[SCM] Debian packaging for sketch 3D line drawing software branch, feature/info-dir, updated. upstream/0.2.89-9-g7aac830

[David Bremner]

The following commit has been merged in the feature/info-dir branch:
commit 7aac830e6ea62a750c337d9d110e865060dd0e15
Merge: 9fa6dbb026f62e22216bb64e77e2373f0a98b252 24509a9cdab1309254a9c6c7844bb52b7390d26d
Author: David Bremner <bremner at unb.ca>
Date:   Sat Jan 9 17:13:42 2010 -0400

    Merge commit 'refs/top-bases/feature/info-dir' into feature/info-dir

diff --combined Doc/sketch.texi
index 4470c6c,b85d780..a18d319
--- a/Doc/sketch.texi
+++ b/Doc/sketch.texi
@@@ -4,11 -4,6 +4,11 @@@
  @include version.texi
  @settitle Sketch
  
 + at dircategory Graphics
 + at direntry
 +* Sketch: (sketch).     Produce 3D line drawings from scene description language.
 + at end direntry
 +
  @c an index for sketch commands
  @defcodeindex sx
  @defcodeindex op
@@@ -1212,10 -1207,11 +1212,11 @@@ vector. @code{U} is optional and defaul
  @code{@w{ }[@math{a_{31}}, at math{a_{32}}, at math{a_{33}}, at math{a_{34}}]}@*
  @code{@w{ }[@math{a_{41}}, at math{a_{42}}, at math{a_{43}}, at math{a_{44}}]]}@*
    @sxindex [[ ][ ][ ][ ]]@r{, transform literal}
+   @cindex direct transform
+   @cindex transform, direct
    @tab 16 scalars 
    @tab Direct transform matrix definition. Each
-   of the @math{a_{ij}} is a scalar expression.  If you don't know what
-   this is about, you don't need it.
+   of the @math{a_{ij}} is a scalar expression. See text for details.
  @end multitable
  @noindent
  The @code{project} 
@@@ -1226,6 -1222,21 +1227,21 @@@ plane.  It is a special purpose transfo
  scenes where three-dimensional objects are being projected onto
  planes.  See, for example, @ref{Overview}.
  
+ The direct transform constructor 
+ @sxindex [[ ][ ][ ][ ]]@r{, transform literal}
+ @cindex direct transform
+ @cindex transform, direct
+ allows direct entry of a 4x4 transformation matrix. Most 3d graphics
+ systems, including @code{sketch}, use 4-dimensional homogeneous
+ coordinates internally. These are transformed by multiplication with
+ 4x4 matrices.  The built-in constructors (@code{rotate}, @code{scale},
+ etc.) are all translated internally to such 4x4 matrices. For more
+ information on homogeneous coordinate transformations, see any good
+ computer graphics textbook. The direct transform feature of
+ @code{sketch} allows you to enter a matrix of your own choice. There
+ are not many cases where this is useful, but if you do need it, you
+ need it badly!
+ 
  @node Arithmetic, Options, Literals, Language basics
  @subsection Arithmetic expressions
  Arithmetic expressions over @code{sketch} literals and

-- 
Debian packaging for sketch 3D line drawing software