From 6dfd55be0cb07c9358695aa5e1b0015d2f5d97bf Mon Sep 17 00:00:00 2001
From: dooglus <dooglus@1f10aa63-cdf2-0310-b900-c93c546f37ac>
Date: Sat, 22 Nov 2008 15:40:24 +0000
Subject: [PATCH] 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
---
 synfig-core/trunk/src/modules/example/metaballs.cpp | 10 +++++++++-
 synfig-core/trunk/src/modules/example/metaballs.h   |  2 ++
 2 files changed, 11 insertions(+), 1 deletion(-)

diff --git a/synfig-core/trunk/src/modules/example/metaballs.cpp b/synfig-core/trunk/src/modules/example/metaballs.cpp
index 6437a42..874d7f9 100644
--- 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
--- 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:
-- 
2.7.4