Refactor and move easing equations

6 files changed, 437 insertions, 335 deletions

diff --git a/COPYRIGHT.txt b/COPYRIGHT.txt
index da60213038..e84302620e 100644
--- a/COPYRIGHT.txt
+++ b/COPYRIGHT.txt
@@ -80,6 +80,13 @@ Copyright: 2008-2016, The Android Open Source Project
  2002, Google, Inc.
 License: Apache-2.0
 
+Files: ./scene/animation/easing_equations.h
+Comment: Robert Penner's Easing Functions
+Copyright: 2001, Robert Penner
+ 2007-2021 Juan Linietsky, Ariel Manzur.
+ 2014-2021 Godot Engine contributors.
+License: Expat
+
 Files: ./servers/physics_3d/collision_solver_3d_sat.cpp
 Comment: Open Dynamics Engine
 Copyright: 2001-2003, Russell L. Smith, Alen Ladavac, Nguyen Binh
@@ -307,11 +314,6 @@ Comment: Fast Filtering of Reflection Probes
 Copyright: 2016, Activision Publishing, Inc.
 License: Expat
 
-Files: ./thirdparty/misc/easing_equations.cpp
-Comment: Robert Penner's Easing Functions
-Copyright: 2001, Robert Penner
-License: BSD-3-clause
-
 Files: ./thirdparty/misc/fastlz.c
  ./thirdparty/misc/fastlz.h
 Comment: FastLZ
diff --git a/scene/animation/SCsub b/scene/animation/SCsub
index cc33a5af84..d0aa0bc8aa 100644
--- a/scene/animation/SCsub
+++ b/scene/animation/SCsub
@@ -6,11 +6,8 @@ Import("env")
 
 thirdparty_obj = []
 
-thirdparty_sources = "#thirdparty/misc/easing_equations.cpp"
-
 env_thirdparty = env.Clone()
 env_thirdparty.disable_warnings()
-env_thirdparty.add_source_files(thirdparty_obj, thirdparty_sources)
 env.scene_sources += thirdparty_obj
 
 # Godot source files
diff --git a/scene/animation/easing_equations.h b/scene/animation/easing_equations.h
new file mode 100644
index 0000000000..c38d083b7f
--- /dev/null
+++ b/scene/animation/easing_equations.h
@@ -0,0 +1,405 @@
+/*************************************************************************/
+/*  easing_equations.h                                                   */
+/*************************************************************************/
+/*                       This file is part of:                           */
+/*                           GODOT ENGINE                                */
+/*                      https://godotengine.org                          */
+/*************************************************************************/
+/* Copyright (c) 2007-2021 Juan Linietsky, Ariel Manzur.                 */
+/* Copyright (c) 2014-2021 Godot Engine contributors (cf. AUTHORS.md).   */
+/*                                                                       */
+/* Permission is hereby granted, free of charge, to any person obtaining */
+/* a copy of this software and associated documentation files (the       */
+/* "Software"), to deal in the Software without restriction, including   */
+/* without limitation the rights to use, copy, modify, merge, publish,   */
+/* distribute, sublicense, and/or sell copies of the Software, and to    */
+/* permit persons to whom the Software is furnished to do so, subject to */
+/* the following conditions:                                             */
+/*                                                                       */
+/* The above copyright notice and this permission notice shall be        */
+/* included in all copies or substantial portions of the Software.       */
