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OpenGL OpenGL Transformation Is Not Working As I Expected!!

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Hello Everyone!

I'm learning openGL, and currently i'm making a simple 2D game engine to test what I've learn so far.  In order to not say to much, i made a video in which i'm showing you the behavior of the rendering.

Video: 

 

What i was expecting to happen, was the player moving around. When i render only the player, he moves as i would expect. When i add a second Sprite object, instead of the Player, this new sprite object is moving and finally if i add a third Sprite object the third one is moving. And the weird think is that i'm transforming the Vertices of the Player so why the transformation is being applied somewhere else?

 

Take a look at my code:

Sprite Class

(You mostly need to see the Constructor, the Render Method and the Move Method)

#include "Brain.h"
#include <glm/gtc/matrix_transform.hpp>
#include <vector>


struct Sprite::Implementation
{

	//Position.
	struct pos pos;

	//Tag.
	std::string tag;

	//Texture.
	Texture *texture;

	//Model matrix.
	glm::mat4 model;

	//Vertex Array Object.
	VertexArray *vao;

	//Vertex Buffer Object.
	VertexBuffer *vbo;

	//Layout.
	VertexBufferLayout *layout;

	//Index Buffer Object.
	IndexBuffer *ibo;

	//Shader.
	Shader *program;

	//Brains.
	std::vector<Brain *> brains;


	//Deconstructor.
	~Implementation();

};






Sprite::Sprite(std::string image_path, std::string tag, float x, float y)
{
	//Create Pointer To Implementaion.
	m_Impl = new Implementation();

	//Set the Position of the Sprite object.
	m_Impl->pos.x = x;
	m_Impl->pos.y = y;

	//Set the tag.
	m_Impl->tag = tag;

	//Create The Texture.
	m_Impl->texture = new Texture(image_path);

	//Initialize the model Matrix.
	m_Impl->model = glm::mat4(1.0f);

	//Get the Width and the Height of the Texture.
	int width  = m_Impl->texture->GetWidth();
	int height = m_Impl->texture->GetHeight();


	//Create the Verticies.
	float verticies[] =
	{

		//Positions                //Texture Coordinates.
		x, y,                      0.0f, 0.0f,
		x + width, y,              1.0f, 0.0f,
		x + width, y + height,     1.0f, 1.0f,
		x, y + height,             0.0f, 1.0f
	};



	//Create the Indicies.
	unsigned int indicies[] =
	{
		0, 1, 2,
		2, 3, 0
	};


	//Create Vertex Array.
	m_Impl->vao = new VertexArray();


	//Create the Vertex Buffer.
	m_Impl->vbo = new VertexBuffer((void *)verticies, sizeof(verticies));


	//Create The Layout.
	m_Impl->layout = new VertexBufferLayout();
	m_Impl->layout->PushFloat(2);
	m_Impl->layout->PushFloat(2);
	m_Impl->vao->AddBuffer(m_Impl->vbo, m_Impl->layout);


	//Create the Index Buffer.
	m_Impl->ibo = new IndexBuffer(indicies, 6);


	//Create the new shader.
	m_Impl->program = new Shader("Shaders/SpriteShader.shader");
}






//Render.
void Sprite::Render(Window * window)
{

	//Create the projection Matrix based on the current window width and height.
	glm::mat4 proj = glm::ortho(0.0f, (float)window->GetWidth(), 0.0f, (float)window->GetHeight(), -1.0f, 1.0f);


	//Set the MVP Uniform.
	m_Impl->program->setUniformMat4f("u_MVP", proj * m_Impl->model);

	
	//Run All The Brains (Scripts) of this game object (sprite).
	for (unsigned int i = 0; i < m_Impl->brains.size(); i++)
	{

		//Get Current Brain.
		Brain *brain = m_Impl->brains[i];

		//Call the start function only once!
		if (brain->GetStart())
		{
			brain->SetStart(false);
			brain->Start();
		}

