Improve the rendering of curvegradient layers near vertices with zero-length tangents...

git-svn-id: https://synfig.svn.sourceforge.net/svnroot/synfig@2148 1f10aa63-cdf2-0310-b900-c93c546f37ac

diff --git a/ETL/trunk/ETL/_bezier.h b/ETL/trunk/ETL/_bezier.h
index a08a42b..70dfe99 100644 (file)
--- a/ETL/trunk/ETL/_bezier.h
+++ b/ETL/trunk/ETL/_bezier.h
@@ -553,8 +553,7 @@ public:
                                bezier<V,T>::operator[](1),
                                bezier<V,T>::operator[](2),
                                bezier<V,T>::operator[](3)};
-                       float t = NearestPointOnCurve(x, array);
-                       return t > 0.999999 ? 0.999999 : t < 0.000001 ? 0.000001 : t;
+                       return NearestPointOnCurve(x, array);
            }
            else
            {

diff --git a/synfig-core/trunk/src/modules/mod_gradient/curvegradient.cpp b/synfig-core/trunk/src/modules/mod_gradient/curvegradient.cpp
index 9e9a5ea..4fa704e 100644 (file)
--- a/synfig-core/trunk/src/modules/mod_gradient/curvegradient.cpp
+++ b/synfig-core/trunk/src/modules/mod_gradient/curvegradient.cpp
@@ -50,6 +50,8 @@
 
 /* === M A C R O S ========================================================= */
 
+#define FAKE_TANGENT_STEP 0.000001
+
 /* === G L O B A L S ======================================================= */
 
 SYNFIG_LAYER_INIT(CurveGradient);
@@ -306,7 +308,7 @@ CurveGradient::color_func(const Point &point_, int quality, float supersample)co
 
                // Calculate our values
                p1=curve(t);                     // the closest point on the curve
-               tangent=deriv(t).norm(); // the unit tangent at that point
+               tangent=deriv(t);                // the tangent at that point
 
                // if the point we're nearest to is at either end of the
                // bline, our distance from the curve is the distance from the
@@ -315,23 +317,64 @@ CurveGradient::color_func(const Point &point_, int quality, float supersample)co
                // this point
                if (t<0.00001 || t>0.99999)
                {
+                       bool zero_tangent = (tangent[0] == 0 && tangent[1] == 0);
+
                        if (t<0.5)
                        {
-                               if (iter->get_split_tangent_flag())
+                               if (iter->get_split_tangent_flag() || zero_tangent)
                                {
-                                       tangent=(iter->get_tangent1().norm()+tangent).norm();
+                                       // fake the current tangent if we need to
+                                       if (zero_tangent) tangent = curve(FAKE_TANGENT_STEP) - curve(0);
+
+                                       // calculate the other tangent
+                                       Vector other_tangent(iter->get_tangent1());
+                                       if (other_tangent[0] == 0 && other_tangent[1] == 0)
+                                       {
+                                               // find the previous blinepoint
+                                               std::vector<synfig::BLinePoint>::const_iterator prev;
+                                               if (iter != bline.begin()) (prev = iter)--;
+                                               else if (loop) (prev = bline.end())--;
+                                               else prev = iter;
+
+                                               etl::hermite<Vector> other_curve(prev->get_vertex(), iter->get_vertex(), prev->get_tangent2(), iter->get_tangent1());
+                                               other_tangent = other_curve(1) - other_curve(1-FAKE_TANGENT_STEP);
+                                       }
+
+                                       // normalise and sum the two tangents
+                                       tangent=(other_tangent.norm()+tangent.norm());
                                        edge_case=true;
                                }
                        }
                        else
                        {
-                               if (next->get_split_tangent_flag())
+                               if (next->get_split_tangent_flag() || zero_tangent)
                                {
-                                       tangent=(next->get_tangent2().norm()+tangent).norm();
+                                       // fake the current tangent if we need to
+                                       if (zero_tangent) tangent = curve(1) - curve(1-FAKE_TANGENT_STEP);
+
+                                       // calculate the other tangent
+                                       Vector other_tangent(next->get_tangent2());
+                                       if (other_tangent[0] == 0 && other_tangent[1] == 0)
+                                       {
+                                               // find the next blinepoint
+                                               std::vector<synfig::BLinePoint>::const_iterator next2(next);
+                                               if (++next2 == bline.end())
+                                               {
+                                                       if (loop) next2 = bline.begin();
+                                                       else next2 = next;
+                                               }
+
+                                               etl::hermite<Vector> other_curve(next->get_vertex(), next2->get_vertex(), next->get_tangent2(), next2->get_tangent1());
+                                               other_tangent = other_curve(FAKE_TANGENT_STEP) - other_curve(0);
+                                       }
+
+                                       // normalise and sum the two tangents
+                                       tangent=(other_tangent.norm()+tangent.norm());
                                        edge_case=true;
                                }
                        }
                }
+               tangent = tangent.norm();
 
                if(perpendicular)
                {