Please could you explain this code?

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  1. #1
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    Please could you explain this code?

    Please could you explain the following code in detail as i am so baffled and i do not know what this code exactly does. This is a game that basically draws multiple 3d objects i don't understand how and where the drawings were achieved so could you please explain thank you in advance

    here is the code:

    Code:
    #ifndef _GAME_OBJECTS_H_ 
    #define _GAME_OBJECTS_H_ 
    
    
    class GameObjects 
    {
    public:
    	GameObjects();
    	virtual void Update()=0;  
    	virtual void Draw()=0; 
    
    	const float* GetPos();
    	void SetPos(float x, float y, float z );
    
    	
    	bool m_deleteMe;
    protected:
    	float m_pos[3];
    };
    
    #endif
    This is a cpp file that i think it is also linked to the drawing of the 3d object

    Code:
    GameObjects::GameObjects()
    {
    	m_deleteMe = false; 
    	m_pos[0] = m_pos[1] = m_pos[2] = 0.0f; 
    }
    
    const float* GameObjects::GetPos(){
    	return m_pos; 
    }
    
    void GameObject::SetPos(float x, float y, float z ){ 
    	m_pos[0] = x;
    	m_pos[1] = y;
    	m_pos[2] = z;
    }
    This is the 1st 3d object that I do not understand how it was drawn

    Code:
    #include <stdlib.h>
    #include <stdio.h>
    #include <math.h>
    #include "glut.h"
    
    #include "Object.h" 
    
    
    Object::Object()
    {
    	m_pos[2] = -2.8;
    }
    void Object::Update(){
    
    }
    
    
    void Object::Draw(){
    	
    	float color[] = {0.2,1.0,0.2,1.0};
    	glMaterialfv(GL_FRONT_AND_BACK, GL_AMBIENT_AND_DIFFUSE, color);
    
    	glPushMatrix();
    	glTranslatef(m_pos[0],m_pos[1],m_pos[2]);
    
    	glPushMatrix();
    	glutSolidCone(0.4,0.4f,12,12);
    	glPopMatrix();
    
    	for(int i=0; i<4; i++){
    		glPushMatrix();
    		glTranslatef(0,0,-0.15*(i+1));
    		glutSolidCone(0.3f,0.4f,12,12);
    		glPopMatrix();
    	}
    	glPushMatrix();
    	glTranslatef(0,0,-0.15*5);
    	glutSolidCone(0.5f,0.4f,12,12);
    	glPopMatrix();
    
    	glPopMatrix();
    
    }

    Please help guys

  2. #2
    Registered User ssharish2005's Avatar
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    What does object.h file contains?

    ssharish
    Life is like riding a bicycle. To keep your balance you must keep moving - Einstein

  3. #3
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    Quote Originally Posted by ssharish2005 View Post
    What does object.h file contains?

    ssharish
    That's what it has

    Code:
    #ifndef _OBJECT_H_
    #define _OBJECT_H_
    
    #include "GameObjects.h"
    
    
    class Object : public GameObjects
    {
    public:
    	Object();
    	void Update();
    	void Draw();
    };
    
    #endif

  4. #4
    Registered User ssharish2005's Avatar
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    Ok class object inherits from class GamesObject. That kind of makes sense now. So its quite diffcult to explain the whole code. I would appreciate if you point out which part of the code you dont understand. You will have to ask smart question rather than just asking anything.

    It will take me ages to explain you that code. And i do not have that much time

    ssharish
    Life is like riding a bicycle. To keep your balance you must keep moving - Einstein

  5. #5
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    like ssharish2005 said, there are many things going on in there. The short version is that object:: Draw() is the one that tell openGL how to "plot" your 3D object-- in this case, it's a solid cone since you're calling glutSolidCone(). OpenGL uses stacks of matrices to manage your object and how you view the object. since matrices are stored in stack, you need to push and pop them.
    "All that we see or seem
    Is but a dream within a dream." - Poe

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    Quote Originally Posted by ssharish2005 View Post
    Ok class object inherits from class GamesObject. That kind of makes sense now. So its quite diffcult to explain the whole code. I would appreciate if you point out which part of the code you dont understand. You will have to ask smart question rather than just asking anything.

    It will take me ages to explain you that code. And i do not have that much time

    ssharish
    Thank you for the response,

    Could you please explain how the 3d object was drawn, and translated into positioned?

  7. #7
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    Quote Originally Posted by Mehdi-110 View Post
    Thank you for the response,

    Could you please explain how the 3d object was drawn, and translated into positioned?
    for that particulate code check out: glutSolidCone
    OpenGL can draw different object as well.
    "All that we see or seem
    Is but a dream within a dream." - Poe

  8. #8
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    Quote Originally Posted by nimitzhunter View Post
    for that particulate code check out: glutSolidCone
    OpenGL can draw different object as well.
    Thank you for that,

    but could you briefly explain how would one figure out the base , height , slices , stacks of glutSolidCone, would it be possible to initially draw it on a graph paper? or how would would initially figure it out before actually translating it into code? and could you also briefly explain how the colouring of that object was achieved, thank you so much for you help

  9. #9
    Registered User ssharish2005's Avatar
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    You should start reading this book to understand the opengl uasage.
    Chapter 1. Introduction to OpenGL

    ssharish
    Life is like riding a bicycle. To keep your balance you must keep moving - Einstein

  10. #10
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    Quote Originally Posted by ssharish2005 View Post
    You should start reading this book to understand the opengl uasage.
    Chapter 1. Introduction to OpenGL

    ssharish
    Thank you so much for your help,

    could please explain the loop there, what does it do

  11. #11
    -bleh-
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    Quote Originally Posted by Mehdi-110 View Post
    Thank you so much for your help,

    could please explain the loop there, what does it do
    be honest here, is this a homework? ssharish gave you the link, go read it and play around.
    "All that we see or seem
    Is but a dream within a dream." - Poe

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