		//Call the update function every frame.
		brain->Update();
	}


	//Render.
	window->GetRenderer()->Draw(m_Impl->vao, m_Impl->ibo, m_Impl->texture, m_Impl->program);
}





void Sprite::Move(float speed, bool left, bool right, bool up, bool down)
{
	if (left)
	{
		m_Impl->pos.x -= speed;
		m_Impl->model = glm::translate(m_Impl->model, glm::vec3(-speed, 0, 0));
	}

	if (right)
	{
		m_Impl->pos.x += speed;
		m_Impl->model = glm::translate(m_Impl->model, glm::vec3(speed, 0, 0));
	}

	if (up)
	{
		m_Impl->pos.y += speed;
		m_Impl->model = glm::translate(m_Impl->model, glm::vec3(0, speed, 0));
	}

	if (down)
	{
		m_Impl->pos.y -= speed;
		m_Impl->model = glm::translate(m_Impl->model, glm::vec3(0, -speed, 0));
	}
}






void Sprite::AddBrain(Brain * brain)
{

	//Push back the brain object.
	m_Impl->brains.push_back(brain);
}





pos *Sprite::GetPos()
{
	return &m_Impl->pos;
}






std::string Sprite::GetTag()
{
	return m_Impl->tag;
}






int Sprite::GetWidth()
{
	return m_Impl->texture->GetWidth();
}






int Sprite::GetHeight()
{
	return m_Impl->texture->GetHeight();
}





Sprite::~Sprite()
{
	delete m_Impl;
}





//Implementation Deconstructor.
Sprite::Implementation::~Implementation()
{
	delete texture;
	delete vao;
	delete vbo;
	delete layout;
	delete ibo;
	delete program;
}

 

Renderer Class

#include "Renderer.h"
#include "Error.h"



Renderer::Renderer()
{
}


Renderer::~Renderer()
{
}

void Renderer::Draw(VertexArray * vao, IndexBuffer * ibo, Texture *texture, Shader * program)
{
	vao->Bind();
	ibo->Bind();
	program->Bind();

	if (texture != NULL)
		texture->Bind();

	GLCall(glDrawElements(GL_TRIANGLES, ibo->GetCount(), GL_UNSIGNED_INT, NULL));
}

void Renderer::Clear(float r, float g, float b)
{
	GLCall(glClearColor(r, g, b, 1.0));
	GLCall(glClear(GL_COLOR_BUFFER_BIT));
}

void Renderer::Update(GLFWwindow *window)
{
	/* Swap front and back buffers */
	glfwSwapBuffers(window);

	/* Poll for and process events */
	glfwPollEvents();
}

 

Shader Code

#shader vertex
#version 330 core

layout(location = 0) in vec4 aPos;
layout(location = 1) in vec2 aTexCoord;

out vec2 t_TexCoord;

uniform mat4 u_MVP;

void main()
{
	gl_Position = u_MVP * aPos;
	t_TexCoord = aTexCoord;
}




#shader fragment
#version 330 core

out vec4 aColor;
in vec2 t_TexCoord;

uniform sampler2D u_Texture;

void main()
{
	aColor = texture(u_Texture, t_TexCoord);
}

Also i'm pretty sure that every time i'm hitting the up, down, left and right arrows on the keyboard, i'm changing the model Matrix of the Player and not the others.

 

Window Class:

#include "Window.h"
#include <GL/glew.h>
#include <GLFW/glfw3.h>

#include "Error.h"
#include "Renderer.h"

#include "Scene.h"
#include "Input.h"



//Global Variables.
int screen_width, screen_height;




//On Window Resize.
void OnWindowResize(GLFWwindow *window, int width, int height);





//Implementation Structure.
struct Window::Implementation
{

	//GLFW Window.
	GLFWwindow *GLFW_window;

	//Renderer.
	Renderer *renderer;

	//Delta Time.
	double delta_time;

	//Frames Per Second.
	int fps;

	//Scene.
	Scene *scnene;

	//Input.
	Input *input;




	//Deconstructor.
	~Implementation();
};





//Window Constructor.
Window::Window(std::string title, int width, int height)
{

	//Initializing width and height.
	screen_width  = width;
	screen_height = height;

