From 332352298ef41b8ac3a4c57b467dd146c0b05e0b Mon Sep 17 00:00:00 2001
From: Mikko Rasa <tdb@tdb.fi>
Date: Mon, 2 Jul 2018 01:01:27 +0300
Subject: [PATCH] Support slopes in keyframe interpolation

---
 source/animation.cpp | 48 +++++++++++++++++++++++++++++++++++---------
 source/animation.h   | 10 ++++++++-
 2 files changed, 48 insertions(+), 10 deletions(-)

diff --git a/source/animation.cpp b/source/animation.cpp
index c7e23b8e..f0e2630a 100644
--- a/source/animation.cpp
+++ b/source/animation.cpp
@@ -43,13 +43,23 @@ const string &Animation::get_uniform_name(unsigned i) const
 }
 
 void Animation::add_keyframe(const Time::TimeDelta &t, const KeyFrame &kf)
+{
+	add_keyframe(t, kf, 1.0f, 1.0f);
+}
+
+void Animation::add_keyframe(const Time::TimeDelta &t, const KeyFrame &kf, float slope)
+{
+	add_keyframe(t, kf, slope, slope);
+}
+
+void Animation::add_keyframe(const Time::TimeDelta &t, const KeyFrame &kf, float ss, float es)
 {
 	RefPtr<const KeyFrame> kfr(&kf);
 	kfr.keep();
-	add_keyframe(t, kfr);
+	add_keyframe(t, kfr, ss, es);
 }
 
-void Animation::add_keyframe(const Time::TimeDelta &t, const RefPtr<const KeyFrame> &kf)
+void Animation::add_keyframe(const Time::TimeDelta &t, const RefPtr<const KeyFrame> &kf, float ss, float es)
 {
 	if(!keyframes.empty() && t<keyframes.back().time)
 		throw invalid_argument("Animation::add_keyframe");
@@ -59,6 +69,8 @@ void Animation::add_keyframe(const Time::TimeDelta &t, const RefPtr<const KeyFra
 	keyframes.push_back(TimedKeyFrame());
 	TimedKeyFrame &tkf = keyframes.back();
 	tkf.time = t;
+	tkf.start_slope = ss;
+	tkf.end_slope = es;
 	tkf.keyframe = kf;
 
 	if(realloc)
@@ -197,7 +209,9 @@ Matrix Animation::MatrixInterpolation::get(float t) const
 
 
 Animation::TimedKeyFrame::TimedKeyFrame():
-	prev(0)
+	prev(0),
+	start_slope(1),
+	end_slope(1)
 { }
 
 void Animation::TimedKeyFrame::prepare(const Animation &animation)
@@ -246,6 +260,7 @@ Animation::Iterator::Iterator(const Animation &a):
 	animation(&a),
 	iter(animation->keyframes.begin()),
 	event_iter(animation->events.begin()),
+	x(0),
 	end(false)
 { }
 
@@ -272,6 +287,9 @@ Animation::Iterator &Animation::Iterator::operator+=(const Time::TimeDelta &t)
 		iter = next;
 	}
 
+	x = time_since_keyframe/iter->delta_t;
+	x += (iter->start_slope-1)*((x-2)*x+1)*x + (1-iter->end_slope)*(1-x)*x*x;
+
 	return *this;
 }
 
@@ -298,7 +316,7 @@ Matrix Animation::Iterator::get_matrix() const
 	if(!iter->prev)
 		return iter->keyframe->get_matrix();
 
-	return iter->matrix.get(time_since_keyframe/iter->delta_t);
+	return iter->matrix.get(x);
 }
 
 KeyFrame::AnimatedUniform Animation::Iterator::get_uniform(unsigned i) const
@@ -312,10 +330,9 @@ KeyFrame::AnimatedUniform Animation::Iterator::get_uniform(unsigned i) const
 	}
 
 	unsigned size = animation->uniforms[i].size;
-	float t = time_since_keyframe/iter->delta_t;
 	KeyFrame::AnimatedUniform result(size, 0.0f);
 	for(unsigned j=0; j<size; ++j)
-		result.values[j] = iter->prev->uniforms[i].values[j]*(1-t)+iter->uniforms[i].values[j]*t;
+		result.values[j] = iter->prev->uniforms[i].values[j]*(1-x)+iter->uniforms[i].values[j]*x;
 	return result;
 }
 
