Added a couple of comments.

[synfig.git] / ETL / trunk / ETL / _curve_func.h

diff --git a/ETL/trunk/ETL/_curve_func.h b/ETL/trunk/ETL/_curve_func.h
index fc33402..b2898aa 100644 (file)
--- a/ETL/trunk/ETL/_curve_func.h
+++ b/ETL/trunk/ETL/_curve_func.h
@@ -36,11 +36,13 @@
 template <class T, class K=float>
 struct affine_combo
 {
+       // from (a) to (x) : x = a(1-t) + b(t)
        T operator()(const T &a,const T &b,const K &t)const
        {
                return T( (b-a)*t+a );
        }
 
+       // from (x) to (a) : a = (x-b(t)) / (1-t)
        T reverse(const T &x, const T &b, const K &t)const
        {
                return T( (x-t*b)*(static_cast<K>(1)/(static_cast<K>(1)-t)) );