	//Create Pointer To Implementation.
	m_Impl = new Implementation();

	//Try initializing GLFW.
	if (!glfwInit())
	{
		std::cout << "GLFW could not be initialized!" << std::endl;
		std::cout << "Press ENTER to exit..." << std::endl;
		std::cin.get();
		exit(-1);
	}


	//Setting up OpenGL Version 3.3 Core Profile.
	glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
	glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
	glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);

	/* Create a windowed mode window and its OpenGL context */
	m_Impl->GLFW_window = glfwCreateWindow(width, height, title.c_str(), NULL, NULL);
	if (!m_Impl->GLFW_window)
	{
		std::cout << "GLFW could not create a window!" << std::endl;
		std::cout << "Press ENTER to exit..." << std::endl;
		std::cin.get();
		glfwTerminate();
		exit(-1);
	}

	/* Make the window's context current */
	glfwMakeContextCurrent(m_Impl->GLFW_window);

	
	//Initialize GLEW.
	if(glewInit() != GLEW_OK)
	{
		std::cout << "GLEW could not be initialized!" << std::endl;
		std::cout << "Press ENTER to exit..." << std::endl;
		std::cin.get();
		glfwTerminate();
		exit(-1);
	}


	//Enabling Blending.
	GLCall(glEnable(GL_BLEND));
	GLCall(glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA));


	//Setting the ViewPort.
	GLCall(glViewport(0, 0, width, height));


	//**********Initializing Implementation**********//
	m_Impl->renderer   = new Renderer();
	m_Impl->delta_time = 0.0;
	m_Impl->fps		   = 0;
	m_Impl->input      = new Input(this);
	//**********Initializing Implementation**********//




	//Set Frame Buffer Size Callback.
	glfwSetFramebufferSizeCallback(m_Impl->GLFW_window, OnWindowResize);
}





//Window Deconstructor.
Window::~Window()
{
	delete m_Impl;
}





//Window Main Loop.
void Window::MainLoop()
{

	//Time Variables.
	double start_time = 0, end_time = 0, old_time = 0, total_time = 0;

	//Frames Counter.
	int frames = 0;

	/* Loop until the user closes the window */
	while (!glfwWindowShouldClose(m_Impl->GLFW_window))
	{

		old_time   = start_time;    //Total time of previous frame.
		start_time = glfwGetTime(); //Current frame start time.


		//Calculate the Delta Time.
		m_Impl->delta_time = start_time - old_time;

		//Get Frames Per Second.
		if (total_time >= 1)
		{
			m_Impl->fps = frames;
			total_time  = 0;
			frames      = 0;
		}

		//Clearing The Screen.
		m_Impl->renderer->Clear(0, 0, 0);


		//Render The Scene.
		if (m_Impl->scnene != NULL)
			m_Impl->scnene->Render(this);

		//Updating the Screen.
		m_Impl->renderer->Update(m_Impl->GLFW_window);


		//Increasing frames counter.
		frames++;

		//End Time.
		end_time = glfwGetTime();

		//Total time after the frame completed.
		total_time += end_time - start_time;
	}

	//Terminate GLFW.
	glfwTerminate();
}






//Load Scene.
void Window::LoadScene(Scene * scene)
{

	//Set the scene.
	m_Impl->scnene = scene;
}






//Get Delta Time.
double Window::GetDeltaTime()
{
	return m_Impl->delta_time;
}






//Get FPS.
int Window::GetFPS()
{
	return m_Impl->fps;
}






//Get Width.
int Window::GetWidth()
{
	return screen_width;
}






//Get Height.
int Window::GetHeight()
{
	return screen_height;
}






//Get Input.
Input * Window::GetInput()
{
	return m_Impl->input;
}






Renderer * Window::GetRenderer()
{
	return m_Impl->renderer;
}






GLFWwindow * Window::GetGLFWindow()
{
	return m_Impl->GLFW_window;
}





//Implementation Deconstructor.
Window::Implementation::~Implementation()
{
	delete renderer;
	delete input;
}






