fire weapon....

Graphics and GPU Programming Programming

Started by FreJa March 16, 2003 04:38 AM

12 comments, last by FreJa 21 years, 1 month ago

154

Author

March 16, 2003 04:38 AM

Hi, I was just experiencing some things in a 2D game to use in another game... In this experience you have ship that should fire whenever you press SPACE... but it doesn''t... look at the code: Player.cpp

  
#include "Player.h"

CPlayer::CPlayer()
{
	health = 100.0f;
	xPos = 0.0f;
	yPos = -6.5;
}

CPlayer::~CPlayer()
{}

void CPlayer::Draw()
{
	glPushMatrix();

		glTranslatef(xPos, yPos, -18.0);
		glBegin(GL_QUADS);
			glVertex2f(-0.2, -0.2);
			glVertex2f(0.2, -0.2);
			glVertex2f(0.2, 0.2);
			glVertex2f(-0.2, 0.2);
		glEnd();

	glPopMatrix();
}

void CPlayer::ChangeDirection(int direction)
{
	if(direction == 1)		//Right

	{
		xPos += 0.01f;
	}
	if(direction == 2)		//Left

	{
		xPos -= 0.01f;
	}
}

void CPlayer::Fire()
{
	CRocket *Rocket = new CRocket;

	Rocket->xPos = xPos;
	Rocket->yPos = yPos;

	Rocket->Draw();	
}

Rocket.cpp

  
#include "Rocket.h"

CRocket::CRocket()
{
	xPos = 0.0;
	yPos = -6.5;
}

CRocket::~CRocket()
{}

void CRocket::Draw()
{
	glPushMatrix();
		glColor3f(1.0, 0.0, 0.0);
		glTranslatef(xPos, yPos, -18.0);
		glBegin(GL_QUADS);
			glVertex2f(-0.04, -0.04);
			glVertex2f(0.04, -0.04);
			glVertex2f(0.04, 0.04);
			glVertex2f(-0.04, 0.04);
		glEnd();
		glColor3f(1.0, 1.0, 1.0);
	glPopMatrix();

	yPos += 0.01f;
}

MainWnd.cpp

  
#include "MainWnd.h"

CDirectInput	DirectInput;
CPlayer			*Player;
CRocket			*Rocket;

/////////////////////////////////////////////////////////////////////////////////////////////////////////////////

/////////////////////////////////////////////////////////////////////////////////////////////////////////////////

bool CApp::Initialize()
{
     glClearColor(0.0, 0.0, 0.0, 0.0);

	if(!DirectInput.Initialize(glWindow.window.hWnd, glWindow.application.hInstance, true, IS_USEKEYBOARD | IS_USEMOUSE)) return false;

	Player = new CPlayer;
	Rocket = new CRocket;

	return true;
}

/////////////////////////////////////////////////////////////////////////////////////////////////////////////////

/////////////////////////////////////////////////////////////////////////////////////////////////////////////////

void CApp::GameCycle()
{
	glEnable(GL_DEPTH_TEST);
	glEnable(GL_SMOOTH);
	glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
	glLoadIdentity();

	Player->Draw();
	
	glFlush();
}	

/////////////////////////////////////////////////////////////////////////////////////////////////////////////////

/////////////////////////////////////////////////////////////////////////////////////////////////////////////////

void CApp::Deinitialize()
{
	DirectInput.Unload();
	
	delete Player;	
}

/////////////////////////////////////////////////////////////////////////////////////////////////////////////////

/////////////////////////////////////////////////////////////////////////////////////////////////////////////////

void CApp::GetInput()
{
	DirectInput.Update();

	if (!inputInUse)
	{
		// quit

		if (DirectInput.KeyDown(DIK_ESCAPE))
			glWindow.TerminateApplication(&glWindow.window);

		if(DirectInput.KeyDown(DIK_RIGHT))	Player->ChangeDirection(1);

		if(DirectInput.KeyDown(DIK_LEFT))	Player->ChangeDirection(2);

		if(DirectInput.KeyDown(DIK_SPACE))	Player->Fire();

		if (DirectInput.KeyDown(DIK_L))		glPolygonMode(GL_FRONT_AND_BACK, GL_LINE);
		if (DirectInput.KeyDown(DIK_F))		glPolygonMode(GL_FRONT_AND_BACK, GL_FILL);
		if (DirectInput.KeyDown(DIK_P))		glPolygonMode(GL_FRONT_AND_BACK, GL_POINT);
	}
}

See the problem? Thanks a lot

"Through me the road to the city of desolation,Through me the road to sorrows diuturnal,Through me the road among the lost creation."

Anonymous

March 16, 2003 04:44 AM

I haven''t looked at it closely, but one thing is immediately apparent..

Your rocket class will only ever be drawn once.. because you construct the CRocket class in the Fire() method and draw it then, but the Fire() method is only called once, when the space button is pressed down.

