From b0dfcfb5cdd73e7515170c0598d6b061d33446a7 Mon Sep 17 00:00:00 2001
From: Mikko Rasa <tdb@tdb.fi>
Date: Sun, 23 Jun 2019 22:38:23 +0300
Subject: [PATCH] Use double for animation curves

Since the t value is raised to the third power, floats with their 24-bit
mantissa started to run out of precision around 30 seconds.  Doubles
should be good for several hours.  If that somehow turns out to not be
enough I'll invent some way to chain animations.
---
 source/animation.cpp | 13 +++++++------
 source/animation.h   |  4 ++--
 2 files changed, 9 insertions(+), 8 deletions(-)

diff --git a/source/animation.cpp b/source/animation.cpp
index 0e4bd3e6..37f583d5 100644
--- a/source/animation.cpp
+++ b/source/animation.cpp
@@ -234,6 +234,7 @@ void Animation::create_curve(CurveTarget target, int component, const T &extract
 		typename Interpolate::SplineValue<float, N>::Type value;
 		if(extract(*i->keyframe, value))
 		{
+			typename Knot::Value dvalue = value;
 			float x = i->time/Time::sec;
 			if(i->control)
 			{
@@ -246,14 +247,14 @@ void Animation::create_curve(CurveTarget target, int component, const T &extract
 				if(n_control==1)
 				{
 					typename Knot::Value cv = knots.back().y;
-					knots.back().y = (knots[knots.size()-2].y+cv*2.0f)/3.0f;
-					knots.push_back(Knot(x, (value+cv*2.0f)/3.0f));
+					knots.back().y = (knots[knots.size()-2].y+cv*2.0)/3.0;
+					knots.push_back(Knot(x, (dvalue+cv*2.0)/3.0));
 				}
 				else if(n_control==0 && !knots.empty())
 				{
 					typename Knot::Value prev = knots.back().y;
-					knots.push_back(Knot(knots.back().x, (prev*2.0f+value)/3.0f));
-					knots.push_back(Knot(x, (prev+value*2.0f)/3.0f));
+					knots.push_back(Knot(knots.back().x, (prev*2.0+dvalue)/3.0));
+					knots.push_back(Knot(x, (prev+dvalue*2.0)/3.0));
 				}
 				n_control = 0;
 			}
@@ -318,7 +319,7 @@ Animation::Curve::Curve(CurveTarget t, int c):
 template<unsigned N>
 Animation::ValueCurve<N>::ValueCurve(CurveTarget t, int c, const vector<Knot> &k):
 	Curve(t, c),
-	spline(Interpolate::BezierSpline<float, 3, N>(k))
+	spline(Interpolate::BezierSpline<double, 3, N>(k))
 { }
 
 template<unsigned N>
@@ -372,7 +373,7 @@ template<unsigned N>
 void Animation::ValueCurve<N>::apply(float x, KeyFrame::AnimatedUniform &uni) const
 {
 	uni.size = N;
-	typename Interpolate::Spline<float, 3, N>::Value value = spline(x);
+	typename Interpolate::Spline<double, 3, N>::Value value = spline(x);
 	for(unsigned i=0; i<N; ++i)
 		uni.values[i] = Interpolate::SplineValue<float, N>::get(value, i);
 }
diff --git a/source/animation.h b/source/animation.h
index d053ee90..6845d23e 100644
--- a/source/animation.h
+++ b/source/animation.h
@@ -83,10 +83,10 @@ private:
 	class ValueCurve: public Curve
 	{
 	public:
-		typedef typename Interpolate::SplineKnot<float, N> Knot;
+		typedef typename Interpolate::SplineKnot<double, N> Knot;
 
 	private:
-		Interpolate::Spline<float, 3, N> spline;
+		Interpolate::Spline<double, 3, N> spline;
 
 	public:
 		ValueCurve(CurveTarget, int, const std::vector<Knot> &);
-- 
2.45.2