synfig-core/src/synfig/valuenode_bline.cpp

   1 /* === S Y N F I G ========================================================= */
   2 /*!     \file valuenode_bline.cpp
   3 **      \brief Implementation of the "BLine" valuenode conversion.
   4 **
   5 **      $Id$
   6 **
   7 **      \legal
   8 **      Copyright (c) 2002-2005 Robert B. Quattlebaum Jr., Adrian Bentley
   9 **      Copyright (c) 2007, 2008 Chris Moore
  10 **
  11 **      This package is free software; you can redistribute it and/or
  12 **      modify it under the terms of the GNU General Public License as
  13 **      published by the Free Software Foundation; either version 2 of
  14 **      the License, or (at your option) any later version.
  15 **
  16 **      This package is distributed in the hope that it will be useful,
  17 **      but WITHOUT ANY WARRANTY; without even the implied warranty of
  18 **      MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  19 **      General Public License for more details.
  20 **      \endlegal
  21 */
  22 /* ========================================================================= */
  23
  24 /* === H E A D E R S ======================================================= */
  25
  26 #ifdef USING_PCH
  27 #       include "pch.h"
  28 #else
  29 #ifdef HAVE_CONFIG_H
  30 #       include <config.h>
  31 #endif
  32
  33 #include "valuenode_bline.h"
  34 #include "valuenode_const.h"
  35 #include "valuenode_composite.h"
  36 #include "general.h"
  37 #include "exception.h"
  38 #include "blinepoint.h"
  39 #include <vector>
  40 #include <list>
  41 #include <algorithm>
  42 #include <ETL/hermite>
  43 #include <ETL/calculus>
  44 #include "segment.h"
  45 #include "curve_helper.h"
  46
  47 #endif
  48
  49 /* === U S I N G =========================================================== */
  50
  51 using namespace std;
  52 using namespace etl;
  53 using namespace synfig;
  54
  55 /* === M A C R O S ========================================================= */
  56
  57 #define EPSILON 0.0000001f
  58
  59 /* === G L O B A L S ======================================================= */
  60
  61 /* === P R O C E D U R E S ================================================= */
  62
  63 inline float
  64 linear_interpolation(const float& a, const float& b, float c)
  65 { return (b-a)*c+a; }
  66
  67 inline Vector
  68 linear_interpolation(const Vector& a, const Vector& b, float c)
  69 { return (b-a)*c+a; }
  70
  71 inline Vector
  72 radial_interpolation(const Vector& a, const Vector& b, float c)
  73 {
  74         // if either extreme is zero then use linear interpolation instead
  75         if (a.is_equal_to(Vector::zero()) || b.is_equal_to(Vector::zero()))
  76                 return linear_interpolation(a, b, c);
  77
  78         affine_combo<Real,float> mag_combo;
  79         affine_combo<Angle,float> ang_combo;
  80
  81         Real mag(mag_combo(a.mag(),b.mag(),c));
  82         Angle angle_a(Angle::tan(a[1],a[0]));
  83         Angle angle_b(Angle::tan(b[1],b[0]));
  84         float diff = Angle::deg(angle_b - angle_a).get();
  85         if (diff < -180) angle_b += Angle::deg(360);
  86         else if (diff > 180) angle_a += Angle::deg(360);
  87         Angle ang(ang_combo(angle_a, angle_b, c));
  88
  89         return Point( mag*Angle::cos(ang).get(),mag*Angle::sin(ang).get() );
  90 }
  91
  92 inline void
  93 transform_coords(Vector in, Vector& out, const Point& coord_origin, const Point *coord_sys)
  94 {
  95         in -= coord_origin;
  96         out[0] = in * coord_sys[0];
  97         out[1] = in * coord_sys[1];
  98 }
  99
 100 inline void
 101 untransform_coords(const Vector& in, Vector& out, const Point& coord_origin, const Point *coord_sys)
 102 {
 103         out[0] = in * coord_sys[0];
 104         out[1] = in * coord_sys[1];
 105         out += coord_origin;
 106 }
 107
 108 ValueBase
 109 synfig::convert_bline_to_segment_list(const ValueBase& bline)
 110 {
 111         std::vector<Segment> ret;
 112
 113 //      std::vector<BLinePoint> list(bline.operator std::vector<BLinePoint>());
 114         //std::vector<BLinePoint> list(bline);
 115         std::vector<BLinePoint> list(bline.get_list().begin(),bline.get_list().end());
 116         std::vector<BLinePoint>::const_iterator iter;
 117
 118         BLinePoint prev,first;
 119
 120         //start with prev = first and iter on the second...
