/*
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* Copyright (C) 2021 Christopher J. Howard
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*
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* This file is part of Antkeeper source code.
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*
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* Antkeeper source code is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* Antkeeper source code is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with Antkeeper source code. If not, see <http://www.gnu.org/licenses/>.
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*/
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#ifndef ANTKEEPER_ANIMATION_HPP
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#define ANTKEEPER_ANIMATION_HPP
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#include <algorithm>
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#include <functional>
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#include <set>
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#include <tuple>
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#include <type_traits>
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#include <unordered_map>
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/**
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* Abstract base class for animations.
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*/
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class animation_base
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{
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public:
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animation_base();
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/**
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* Advances the animation position (t) by @p dt.
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*
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* @param dt Delta time by which the animation position will be advanced.
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*/
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virtual void advance(double dt) = 0;
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/**
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* Sets the animation position to @p t.
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*
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* @param t Position in time to which the animation position will be set.
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*/
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void seek(double t);
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/// Sets the animation position to `0.0`.
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void rewind();
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/// Enables or disables looping of the animation.
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void loop(bool enabled);
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/// Pauses the animation.
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void pause();
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/// Plays the animation.
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void play();
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/// Stops the animation, rewinds it, and resets the loop count.
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void stop();
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/**
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* Sets the speed of the animation.
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*
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* @param speed Speed multiplier.
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*/
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void set_speed(double speed);
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/// Returns `true` if looping of the animation is enabled, `false` otherwise.
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bool is_looped() const;
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/// Returns `true` if the animation is paused, `false` otherwise.
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bool is_paused() const;
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/// Returns `true` if the animation is stopped, `false` otherwise.
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bool is_stopped() const;
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/// Returns the current position in time of the animation.
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double get_position() const;
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/// Returns the current loop count of the animation.
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int get_loop_count() const;
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/// Returns the duration of the animation.
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virtual double get_duration() const = 0;
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/// Sets the callback that's executed when the animation is started from a stopped state.
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void set_start_callback(std::function<void()> callback);
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/// Sets the callback that's executed when a non-looped animation has finished.
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void set_end_callback(std::function<void()> callback);
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/**
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* Sets the callback that's executed when the animation loops.
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*
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* @param callback Loop callback function which is passed the current loop count.
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*/
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void set_loop_callback(std::function<void(int)> callback);
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protected:
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bool looped;
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int loop_count;
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bool paused;
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bool stopped;
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double position;
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double speed;
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std::function<void()> start_callback;
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std::function<void()> end_callback;
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std::function<void(int)> loop_callback;
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};
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inline bool animation_base::is_looped() const
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{
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return looped;
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}
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inline bool animation_base::is_paused() const
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{
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return paused;
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}
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inline bool animation_base::is_stopped() const
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{
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return stopped;
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}
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inline double animation_base::get_position() const
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{
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return position;
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}
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inline int animation_base::get_loop_count() const
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{
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return loop_count;
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}
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template <typename T>
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class animation_channel
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{
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public:
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/// Keyframe consisting of a time and a value.
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typedef std::tuple<double, T> keyframe;
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/**
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* Creates an animation channel.
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*
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* @param id ID of the channel.
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*/
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animation_channel(int id);
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/// Creates an animation channel.
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animation_channel();
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/// Creates an animation channel.
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animation_channel(const animation_channel& other);
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/// Assigns the contents of another channel to this channel.
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animation_channel& operator=(const animation_channel& other);
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/**
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* Adds a keyframe to the animation.
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*
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* @param k Keyframe to add.
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*/
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void insert_keyframe(const keyframe& k);
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/**
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* Removes all keyframes on `[start, end)`.
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*
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* @param start Starting position in time (inclusive).
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* @param end Ending position in time (non-inclusive).
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*/
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void remove_keyframes(double start, double end);
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/// Removes all keyframes from the animation.
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void remove_keyframes();
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/**
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* Finds the keyframes to the left and right of @p position.
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*
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* @param position Position in time.
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* @return Array containing the the keyframes on the left and right of @p position.
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*/
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std::array<const keyframe*, 2> find_keyframes(double position) const;
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/**
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* Finds all the keyframes on `[start, end)`.
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*
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* @param start Starting position in time (inclusive).
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* @param end Ending position in time (non-inclusive).
