initial commit, 4.5 stable

core/templates/interpolated_property.h

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+/**************************************************************************/
+/*  interpolated_property.h                                               */
+/**************************************************************************/
+/*                         This file is part of:                          */
+/*                             GODOT ENGINE                               */
+/*                        https://godotengine.org                         */
+/**************************************************************************/
+/* Copyright (c) 2014-present Godot Engine contributors (see AUTHORS.md). */
+/* Copyright (c) 2007-2014 Juan Linietsky, Ariel Manzur.                  */
+/*                                                                        */
+/* 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.                 */
+/**************************************************************************/
+
+#pragma once
+
+struct Vector2;
+
+namespace InterpolatedPropertyFuncs {
+float lerp(float p_a, float p_b, float p_fraction);
+double lerp(double p_a, double p_b, float p_fraction);
+Vector2 lerp(const Vector2 &p_a, const Vector2 &p_b, float p_fraction);
+} //namespace InterpolatedPropertyFuncs
+
+// This class is intended to reduce the boiler plate involved to
+// support custom properties to be physics interpolated.
+
+template <class T>
+class InterpolatedProperty {
+	// Only needs interpolating / updating the servers when
+	// curr and prev are different.
+	bool _needs_interpolating = false;
+	T _interpolated;
+	T curr;
+	T prev;
+
+public:
+	// FTI depends on the constant flow between current values
+	// (on the current tick) and stored previous values (on the previous tick).
+	// These should be updated both on each tick, and also on resets.
+	void pump() {
+		prev = curr;
+		_needs_interpolating = false;
+	}
+	void reset() { pump(); }
+
+	void set_interpolated_value(const T &p_val) {
+		_interpolated = p_val;
+	}
+	const T &interpolated() const { return _interpolated; }
+	bool needs_interpolating() const { return _needs_interpolating; }
+
+	bool interpolate(float p_interpolation_fraction) {
+		if (_needs_interpolating) {
+			_interpolated = InterpolatedPropertyFuncs::lerp(prev, curr, p_interpolation_fraction);
+			return true;
+		}
+		return false;
+	}
+
+	operator T() const {
+		return curr;
+	}
+
+	bool operator==(const T &p_o) const {
+		return p_o == curr;
+	}
+
+	bool operator!=(const T &p_o) const {
+		return p_o != curr;
+	}
+
+	InterpolatedProperty &operator=(T p_val) {
+		curr = p_val;
+		_interpolated = p_val;
+		_needs_interpolating = true;
+		return *this;
+	}
+	InterpolatedProperty(T p_val) {
+		curr = p_val;
+		_interpolated = p_val;
+		pump();
+	}
+	InterpolatedProperty() {
+		// Ensure either the constructor is run,
+		// or the memory is zeroed if using a fundamental type.
+		_interpolated = T{};
+		curr = T{};
+		prev = T{};
+	}
+};