 121
 122         if(list.empty()) return ValueBase(ret,bline.get_loop());
 123         first = prev = list.front();
 124
 125         for(iter=++list.begin();iter!=list.end();++iter)
 126         {
 127                 ret.push_back(
 128                         Segment(
 129                                 prev.get_vertex(),
 130                                 prev.get_tangent2(),
 131                                 iter->get_vertex(),
 132                                 iter->get_tangent1()
 133                         )
 134                 );
 135                 prev=*iter;
 136         }
 137         if(bline.get_loop())
 138         {
 139                 ret.push_back(
 140                         Segment(
 141                                 prev.get_vertex(),
 142                                 prev.get_tangent2(),
 143                                 first.get_vertex(),
 144                                 first.get_tangent1()
 145                         )
 146                 );
 147         }
 148         return ValueBase(ret,bline.get_loop());
 149 }
 150
 151 ValueBase
 152 synfig::convert_bline_to_width_list(const ValueBase& bline)
 153 {
 154         std::vector<Real> ret;
 155 //      std::vector<BLinePoint> list(bline.operator std::vector<BLinePoint>());
 156         //std::vector<BLinePoint> list(bline);
 157         std::vector<BLinePoint> list(bline.get_list().begin(),bline.get_list().end());
 158         std::vector<BLinePoint>::const_iterator iter;
 159
 160         if(bline.empty())
 161                 return ValueBase(ValueBase::TYPE_LIST);
 162
 163         for(iter=list.begin();iter!=list.end();++iter)
 164                 ret.push_back(iter->get_width());
 165
 166         if(bline.get_loop())
 167                 ret.push_back(list.front().get_width());
 168
 169         return ValueBase(ret,bline.get_loop());
 170 }
 171
 172 Real
 173 synfig::find_closest_point(const ValueBase &bline, const Point &pos, Real &radius, bool loop, Point *out_point)
 174 {
 175         Real d,step;
 176         float time = 0;
 177         float best_time = 0;
 178         int best_index = -1;
 179         synfig::Point best_point;
 180
 181         if(radius==0)radius=10000000;
 182         Real closest(10000000);
 183
 184         int i=0;
 185         std::vector<BLinePoint> list(bline.get_list().begin(),bline.get_list().end());
 186         typedef std::vector<BLinePoint>::const_iterator iterT;
 187         iterT iter, prev, first;
 188         for(iter=list.begin(); iter!=list.end(); ++i, ++iter)
 189         {
 190                 if( first == iterT() )
 191                         first = iter;
 192
 193                 if( prev != iterT() )
 194                 {
 195                         bezier<Point>   curve;
 196
 197                         curve[0] = (*prev).get_vertex();
 198                         curve[1] = curve[0] + (*prev).get_tangent2()/3;
 199                         curve[3] = (*iter).get_vertex();
 200                         curve[2] = curve[3] - (*iter).get_tangent1()/3;
 201                         curve.sync();
 202
 203                         #if 0
 204                         // I don't know why this doesn't work
 205                         time=curve.find_closest(pos,6);
 206                         d=((curve(time)-pos).mag_squared());
 207
 208                         #else
 209                         //set the step size based on the size of the picture
 210                         d = (curve[1] - curve[0]).mag() + (curve[2]-curve[1]).mag()     + (curve[3]-curve[2]).mag();
 211
 212                         step = d/(2*radius); //want to make the distance between lines happy
 213
 214                         step = max(step,0.01); //100 samples should be plenty
 215                         step = min(step,0.1); //10 is minimum
 216
 217                         d = find_closest(curve,pos,step,&closest,&time);
 218                         #endif
 219
 220                         if(d < closest)
 221                         {
 222                                 closest = d;
 223                                 best_time = time;
 224                                 best_index = i;
 225                                 best_point = curve(best_time);
 226                         }
 227
 228                 }
 229
 230                 prev = iter;
 231         }
 232
 233         // Loop if necessary
 234         if( loop && ( first != iterT() ) && ( prev != iterT() ) )
 235         {
 236                 bezier<Point>   curve;
 237
 238                 curve[0] = (*prev).get_vertex();
 239                 curve[1] = curve[0] + (*prev).get_tangent2()/3;
 240                 curve[3] = (*first).get_vertex();
 241                 curve[2] = curve[3] - (*first).get_tangent1()/3;
 242                 curve.sync();
 243
 244                 #if 0
 245                 // I don't know why this doesn't work
 246                 time=curve.find_closest(pos,6);
 247                 d=((curve(time)-pos).mag_squared());