@@ -336,7 +353,7 @@ Matrix Animation::Iterator::get_pose_matrix(unsigned link) const
 
 	// We must redo the base point correction since interpolation throws it off
 	// XXX This should probably be done on local matrices
-	Matrix result = iter->pose_matrices[link].get(time_since_keyframe/iter->delta_t);
+	Matrix result = iter->pose_matrices[link].get(x);
 	const Vector3 &base = animation->armature->get_link(link).get_base();
 	Vector3 new_base = result*base;
 	result = Matrix::translation(base-new_base)*result;
@@ -358,6 +375,8 @@ Animation::Loader::Loader(Animation &a, Collection &c):
 
 void Animation::Loader::init()
 {
+	start_slope = 1;
+	end_slope = 1;
 	add("armature", &Animation::armature);
 	add("event", &Loader::event);
 	add("event", &Loader::event1i);
@@ -369,6 +388,7 @@ void Animation::Loader::init()
 	add("keyframe", &Loader::keyframe);
 	add("keyframe", &Loader::keyframe_inline);
 	add("looping", &Animation::looping);
+	add("slopes", &Loader::slopes);
 }
 
 void Animation::Loader::event(const string &n)
@@ -408,7 +428,9 @@ void Animation::Loader::interval(float t)
 
 void Animation::Loader::keyframe(const string &n)
 {
-	obj.add_keyframe(current_time, get_collection().get<KeyFrame>(n));
+	obj.add_keyframe(current_time, get_collection().get<KeyFrame>(n), start_slope, end_slope);
+	start_slope = end_slope;
+	end_slope = 1;
 }
 
 void Animation::Loader::keyframe_inline()
@@ -419,7 +441,15 @@ void Animation::Loader::keyframe_inline()
 	else
 		load_sub(*kf);
 
-	obj.add_keyframe(current_time, kf);
+	obj.add_keyframe(current_time, kf, start_slope, end_slope);
+	start_slope = end_slope;
+	end_slope = 1;
+}
+
+void Animation::Loader::slopes(float s, float e)
+{
+	start_slope = s;
+	end_slope = e;
 }
 
 } // namespace GL
diff --git a/source/animation.h b/source/animation.h
index 3404f45b..e3fb79ee 100644
--- a/source/animation.h
+++ b/source/animation.h
@@ -25,6 +25,8 @@ public:
 	{
 	private:
 		Time::TimeDelta current_time;
+		float start_slope;
+		float end_slope;
 
 	public:
 		Loader(Animation &);
@@ -41,6 +43,7 @@ public:
 		void interval(float);
 		void keyframe(const std::string &);
 		void keyframe_inline();
+		void slopes(float, float);
 	};
 
 private:
@@ -70,6 +73,8 @@ private:
 		const TimedKeyFrame *prev;
 		Time::TimeDelta time;
 		Time::TimeDelta delta_t;
+		float start_slope;
+		float end_slope;
 		RefPtr<const KeyFrame> keyframe;
 		MatrixInterpolation matrix;
 		std::vector<KeyFrame::AnimatedUniform> uniforms;
@@ -102,6 +107,7 @@ public:
 		std::vector<TimedKeyFrame>::const_iterator iter;
 		std::vector<Event>::const_iterator event_iter;
 		Time::TimeDelta time_since_keyframe;
+		float x;
 		bool end;
 
 	public:
@@ -135,8 +141,10 @@ public:
 	const std::string &get_uniform_name(unsigned) const;
 
 	void add_keyframe(const Time::TimeDelta &, const KeyFrame &);
+	void add_keyframe(const Time::TimeDelta &, const KeyFrame &, float);
+	void add_keyframe(const Time::TimeDelta &, const KeyFrame &, float, float);
 private:
-	void add_keyframe(const Time::TimeDelta &, const RefPtr<const KeyFrame> &);
+	void add_keyframe(const Time::TimeDelta &, const RefPtr<const KeyFrame> &, float, float);
 	void prepare_keyframe(TimedKeyFrame &);
 public:
 	void add_event(const Time::TimeDelta &, const std::string &, const Variant & = Variant());
-- 
2.43.0