/**************************************************************************/
/* interpolated_property.h */
/**************************************************************************/
/* This file is part of: */
/* GODOT ENGINE */
/* https://godotengine.org */
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/* 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 */
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#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;
// Each time we hit a physics tick, curr = prev,
// BUT the server may be out of date, and needs an update
// on the next frame, OR taking the node off the property update list.
bool _server_stale = 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;
_server_stale = true;
}
void reset() { pump(); }
void set_interpolated_value(const T &p_val) {
_interpolated = p_val;
}
const T &interpolated() const { return _interpolated; }
// Returns true if an update to the server is needed.
bool interpolate(float p_interpolation_fraction) {
if (_needs_interpolating) {
_interpolated = InterpolatedPropertyFuncs::lerp(prev, curr, p_interpolation_fraction);
return true;
}
if (_server_stale) {
_interpolated = curr;
_server_stale = false;
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{};
}
};