I would suggest maintaining a Rocket pointer in your CPlayer class. Then construct the rocket and store its pointer in the CPlayer class. That way, you could do something like this in your Player::Draw() method:

if ( Rocket ) // Rocket is CRocket pointer in CPlayer class
{
Rocket->Draw();
}

FreJa

154

Author

March 16, 2003 05:10 AM

But isn''t it my intention to construct and draw the rocket every time I press the space button?

"Through me the road to the city of desolation,Through me the road to sorrows diuturnal,Through me the road among the lost creation."

Anonymous

March 16, 2003 05:15 AM

Well, you are right in that you only want to _construct_ the rocket when the space button is pressed, so that is where you would set up the pointer with a new operator or something like that, and then destruct it when the rocket is out of range...

But, because your CApp::GameCycle() function calls glClear() to clear the frame buffer each frame, you need to draw the rocket every frame, not just when it''s constructed...

FreJa

154

Author

March 16, 2003 06:18 AM

Well... I think it''s kinda working right now, as when I press space the rocket appears, but it isn''t affected by the translation (yPos += 0.01f), so it remains on the same spot..... why is that?

"Through me the road to the city of desolation,Through me the road to sorrows diuturnal,Through me the road among the lost creation."

stephanh

174

March 16, 2003 08:13 AM

Why should it move? Every time you press your fire button and Fire is invoked you create a new Rocket instance, forgetting about the old one (-> memory leak)

CRocket *Rocket = new CRocket;
Rocket->xPos = xPos;
Rocket->yPos = yPos;
Rocket->Draw();

So Draw for each instance is only called once.

You have to create a list of all active rockets, assign each rocket a lifetime (or whatever) and update them until they "die". And perhaps re-read the chapter about dynamic memory allocation and pointers.

FreJa

154

Author

March 16, 2003 11:52 AM

This is starting to get on my nerves.... I really can''t find a way to make this work!

If I do this:

CRocket *Rocket = new CRocket;
Rocket->Draw();

and in CRocket::Draw() do yPos += 0.01f

shouldn''t it create a new instance of CRocket, and affect it with yPos+=0.01f ??????

"Through me the road to the city of desolation,Through me the road to sorrows diuturnal,Through me the road among the lost creation."

HellRiZZer

308

March 16, 2003 03:31 PM

Here's what I would do:

    class CRocket{.......bool m_bCreated;CVector m_Speed;virtual void Draw();virtual void Update();};class CPlayer{.......CRocket rockets[MAX_ROCKETS];virtual void Draw();virtual void Update();void Fire(CVector speed, CVector start_pos);};// ROCKET RELATEDvoid CRocket::Draw(){ // Draw rocket code}void CRocket::Update(){ // Update position based on given speed if(m_Pos.y > 800) {  m_bCreated = false;  Destroy(); // Basically this has to de-initialize all variables you use for CRocket class } else    m_Pos+=m_Speed;}// PLAYER RELATEDvoid CPlayer::Draw(){// Do your drawing for player for (int i=0; i<MAX_ROCKETS; i++) {   if(rockets[i].m_bCreated)      rockets[i].Draw(); }}void CPlayer::Update(){ // Update player variables based on input, its X, Y and Z poss // Similar to ChangeDirection for (int i=0; i<MAX_ROCKETS; i++) {   if(rockets[i].m_bCreated)       rockets[i].Update(); }}void CPlayer::Fire(CVector dir, CVector start_pos){// Find free rocket for (int i=0; i<MAX_ROCKETS; i++)  {    if(!rockets[i].m_bCreated)    {        rockets[i].m_Pos = start_pos;        rockets[i].m_Speed = dir;         rockets[i].m_bCreated = true;        break;    }  }}

" Do we need us? "

Ionware Productions - Games and Game Tools Development

[edited by - HellRiZZer on March 16, 2003 4:34:05 PM]

" Do we need us? "Ionware Productions - Games and Game Tools Development

FreJa

154

Author

March 17, 2003 01:03 PM

Just another doubt:
if I do something like this:

  void CPlayer::Fire(){	Rocket = new CRocket;	Rocket->xPos = xPos;	Rocket->yPos = yPos++;		Rocket->Draw();	if(Rocket->yPos >= (glWindow.window.init.height-38)-5)	{		DeleteRocket();	}}void CPlayer::DeleteRocket(){	delete Rocket;}

it won''t work... but shouldn''t it work? because I press space, it is created a new instance of CRocket, and if the position of that rocket is X, it will delete it... and when I press again it will be created another instance of CRocket, and if the position .......... bla bla bla ?

"Through me the road to the city of desolation,Through me the road to sorrows diuturnal,Through me the road among the lost creation."

HellRiZZer

308

March 17, 2003 03:03 PM

Am I getting you right, that you can have ONLY 1 rocket? Because if its true, then you might simplify my code a lot.

" Do we need us? "

Ionware Productions - Games and Game Tools Development

" Do we need us? "Ionware Productions - Games and Game Tools Development