+/*                                                                       */
+/* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,       */
+/* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF    */
+/* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.*/
+/* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY  */
+/* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,  */
+/* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE     */
+/* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.                */
+/*************************************************************************/
+
+/*
+ * Derived from Robert Penner's easing equations: http://robertpenner.com/easing/
+ *
+ * Copyright (c) 2001 Robert Penner
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+#ifndef EASING_EQUATIONS_H
+#define EASING_EQUATIONS_H
+
+namespace linear {
+static real_t in(real_t t, real_t b, real_t c, real_t d) {
+	return c * t / d + b;
+}
+}; // namespace linear
+
+namespace sine {
+static real_t in(real_t t, real_t b, real_t c, real_t d) {
+	return -c * cos(t / d * (Math_PI / 2)) + c + b;
+}
+
+static real_t out(real_t t, real_t b, real_t c, real_t d) {
+	return c * sin(t / d * (Math_PI / 2)) + b;
+}
+
+static real_t in_out(real_t t, real_t b, real_t c, real_t d) {
+	return -c / 2 * (cos(Math_PI * t / d) - 1) + b;
+}
+
+static real_t out_in(real_t t, real_t b, real_t c, real_t d) {
+	if (t < d / 2) {
+		return out(t * 2, b, c / 2, d);
+	}
+	return in(t * 2 - d, b + c / 2, c / 2, d);
+}
+}; // namespace sine
+
+namespace quint {
+static real_t in(real_t t, real_t b, real_t c, real_t d) {
+	return c * pow(t / d, 5) + b;
+}
+
+static real_t out(real_t t, real_t b, real_t c, real_t d) {
+	return c * (pow(t / d - 1, 5) + 1) + b;
+}
+
+static real_t in_out(real_t t, real_t b, real_t c, real_t d) {
+	t = t / d * 2;
+
+	if (t < 1) {
+		return c / 2 * pow(t, 5) + b;
+	}
+	return c / 2 * (pow(t - 2, 5) + 2) + b;
+}
+
+static real_t out_in(real_t t, real_t b, real_t c, real_t d) {
+	if (t < d / 2) {
+		return out(t * 2, b, c / 2, d);
+	}
+	return in(t * 2 - d, b + c / 2, c / 2, d);
+}
+}; // namespace quint
+
+namespace quart {
+static real_t in(real_t t, real_t b, real_t c, real_t d) {
+	return c * pow(t / d, 4) + b;
+}
+
+static real_t out(real_t t, real_t b, real_t c, real_t d) {
+	return -c * (pow(t / d - 1, 4) - 1) + b;
+}
+
+static real_t in_out(real_t t, real_t b, real_t c, real_t d) {
+	t = t / d * 2;
+
+	if (t < 1) {
+		return c / 2 * pow(t, 4) + b;
+	}
+	return -c / 2 * (pow(t - 2, 4) - 2) + b;
+}
+
+static real_t out_in(real_t t, real_t b, real_t c, real_t d) {
+	if (t < d / 2) {
+		return out(t * 2, b, c / 2, d);
+	}
+	return in(t * 2 - d, b + c / 2, c / 2, d);
+}
+}; // namespace quart
+
+namespace quad {
+static real_t in(real_t t, real_t b, real_t c, real_t d) {
+	return c * pow(t / d, 2) + b;
+}
+
+static real_t out(real_t t, real_t b, real_t c, real_t d) {
+	t /= d;
+	return -c * t * (t - 2) + b;
+}
+
+static real_t in_out(real_t t, real_t b, real_t c, real_t d) {
+	t = t / d * 2;
+
+	if (t < 1) {
+		return c / 2 * pow(t, 2) + b;
+	}
+	return -c / 2 * ((t - 1) * (t - 3) - 1) + b;
+}
+
+static real_t out_in(real_t t, real_t b, real_t c, real_t d) {
+	if (t < d / 2) {
+		return out(t * 2, b, c / 2, d);
+	}
