76 lines
1.8 KiB
C++
76 lines
1.8 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 LinearState : 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 = animate::zero<T>();
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T target = animate::zero<T>();
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struct {
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double speed = 1.0;
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double epsilon = 1e-2;
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} config;
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struct {
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TimePoint last_timestamp;
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} details;
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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 - details.last_timestamp;
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if (elapsed_time > threshold) {
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details.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 - details.last_timestamp;
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const auto dt = std::chrono::duration<double>(duration).count();
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if (dt <= 0.0) {
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details.last_timestamp = now;
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return animate::magnitude(target - value) > config.epsilon;
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}
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const auto delta = target - value;
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const auto dist = animate::magnitude(delta);
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if (dist <= config.epsilon) {
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value = target;
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details.last_timestamp = now;
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return false;
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}
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const auto direction = animate::normalize(delta);
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const auto step = config.speed * dt;
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if (step >= dist) {
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value = target;
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} else {
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value += direction * step;
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}
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details.last_timestamp = now;
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return true;
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}
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};
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}
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