 248
 249                 #else
 250                 //set the step size based on the size of the picture
 251                 d = (curve[1] - curve[0]).mag() + (curve[2]-curve[1]).mag()     + (curve[3]-curve[2]).mag();
 252
 253                 step = d/(2*radius); //want to make the distance between lines happy
 254
 255                 step = max(step,0.01); //100 samples should be plenty
 256                 step = min(step,0.1); //10 is minimum
 257
 258                         d = find_closest(curve,pos,step,&closest,&time);
 259                 #endif
 260
 261                 if(d < closest)
 262                 {
 263                         closest = d;
 264                         best_time = time;
 265                         best_index = 0;
 266                         best_point = curve(best_time);
 267                 }
 268         }
 269
 270         if(best_index != -1)
 271         {
 272                 if(out_point)
 273                         *out_point = best_point;
 274
 275                 int loop_adjust(loop ? 0 : -1);
 276                 int size = list.size();
 277                 Real amount = (best_index + best_time + loop_adjust) / (size + loop_adjust);
 278                 return amount;
 279         }
 280
 281         return 0.0;
 282
 283 }
 284
 285 /* === M E T H O D S ======================================================= */
 286
 287
 288 ValueNode_BLine::ValueNode_BLine():
 289         ValueNode_DynamicList(ValueBase::TYPE_BLINEPOINT)
 290 {
 291 }
 292
 293 ValueNode_BLine::~ValueNode_BLine()
 294 {
 295 }
 296
 297 ValueNode_BLine*
 298 ValueNode_BLine::create(const ValueBase &value)
 299 {
 300         if(value.get_type()!=ValueBase::TYPE_LIST)
 301                 return 0;
 302
 303         ValueNode_BLine* value_node(new ValueNode_BLine());
 304
 305         if(!value.empty())
 306         {
 307                 switch(value.get_contained_type())
 308                 {
 309                 case ValueBase::TYPE_BLINEPOINT:
 310                 {
 311 //                      std::vector<BLinePoint> bline_points(value.operator std::vector<BLinePoint>());
 312                         //std::vector<BLinePoint> bline_points(value);
 313                         std::vector<BLinePoint> bline_points(value.get_list().begin(),value.get_list().end());
 314                         std::vector<BLinePoint>::const_iterator iter;
 315
 316                         for(iter=bline_points.begin();iter!=bline_points.end();iter++)
 317                         {
 318                                 value_node->add(ValueNode::Handle(ValueNode_Composite::create(*iter)));
 319                         }
 320                         value_node->set_loop(value.get_loop());
 321                 }
 322                         break;
 323                 case ValueBase::TYPE_SEGMENT:
 324                 {
 325                         // Here, we want to convert a list of segments
 326                         // into a list of BLinePoints. We make an assumption
 327                         // that the segment list is continuous(sp), but not necessarily
 328                         // smooth.
 329
 330                         value_node->set_loop(false);
 331 //                      std::vector<Segment> segments(value.operator std::vector<Segment>());
 332 //                      std::vector<Segment> segments(value);
 333                         std::vector<Segment> segments(value.get_list().begin(),value.get_list().end());
 334                         std::vector<Segment>::const_iterator iter,last(segments.end());
 335                         --last;
 336                         ValueNode_Const::Handle prev,first;
 337
 338                         for(iter=segments.begin();iter!=segments.end();iter++)
 339                         {
 340 #define PREV_POINT      prev->get_value().get(BLinePoint())
 341 #define FIRST_POINT     first->get_value().get(BLinePoint())
 342 #define CURR_POINT      curr->get_value().get(BLinePoint())
 343                                 if(iter==segments.begin())
 344                                 {
 345                                         prev=ValueNode_Const::create(ValueBase::TYPE_BLINEPOINT);
 346                                         {
 347                                                 BLinePoint prev_point(PREV_POINT);
 348                                                 prev_point.set_vertex(iter->p1);
 349                                                 prev_point.set_tangent1(iter->t1);
 350                                                 prev_point.set_width(0.01);
 351                                                 prev_point.set_origin(0.5);
 352                                                 prev_point.set_split_tangent_flag(false);
 353                                                 prev->set_value(prev_point);
 354                                         }
 355                                         first=prev;
 356                                         value_node->add(ValueNode::Handle(prev));