+	return in(t * 2 - d, b + c / 2, c / 2, d);
+}
+}; // namespace quad
+
+namespace expo {
+static real_t in(real_t t, real_t b, real_t c, real_t d) {
+	if (t == 0) {
+		return b;
+	}
+	return c * pow(2, 10 * (t / d - 1)) + b - c * 0.001;
+}
+
+static real_t out(real_t t, real_t b, real_t c, real_t d) {
+	if (t == d) {
+		return b + c;
+	}
+	return c * 1.001 * (-pow(2, -10 * t / d) + 1) + b;
+}
+
+static real_t in_out(real_t t, real_t b, real_t c, real_t d) {
+	if (t == 0) {
+		return b;
+	}
+
+	if (t == d) {
+		return b + c;
+	}
+
+	t = t / d * 2;
+
+	if (t < 1) {
+		return c / 2 * pow(2, 10 * (t - 1)) + b - c * 0.0005;
+	}
+	return c / 2 * 1.0005 * (-pow(2, -10 * (t - 1)) + 2) + b;
+}
+
+static real_t out_in(real_t t, real_t b, real_t c, real_t d) {
+	if (t < d / 2) {
+		return out(t * 2, b, c / 2, d);
+	}
+	return in(t * 2 - d, b + c / 2, c / 2, d);
+}
+}; // namespace expo
+
+namespace elastic {
+static real_t in(real_t t, real_t b, real_t c, real_t d) {
+	if (t == 0) {
+		return b;
+	}
+
+	t /= d;
+	if (t == 1) {
+		return b + c;
+	}
+
+	t -= 1;
+	float p = d * 0.3f;
+	float a = c * pow(2, 10 * t);
+	float s = p / 4;
+
+	return -(a * sin((t * d - s) * (2 * Math_PI) / p)) + b;
+}
+
+static real_t out(real_t t, real_t b, real_t c, real_t d) {
+	if (t == 0) {
+		return b;
+	}
+
+	t /= d;
+	if (t == 1) {
+		return b + c;
+	}
+
+	float p = d * 0.3f;
+	float s = p / 4;
+
+	return (c * pow(2, -10 * t) * sin((t * d - s) * (2 * Math_PI) / p) + c + b);
+}
+
+static real_t in_out(real_t t, real_t b, real_t c, real_t d) {
+	if (t == 0) {
+		return b;
+	}
+
+	if ((t /= d / 2) == 2) {
+		return b + c;
+	}
+
+	float p = d * (0.3f * 1.5f);
+	float a = c;
+	float s = p / 4;
+
+	if (t < 1) {
+		t -= 1;
+		a *= pow(2, 10 * t);
+		return -0.5f * (a * sin((t * d - s) * (2 * Math_PI) / p)) + b;
+	}
+
+	t -= 1;
+	a *= pow(2, -10 * t);
+	return a * sin((t * d - s) * (2 * Math_PI) / p) * 0.5f + c + b;
+}
+
+static real_t out_in(real_t t, real_t b, real_t c, real_t d) {
+	if (t < d / 2) {
+		return out(t * 2, b, c / 2, d);
+	}
+	return in(t * 2 - d, b + c / 2, c / 2, d);
+}
+}; // namespace elastic
+
+namespace cubic {
+static real_t in(real_t t, real_t b, real_t c, real_t d) {
+	t /= d;
+	return c * t * t * t + b;
+}
+
+static real_t out(real_t t, real_t b, real_t c, real_t d) {
+	t = t / d - 1;
+	return c * (t * t * t + 1) + b;
+}
+
+static real_t in_out(real_t t, real_t b, real_t c, real_t d) {
+	t /= d / 2;
+	if (t < 1) {
+		return c / 2 * t * t * t + b;
+	}
+
+	t -= 2;
+	return c / 2 * (t * t * t + 2) + b;
+}
+
+static real_t out_in(real_t t, real_t b, real_t c, real_t d) {
+	if (t < d / 2) {
+		return out(t * 2, b, c / 2, d);
+	}
+	return in(t * 2 - d, b + c / 2, c / 2, d);
+}
+}; // namespace cubic
+
+namespace circ {
+static real_t in(real_t t, real_t b, real_t c, real_t d) {
+	t /= d;
+	return -c * (sqrt(1 - t * t) - 1) + b;
+}
+
+static real_t out(real_t t, real_t b, real_t c, real_t d) {
+	t = t / d - 1;
+	return c * sqrt(1 - t * t) + b;
+}
+
+static real_t in_out(real_t t, real_t b, real_t c, real_t d) {
+	t /= d / 2;
+	if (t < 1) {
+		return -c / 2 * (sqrt(1 - t * t) - 1) + b;
+	}
+
+	t -= 2;
+	return c / 2 * (sqrt(1 - t * t) + 1) + b;
+}
+
+static real_t out_in(real_t t, real_t b, real_t c, real_t d) {
+	if (t < d / 2) {
