camera.h

#pragma once

#include <glad/glad.h>
#include <glm/glm.hpp>
#include <glm/gtc/matrix_transform.hpp>

enum Movement {
	FORWARD,
	BACKWARD,
	LEFT,
	RIGHT
};

const float YAW = -90.0f;
const float PITCH = 0.0f;
const float SPEED = 2.5f;
const float SENSITIVITY = 0.1f;
const float ZOOM = 45.0f;
const float NEAR = 0.1f;
const float FAR = 100.0f;

class Camera
{
public:
	glm::vec3 Position;
	glm::vec3 Front;
	glm::vec3 Up;
	glm::vec3 Right;
	glm::vec3 WorldUp;
    bool active = true;

	float Yaw;
	float Pitch;

	float MovementSpeed;
	float MouseSensitivity;
	float Zoom;

    // constructor with vectors
    Camera(glm::vec3 position = glm::vec3(0.0f, 0.0f, 0.0f), glm::vec3 up = glm::vec3(0.0f, 1.0f, 0.0f), float yaw = YAW, float pitch = PITCH) : Front(glm::vec3(0.0f, 0.0f, -1.0f)), MovementSpeed(SPEED), MouseSensitivity(SENSITIVITY), Zoom(ZOOM)
    {
        Position = position;
        WorldUp = up;
        Yaw = yaw;
        Pitch = pitch;
        updateCameraVectors();
    }
    // constructor with scalar values
    Camera(float posX, float posY, float posZ, float upX, float upY, float upZ, float yaw, float pitch) : Front(glm::vec3(0.0f, 0.0f, -1.0f)), MovementSpeed(SPEED), MouseSensitivity(SENSITIVITY), Zoom(ZOOM)
    {
        Position = glm::vec3(posX, posY, posZ);
        WorldUp = glm::vec3(upX, upY, upZ);
        Yaw = yaw;
        Pitch = pitch;
        updateCameraVectors();
    }

    glm::mat4 GetViewMatrix()
    {
        return glm::lookAt(Position, Position + Front, Up);
    }

    glm::mat4 GetProjectionMatrix(float aspectRatio)
    {
        return glm::perspective(glm::radians(Zoom), aspectRatio, NEAR, FAR);
    }

    void ProcessKeyboard(Movement direction, float deltaTime)
    {
        float velocity = MovementSpeed * deltaTime;
        if (direction == FORWARD)
            Position += Front * velocity;
        if (direction == BACKWARD)
            Position -= Front * velocity;
        if (direction == LEFT)
            Position -= Right * velocity;
        if (direction == RIGHT)
            Position += Right * velocity;
    }

    void ProcessMouseMovement(float xoffset, float yoffset, GLboolean constrainPitch = true)
    {
        if (!active) return;

        xoffset *= MouseSensitivity;
        yoffset *= MouseSensitivity;

        Yaw += xoffset;
        Pitch += yoffset;

        // make sure that when pitch is out of bounds, screen doesn't get flipped
        if (constrainPitch)
        {
            if (Pitch > 89.0f)
                Pitch = 89.0f;
            if (Pitch < -89.0f)
                Pitch = -89.0f;
        }

        // update Front, Right and Up Vectors using the updated Euler angles
        updateCameraVectors();
    }

    void ProcessMouseScroll(float yoffset)
    {
        if (!active) return;

        Zoom -= (float) yoffset;
        if (Zoom < 1.0f)
            Zoom = 1.0f;
        if (Zoom > 45.0f)
            Zoom = 45.0f;
    }
private:
    void updateCameraVectors()
    {
        glm::vec3 front;
        front.x = cos(glm::radians(Yaw)) * cos(glm::radians(Pitch));
        front.y = sin(glm::radians(Pitch));
        front.z = sin(glm::radians(Yaw)) * cos(glm::radians(Pitch));
        Front = glm::normalize(front);

        Right = glm::normalize(glm::cross(Front, WorldUp));  // normalize the vectors, because their length gets closer to 0 the more you look up or down which results in slower movement.
        Up = glm::normalize(glm::cross(Right, Front));
    }
};