 357
 358                                 }
 359                                 if(iter==last && iter->p2.is_equal_to(FIRST_POINT.get_vertex()))
 360                                 {
 361                                         value_node->set_loop(true);
 362                                         if(!iter->t2.is_equal_to(FIRST_POINT.get_tangent1()))
 363                                         {
 364                                                 BLinePoint first_point(FIRST_POINT);
 365                                                 first_point.set_tangent1(iter->t2);
 366                                                 first->set_value(first_point);
 367                                         }
 368                                         continue;
 369                                 }
 370
 371                                 ValueNode_Const::Handle curr;
 372                                 curr=ValueNode_Const::create(ValueBase::TYPE_BLINEPOINT);
 373                                 {
 374                                         BLinePoint curr_point(CURR_POINT);
 375                                         curr_point.set_vertex(iter->p2);
 376                                         curr_point.set_tangent1(iter->t2);
 377                                         curr_point.set_width(0.01);
 378                                         curr_point.set_origin(0.5);
 379                                         curr_point.set_split_tangent_flag(false);
 380                                         curr->set_value(curr_point);
 381                                 }
 382                                 if(!PREV_POINT.get_tangent1().is_equal_to(iter->t1))
 383                                 {
 384                                         BLinePoint prev_point(PREV_POINT);
 385                                         prev_point.set_split_tangent_flag(true);
 386                                         prev_point.set_tangent2(iter->t1);
 387                                         prev->set_value(prev_point);
 388                                 }
 389                                 value_node->add(ValueNode::Handle(curr));
 390                                 prev=curr;
 391                         }
 392
 393                 }
 394                         break;
 395                 default:
 396                         // We got a list of who-knows-what. We don't have any idea
 397                         // what to do with it.
 398                         return 0;
 399                         break;
 400                 }
 401         }
 402
 403         return value_node;
 404 }
 405
 406 ValueNode_BLine::ListEntry
 407 ValueNode_BLine::create_list_entry(int index, Time time, Real origin)
 408 {
 409         ValueNode_BLine::ListEntry ret;
 410
 411         synfig::BLinePoint prev,next;
 412
 413         int prev_i,next_i;
 414
 415         index=index%link_count();
 416
 417         assert(index>=0);
 418         ret.index=index;
 419         ret.set_parent_value_node(this);
 420
 421         if(!list[index].status_at_time(time))
 422                 next_i=find_next_valid_entry(index,time);
 423         else
 424                 next_i=index;
 425         prev_i=find_prev_valid_entry(index,time);
 426
 427         //synfig::info("index=%d, next_i=%d, prev_i=%d",index,next_i,prev_i);
 428
 429         next=(*list[next_i].value_node)(time);
 430         prev=(*list[prev_i].value_node)(time);
 431
 432         etl::hermite<Vector> curve(prev.get_vertex(),next.get_vertex(),prev.get_tangent2(),next.get_tangent1());
 433         etl::derivative< etl::hermite<Vector> > deriv(curve);
 434
 435         synfig::BLinePoint bline_point;
 436         bline_point.set_vertex(curve(origin));
 437         bline_point.set_width((next.get_width()-prev.get_width())*origin+prev.get_width());
 438         bline_point.set_tangent1(deriv(origin)*min(1.0-origin,origin));
 439         bline_point.set_tangent2(bline_point.get_tangent1());
 440         bline_point.set_split_tangent_flag(false);
 441         bline_point.set_origin(origin);
 442
 443         ret.value_node=ValueNode_Composite::create(bline_point);
 444
 445         return ret;
 446 }
 447
 448 // Remove this variable because it is not used.
 449 //static int instance_count;
 450
 451 ValueBase
 452 ValueNode_BLine::operator()(Time t)const
 453 {
 454         if (getenv("SYNFIG_DEBUG_VALUENODE_OPERATORS"))
 455                 printf("%s:%d operator()\n", __FILE__, __LINE__);
 456
 457         std::vector<BLinePoint> ret_list;
 458
 459         std::vector<ListEntry>::const_iterator iter,first_iter;
 460         bool first_flag(true);
 461         bool rising;
 462         int index(0);
 463         float next_scale(1.0f);
 464
 465         BLinePoint prev,first;
 466         first.set_origin(100.0f);
 467
 468         // loop through all the list's entries
 469         for(iter=list.begin();iter!=list.end();++iter,index++)
 470         {
 471                 // how 'on' is this vertex?
