math.affine-transforms: some docs for the vocab

extra/math/affine-transforms/affine-transforms-docs.factor

@@ -0,0 +1,21 @@
+! Copyright (C) 2018 Björn Lindqvist
+! See http://factorcode.org/license.txt for BSD license
+USING: help.markup help.syntax ;
+IN: math.affine-transforms
+
+ARTICLE: "math.affine-transforms" "Affine Transformations of 2d Vectors"
+"This vocab provides words for affine transformations of 2d vectors. It can sometimes be more suitable to use the words in this vocab, than setting up the affine transformation matrices manually."
+{ $examples
+  "Creates a 45 degree counter clock-wise rotation matrix and applies it to a vector:"
+  { $example
+    "USING: math.affine-transforms math.trig prettyprint ;\n45 deg>rad <rotation> { 0 4 } a.v ."
+    "{ -2.82842712474619 2.82842712474619 }"
+  }
+  "Applies a combined scaling and translation transform to a vector:"
+  { $example
+    "USING: math.affine-transforms math.trig prettyprint ;\n{ 0 -5 } <translation> 1 2  <scale>  a. { 4 3 } a.v ."
+    "{ 4.0 1.0 }"
+  }
+} ;
+
+ABOUT: "math.affine-transforms"

extra/math/affine-transforms/affine-transforms.factor

@@ -1,12 +1,16 @@
 ! (c)2009 Joe Groff, see BSD license
-USING: accessors arrays combinators combinators.short-circuit kernel math math.vectors
-math.functions sequences ;
+USING: accessors arrays combinators combinators.short-circuit kernel
+math math.functions math.vectors sequences ;
 IN: math.affine-transforms
 
-TUPLE: affine-transform { x read-only } { y read-only } { origin read-only } ;
+TUPLE: affine-transform
+    { x read-only }
+    { y read-only }
+    { origin read-only } ;
 C: <affine-transform> affine-transform
 
-CONSTANT: identity-transform T{ affine-transform f { 1.0 0.0 } { 0.0 1.0 } { 0.0 0.0 } }
+CONSTANT: identity-transform T{ affine-transform f
+                                { 1.0 0.0 } { 0.0 1.0 } { 0.0 0.0 } }
 
 : axes ( a -- a' )
      [ x>> ] [ y>> ] bi { 0.0 0.0 } <affine-transform> ;
@@ -28,7 +32,8 @@ CONSTANT: identity-transform T{ affine-transform f { 1.0 0.0 } { 0.0 1.0 } { 0.0
     [ 0.0 2array ] [ 0.0 swap 2array ] bi* { 0.0 0.0 } <affine-transform> ;
 
 : center-rotation ( transform center -- transform )
-    [ [ x>> ] [ y>> ] [ ] tri ] dip [ vneg a.v ] [ v+ ] bi <affine-transform> ;
+    [ [ x>> ] [ y>> ] [ ] tri ] dip [ vneg a.v ] [ v+ ] bi
+    <affine-transform> ;
 
 : flatten-transform ( transform -- array )
     [ x>> ] [ y>> ] [ origin>> ] tri 3append ;

extra/math/affine-transforms/tags.txt

@@ -1 +1,2 @@
+graphics
 math