81

diff --git a/doc/sp65.sgml b/doc/sp65.sgml
index 17b610425e80dda095d7fdb693d4933a89bf20f3..32dead645614917161a5d1e2b13e4333b537abe1 100644 (file)
--- a/doc/sp65.sgml
+++ b/doc/sp65.sgml
@@ -254,6 +254,58 @@ bytes). There are no additional attributes for this conversion.
 
 <sect1>Lynx sprite<p>
 
+Lynx can handle 1, 2, 3 and 4 bits per pixel indexed sprites. The maximum size
+of a sprite is roughly 508 pixels but in reality the Lynx screen is only 160 by
+102 pixels which makes very large sprites useless.
+
+The number per pixels is taken from the number of colors of the input bitmap.
+
+There are a few attributes that you can give to the conversion software.
+
+<descrip>
+
+  <tag/mode/
+  The first is what kind of encoding to use for the sprite. The attribute for
+  this is called "mode" and the possible values are "literal", "packed" or
+  "transparent". The default is "packed" if no mode is specified.
+
+  The "literal" is a totally literal mode with no packing. In this mode the
+  number of pixels per scanline will be a multiple of 8 both right and left from
+  the action point.
+
+  If the source bitmap edge ends with a color where the least significant bit is
+  one then there will be an extra 8 zero bits on that scan line.
+
+  So if you are using totally literal sprites and intend to change them at
+  runtime then please add a single pixel border far left and far right with
+  zeros in order to prevent graphical glitches in the game.
+
+  The standard encoding is called "packed". In this mode the sprite is packed
+  using run-length encoding and literal coding mixed for optimisation to
+  produce a small sprite.
+
+  The last encoding mode "transparent" is like packed. But here we know that
+  the index 0 will be transparent so we can clip off all 0 pixels from the left
+  and right edge of the sprite. This will produce the smallest sprite possible
+  on the Lynx. The sprite is not rectangular anymore.
+
+  <tag/ax/
+  The sprite is painted around the Anchor point. The anchor point x can be
+  between 0 and the width of the sprite - 1. If anchor point x is zero then
+  painting the sprite in location 10,20 will set the left edge of the sprite
+  10 pixels from the left of the Lynx screen. When the sprite is scaled by
+  hardware the anchor point stays in place and the sprite grows or shrinks
+  around the anchor point. The default value is 0 (left).
+
+  <tag/ay/
+  The sprite is painted around the Anchor point. The anchor point y can be
+  between 0 and the height of the sprite - 1. If anchor point y is zero then
+  painting the sprite in location 10,20 will set the top of the sprite 20
+  pixels from the top of the Lynx screen. When the sprite is scaled by
+  hardware the anchor point stays in place and the sprite grows or shrinks
+  around the anchor point. The default value is 0 (top).
+
+</descrip>
 
 <sect1>VIC2 sprite<p>