 472                 float amount(iter->amount_at_time(t,&rising));
 473
 474                 assert(amount>=0.0f);
 475                 assert(amount<=1.0f);
 476
 477                 // it's fully on
 478                 if (amount > 1.0f - EPSILON)
 479                 {
 480                         if(first_flag)
 481                         {
 482                                 first_iter=iter;
 483                                 first=prev=(*iter->value_node)(t).get(prev);
 484                                 first_flag=false;
 485                                 ret_list.push_back(first);
 486                                 continue;
 487                         }
 488
 489                         BLinePoint curr;
 490                         curr=(*iter->value_node)(t).get(prev);
 491
 492                         if(next_scale!=1.0f)
 493                         {
 494                                 ret_list.back().set_split_tangent_flag(true);
 495                                 ret_list.back().set_tangent2(prev.get_tangent2()*next_scale);
 496
 497                                 ret_list.push_back(curr);
 498
 499                                 ret_list.back().set_split_tangent_flag(true);
 500                                 ret_list.back().set_tangent2(curr.get_tangent2());
 501                                 ret_list.back().set_tangent1(curr.get_tangent1()*next_scale);
 502
 503                                 next_scale=1.0f;
 504                         }
 505                         else
 506                         {
 507                                 ret_list.push_back(curr);
 508                         }
 509
 510                         prev=curr;
 511                 }
 512                 // it's partly on
 513                 else if(amount>0.0f)
 514                 {
 515                         std::vector<ListEntry>::const_iterator begin_iter,end_iter;
 516
 517                         // This is where the interesting stuff happens
 518                         // We need to seek forward in the list to see what the next
 519                         // active point is
 520
 521                         BLinePoint blp_here_on;  // the current vertex, when fully on
 522                         BLinePoint blp_here_off; // the current vertex, when fully off
 523                         BLinePoint blp_here_now; // the current vertex, right now (between on and off)
 524                         BLinePoint blp_prev_off; // the beginning of dynamic group when fully off
 525                         BLinePoint blp_next_off; // the end of the dynamic group when fully off
 526
 527                         int dist_from_begin(0), dist_from_end(0);
 528                         Time off_time, on_time;
 529
 530                         if(!rising)     // if not rising, then we were fully on in the past, and will be fully off in the future
 531                         {
 532                                 try{ on_time=iter->find_prev(t)->get_time(); }
 533                                 catch(...) { on_time=Time::begin(); }
 534                                 try{ off_time=iter->find_next(t)->get_time(); }
 535                                 catch(...) { off_time=Time::end(); }
 536                         }
 537                         else // otherwise we were fully off in the past, and will be fully on in the future
 538                         {
 539                                 try{ off_time=iter->find_prev(t)->get_time(); }
 540                                 catch(...) { off_time=Time::begin(); }
 541                                 try{ on_time=iter->find_next(t)->get_time(); }
 542                                 catch(...) { on_time=Time::end(); }
 543                         }
 544
 545                         blp_here_on=(*iter->value_node)(on_time).get(blp_here_on);
 546 //                      blp_here_on=(*iter->value_node)(t).get(blp_here_on);
 547
 548                         // Find "end" of dynamic group - ie. search forward along
 549                         // the bline from the current point until we find a point
 550                         // which is more 'on' than the current one
 551                         end_iter=iter;
 552 //                      for(++end_iter;begin_iter!=list.end();++end_iter)
 553                         for(++end_iter;end_iter!=list.end();++end_iter)
 554                                 if(end_iter->amount_at_time(t)>amount)
 555                                         break;
 556
 557                         // If we did not find an end of the dynamic group...
 558                         // Writeme!  at least now it doesn't crash if first_iter
 559                         // isn't set yet
 560                         if(end_iter==list.end())
 561                         {
 562                                 if(get_loop() && !first_flag)
 563                                         end_iter=first_iter;
 564                                 else
 565                                         end_iter=--list.end();
 566                         }
 567
 568                         blp_next_off=(*end_iter->value_node)(off_time).get(prev);
 569
 570                         // Find "begin" of dynamic group
 571                         begin_iter=iter;
 572                         blp_prev_off.set_origin(100.0f); // set the origin to 100 (which is crazy) so that we can check to see if it was found
 573                         do
 574                         {
 575                                 if(begin_iter==list.begin())
 576                                 {
 577                                         if(get_loop())