+		return out(t * 2, b, c / 2, d);
+	}
+	return in(t * 2 - d, b + c / 2, c / 2, d);
+}
+}; // namespace circ
+
+namespace bounce {
+static real_t out(real_t t, real_t b, real_t c, real_t d) {
+	t /= d;
+
+	if (t < (1 / 2.75f)) {
+		return c * (7.5625f * t * t) + b;
+	}
+
+	if (t < (2 / 2.75f)) {
+		t -= 1.5f / 2.75f;
+		return c * (7.5625f * t * t + 0.75f) + b;
+	}
+
+	if (t < (2.5 / 2.75)) {
+		t -= 2.25f / 2.75f;
+		return c * (7.5625f * t * t + 0.9375f) + b;
+	}
+
+	t -= 2.625f / 2.75f;
+	return c * (7.5625f * t * t + 0.984375f) + b;
+}
+
+static real_t in(real_t t, real_t b, real_t c, real_t d) {
+	return c - out(d - t, 0, c, d) + b;
+}
+
+static real_t in_out(real_t t, real_t b, real_t c, real_t d) {
+	if (t < d / 2) {
+		return in(t * 2, b, c / 2, d);
+	}
+	return out(t * 2 - d, b + c / 2, c / 2, d);
+}
+
+static real_t out_in(real_t t, real_t b, real_t c, real_t d) {
+	if (t < d / 2) {
+		return out(t * 2, b, c / 2, d);
+	}
+	return in(t * 2 - d, b + c / 2, c / 2, d);
+}
+}; // namespace bounce
+
+namespace back {
+static real_t in(real_t t, real_t b, real_t c, real_t d) {
+	float s = 1.70158f;
+	t /= d;
+
+	return c * t * t * ((s + 1) * t - s) + b;
+}
+
+static real_t out(real_t t, real_t b, real_t c, real_t d) {
+	float s = 1.70158f;
+	t = t / d - 1;
+
+	return c * (t * t * ((s + 1) * t + s) + 1) + b;
+}
+
+static real_t in_out(real_t t, real_t b, real_t c, real_t d) {
+	float s = 1.70158f * 1.525f;
+	t /= d / 2;
+
+	if (t < 1) {
+		return c / 2 * (t * t * ((s + 1) * t - s)) + b;
+	}
+
+	t -= 2;
+	return c / 2 * (t * t * ((s + 1) * t + s) + 2) + b;
+}
+
+static real_t out_in(real_t t, real_t b, real_t c, real_t d) {
+	if (t < d / 2) {
+		return out(t * 2, b, c / 2, d);
+	}
+	return in(t * 2 - d, b + c / 2, c / 2, d);
+}
+}; // namespace back
+
+#endif
diff --git a/scene/animation/tween.cpp b/scene/animation/tween.cpp
index 2847031375..c43b83747b 100644
--- a/scene/animation/tween.cpp
+++ b/scene/animation/tween.cpp
@@ -30,8 +30,23 @@
 
 #include "tween.h"
 
+#include "scene/animation/easing_equations.h"
 #include "scene/main/node.h"
 
+Tween::interpolater Tween::interpolaters[Tween::TRANS_MAX][Tween::EASE_MAX] = {
+	{ &linear::in, &linear::in, &linear::in, &linear::in }, // Linear is the same for each easing.
+	{ &sine::in, &sine::out, &sine::in_out, &sine::out_in },
+	{ &quint::in, &quint::out, &quint::in_out, &quint::out_in },
+	{ &quart::in, &quart::out, &quart::in_out, &quart::out_in },
+	{ &quad::in, &quad::out, &quad::in_out, &quad::out_in },
+	{ &expo::in, &expo::out, &expo::in_out, &expo::out_in },
+	{ &elastic::in, &elastic::out, &elastic::in_out, &elastic::out_in },
+	{ &cubic::in, &cubic::out, &cubic::in_out, &cubic::out_in },
+	{ &circ::in, &circ::out, &circ::in_out, &circ::out_in },
+	{ &bounce::in, &bounce::out, &bounce::in_out, &bounce::out_in },
+	{ &back::in, &back::out, &back::in_out, &back::out_in },
+};
+
 void Tweener::set_tween(Ref<Tween> p_tween) {
 	tween = p_tween;
 }
@@ -317,6 +332,16 @@ bool Tween::should_pause() {
 	return pause_mode != TWEEN_PAUSE_PROCESS;
 }
 
+real_t Tween::run_equation(TransitionType p_trans_type, EaseType p_ease_type, real_t p_time, real_t p_initial, real_t p_delta, real_t p_duration) {
+	if (p_duration == 0) {
+		// Special case to avoid dividing by 0 in equations.
