73 lines
1.9 KiB
C++
73 lines
1.9 KiB
C++
#pragma once
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#include "modern-qt/utility/animation/math.hh"
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#include "modern-qt/utility/animation/state/accessor.hh"
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#include <chrono>
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namespace creeper {
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template <typename T>
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struct SpringState : public NormalAccessor {
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using ValueT = T;
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using Clock = std::chrono::steady_clock;
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using TimePoint = Clock::time_point;
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T value;
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T target;
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T velocity = animate::zero<T>();
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TimePoint last_timestamp = Clock::now();
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struct {
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double k = 1.0;
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double d = 0.1;
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double epsilon = 1e-1;
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} config;
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auto set_target(T new_target) noexcept -> void {
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target = new_target;
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const auto current_time = Clock::now();
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using namespace std::chrono_literals;
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const auto threshold = 16ms;
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const auto elapsed_time = current_time - last_timestamp;
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if (elapsed_time > threshold) {
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const auto error = target - value;
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velocity = animate::zero<T>();
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last_timestamp = current_time;
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}
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}
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auto update() noexcept -> bool {
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const auto now = Clock::now();
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const auto duration = now - last_timestamp;
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const double dt = std::chrono::duration<double>(duration).count();
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if (dt <= 0.0) {
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last_timestamp = now;
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return std::abs(animate::magnitude(target - value)) > config.epsilon;
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}
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const auto error = value - target;
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const auto a_force = -config.k * error;
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const auto a_damping = -config.d * velocity;
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const auto a_total = a_force + a_damping;
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velocity += a_total * dt;
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value += velocity * dt;
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last_timestamp = now;
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const bool done =
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animate::magnitude(error) < config.epsilon && std::abs(velocity) < config.epsilon;
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if (done) velocity = animate::zero<T>();
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return !done;
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}
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};
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}
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