X-Git-Url: https://git.pterodactylus.net/?a=blobdiff_plain;f=ETL%2Ftrunk%2FETL%2F_curve_func.h;h=b2898aaf201fa772c5dd83febe3e14b77ec5e0bf;hb=b0d82d28d294043cd7bf90f89ac802bf2b2f71fe;hp=fc33402c6f4cac2137b6a2b6074872226e74c773;hpb=337c51f149144c0844874ed20f71d780785c4127;p=synfig.git

diff --git a/ETL/trunk/ETL/_curve_func.h b/ETL/trunk/ETL/_curve_func.h
index fc33402..b2898aa 100644
--- 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)) );