+		return p_initial + p_delta;
+	}
+
+	interpolater func = interpolaters[p_trans_type][p_ease_type];
+	return func(p_time, p_initial, p_delta, p_duration);
+}
+
 Variant Tween::interpolate_variant(Variant p_initial_val, Variant p_delta_val, float p_time, float p_duration, TransitionType p_trans, EaseType p_ease) {
 	ERR_FAIL_INDEX_V(p_trans, TransitionType::TRANS_MAX, Variant());
 	ERR_FAIL_INDEX_V(p_ease, EaseType::EASE_MAX, Variant());
diff --git a/thirdparty/README.md b/thirdparty/README.md
index 990bd30320..2d24beec15 100644
--- a/thirdparty/README.md
+++ b/thirdparty/README.md
@@ -422,10 +422,6 @@ Collection of single-file libraries used in Godot components.
   * Upstream: https://research.activision.com/publications/archives/fast-filtering-of-reflection-probes
     File coeffs_const_8.txt (retrieved April 2020)
   * License: MIT
-- `easing_equations.cpp`
-  * Upstream: http://robertpenner.com/easing/ via https://github.com/jesusgollonet/ofpennereasing (modified to fit Godot types)
-  * Version: git (af72c147c3a74e7e872aa28c7e2abfcced04fdce, 2008) + Godot types and style changes
-  * License: BSD-3-Clause
 - `fastlz.{c,h}`
   * Upstream: https://github.com/ariya/FastLZ
   * Version: 0.5.0 (4f20f54d46f5a6dd4fae4def134933369b7602d2, 2020)
diff --git a/thirdparty/misc/easing_equations.cpp b/thirdparty/misc/easing_equations.cpp
deleted file mode 100644
index d164e3d560..0000000000
--- a/thirdparty/misc/easing_equations.cpp
+++ /dev/null
@@ -1,323 +0,0 @@
-/**
- *  Adapted from Penner Easing equations' C++ port.
- *  Source: https://github.com/jesusgollonet/ofpennereasing
- *  License: BSD-3-clause
- */
-
-#include "scene/animation/tween.h"
-
-const real_t pi = 3.1415926535898;
-
-///////////////////////////////////////////////////////////////////////////
-// linear
-///////////////////////////////////////////////////////////////////////////
-namespace linear {
-static real_t in(real_t t, real_t b, real_t c, real_t d) {
-	return c * t / d + b;
-}
-
-static real_t out(real_t t, real_t b, real_t c, real_t d) {
-	return c * t / d + b;
-}
-
-static real_t in_out(real_t t, real_t b, real_t c, real_t d) {
-	return c * t / d + b;
-}
-
-static real_t out_in(real_t t, real_t b, real_t c, real_t d) {
-	return c * t / d + b;
-}
-}; // namespace linear
-///////////////////////////////////////////////////////////////////////////
-// sine
-///////////////////////////////////////////////////////////////////////////
-namespace sine {
-static real_t in(real_t t, real_t b, real_t c, real_t d) {
-	return -c * cos(t / d * (pi / 2)) + c + b;
-}
-
-static real_t out(real_t t, real_t b, real_t c, real_t d) {
-	return c * sin(t / d * (pi / 2)) + b;
-}
-
-static real_t in_out(real_t t, real_t b, real_t c, real_t d) {
-	return -c / 2 * (cos(pi * t / d) - 1) + b;
-}
-
-static real_t out_in(real_t t, real_t b, real_t c, real_t d) {
-	return (t < d / 2) ? out(t * 2, b, c / 2, d) : in((t * 2) - d, b + c / 2, c / 2, d);
-}
-}; // namespace sine
-///////////////////////////////////////////////////////////////////////////
-// quint