 578                                                 begin_iter=list.end();
 579                                         else
 580                                                 break;
 581                                 }
 582
 583                                 --begin_iter;
 584                                 dist_from_begin++;
 585
 586                                 // if we've gone all around the loop, give up
 587                                 if(begin_iter==iter)
 588                                         break;
 589
 590                                 if(begin_iter->amount_at_time(t)>amount)
 591                                 {
 592                                         blp_prev_off=(*begin_iter->value_node)(off_time).get(prev);
 593                                         break;
 594                                 }
 595                         }while(true);
 596
 597                         // If we did not find a begin
 598                         if(blp_prev_off.get_origin()==100.0f)
 599                         {
 600                                 // Writeme! - this needs work, but at least now it
 601                                 // doesn't crash
 602                                 if(first_flag)
 603                                         begin_iter=list.begin();
 604                                 else
 605                                         begin_iter=first_iter;
 606                                 blp_prev_off=(*begin_iter->value_node)(off_time).get(prev);
 607                         }
 608
 609                         // this is how the curve looks when we have completely vanished
 610                         etl::hermite<Vector> curve(blp_prev_off.get_vertex(),   blp_next_off.get_vertex(),
 611                                                                            blp_prev_off.get_tangent2(), blp_next_off.get_tangent1());
 612                         etl::derivative< etl::hermite<Vector> > deriv(curve);
 613
 614                         // where would we be on this curve, how wide will we be, and
 615                         // where will our tangents point (all assuming that we hadn't vanished)
 616                         blp_here_off.set_vertex(curve(blp_here_on.get_origin()));
 617                         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());
 618                         blp_here_off.set_tangent1(deriv(blp_here_on.get_origin()));
 619                         blp_here_off.set_tangent2(deriv(blp_here_on.get_origin()));
 620
 621                         float prev_tangent_scalar(1.0f);
 622                         float next_tangent_scalar(1.0f);
 623
 624                         //synfig::info("index_%d:dist_from_begin=%d",index,dist_from_begin);
 625                         //synfig::info("index_%d:dist_from_end=%d",index,dist_from_end);
 626
 627                         // If we are the next to the begin
 628                         if(begin_iter==--std::vector<ListEntry>::const_iterator(iter) || dist_from_begin==1)
 629                                 prev_tangent_scalar=linear_interpolation(blp_here_on.get_origin(), 1.0f, amount);
 630                         else
 631                                 prev_tangent_scalar=linear_interpolation(blp_here_on.get_origin()-prev.get_origin(), 1.0f, amount);
 632
 633                         // If we are the next to the end
 634                         if(end_iter==++std::vector<ListEntry>::const_iterator(iter) || dist_from_end==1)
 635                                 next_tangent_scalar=linear_interpolation(1.0-blp_here_on.get_origin(), 1.0f, amount);
 636                         else if(list.end()!=++std::vector<ListEntry>::const_iterator(iter))
 637                         {
 638                                 BLinePoint next;
 639                                 next=((*(++std::vector<ListEntry>::const_iterator(iter))->value_node)(t).get(prev));
 640                                 next_tangent_scalar=linear_interpolation(next.get_origin()-blp_here_on.get_origin(), 1.0f, amount);
 641                         }
 642                         else
 643                                 //! \todo this isn't quite right; we should handle looped blines identically no matter where the loop happens
 644                                 //! and we currently don't.  this at least makes it a lot better than it was before
 645                                 next_tangent_scalar=linear_interpolation(blp_next_off.get_origin()-blp_here_on.get_origin(), 1.0f, amount);
 646                         next_scale=next_tangent_scalar;
 647
 648                         //blp_here_now.set_vertex(linear_interpolation(blp_here_off.get_vertex(), blp_here_on.get_vertex(), amount));
 649                         // if(false)
 650                         // {
 651                         //      // My first try
 652                         //      Point ref_point_begin(((*begin_iter->value_node)(off_time).get(prev).get_vertex() +
 653                         //                                                 (*end_iter->value_node)(off_time).get(prev).get_vertex()) * 0.5);
 654                         //      Point ref_point_end(((*begin_iter->value_node)(on_time).get(prev).get_vertex() +
 655                         //                                               (*end_iter->value_node)(on_time).get(prev).get_vertex()) * 0.5);
 656                         //      Point ref_point_now(((*begin_iter->value_node)(t).get(prev).get_vertex() +
 657                         //                                               (*end_iter->value_node)(t).get(prev).get_vertex()) * 0.5);