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* @return All keyframes on `[start, end)`.
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*/
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std::list<keyframe> find_keyframes(double start, double end) const;
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/// Returns the ID of the animation channel.
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int get_id() const;
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/// Returns the duration of the animation channel.
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double get_duration() const;
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private:
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struct keyframe_compare
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{
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inline bool operator()(const keyframe& lhs, const keyframe& rhs) const
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{
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return std::get<0>(lhs) < std::get<0>(rhs);
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}
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};
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int id;
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std::set<keyframe, keyframe_compare> keyframes;
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};
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template <typename T>
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animation_channel<T>::animation_channel(int id):
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id(id),
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keyframes(keyframe_compare())
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{}
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template <typename T>
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animation_channel<T>::animation_channel():
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animation_channel(-1)
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{}
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template <typename T>
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animation_channel<T>::animation_channel(const animation_channel& other):
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id(other.id),
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keyframes(other.keyframes)
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{}
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template <typename T>
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animation_channel<T>& animation_channel<T>::operator=(const animation_channel& other)
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{
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id = other.id;
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keyframes = other.keyframes;
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}
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template <typename T>
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void animation_channel<T>::insert_keyframe(const keyframe& k)
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{
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keyframes.emplace(k);
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}
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template <typename T>
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void animation_channel<T>::remove_keyframes(double start, double end)
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{
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auto lower_bound = keyframes.lower_bound({start, T()});
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auto upper_bound = keyframes.upper_bound({end, T()});
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keyframes.erase(lower_bound, upper_bound);
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}
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template <typename T>
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void animation_channel<T>::remove_keyframes()
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{
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keyframes.clear();
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}
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template <typename T>
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std::array<const typename animation_channel<T>::keyframe*, 2> animation_channel<T>::find_keyframes(double position) const
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{
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// Find the following keyframe
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auto upper_bound = keyframes.upper_bound({position, T()});
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// Find the preceding keyframe
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auto lower_bound = upper_bound;
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--lower_bound;
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std::array<const keyframe*, 2> frames;
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frames[0] = (lower_bound != keyframes.end()) ? &(*lower_bound) : nullptr;
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frames[1] = (upper_bound != keyframes.end()) ? &(*upper_bound) : nullptr;
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return frames;
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}
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template <typename T>
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std::list<typename animation_channel<T>::keyframe> animation_channel<T>::find_keyframes(double start, double end) const
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{
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std::list<keyframe> keyframe_list;
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auto lower_bound = keyframes.lower_bound({start, T()});
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auto upper_bound = keyframes.upper_bound({end, T()});
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for (auto iterator = lower_bound; iterator != upper_bound; ++iterator)
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{
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keyframe_list.push_back(*iterator);
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}
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return keyframe_list;
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}
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template <typename T>
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inline int animation_channel<T>::get_id() const
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{
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return id;
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}
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template <typename T>
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double animation_channel<T>::get_duration() const
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{
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if (keyframes.empty())
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{
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return 0.0;
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}
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return std::get<0>(*keyframes.rbegin());
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}
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/**
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* Templated keyframe animation class.
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*/
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template <typename T>
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class animation: public animation_base
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{
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public:
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/// Channel for this animation type.
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typedef animation_channel<T> channel;
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// Keyframe type for this animation.
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typedef typename channel::keyframe keyframe;
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/// Interpolator function type.
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typedef typename std::decay<std::function<T(const T&, const T&, double)>>::type interpolator_type;
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/// Creates an animation.
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animation();
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/// @copydoc animation_base::advance()
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virtual void advance(double dt);
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/**
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* Adds a channel to the animation.
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*
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* @param id ID of the channel.
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* @return Added or pre-existing channel.
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*/
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channel* add_channel(int id);
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/**
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* Removes a channel from the animation.
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*
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* @param id ID of the channel to remove.
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*/
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void remove_channel(int id);
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/// Removes all channels from the animation.
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void remove_channels();
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/**
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* Sets the frame interpolator function object.
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*
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* @param interpolator Frame interpolator function object.
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*/
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void set_interpolator(interpolator_type interpolator);
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/**
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* Sets the callback that's executed on each frame of animation.
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*
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* @param callback Frame callback which receives the index of an animation channel and value of an interpolated frame.