-///////////////////////////////////////////////////////////////////////////
-namespace quint {
-static real_t in(real_t t, real_t b, real_t c, real_t d) {
-	return c * pow(t / d, 5) + b;
-}
-
-static real_t out(real_t t, real_t b, real_t c, real_t d) {
-	return c * (pow(t / d - 1, 5) + 1) + b;
-}
-
-static real_t in_out(real_t t, real_t b, real_t c, real_t d) {
-	t = t / d * 2;
-	if (t < 1) return c / 2 * pow(t, 5) + b;
-	return c / 2 * (pow(t - 2, 5) + 2) + b;
-}
-
-static real_t out_in(real_t t, real_t b, real_t c, real_t d) {
-	return (t < d / 2) ? out(t * 2, b, c / 2, d) : in((t * 2) - d, b + c / 2, c / 2, d);
-}
-}; // namespace quint
-///////////////////////////////////////////////////////////////////////////
-// quart
-///////////////////////////////////////////////////////////////////////////
-namespace quart {
-static real_t in(real_t t, real_t b, real_t c, real_t d) {
-	return c * pow(t / d, 4) + b;
-}
-
-static real_t out(real_t t, real_t b, real_t c, real_t d) {
-	return -c * (pow(t / d - 1, 4) - 1) + b;
-}
-
-static real_t in_out(real_t t, real_t b, real_t c, real_t d) {
-	t = t / d * 2;
-	if (t < 1) return c / 2 * pow(t, 4) + b;
-	return -c / 2 * (pow(t - 2, 4) - 2) + b;
-}
-
-static real_t out_in(real_t t, real_t b, real_t c, real_t d) {
-	return (t < d / 2) ? out(t * 2, b, c / 2, d) : in((t * 2) - d, b + c / 2, c / 2, d);
-}
-}; // namespace quart
-///////////////////////////////////////////////////////////////////////////
-// quad
-///////////////////////////////////////////////////////////////////////////
-namespace quad {
-static real_t in(real_t t, real_t b, real_t c, real_t d) {
-	return c * pow(t / d, 2) + b;
-}
-
-static real_t out(real_t t, real_t b, real_t c, real_t d) {
-	t = t / d;
-	return -c * t * (t - 2) + b;
-}
-
-static real_t in_out(real_t t, real_t b, real_t c, real_t d) {
-	t = t / d * 2;
-	if (t < 1) return c / 2 * pow(t, 2) + b;
-	return -c / 2 * ((t - 1) * (t - 3) - 1) + b;
-}
-
-static real_t out_in(real_t t, real_t b, real_t c, real_t d) {
-	return (t < d / 2) ? out(t * 2, b, c / 2, d) : in((t * 2) - d, b + c / 2, c / 2, d);
-}
-}; // namespace quad
-///////////////////////////////////////////////////////////////////////////
-// expo
-///////////////////////////////////////////////////////////////////////////
-namespace expo {
-static real_t in(real_t t, real_t b, real_t c, real_t d) {
-	if (t == 0) return b;
-	return c * pow(2, 10 * (t / d - 1)) + b - c * 0.001;
-}
-
-static real_t out(real_t t, real_t b, real_t c, real_t d) {
-	if (t == d) return b + c;
-	return c * 1.001 * (-pow(2, -10 * t / d) + 1) + b;
-}
-
-static real_t in_out(real_t t, real_t b, real_t c, real_t d) {
-	if (t == 0) return b;
-	if (t == d) return b + c;
-	t = t / d * 2;
-	if (t < 1) return c / 2 * pow(2, 10 * (t - 1)) + b - c * 0.0005;
-	return c / 2 * 1.0005 * (-pow(2, -10 * (t - 1)) + 2) + b;
-}
-
-static real_t out_in(real_t t, real_t b, real_t c, real_t d) {
-	return (t < d / 2) ? out(t * 2, b, c / 2, d) : in((t * 2) - d, b + c / 2, c / 2, d);
-}
-}; // namespace expo
-///////////////////////////////////////////////////////////////////////////
