camera.h

#ifndef CAMERA_H
#define CAMERA_H

#include <glad/glad.h>
#include <glm/glm.hpp>
#include <glm/gtc/matrix_transform.hpp>
#include<iostream>
#include <vector>
using namespace std;

// Defines several possible options for camera movement. Used as abstraction to stay away from window-system specific input methods
enum Camera_Movement {
	FORWARD,
	BACKWARD,
	LEFT,
	RIGHT
};

// Default camera values
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;


// An abstract camera class that processes input and calculates the corresponding Euler Angles, Vectors and Matrices for use in OpenGL
class Camera
{
public:
	// Camera Attributes
	glm::vec3 Position;
	glm::vec3 Front;
	glm::vec3 Up;
	glm::vec3 Right;
	glm::vec3 WorldUp;
	// Euler Angles
	float Yaw;
	float Pitch;
	// Camera options
	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();
	}

	// specially for double window
	//--------------------------------------------------------------------------------------
	//--------------------------------------------------------------------------------------
	void ChangePos(glm::vec3 Pos)
	{
		Position = Pos;
	}

	// Returns the view matrix calculated using Euler Angles and the LookAt Matrix
	glm::mat4 GetViewMatrix()
	{
		return glm::lookAt(Position, Position + Front, Up);
	}

	// Processes input received from any keyboard-like input system. Accepts input parameter in the form of camera defined ENUM (to abstract it from windowing systems)
	void ProcessKeyboard(Camera_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;
	}

	// Processes input received from a mouse input system. Expects the offset value in both the x and y direction.
	void ProcessMouseMovement(float xoffset, float yoffset, GLboolean constrainPitch = true)
	{
		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();
	}

	// Processes input received from a mouse scroll-wheel event. Only requires input on the vertical wheel-axis
	void ProcessMouseScroll(float yoffset)
	{
		if (Zoom >= 1.0f && Zoom <= 45.0f)
			Zoom -= yoffset;
		if (Zoom <= 1.0f)
			Zoom = 1.0f;
		if (Zoom >= 45.0f)
			Zoom = 45.0f;
	}

	// Calculates the front vector from the Camera's (updated) Euler Angles
	void updateCameraVectors()
	{
		// Calculate the new Front vector
		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);
		// Also re-calculate the Right and Up vector
		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));
	}
};

class Two_Camera
{
public:
	glm::vec3 dis; // ÊÓ²î
	Camera camera1;
	Camera camera2;

	Two_Camera(glm::vec3 dis_ = glm::vec3(2.0f, 0.0f, 0.0f), Camera camera1_ = Camera(glm::vec3(3.5f, -2.0f, -2.0f)))
	{
		dis = dis_;
		//std::cout << dis << glm::vec3(0.0f, 0.0f, 3.0f) + dis << endl;
		camera1 = camera1_;
		camera2 = Camera(glm::vec3(3.5f, -2.0f, -2.0f) + dis);
	}

	glm::mat4 GetViewMatrix()
	{
		return camera1.GetViewMatrix();
	}

	void ProcessKeyboard(Camera_Movement direction, float deltaTime)
	{
		float velocity = camera1.MovementSpeed * deltaTime;
		if (direction == FORWARD)
		{
			camera1.Position += camera1.Front * velocity;
			camera2.Position = camera1.Position + dis;
		}
		if (direction == BACKWARD)
		{
			camera1.Position -= camera1.Front * velocity;
			camera2.Position = camera1.Position + dis;
		}
		if (direction == LEFT)
		{
			camera1.Position -= camera1.Right * velocity;
			camera2.Position = camera1.Position + dis;
		}
		if (direction == RIGHT)
		{
			camera1.Position += camera1.Right * velocity;
			camera2.Position = camera1.Position + dis;
		}
	}

	void ProcessMouseMovement(float xoffset, float yoffset, GLboolean constrainPitch = true)
	{
		xoffset *= camera1.MouseSensitivity;
		yoffset *= camera1.MouseSensitivity;

		camera1.Yaw += xoffset;
		camera2.Yaw += xoffset;
		camera1.Pitch += yoffset;
		camera2.Pitch += yoffset;

		// Make sure that when pitch is out of bounds, screen doesn't get flipped
		if (constrainPitch)
		{
			if (camera1.Pitch > 89.0f) {
				camera1.Pitch = 89.0f;
				camera2.Pitch = 89.0f;
			}
			if (camera1.Pitch < -89.0f) {
				camera1.Pitch = -89.0f;
				camera2.Pitch = -89.0f;
			}
				
		}

		// Update Front, Right and Up Vectors using the updated Euler angles
		camera1.updateCameraVectors();
		camera2.updateCameraVectors();
	}

	void ProcessMouseScroll(float yoffset)
	{
		if (camera1.Zoom >= 1.0f && camera1.Zoom <= 45.0f) {
			camera1.Zoom -= yoffset;
			camera2.Zoom -= yoffset;
		}
			
		if (camera1.Zoom <= 1.0f) {
			camera1.Zoom = 1.0f;
			camera2.Zoom = 1.0f;
		}
			
		if (camera1.Zoom >= 45.0f) {
			camera1.Zoom = 45.0f;
			camera2.Zoom = 45.0f;
		}	
	}

};

#endif