Author: Carlos Lopez <[email protected]>
Date: Wed Jul 13 21:03:45 2011 +0200
Add functions to convert from standard index to homogeneous index (consider the
length as basis of the index)
---
synfig-core/src/synfig/valuenode_bline.cpp | 152 ++++++++++++++++++++++++++++
synfig-core/src/synfig/valuenode_bline.h | 8 ++
2 files changed, 160 insertions(+), 0 deletions(-)
diff --git a/synfig-core/src/synfig/valuenode_bline.cpp
b/synfig-core/src/synfig/valuenode_bline.cpp
index e1c1da0..0da9d0c 100644
--- a/synfig-core/src/synfig/valuenode_bline.cpp
+++ b/synfig-core/src/synfig/valuenode_bline.cpp
@@ -283,6 +283,158 @@ synfig::find_closest_point(const ValueBase &bline, const
Point &pos, Real &radiu
}
+Real
+synfig::std_to_hom(const ValueBase &bline, Real pos, bool loop, bool looped)
+{
+ BLinePoint blinepoint0, blinepoint1;
+ const std::vector<BLinePoint>
list(bline.get_list().begin(),bline.get_list().end());
+ int size = list.size(), from_vertex;
+ if(!looped) size--;
+ if(size < 1) return Real();
+ if (loop)
+ {
+ pos = pos - int(pos);
+ if (pos < 0) pos++;
+ }
+ else
+ {
+ if (pos < 0) pos = 0;
+ if (pos > 1) pos = 1;
+ }
+ // Calculate the lengths and the total length
+ Real tl=0, pl=0, l;
+ std::vector<Real> lengths;
+ vector<BLinePoint>::const_iterator iter, next(list.begin());
+ iter = looped ? --list.end() : next++;
+ for(;next!=list.end(); next++)
+ {
+ blinepoint0 = *iter;
+ blinepoint1 = *next;
+ etl::hermite<Vector> curve(blinepoint0.get_vertex(),
blinepoint1.get_vertex(),
+
blinepoint0.get_tangent2(), blinepoint1.get_tangent1());
+ l=curve.length();
+ tl+=l;
+ lengths.push_back(l);
+ iter=next;
+ }
+ // If the total length of the bline is zero return pos
+ if(tl==0.0) return pos;
+ from_vertex = int(pos*size);
+ // Calculate the partial length until the bezier that holds the current
+ std::vector<Real>::const_iterator liter(lengths.begin());
+ for(int i=0;i<from_vertex; i++, liter++)
+ pl+=*liter;
+ // Calculate the remaining length of the position over current bezier
+ // Setup the curve of the current bezier.
+ next=list.begin();
+ iter = looped ? --list.end() : next++;
+ if (from_vertex > size-1) from_vertex = size-1; // if we are at the end
of the last bezier
+ blinepoint0 = from_vertex ? *(next+from_vertex-1) : *iter;
+ blinepoint1 = *(next+from_vertex);
+ etl::hermite<Vector> curve(blinepoint0.get_vertex(),
blinepoint1.get_vertex(),
+
blinepoint0.get_tangent2(), blinepoint1.get_tangent1());
+ // add the distance on the bezier we are on.
