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

[synfig.git] / synfig-core / trunk / src / modules / mod_gradient / curvegradient.cpp

diff --git a/synfig-core/trunk/src/modules/mod_gradient/curvegradient.cpp b/synfig-core/trunk/src/modules/mod_gradient/curvegradient.cpp
index 9f2c42a..4fa704e 100644 (file)
--- a/synfig-core/trunk/src/modules/mod_gradient/curvegradient.cpp
+++ b/synfig-core/trunk/src/modules/mod_gradient/curvegradient.cpp
@@ -1,11 +1,12 @@
 /* === S Y N F I G ========================================================= */
 /*!    \file curvegradient.cpp
-**     \brief Template Header
+**     \brief Implementation of the "Curve Gradient" layer
 **
 **     $Id$
 **
 **     \legal
 **     Copyright (c) 2002-2005 Robert B. Quattlebaum Jr., Adrian Bentley
+**     Copyright (c) 2007-2008 Chris Moore
 **
 **     This package is free software; you can redistribute it and/or
 **     modify it under the terms of the GNU General Public License as
@@ -49,12 +50,14 @@
 
 /* === M A C R O S ========================================================= */
 
+#define FAKE_TANGENT_STEP 0.000001
+
 /* === G L O B A L S ======================================================= */
 
 SYNFIG_LAYER_INIT(CurveGradient);
 SYNFIG_LAYER_SET_NAME(CurveGradient,"curve_gradient");
-SYNFIG_LAYER_SET_LOCAL_NAME(CurveGradient,_("Curve Gradient"));
-SYNFIG_LAYER_SET_CATEGORY(CurveGradient,_("Gradients"));
+SYNFIG_LAYER_SET_LOCAL_NAME(CurveGradient,N_("Curve Gradient"));
+SYNFIG_LAYER_SET_CATEGORY(CurveGradient,N_("Gradients"));
 SYNFIG_LAYER_SET_VERSION(CurveGradient,"0.0");
 SYNFIG_LAYER_SET_CVS_ID(CurveGradient,"$Id$");
 
@@ -202,7 +205,7 @@ CurveGradient::sync()
 
 
 CurveGradient::CurveGradient():
-       offset(0,0),
+       origin(0,0),
        width(0.25),
        gradient(Color::black(), Color::white()),
        loop(false),
@@ -250,7 +253,7 @@ CurveGradient::color_func(const Point &point_, int quality, float supersample)co
        else
        {
                float t;
-               Point point(point_-offset);
+               Point point(point_-origin);
 
                std::vector<synfig::BLinePoint>::const_iterator iter,next;
 
@@ -305,7 +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
@@ -314,23 +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)
                {
@@ -361,14 +405,14 @@ CurveGradient::color_func(const Point &point_, int quality, float supersample)co
                        const Real mag(diff.inv_mag());
                        supersample=supersample*mag;
                        diff*=mag*mag;
-                       dist=((point_-offset)*diff-p1*diff);
+                       dist=(point_-origin - p1)*diff;
                }
        }
        else                                            // not perpendicular
        {
                if (edge_case)
                {
-                       diff=(p1-(point_-offset));
+                       diff=(p1-(point_-origin));
                        if(diff*tangent.perp()<0) diff=-diff;
                        diff=diff.norm()*thickness*width;
                }
@@ -379,7 +423,7 @@ CurveGradient::color_func(const Point &point_, int quality, float supersample)co
                const Real mag(diff.inv_mag());
                supersample=supersample*mag;
                diff*=mag*mag;
-               dist=((point_-offset)*diff-p1*diff);
+               dist=(point_-origin - p1)*diff;
        }
 
        if(loop)
@@ -439,7 +483,7 @@ CurveGradient::set_param(const String & param, const ValueBase &value)
 {
 
 
-       IMPORT(offset);
+       IMPORT(origin);
        IMPORT(perpendicular);
        IMPORT(fast);
 
@@ -456,13 +500,16 @@ CurveGradient::set_param(const String & param, const ValueBase &value)
        IMPORT(gradient);
        IMPORT(loop);
        IMPORT(zigzag);
+
+       IMPORT_AS(origin,"offset");
+
        return Layer_Composite::set_param(param,value);
 }
 
 ValueBase
 CurveGradient::get_param(const String & param)const
 {
-       EXPORT(offset);
+       EXPORT(origin);
        EXPORT(bline);
        EXPORT(gradient);
        EXPORT(loop);
@@ -482,8 +529,8 @@ CurveGradient::get_param_vocab()const
 {
        Layer::Vocab ret(Layer_Composite::get_param_vocab());
 
-       ret.push_back(ParamDesc("offset")
-                                 .set_local_name(_("Offset")));
+       ret.push_back(ParamDesc("origin")
+                                 .set_local_name(_("Origin")));
 
        ret.push_back(ParamDesc("width")
                                  .set_is_distance()
@@ -491,8 +538,8 @@ CurveGradient::get_param_vocab()const
 
        ret.push_back(ParamDesc("bline")
                                  .set_local_name(_("Vertices"))
-                                 .set_origin("offset")
-                                 .set_scalar("width")
+                                 .set_origin("origin")
+                                 .set_hint("width")
                                  .set_description(_("A list of BLine Points")));
 
        ret.push_back(ParamDesc("gradient")