arm sway controller class, responsible for arm sway on mouse movement and pullback to center

ArmSwayController.cpp

#include <iostream>

#include "glm/gtx/string_cast.hpp"
#include "vel/App.h"
#include "vel/helpers/functions.h"

#include "ArmSwayController.h"


ArmSwayController::ArmSwayController() :
	input(vel::App::get().getInputState()),
	swayXYPos(glm::vec2(0.0f, 0.0f)),
	swaySpeed(0.0f),
	firstMouseInput(true),
	currentMousePosition(glm::vec2(0.0f, 0.0f)),
	lastMousePosition(glm::vec2(0.0f, 0.0f)),
	mouseDelta(glm::vec2(0.0f, 0.0f)),

	prevVecToAdd(glm::vec2(0.0f, 0.0f)),

	m_coeff(10.0f),
	m_mouse_abs(glm::vec2(0.0f, 0.0f)),
	m_out(glm::vec2(0.0f, 0.0f)),
	m_prev_out(glm::vec2(0.0f, 0.0f))

{};


void ArmSwayController::updateMouseDelta(float dt)
{
	this->currentMousePosition.x = this->input.mouseXPos;
	this->currentMousePosition.y = this->input.mouseYPos;

	if (this->firstMouseInput)
	{
		this->lastMousePosition = this->currentMousePosition;
		this->firstMouseInput = false;
	}

	this->mouseDelta.x = (this->currentMousePosition.x - this->lastMousePosition.x);
	this->mouseDelta.y = (this->lastMousePosition.y - this->currentMousePosition.y);

	this->lastMousePosition = this->currentMousePosition;
}

glm::vec2 ArmSwayController::getSmoothedMouseDelta(float dt)
{
	this->updateMouseDelta(dt);

	this->m_mouse_abs += this->mouseDelta;
	this->m_out -= std::expm1(-this->m_coeff * dt) * (this->m_mouse_abs - this->m_out);

	auto smd = this->m_out - this->m_prev_out;

	this->m_prev_out = this->m_out;

	return smd;
}

glm::vec2 ArmSwayController::update(float dt)
{
	this->swaySpeed = 0.004f;

	glm::vec2 vecToAdd = vel::helpers::functions::invertVec2(this->getSmoothedMouseDelta(dt));

	auto pullBackAmount = vel::helpers::functions::invertVec2(this->prevVecToAdd);

	this->swayXYPos += (vecToAdd + pullBackAmount) * this->swaySpeed;
	//this->swayXYPos += vecToAdd * this->swaySpeed; // commenting out the above and uncommenting this verifies smooth movement without pullback

	this->prevVecToAdd = vecToAdd;
	
	return this->swayXYPos;
}