Added trigonometry functions for fun and profit.

Closes GH-201.

doc-src/content/CHANGELOG.markdown

@@ -37,6 +37,13 @@ COMPASS CHANGELOG
   make it easier to construct apis that manipulate these color attributes.
 * The `elements-of-type()` helper now returns html5 elements when the display is `block`
   and also will return only html5 elements for `elements-of-type(html5)`
+* Compass now provides several helper functions related to trigonometry.
+  There's no practical use, but it's hoped that users will find fun things to
+  do with these for technology demonstrations:
+  * `sin($number)` - Takes the sine of the number.
+  * `cos($number)` - Takes the cosine of the number.
+  * `tan($number)` - Takes the tangent of the number.
+  * `pi()` - Returns the value of π.
 
 ### Rails
 

lib/compass/sass_extensions/functions.rb

@@ -4,7 +4,7 @@ end
 %w(
   selectors enumerate urls display
   inline_image image_size gradient_support
-  font_files constants lists colors
+  font_files constants lists colors trig
 ).each do |func|
   require "compass/sass_extensions/functions/#{func}"
 end
@@ -21,6 +21,7 @@ module Sass::Script::Functions
   include Compass::SassExtensions::Functions::Constants
   include Compass::SassExtensions::Functions::Lists
   include Compass::SassExtensions::Functions::Colors
+  include Compass::SassExtensions::Functions::Trig
 end
 
 # Wierd that this has to be re-included to pick up sub-modules. Ruby bug?

lib/compass/sass_extensions/functions/trig.rb

@@ -0,0 +1,27 @@
+module Compass::SassExtensions::Functions::Trig
+
+  def pi()
+    Sass::Script::Number.new(Math::PI)
+  end
+
+  def sin(number)
+    trig(:sin, number)
+  end
+
+  def cos(number)
+    trig(:cos, number)
+  end
+
+  def tan(number)
+    trig(:tan, number)
+  end
+  
+  private
+  def trig(operation, number)
+    if number.numerator_units == ["deg"] && number.denominator_units == []
+      Sass::Script::Number.new(Math.send(operation, Math::PI * number.value / 360))
+    else
+      Sass::Script::Number.new(Math.send(operation, number.value), number.numerator_units, number.denominator_units)
+    end
+  end
+end

test/sass_extensions_test.rb

@@ -59,6 +59,23 @@ class SassExtensionsTest < Test::Unit::TestCase
     assert_equal "25%", evaluate("saturation(adjust-saturation(hsl(50deg, 50%, 50%), -25%))")
   end
 
+  def test_trig_functions
+    assert_equal "0.841px", evaluate("sin(1px)")
+    assert_equal "0.0", evaluate("sin(pi())")
+    assert_equal "1",   evaluate("sin(pi() / 2)")
+    assert_equal "1",   evaluate("sin(180deg)")
+    assert_equal "-1",  evaluate("sin(3* pi() / 2)")
+    assert_equal "-1", evaluate("cos(pi())")
+    assert_equal "-1", evaluate("cos(360deg)")
+    assert_equal "1", evaluate("cos(2*pi())")
+    assert_equal "0.0",   evaluate("cos(pi() / 2)")
+    assert_equal "0.0",  evaluate("cos(3* pi() / 2)")
+    assert_equal "0.0",  evaluate("tan(pi())")
+    assert_equal "0.0", evaluate("tan(360deg)")
+    assert evaluate("tan(pi()/2 - 0.0001)").to_f > 1000, evaluate("tan(pi()/2 - 0.0001)")
+    assert evaluate("tan(pi()/2 + 0.0001)").to_f < -1000, evaluate("tan(pi()/2 - 0.0001)")
+  end
+
 protected
   def evaluate(value)
     Sass::Script::Parser.parse(value, 0, 0).perform(Sass::Environment.new).to_s