//OnWindowResize
void OnWindowResize(GLFWwindow *window, int width, int height)
{
	screen_width  = width;
	screen_height = height;

	//Updating the ViewPort.
	GLCall(glViewport(0, 0, width, height));
}

 

Brain Class

#include "Brain.h"
#include "Sprite.h"
#include "Window.h"


struct Brain::Implementation
{

	//Just A Flag.
	bool started;

	//Window Pointer.
	Window *window;

	//Sprite Pointer.
	Sprite *sprite;
};






Brain::Brain(Window *window, Sprite *sprite)
{

	//Create Pointer To Implementation.
	m_Impl = new Implementation();

	//Initialize Implementation.
	m_Impl->started = true;
	m_Impl->window  = window;
	m_Impl->sprite  = sprite;
}






Brain::~Brain()
{

	//Delete Pointer To Implementation.
	delete m_Impl;
}






void Brain::Start()
{
}






void Brain::Update()
{
}






Window * Brain::GetWindow()
{
	return m_Impl->window;
}






Sprite * Brain::GetSprite()
{
	return m_Impl->sprite;
}





bool Brain::GetStart()
{
	return m_Impl->started;
}





void Brain::SetStart(bool value)
{
	m_Impl->started = value;
}

Script Class (Its a Brain Subclass!!!)

#include "Script.h"



Script::Script(Window *window, Sprite *sprite) : Brain(window, sprite)
{
}






Script::~Script()
{
}






void Script::Start()
{
	std::cout << "Game Started!" << std::endl;
}






void Script::Update()
{

	Input *input = this->GetWindow()->GetInput();
	Sprite *sp   = this->GetSprite();

	//Move this sprite.
	this->GetSprite()->Move(200 * this->GetWindow()->GetDeltaTime(), 
							 input->GetKeyDown("left"),
							 input->GetKeyDown("right"), 
							 input->GetKeyDown("up"), 
							 input->GetKeyDown("down"));

	std::cout << sp->GetTag().c_str() << ".x = " << sp->GetPos()->x << ", " << sp->GetTag().c_str() << ".y = " << sp->GetPos()->y << std::endl;
}

 

Main:

#include "SpaceShooterEngine.h"
#include "Script.h"

int main()
{
	Window w("title", 600,600);

	Scene *scene = new Scene();

	Sprite *player = new Sprite("Resources/Images/player.png", "Player", 100,100);
	Sprite *other = new Sprite("Resources/Images/cherno.png", "Other", 400, 100);
	Sprite *other2 = new Sprite("Resources/Images/cherno.png", "Other", 300, 400);

	Brain *brain = new Script(&w, player);
	player->AddBrain(brain);



	scene->AddSprite(player);
	scene->AddSprite(other);
	scene->AddSprite(other2);
	w.LoadScene(scene);
	w.MainLoop();

	return 0;
}

 

 

I literally can't find what is wrong. If you need more code, ask me to post it. I will also attach all the source files.

Brain.cpp

Error.cpp

IndexBuffer.cpp

Input.cpp

Renderer.cpp

Scene.cpp

Shader.cpp

Sprite.cpp

Texture.cpp

VertexArray.cpp

VertexBuffer.cpp

VertexBufferLayout.cpp

Window.cpp

Brain.h

Error.h

IndexBuffer.h

Input.h

Renderer.h

Scene.h

Shader.h

SpaceShooterEngine.h

Sprite.h

Texture.h

VertexArray.h

VertexBuffer.h

VertexBufferLayout.h

Window.h

Edited by frob
Please do not relabel discussions as "solved". This is not a Q&A site, more discussion may follow.

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I think there's some code missing. I can't see where Sprite::Move is called, nor where Input::GetKeyDown is called. The problem looks like it is wherever those two get tied together; I'm betting you're calling Move on the last Sprite created, not the designated Player sprite.

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8 minutes ago, Wyrframe said:

I think there's some code missing. I can't see where Sprite::Move is called, nor where Input::GetKeyDown is called. The problem looks like it is wherever those two get tied together; I'm betting you're calling Move on the last Sprite created, not the designated Player sprite.