 658                         //      Point ref_point_linear(linear_interpolation(ref_point_begin, ref_point_end, amount));
 659                         //
 660                         //      blp_here_now.set_vertex(linear_interpolation(blp_here_off.get_vertex(), blp_here_on.get_vertex(), amount) +
 661                         //                                                      (ref_point_now-ref_point_linear));
 662                         //      blp_here_now.set_tangent1(linear_interpolation(blp_here_off.get_tangent1(), blp_here_on.get_tangent1(), amount));
 663                         //      blp_here_now.set_split_tangent_flag(blp_here_on.get_split_tangent_flag());
 664                         //      if(blp_here_now.get_split_tangent_flag())
 665                         //              blp_here_now.set_tangent2(linear_interpolation(blp_here_off.get_tangent2(), blp_here_on.get_tangent2(), amount));
 666                         // }
 667                         // else
 668                         {
 669                                 // My second try
 670
 671                                 // define 3 coordinate systems:
 672                                 Point off_coord_sys[2],   off_coord_origin; // when the current vertex is completely off
 673                                 Point on_coord_sys[2] ,    on_coord_origin; // when the current vertex is completely on
 674                                 Point curr_coord_sys[2], curr_coord_origin; // the current state - somewhere in between
 675
 676                                 // for each of the 3 systems, the origin is half way between the previous and next active point
 677                                 // and the axes are based on a vector from the next active point to the previous
 678                                 {
 679                                         const Point   end_pos_at_off_time((  *end_iter->value_node)(off_time).get(prev).get_vertex());
 680                                         const Point begin_pos_at_off_time((*begin_iter->value_node)(off_time).get(prev).get_vertex());
 681                                         off_coord_origin=(begin_pos_at_off_time + end_pos_at_off_time)/2;
 682                                         off_coord_sys[0]=(begin_pos_at_off_time - end_pos_at_off_time).norm();
 683                                         off_coord_sys[1]=off_coord_sys[0].perp();
 684
 685                                         const Point   end_pos_at_on_time((  *end_iter->value_node)(on_time).get(prev).get_vertex());
 686                                         const Point begin_pos_at_on_time((*begin_iter->value_node)(on_time).get(prev).get_vertex());
 687                                         on_coord_origin=(begin_pos_at_on_time + end_pos_at_on_time)/2;
 688                                         on_coord_sys[0]=(begin_pos_at_on_time - end_pos_at_on_time).norm();
 689                                         on_coord_sys[1]=on_coord_sys[0].perp();
 690
 691                                         const Point   end_pos_at_current_time((  *end_iter->value_node)(t).get(prev).get_vertex());
 692                                         const Point begin_pos_at_current_time((*begin_iter->value_node)(t).get(prev).get_vertex());
 693                                         curr_coord_origin=(begin_pos_at_current_time + end_pos_at_current_time)/2;
 694                                         curr_coord_sys[0]=(begin_pos_at_current_time - end_pos_at_current_time).norm();
 695                                         curr_coord_sys[1]=curr_coord_sys[0].perp();
 696
 697                                         // Invert (transpose) the last of these matrices, since we use it for transform back
 698                                         swap(curr_coord_sys[0][1],curr_coord_sys[1][0]);
 699                                 }
 700
 701                                 /* The code that was here before used just end_iter as the origin, rather than the mid-point */
 702
 703                                 // We know our location and tangent(s) when fully on and fully off
 704                                 // Transform each of these into their corresponding coordinate system
 705                                 Point trans_on_point, trans_off_point;
 706                                 Vector trans_on_t1, trans_on_t2, trans_off_t1, trans_off_t2;
 707
 708                                 transform_coords(blp_here_on.get_vertex(),  trans_on_point,  on_coord_origin,  on_coord_sys);
 709                                 transform_coords(blp_here_off.get_vertex(), trans_off_point, off_coord_origin, off_coord_sys);
 710
 711 #define COORD_SYS_RADIAL_TAN_INTERP 1
 712
 713 #ifdef COORD_SYS_RADIAL_TAN_INTERP
 714                                 transform_coords(blp_here_on.get_tangent1(),  trans_on_t1,  Point::zero(), on_coord_sys);
 715                                 transform_coords(blp_here_off.get_tangent1(), trans_off_t1, Point::zero(), off_coord_sys);
 716
 717                                 if(blp_here_on.get_split_tangent_flag())
 718                                 {
 719                                         transform_coords(blp_here_on.get_tangent2(),  trans_on_t2,  Point::zero(), on_coord_sys);
 720                                         transform_coords(blp_here_off.get_tangent2(), trans_off_t2, Point::zero(), off_coord_sys);
 721                                 }
 722 #endif
 723
 724                                 {
 725                                         // Interpolate between the 'on' point and the 'off' point and untransform to get our point's location