-// elastic
-///////////////////////////////////////////////////////////////////////////
-namespace elastic {
-static real_t in(real_t t, real_t b, real_t c, real_t d) {
-	if (t == 0) return b;
-	if ((t /= d) == 1) return b + c;
-	float p = d * 0.3f;
-	float a = c;
-	float s = p / 4;
-	float postFix = a * pow(2, 10 * (t -= 1)); // this is a fix, again, with post-increment operators
-	return -(postFix * sin((t * d - s) * (2 * pi) / p)) + b;
-}
-
-static real_t out(real_t t, real_t b, real_t c, real_t d) {
-	if (t == 0) return b;
-	if ((t /= d) == 1) return b + c;
-	float p = d * 0.3f;
-	float a = c;
-	float s = p / 4;
-	return (a * pow(2, -10 * t) * sin((t * d - s) * (2 * pi) / p) + c + b);
-}
-
-static real_t in_out(real_t t, real_t b, real_t c, real_t d) {
-	if (t == 0) return b;
-	if ((t /= d / 2) == 2) return b + c;
-	float p = d * (0.3f * 1.5f);
-	float a = c;
-	float s = p / 4;
-
-	if (t < 1) {
-		float postFix = a * pow(2, 10 * (t -= 1)); // postIncrement is evil
-		return -0.5f * (postFix * sin((t * d - s) * (2 * pi) / p)) + b;
-	}
-	float postFix = a * pow(2, -10 * (t -= 1)); // postIncrement is evil
-	return postFix * sin((t * d - s) * (2 * pi) / p) * 0.5f + c + b;
-}
-
-static real_t out_in(real_t t, real_t b, real_t c, real_t d) {
-	return (t < d / 2) ? out(t * 2, b, c / 2, d) : in((t * 2) - d, b + c / 2, c / 2, d);
-}
-}; // namespace elastic
-///////////////////////////////////////////////////////////////////////////
-// cubic
-///////////////////////////////////////////////////////////////////////////
-namespace cubic {
-static real_t in(real_t t, real_t b, real_t c, real_t d) {
-	t /= d;
-	return c * t * t * t + b;
-}
-
-static real_t out(real_t t, real_t b, real_t c, real_t d) {
-	t = t / d - 1;
-	return c * (t * t * t + 1) + b;
-}
-
-static real_t in_out(real_t t, real_t b, real_t c, real_t d) {
-	t /= d / 2;
-	if (t < 1) return c / 2 * t * t * t + b;
-	t -= 2;
-	return c / 2 * (t * t * t + 2) + b;
-}
-
-static real_t out_in(real_t t, real_t b, real_t c, real_t d) {
-	return (t < d / 2) ? out(t * 2, b, c / 2, d) : in((t * 2) - d, b + c / 2, c / 2, d);
-}
-}; // namespace cubic
-///////////////////////////////////////////////////////////////////////////
-// circ
-///////////////////////////////////////////////////////////////////////////
-namespace circ {
-static real_t in(real_t t, real_t b, real_t c, real_t d) {
-	t /= d;
-	return -c * (sqrt(1 - t * t) - 1) + b;
-}
-
-static real_t out(real_t t, real_t b, real_t c, real_t d) {
-	t = t / d - 1;
-	return c * sqrt(1 - t * t) + b;
-}
-
-static real_t in_out(real_t t, real_t b, real_t c, real_t d) {
-	t /= d / 2;
-	if (t < 1) {
-		return -c / 2 * (sqrt(1 - t * t) - 1) + b;
-	}
-	t -= 2;
-	return c / 2 * (sqrt(1 - t * t) + 1) + b;
-}
-
-static real_t out_in(real_t t, real_t b, real_t c, real_t d) {
-	return (t < d / 2) ? out(t * 2, b, c / 2, d) : in((t * 2) - d, b + c / 2, c / 2, d);
-}
-}; // namespace circ
-///////////////////////////////////////////////////////////////////////////
-// bounce
-///////////////////////////////////////////////////////////////////////////