+ pl+=curve.find_distance(0.0, pos*size - from_vertex);
+ // and return the homogenous position
+ return pl/tl;
+}
+
+Real
+synfig::hom_to_std(const ValueBase &bline, Real pos, bool loop, bool looped)
+{
+ BLinePoint blinepoint0, blinepoint1;
+ const std::vector<BLinePoint>
list(bline.get_list().begin(),bline.get_list().end());
+ int size = list.size(), from_vertex(0);
+ if(!looped) size--;
+ if(size < 1) return Real();
+ if (loop)
+ {
+ pos = pos - int(pos);
+ if (pos < 0) pos++;
+ }
+ else
+ {
+ if (pos < 0) pos = 0;
+ if (pos > 1) pos = 1;
+ }
+ // Calculate the lengths and the total length
+ Real tl(0), pl(0), mpl, bl, l;
+ std::vector<Real> lengths;
+ vector<BLinePoint>::const_iterator iter, next(list.begin());
+ iter = looped ? --list.end() : next++;
+ for(;next!=list.end(); next++)
+ {
+ blinepoint0 = *iter;
+ blinepoint1 = *next;
+ etl::hermite<Vector> curve(blinepoint0.get_vertex(),
blinepoint1.get_vertex(),
+
blinepoint0.get_tangent2(), blinepoint1.get_tangent1());
+ l=curve.length();
+ tl+=l;
+ lengths.push_back(l);
+ iter=next;
+ }
+ // Calculate the my partial length (the length where pos is)
+ mpl=pos*tl;
+ next=list.begin();
+ iter = looped ? --list.end() : next++;
+ std::vector<Real>::const_iterator liter(lengths.begin());
+ // Find the previous bezier where we pos is placed and the sum
+ // of lengths to it (pl)
+ // also remember the bezier's length where we stop
+ while(mpl > pl && next!=list.end())
+ {
+ pl+=*liter;
+ bl=*liter;
+ iter=next;
+ next++;
+ liter++;
+ from_vertex++;
+ }
+ // correct the iters and partial length in case we passed over
+ if(pl > mpl)
+ {
+ liter--;
+ next--;
+ if(next==list.begin())
+ iter=--list.end();
+ else
+ iter--;
+ pl-=*liter;
+ from_vertex--;
+ }
+ // set up the cureve
+ blinepoint0 = *iter;
+ blinepoint1 = *next;
+ etl::hermite<Vector> curve(blinepoint0.get_vertex(),
blinepoint1.get_vertex(),
+
blinepoint0.get_tangent2(), blinepoint1.get_tangent1());
+ // Find the solution to which is the standard postion which matches the
current
+ // homogenous position
+ // Secant method: http://en.wikipedia.org/wiki/Secant_method
+ Real sn(0.0); // the standard position on current bezier
+ Real sn1(0.0), sn2(1.0);
+ Real t0((mpl-pl)/bl); // the homogenous position on the current bezier
+ int iterations=0;
+ int max_iterations=100;
+ Real max_error(0.00001);
+ Real error;
+ Real fsn1(t0-curve.find_distance(0.0,sn1)/bl);
+ Real fsn2(t0-curve.find_distance(0.0,sn2)/bl);
+ Real fsn;
+ do
+ {
+ sn=sn1-fsn1*((sn1-sn2)/(fsn1-fsn2));
+ fsn=t0-curve.find_distance(0.0, sn)/bl;
+ sn2=sn1;
+ sn1=sn;
+ fsn2=fsn1;
+ fsn1=fsn;
+ error=fabs(fsn2-fsn1);
+ iterations++;
+ }while (error>max_error && max_iterations > iterations);
+ // convert the current standard index (s) to the bline's standard index
+ // and return it
+ return Real(from_vertex + sn)/size;
+}
/* === M E T H O D S ======================================================= */
diff --git a/synfig-core/src/synfig/valuenode_bline.h
b/synfig-core/src/synfig/valuenode_bline.h
index 66b592d..c9be9bc 100644
--- a/synfig-core/src/synfig/valuenode_bline.h
+++ b/synfig-core/src/synfig/valuenode_bline.h
@@ -54,6 +54,14 @@ ValueBase convert_bline_to_width_list(const ValueBase
&bline);
//! Finds the closest point to pos in bline
Real find_closest_point(const ValueBase &bline, const Point &pos, Real
&radius, bool loop, Point *out_point = 0);
+//! Converts from standard to homogeneous index (considers the length)
+//! looped is for bline looping and loop is for index looping
+Real std_to_hom(const ValueBase &bline, Real pos, bool loop, bool looped);
+
+//! Converts from homogeneous to standard index
+Real hom_to_std(const ValueBase &bline, Real pos, bool loop, bool looped);
+
+
/*! \class ValueNode_BLine
** \brief \writeme
*/
------------------------------------------------------------------------------
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