I updated my Post and i added all the Classes. I think i'm sure i'm calling move on the right sprite object.

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'k, seems like you're attaching the control binding script to the right sprite. Time to crack open a debugger and confirm that the guts of each Sprite are what you expect them to be. I'm guessing something's going wrong with the private implementation management. Try instantiating your sprites in a different order, and seeing if that gives different results; that would suggest there is some data sharing going on which you're not expecting.

Edited by Wyrframe

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2 minutes ago, Wyrframe said:

'k, seems like you're attaching the control binding script to the right sprite. Time to crack open a debugger and confirm that the guts of each Sprite are what you expect them to be. I'm guessing something's going wrong with the private implementation management. Try instantiating your sprites in a different order, and seeing if that gives different results; that would suggest there is some data sharing going on which you're not expecting.

You are right. When I change the order of the sprite objects instantiation, I see another sprite moving. 

But I can't understand why they could exchange data with each other. If you see the sprite constructor, it creates a new Implementation object, so each sprite object should have it's own.

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Your Brain destructor needs to be virtual. I don't think that should be causing this issue, but it may not be helping if the issue is being caused by copying of Brains and Sprites by the Vectors which contain them.

Beyond that, I can't see the issue either. You'll have to just run it in a debugger and see if you can spot when it goes wrong.

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28 minutes ago, Wyrframe said:

Your Brain destructor needs to be virtual. I don't think that should be causing this issue, but it may not be helping if the issue is being caused by copying of Brains and Sprites by the Vectors which contain them.

Beyond that, I can't see the issue either. You'll have to just run it in a debugger and see if you can spot when it goes wrong.

Ok I'll check it. The problem is that I'm creating the game engine in a different project and compiling it as a dynamic library. Then I'm linking it with the actual game project in where I have the Main.cpp file. If I put a break point into Main, it won't jump inside methods which are coming from the dynamic library. Is there something I can do about that, or I must create the whole game as one project which compiles into an executable????

Edited by babaliaris

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4 minutes ago, babaliaris said:

Is there something I can do about that, or I must create the whole game as one project which compiles into an executable????

That one's outside my realm of experience, sorry. My C++ development environment never gets more complex than a single Makefile and vim. If it was a Java program, I might be able to help you out there. :)

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I have news!

I debugged the application and i noticed the followings:

The Model Matrix of the Player is being updating as i expected.

The Model Matrices of the other two sprite objects are not being updated as i expected (They remain as identity matrices)

So the problem is not there. What else do you think might cause this???

Could be the Renderer? But inside the renderer i'm binding the vao, ibo, texture and shader of the current sprite object, and each sprite has it's own unique vao, vbo, ibo, and shader and since i saw that indeed the Player's model Matrix is being updating correctly, i can't understand why it's not the Player's Vertices which are being transformed. It's like the MVP Matrix does not affect the Player's vertices but only the last object which i instantiate. According to what i said above this is impossible!!!

Edited by babaliaris

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I also noticed this (Check out the image i attached):

Player's VAO, VBO and program (shader) have exactly the same id. Is this reasonably? Does openGL assign different ids for each of these components, so a vao and a vbo can have the same id for example?

Also i checked the ids of the other two sprite object and each sprite object has a unique id for vao, vbo, ibo and program and also when i'm binding all these inside the Renderer i'm sure i'm binding the correct ones for the correct corresponding sprite object.

