A few more comments and other small changes.

git-svn-id: http://svn.voria.com/code@461 1f10aa63-cdf2-0310-b900-c93c546f37ac

diff --git a/synfig-core/trunk/src/synfig/valuenode_bline.cpp b/synfig-core/trunk/src/synfig/valuenode_bline.cpp
index 9c7aced..2435814 100644 (file)
--- a/synfig-core/trunk/src/synfig/valuenode_bline.cpp
+++ b/synfig-core/trunk/src/synfig/valuenode_bline.cpp
@@ -81,7 +81,7 @@ radial_interpolation(const Vector& a, const Vector& b, float c)
 }
 
 inline void
-transform(Vector in, Vector& out, Point& coord_origin, Point *coord_sys)
+transform_coords(Vector in, Vector& out, const Point& coord_origin, const Point *coord_sys)
 {
        in -= coord_origin;
        out[0] = in * coord_sys[0];
@@ -89,7 +89,7 @@ transform(Vector in, Vector& out, Point& coord_origin, Point *coord_sys)
 }
 
 inline void
-untransform(const Vector& in, Vector& out, Point& coord_origin, Point *coord_sys)
+untransform_coords(const Vector& in, Vector& out, const Point& coord_origin, const Point *coord_sys)
 {
        out[0] = in * coord_sys[0];
        out[1] = in * coord_sys[1];
@@ -394,19 +394,19 @@ ValueNode_BLine::operator()(Time t)const
                        BLinePoint blp_here_off; // the current vertex, when fully off
                        BLinePoint blp_here_now; // the current vertex, right now (between on and off)
                        BLinePoint blp_prev_off; // the beginning of dynamic group when fully off
-                       BLinePoint blp_next_off; // end of the dynamic group when fully off
+                       BLinePoint blp_next_off; // the end of the dynamic group when fully off
 
                        int dist_from_begin(0), dist_from_end(0);
                        Time off_time, on_time;
 
-                       if(!rising)
+                       if(!rising)     // if not rising, then we were fully on in the past, and will be fully off in the future
                        {
                                try{ on_time=iter->find_prev(t)->get_time(); }
                                catch(...) { on_time=Time::begin(); }
                                try{ off_time=iter->find_next(t)->get_time(); }
                                catch(...) { off_time=Time::end(); }
                        }
-                       else
+                       else // otherwise we were fully off in the past, and will be fully on in the future
                        {
                                try{ off_time=iter->find_prev(t)->get_time(); }
                                catch(...) { off_time=Time::begin(); }
@@ -489,14 +489,15 @@ ValueNode_BLine::operator()(Time t)const
                                }
                        }
 
+                       // this is how the curve looks when we have completely vanished
                        etl::hermite<Vector> curve(blp_prev_off.get_vertex(),   blp_next_off.get_vertex(),
                                                                           blp_prev_off.get_tangent2(), blp_next_off.get_tangent1());
                        etl::derivative< etl::hermite<Vector> > deriv(curve);
 
+                       // where would we be on this curve, how wide will we be, and
+                       // where will our tangents point (all assuming that we hadn't vanished)
                        blp_here_off.set_vertex(curve(blp_here_on.get_origin()));
-
                        blp_here_off.set_width((blp_next_off.get_width()-blp_prev_off.get_width())*blp_here_on.get_origin()+blp_prev_off.get_width());
-
                        blp_here_off.set_tangent1(deriv(blp_here_on.get_origin()));
                        blp_here_off.set_tangent2(deriv(blp_here_on.get_origin()));
 
@@ -584,20 +585,20 @@ ValueNode_BLine::operator()(Time t)const
                                Vector trans_on_t1, trans_on_t2, trans_off_t1, trans_off_t2, untrans_curr_t1, untrans_curr_t2;
 
                                // Convert points where vertex is fully on and fully off
-                               transform(blp_here_on.get_vertex(),  trans_on_point,  on_coord_origin,  on_coord_sys);
-                               transform(blp_here_off.get_vertex(), trans_off_point, off_coord_origin, off_coord_sys);
+                               transform_coords(blp_here_on.get_vertex(),  trans_on_point,  on_coord_origin,  on_coord_sys);
+                               transform_coords(blp_here_off.get_vertex(), trans_off_point, off_coord_origin, off_coord_sys);
 
 #define COORD_SYS_RADIAL_TAN_INTERP 1
 
 #ifdef COORD_SYS_RADIAL_TAN_INTERP
                                // this I don't understand.  why add on this bit ---v
-                               transform(blp_here_on.get_tangent1()  + blp_here_on.get_vertex(),  trans_on_t1,  on_coord_origin,  on_coord_sys);
-                               transform(blp_here_off.get_tangent1() + blp_here_off.get_vertex(), trans_off_t1, off_coord_origin, off_coord_sys);
+                               transform_coords(blp_here_on.get_tangent1()  + blp_here_on.get_vertex(),  trans_on_t1,  on_coord_origin,  on_coord_sys);
+                               transform_coords(blp_here_off.get_tangent1() + blp_here_off.get_vertex(), trans_off_t1, off_coord_origin, off_coord_sys);
 
                                if(blp_here_on.get_split_tangent_flag())
                                {
-                                       transform(blp_here_on.get_tangent2()+blp_here_on.get_vertex(),   trans_on_t2,  on_coord_origin,  on_coord_sys);
-                                       transform(blp_here_off.get_tangent2()+blp_here_off.get_vertex(), trans_off_t2, off_coord_origin, off_coord_sys);
+                                       transform_coords(blp_here_on.get_tangent2()  + blp_here_on.get_vertex(),  trans_on_t2,  on_coord_origin,  on_coord_sys);
+                                       transform_coords(blp_here_off.get_tangent2() + blp_here_off.get_vertex(), trans_off_t2, off_coord_origin, off_coord_sys);
                                }
 #endif
                                // Convert current point
@@ -605,21 +606,21 @@ ValueNode_BLine::operator()(Time t)const
                                swap(curr_coord_sys[0][1],curr_coord_sys[1][0]);
 
                                // interpolate between the 'on' point and the 'off' point and untransform to get our point's location
-                               untransform(linear_interpolation(trans_off_point, trans_on_point, amount),
-                                                       untrans_curr_point, curr_coord_origin, curr_coord_sys);
+                               untransform_coords(linear_interpolation(trans_off_point, trans_on_point, amount),
+                                                                  untrans_curr_point, curr_coord_origin, curr_coord_sys);
 
 #define INTERP_FUNCTION                radial_interpolation
 //#define INTERP_FUNCTION      linear_interpolation
 
 #ifdef COORD_SYS_RADIAL_TAN_INTERP
-                               untransform(INTERP_FUNCTION(trans_off_t1,trans_on_t1,amount),
-                                                       untrans_curr_t1, curr_coord_origin, curr_coord_sys);
+                               untransform_coords(INTERP_FUNCTION(trans_off_t1,trans_on_t1,amount),
+                                                                  untrans_curr_t1, curr_coord_origin, curr_coord_sys);
                                untrans_curr_t1 -= untrans_curr_point;
 
                                if(blp_here_on.get_split_tangent_flag())
                                {
-                                       untransform(INTERP_FUNCTION(trans_off_t2,trans_on_t2,amount),
-                                                               untrans_curr_t2, curr_coord_origin, curr_coord_sys);
+                                       untransform_coords(INTERP_FUNCTION(trans_off_t2,trans_on_t2,amount),
+                                                                          untrans_curr_t2, curr_coord_origin, curr_coord_sys);
                                        untrans_curr_t2 -= untrans_curr_point;
                                }
 #endif