-namespace bounce {
-static real_t out(real_t t, real_t b, real_t c, real_t d);
-
-static real_t in(real_t t, real_t b, real_t c, real_t d) {
-	return c - out(d - t, 0, c, d) + b;
-}
-
-static real_t out(real_t t, real_t b, real_t c, real_t d) {
-	if ((t /= d) < (1 / 2.75f)) {
-		return c * (7.5625f * t * t) + b;
-	} else if (t < (2 / 2.75f)) {
-		float postFix = t -= (1.5f / 2.75f);
-		return c * (7.5625f * (postFix)*t + .75f) + b;
-	} else if (t < (2.5 / 2.75)) {
-		float postFix = t -= (2.25f / 2.75f);
-		return c * (7.5625f * (postFix)*t + .9375f) + b;
-	} else {
-		float postFix = t -= (2.625f / 2.75f);
-		return c * (7.5625f * (postFix)*t + .984375f) + b;
-	}
-}
-
-static real_t in_out(real_t t, real_t b, real_t c, real_t d) {
-	return (t < d / 2) ? in(t * 2, b, c / 2, d) : out((t * 2) - d, b + c / 2, c / 2, d);
-}
-
-static real_t out_in(real_t t, real_t b, real_t c, real_t d) {
-	return (t < d / 2) ? out(t * 2, b, c / 2, d) : in((t * 2) - d, b + c / 2, c / 2, d);
-}
-}; // namespace bounce
-///////////////////////////////////////////////////////////////////////////
-// back
-///////////////////////////////////////////////////////////////////////////
-namespace back {
-static real_t in(real_t t, real_t b, real_t c, real_t d) {
-	float s = 1.70158f;
-	float postFix = t /= d;
-	return c * (postFix)*t * ((s + 1) * t - s) + b;
-}
-
-static real_t out(real_t t, real_t b, real_t c, real_t d) {
-	float s = 1.70158f;
-	t = t / d - 1;
-	return c * (t * t * ((s + 1) * t + s) + 1) + b;
-}
-
-static real_t in_out(real_t t, real_t b, real_t c, real_t d) {
-	float s = 1.70158f * 1.525f;
-	t /= d / 2;
-	if (t < 1) return c / 2 * (t * t * ((s + 1) * t - s)) + b;
-	t -= 2;
-	return c / 2 * (t * t * ((s + 1) * t + s) + 2) + b;
-}
-
-static real_t out_in(real_t t, real_t b, real_t c, real_t d) {
-	return (t < d / 2) ? out(t * 2, b, c / 2, d) : in((t * 2) - d, b + c / 2, c / 2, d);
-}
-}; // namespace back
-
-Tween::interpolater Tween::interpolaters[Tween::TRANS_MAX][Tween::EASE_MAX] = {
-	{ &linear::in, &linear::out, &linear::in_out, &linear::out_in },
-	{ &sine::in, &sine::out, &sine::in_out, &sine::out_in },
-	{ &quint::in, &quint::out, &quint::in_out, &quint::out_in },
-	{ &quart::in, &quart::out, &quart::in_out, &quart::out_in },
-	{ &quad::in, &quad::out, &quad::in_out, &quad::out_in },
-	{ &expo::in, &expo::out, &expo::in_out, &expo::out_in },
-	{ &elastic::in, &elastic::out, &elastic::in_out, &elastic::out_in },
-	{ &cubic::in, &cubic::out, &cubic::in_out, &cubic::out_in },
-	{ &circ::in, &circ::out, &circ::in_out, &circ::out_in },
-	{ &bounce::in, &bounce::out, &bounce::in_out, &bounce::out_in },
-	{ &back::in, &back::out, &back::in_out, &back::out_in },
-};
-
-real_t Tween::run_equation(TransitionType p_trans_type, EaseType p_ease_type, real_t t, real_t b, real_t c, real_t d) {
-	if (d == 0) {
-		// Special case to avoid dividing by 0 in equations.
-		return b + c;
-	}
-
-	interpolater cb = interpolaters[p_trans_type][p_ease_type];
-	ERR_FAIL_COND_V(cb == NULL, b);
-	return cb(t, b, c, d);
-}