Help figuring out the unresolved externals errors?

[procastination]

Write your question here.

I keep getting these errors. But i cant figure out what library i didnt call

Error	4	error LNK1120: 2 unresolved externals	
Error	1	error LNK2001: unresolved external symbol "private: virtual void __thiscall SceneNode::drawCurrent(class sf::RenderTarget &,class sf::RenderStates)const " (?drawCurrent@SceneNode@@EBEXAAVRenderTarget@sf@@VRenderStates@3@@Z)	
Error	2	error LNK2001: unresolved external symbol "private: virtual void __thiscall SceneNode::drawCurrent(class sf::RenderTarget &,class sf::RenderStates)const " (?drawCurrent@SceneNode@@EBEXAAVRenderTarget@sf@@VRenderStates@3@@Z)	
Error	3	error LNK2019: unresolved external symbol "public: class sf::Texture const & __thiscall ResourceHolder<class sf::Texture,enum Textures::ID>::get(enum Textures::ID)const " (?get@?$ResourceHolder@VTexture@sf@@W4ID@Textures@@@@QBEABVTexture@sf@@W4ID@Textures@@@Z) referenced in function "public: __thiscall Aircraft::Aircraft(enum Aircraft::Type,class ResourceHolder<class sf::Texture,enum Textures::ID> const &)" (??0Aircraft@@QAE@W4Type@0@ABV?$ResourceHolder@VTexture@sf@@W4ID@Textures@@@@@Z)

Here are all the header files

SceneNode.h

#pragma once

#ifdef SFML_STATIC
#pragma comment(lib, "glew.lib")
#pragma comment(lib, "freetype.lib")
#pragma comment(lib, "jpeg.lib")
#pragma comment(lib, "opengl32.lib")
#pragma comment(lib, "winmm.lib")
#pragma comment(lib, "gdi32.lib")  

#endif // SFML_STATIC
#include <SFML/Graphics.hpp>
#include <SFML/System.hpp>
#include<assert.h>
#include<map>
#include <iostream>
#include <vector>
#include <memory>
class SceneNode : public sf::Transformable, public sf::Drawable,private sf::NonCopyable 
{
public:
	typedef std::unique_ptr<SceneNode> Ptr;
	SceneNode();

	void  attachChild(Ptr child);
	Ptr detachChild(const SceneNode& node);

	void update(sf::Time dt);	
	sf::Transform getWorldTransform() const;
	sf::Vector2f getWorldPosition() const;

private:
	std::vector<Ptr> mChildren;
	SceneNode* mParent;

	void updateChldrean(sf::Time dt);	// update for the child nodes

	virtual  void  draw(sf::RenderTarget &target, sf::RenderStates states) const final;
	virtual void drawCurrent(sf::RenderTarget &target, sf::RenderStates states) const;
	virtual void updateCurrent(sf::Time dt);	// update for the current nodes
	
};

ResourceHolder.h

#pragma once

#ifdef SFML_STATIC
#pragma comment(lib, "glew.lib")
#pragma comment(lib, "freetype.lib")
#pragma comment(lib, "jpeg.lib")
#pragma comment(lib, "opengl32.lib")
#pragma comment(lib, "winmm.lib")
#pragma comment(lib, "gdi32.lib")  
#endif // SFML_STATIC

#include <SFML/Graphics.hpp>
#include <SFML/System.hpp>
#include<assert.h>
#include<map>
#include <iostream>
#include <memory>
#include <string>
using namespace std;


template<typename Resource, typename Identifier>
class ResourceHolder{
public:
	void load(Identifier id, const std::string &filename);

	template<typename Parameter>
	void load(Identifier id, const std::string &filename, const Parameter &secondParam);

	Resource &get(Identifier id);
	const Resource &get(Identifier id) const;
private:
	void	insertResource(Identifier id, std::unique_ptr<Resource> resource);


private:
	std::map<Identifier, std::unique_ptr<Resource>> mResourceMap;
	
};

Aircraft.h

#pragma once

#ifdef SFML_STATIC
#pragma comment(lib, "glew.lib")
#pragma comment(lib, "freetype.lib")
#pragma comment(lib, "jpeg.lib")
#pragma comment(lib, "opengl32.lib")
#pragma comment(lib, "winmm.lib")
#pragma comment(lib, "gdi32.lib")  

#endif // SFML_STATIC
#include "Entity.h"
#include "ResourceIdentifiers.h"
#include "ResourceHolder.h"
class Aircraft : public Entity
{
public:
	enum  Type{
		Eagle,
		Raptor
	};


	Aircraft(Type type, const TextureHolder& textures);

private:
	virtual void drawCurrent(sf::RenderTarget &target, sf::RenderStates states) const;
	
private:
	Type mType;
	sf::Sprite mSprite;
};

There is something missing in SceneNode class and Aircraft class.

Error is all about the virtual function of SceneNode and Aircraft. and get() of ResourceHolder.


I search on this error and some said that I access an object but the linker cant find the definition?

Everything is defined on header. and header is included on every cpp class.. How can i have this error?