 726                                         Point tmp;
 727                                         untransform_coords(linear_interpolation(trans_off_point, trans_on_point, amount),
 728                                                                            tmp, curr_coord_origin, curr_coord_sys);
 729                                         blp_here_now.set_vertex(tmp);
 730                                 }
 731
 732 #define INTERP_FUNCTION         radial_interpolation
 733 //#define INTERP_FUNCTION       linear_interpolation
 734
 735 #ifdef COORD_SYS_RADIAL_TAN_INTERP
 736                                 {
 737                                         Vector tmp;
 738                                         untransform_coords(INTERP_FUNCTION(trans_off_t1,trans_on_t1,amount), tmp, Point::zero(), curr_coord_sys);
 739                                         blp_here_now.set_tangent1(tmp);
 740                                 }
 741 #else
 742                                 blp_here_now.set_tangent1(radial_interpolation(blp_here_off.get_tangent1(),blp_here_on.get_tangent1(),amount));
 743 #endif
 744
 745                                 if (blp_here_on.get_split_tangent_flag())
 746                                 {
 747                                         blp_here_now.set_split_tangent_flag(true);
 748 #ifdef COORD_SYS_RADIAL_TAN_INTERP
 749                                         {
 750                                                 Vector tmp;
 751                                                 untransform_coords(INTERP_FUNCTION(trans_off_t2,trans_on_t2,amount), tmp, Point::zero(), curr_coord_sys);
 752                                                 blp_here_now.set_tangent2(tmp);
 753                                         }
 754 #else
 755                                         blp_here_now.set_tangent2(radial_interpolation(blp_here_off.get_tangent2(),blp_here_on.get_tangent2(),amount));
 756 #endif
 757                                 }
 758                                 else
 759                                         blp_here_now.set_split_tangent_flag(false);
 760                         }
 761
 762                         blp_here_now.set_origin(blp_here_on.get_origin());
 763                         blp_here_now.set_width(linear_interpolation(blp_here_off.get_width(), blp_here_on.get_width(), amount));
 764
 765                         // Handle the case where we are the first vertex
 766                         if(first_flag)
 767                         {
 768                                 blp_here_now.set_tangent1(blp_here_now.get_tangent1()*prev_tangent_scalar);
 769                                 first_iter=iter;
 770                                 first=prev=blp_here_now;
 771                                 first_flag=false;
 772                                 ret_list.push_back(blp_here_now);
 773                                 continue;
 774                         }
 775
 776                         ret_list.back().set_split_tangent_flag(true);
 777                         ret_list.back().set_tangent2(prev.get_tangent2()*prev_tangent_scalar);
 778                         ret_list.push_back(blp_here_now);
 779                         ret_list.back().set_split_tangent_flag(true);
 780                         //ret_list.back().set_tangent2(blp_here_now.get_tangent1());
 781                         ret_list.back().set_tangent1(blp_here_now.get_tangent1()*prev_tangent_scalar);
 782
 783                         prev=blp_here_now;
 784                 }
 785         }
 786
 787         if(next_scale!=1.0f)
 788         {
 789                 ret_list.back().set_split_tangent_flag(true);
 790                 ret_list.back().set_tangent2(prev.get_tangent2()*next_scale);
 791         }
 792
 793 /*
 794         if(get_loop() && !first_flag)
 795         {
 796                 ret_list.push_back(
 797                         Segment(
 798                         prev.get_vertex(),
 799                         prev.get_tangent2(),
 800                         first.get_vertex(),
 801                         first.get_tangent1()
 802                         )
 803                 );
 804         }
 805 */
 806
 807         if(list.empty())
 808                 synfig::warning(string("ValueNode_BLine::operator()():")+_("No entries in list"));
 809         else
 810         if(ret_list.empty())
 811                 synfig::warning(string("ValueNode_BLine::operator()():")+_("No entries in ret_list"));
 812
 813         return ValueBase(ret_list,get_loop());
 814 }
 815
 816 String
 817 ValueNode_BLine::link_local_name(int i)const
 818 {
 819         assert(i>=0 && (unsigned)i<list.size());
 820         return etl::strprintf(_("Vertex %03d"),i+1);
 821 }
 822
 823 String
 824 ValueNode_BLine::get_name()const
 825 {
 826         return "bline";
 827 }
 828
 829 String
 830 ValueNode_BLine::get_local_name()const
 831 {
 832         return _("BLine");
 833 }
 834
 835 LinkableValueNode*
 836 ValueNode_BLine::create_new()const
 837 {
 838         return new ValueNode_BLine();
 839 }
 840
 841 bool
 842 ValueNode_BLine::check_type(ValueBase::Type type)
 843 {
 844         return type==ValueBase::TYPE_LIST;
 845 }
 846
 847 LinkableValueNode::Vocab
 848 ValueNode_BLine::get_children_vocab_vfunc()const
 849 {
 850         LinkableValueNode::Vocab ret;
 851         for(unsigned int i=0; i<list.size();i++)
 852         {
 853                 ret.push_back(ParamDesc(ValueBase(),strprintf("item%04d",i))
 854                         .set_local_name(etl::strprintf(_("Vertex %03d"),i+1))
 855                 );
 856         }
 857
 858         return ret;
 859 }