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*/
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void set_frame_callback(std::function<void(int, const T&)> callback);
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/**
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* Returns the channel with the specified ID.
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*
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* @param id ID of the channel to get.
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*/
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const channel* get_channel(int id) const;
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/// @copydoc animation::get_channel(int) const
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channel* get_channel(int id);
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/// @copydoc animation_base::get_duration() const
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virtual double get_duration() const;
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private:
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std::unordered_map<int, channel> channels;
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interpolator_type interpolator;
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std::function<void(int, const T&)> frame_callback;
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};
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template <typename T>
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animation<T>::animation():
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interpolator(nullptr),
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frame_callback(nullptr)
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{}
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template <typename T>
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void animation<T>::advance(double dt)
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{
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if (paused || stopped)
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{
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return;
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}
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// Advance position by dt
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position += dt * speed;
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// Determine duration of the animation
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double duration = get_duration();
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if (position < duration)
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{
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if (frame_callback != nullptr && interpolator != nullptr)
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{
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for (std::size_t i = 0; i < channels.size(); ++i)
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{
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auto frames = channels[i].find_keyframes(position);
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if (frames[0] != nullptr && frames[1] != nullptr)
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{
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// Calculate interpolated frame
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double t0 = std::get<0>(*frames[0]);
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double t1 = std::get<0>(*frames[1]);
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double alpha = (position - t0) / (t1 - t0);
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T frame = interpolator(std::get<1>(*frames[0]), std::get<1>(*frames[1]), alpha);
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// Pass frame to frame callback
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frame_callback(static_cast<int>(i), frame);
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}
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else if (frames[0] != nullptr)
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{
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// Pass frame to frame callback
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frame_callback(static_cast<int>(i), std::get<1>(*frames[0]));
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}
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else if (frames[1] != nullptr)
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{
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// Pass frame to frame callback
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frame_callback(static_cast<int>(i), std::get<1>(*frames[1]));
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}
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}
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}
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}
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else
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{
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if (looped)
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{
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++loop_count;
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// Subtract duration of animation from position
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position -= duration;
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// Execute loop callback
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if (loop_callback)
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{
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loop_callback(loop_count);
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}
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// Call frame callback on looped frame
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if (frame_callback)
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{
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advance(0.0);
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}
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}
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else
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{
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// Call frame callback for end frame
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if (frame_callback != nullptr)
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{
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for (std::size_t i = 0; i < channels.size(); ++i)
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{
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auto frames = channels[i].find_keyframes(channels[i].get_duration());
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if (frames[0] != nullptr)
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{
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frame_callback(static_cast<int>(i), std::get<1>(*frames[0]));
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}
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}
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}
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stopped = true;
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// Call end callback
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if (end_callback)
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{
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end_callback();
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}
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}
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}
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}
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template <typename T>
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typename animation<T>::channel* animation<T>::add_channel(int id)
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{
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return &(*channels.emplace(id, id).first).second;
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}
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template <typename T>
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void animation<T>::remove_channel(int id)
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{
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auto it = channels.find(id);
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if (it != channels.end())
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{
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channels.erase(it);
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}
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}
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template <typename T>
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void animation<T>::remove_channels()
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{
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channels.clear();
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}
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template <typename T>
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void animation<T>::set_interpolator(interpolator_type interpolator)
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{
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this->interpolator = interpolator;
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}
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template <typename T>
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void animation<T>::set_frame_callback(std::function<void(int, const T&)> callback)
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{
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this->frame_callback = callback;
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}
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template <typename T>
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const typename animation<T>::channel* animation<T>::get_channel(int id) const
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{
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auto it = channels.find(id);
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if (it != channels.end())
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{
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return &it->second;
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}
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return nullptr;
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}
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template <typename T>
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typename animation<T>::channel* animation<T>::get_channel(int id)
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{
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auto it = channels.find(id);
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if (it != channels.end())
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{
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return &it->second;
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}
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return nullptr;
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}
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template <typename T>
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double animation<T>::get_duration() const
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{
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double duration = 0.0;
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for (auto it = channels.begin(); it != channels.end(); ++it)
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{
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duration = std::max<double>(duration, it->second.get_duration());
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}
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return duration;
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}
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#endif // ANTKEEPER_ANIMATION_HPP
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