And at the end we will probably find a bug so stupid and we all are going to laugh 😛 

Capture.PNG

Edited by babaliaris

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      To my understanding HLSL/D3D11 offers not just the traditional floating point model in half-,single-, and double-precision, but also the fixed-point model in form of signed/unsigned normalized integers in 8-,10-,16-,24-, and 32-bit variants. Both models offer a finite sequence of "grid-points". The obvious difference between the two models is that the fixed-point model offers a constant spacing between values in the normalized range of [0,1] or [-1,1], while the floating point model allows for smaller "deltas" as you get closer to 0, and larger "deltas" the further you are away from 0.
      To add some context, let me define a struct as an example:
      struct VertexData { float[3] position; //3x32-bits float[2] texCoord; //2x32-bits float[3] normals; //3x32-bits } //Total of 32 bytes Every vertex gets a position, a coordinate on my texture, and a normal to do some light calculations. In this case we have 8x32=256bits per vertex. Since the texture coordinates lie in the interval [0,1] and the normal vector components are in the interval [-1,1] it would seem useful to use normalized representation as suggested in the topic linked at the top of the post. The texture coordinates might as well be represented in a fixed-point model, because it seems most useful to be able to sample the texture in a uniform manner, as the pixels don't get any "denser" as we get closer to 0. In other words the "delta" does not need to become any smaller as the texture coordinates approach (0,0). A similar argument can be made for the normal-vector, as a normal vector should be normalized anyway, and we want as many points as possible on the sphere around (0,0,0) with a radius of 1, and we don't care about precision around the origin. Even if we have large textures such as 4k by 4k (or the maximum allowed by D3D11, 16k by 16k) we only need as many grid-points on one axis, as there are pixels on one axis. An unsigned normalized 14 bit integer would be ideal, but because it is both unsupported and impractical, we will stick to an unsigned normalized 16 bit integer. The same type should take care of the normal vector coordinates, and might even be a bit overkill.
      struct VertexData { float[3] position; //3x32-bits uint16_t[2] texCoord; //2x16bits uint16_t[3] normals; //3x16bits } //Total of 22 bytes Seems like a good start, and we might even be able to take it further, but before we pursue that path, here is my first question: can the GPU even work with the data in this format, or is all I have accomplished minimizing CPU-side RAM usage? Does the GPU have to convert the texture coordinates back to a floating-point model when I hand them over to the sampler in my pixel shader? I have looked up the data types for HLSL and I am not sure I even comprehend how to declare the vertex input type in HLSL. Would the following work?
      struct VertexInputType { float3 pos; //this one is obvious unorm half2 tex; //half corresponds to a 16-bit float, so I assume this is wrong, but this the only 16-bit type I found on the linked MSDN site snorm half3 normal; //same as above } I assume this is possible somehow, as I have found input element formats such as: DXGI_FORMAT_R16G16B16A16_SNORM and DXGI_FORMAT_R16G16B16A16_UNORM (also available with a different number of components, as well as different component lengths). I might have to avoid 3-component vectors because there is no 3-component 16-bit input element format, but that is the least of my worries. The next question would be: what happens with my normals if I try to do lighting calculations with them in such a normalized-fixed-point format? Is there no issue as long as I take care not to mix floating- and fixed-point data? Or would that work as well? In general this gives rise to the question: how does the GPU handle fixed-point arithmetic? Is it the same as integer-arithmetic, and/or is it faster/slower than floating-point arithmetic?
      Assuming that we still have a valid and useful VertexData format, how far could I take this while remaining on the sensible side of what could be called optimization? Theoretically I could use the an input element format such as DXGI_FORMAT_R10G10B10A2_UNORM to pack my normal coordinates into a 10-bit fixed-point format, and my verticies (in object space) might even be representable in a 16-bit unsigned normalized fixed-point format. That way I could end up with something like the following struct:
      struct VertexData { uint16_t[3] pos; //3x16bits uint16_t[2] texCoord; //2x16bits uint32_t packedNormals; //10+10+10+2bits } //Total of 14 bytes Could I use a vertex structure like this without too much performance-loss on the GPU-side? If the GPU has to execute some sort of unpacking algorithm in the background I might as well let it be. In the end I have a functioning deferred renderer, but I would like to reduce the memory footprint of the huge amount of vertecies involved in rendering my landscape. 
      TLDR: I have a lot of vertices that I need to render and I want to reduce the RAM-usage without introducing crazy compression/decompression algorithms to the CPU or GPU. I am hoping to find a solution by involving fixed-point data-types, but I am not exactly sure how how that would work.
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