Add boolean parameter 'Positive Only' to stop negative affect from large distances.

git-svn-id: https://synfig.svn.sourceforge.net/svnroot/synfig@2251 1f10aa63-cdf2-0310-b900-c93c546f37ac

diff --git a/synfig-core/trunk/src/modules/example/metaballs.cpp b/synfig-core/trunk/src/modules/example/metaballs.cpp
index 6437a42..874d7f9 100644 (file)
--- a/synfig-core/trunk/src/modules/example/metaballs.cpp
+++ b/synfig-core/trunk/src/modules/example/metaballs.cpp
@@ -68,7 +68,8 @@ Metaballs::Metaballs():
        Layer_Composite(1.0,Color::BLEND_STRAIGHT),
        gradient(Color::black(), Color::white()),
        threshold(0),
-       threshold2(1)
+       threshold2(1),
+       positive(false)
 {
        centers.push_back(Point( 0, -1.5));     radii.push_back(2.5);   weights.push_back(1);
        centers.push_back(Point(-2,  1));       radii.push_back(2.5);   weights.push_back(1);
@@ -99,6 +100,7 @@ Metaballs::set_param(const String & param, const ValueBase &value)
        IMPORT(gradient);
        IMPORT(threshold);
        IMPORT(threshold2);
+       IMPORT(positive);
 
        return Layer_Composite::set_param(param,value);
 }
@@ -113,6 +115,7 @@ Metaballs::get_param(const String &param)const
        EXPORT(centers);
        EXPORT(threshold);
        EXPORT(threshold2);
+       EXPORT(positive);
 
        EXPORT_NAME();
        EXPORT_VERSION();
@@ -149,6 +152,10 @@ Metaballs::get_param_vocab()const
                .set_local_name(_("Gradient Right"))
        );
 
+       ret.push_back(ParamDesc("positive")
+               .set_local_name(_("Positive Only"))
+       );
+
        return ret;
 }
 
@@ -158,6 +165,7 @@ static inline Real densityfunc(const synfig::Point &p, const synfig::Point &c, R
        const Real dy = p[1] - c[1];
 
        const Real n = (1 - (dx*dx + dy*dy)/(R*R));
+       if (positive && n < 0) return 0;
        return (n*n*n);
 
        /*

diff --git a/synfig-core/trunk/src/modules/example/metaballs.h b/synfig-core/trunk/src/modules/example/metaballs.h
index b52d98e..ee3bda5 100644 (file)
--- a/synfig-core/trunk/src/modules/example/metaballs.h
+++ b/synfig-core/trunk/src/modules/example/metaballs.h
@@ -53,6 +53,8 @@ private:
        synfig::Real    threshold;
        synfig::Real    threshold2;
 
+       bool positive;
+
        synfig::Real totaldensity(const synfig::Point &pos)const;
 
 public: