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Help with array in Space Invaders clone

Started by AlienCharm Nov 22, 2003 at 2:52 PM 2 replies 1k views

Original Post

Nov 22, 2003 at 2:52 PM

I am making a Space Invaders clone for my final project in Visual C++/MFC. The lil tank moves and fires, I even have the "invaders" on the screen and moving back and forth. As of right now i display the invaders using a for loop. Here is the code I use:

// draws the first row of invaders, the "red invaders"

void CSpace_Invaders_CloneView::DrawFirstSet()
{
	CBitmap bmp;

	// chooses which bitmap to load

	if( m_blInvaderState == false )
	{
		bmp.LoadBitmap( IDB_TOP_INVADER_CLOSE );
	}
	else
	{
		bmp.LoadBitmap( IDB_TOP_INVADER_OPEN );
	}
	
	CClientDC dc(this);
	CDC bmDC;
	bmDC.CreateCompatibleDC(&dc);
	CBitmap *pOldbmp = bmDC.SelectObject(&bmp);

	BITMAP  bi;
	bmp.GetBitmap(&bi);

	for( int i = 0; i < 550; i += 50 )
	{
		dc.BitBlt(( 5 + i ) + m_nMoveInvaderX,60 + m_nMoveInvaderY,bi.bmWidth,bi.bmHeight,&bmDC,0,0,SRCCOPY);
	}

	bmDC.SelectObject(pOldbmp);
}

// draws the second and third rows of invaders, the "blue invaders"

void CSpace_Invaders_CloneView::DrawSecondSet()
{
	CBitmap bmp;

	// chooses which bitmap to load

	if( m_blInvaderState == false )
	{
		bmp.LoadBitmap( IDB_MIDDLE_INVADER_CLOSE );
	}
	else
	{
		bmp.LoadBitmap( IDB_MIDDLE_INVADER_OPEN );
	}
	  
	CClientDC dc(this);
	CDC bmDC;
	bmDC.CreateCompatibleDC(&dc);
	CBitmap *pOldbmp = bmDC.SelectObject(&bmp);

	BITMAP  bi;
	bmp.GetBitmap(&bi);

	for( int i = 0; i < 550; i += 50 )
	{
		dc.BitBlt(( 0 + i ) + m_nMoveInvaderX,100 + m_nMoveInvaderY,bi.bmWidth,bi.bmHeight,&bmDC,0,0,SRCCOPY);
		dc.BitBlt(( 0 + i ) + m_nMoveInvaderX,140 + m_nMoveInvaderY,bi.bmWidth,bi.bmHeight,&bmDC,0,0,SRCCOPY);
	}

	bmDC.SelectObject(pOldbmp);
}

// draws the fourth and fifth rows of invaders, the "white invaders"

void CSpace_Invaders_CloneView::DrawThirdSet()
{
	CBitmap bmp;

	// chooses which bitmap to load

	if( m_blInvaderState == false )
	{
		bmp.LoadBitmap( IDB_BOTTOM_INVADER_CLOSE );
	}
	else
	{
		bmp.LoadBitmap( IDB_BOTTOM_INVADER_OPEN );
	}
   
	CClientDC dc(this);
	CDC bmDC;
	bmDC.CreateCompatibleDC(&dc);
	CBitmap *pOldbmp = bmDC.SelectObject(&bmp);

	BITMAP  bi;
	bmp.GetBitmap(&bi);

	for( int i = 0; i < 550; i += 50 )
	{
		dc.BitBlt(( 0 + i ) + m_nMoveInvaderX,180 + m_nMoveInvaderY,bi.bmWidth,bi.bmHeight,&bmDC,0,0,SRCCOPY);
		dc.BitBlt(( 0 + i ) + m_nMoveInvaderX,220 + m_nMoveInvaderY,bi.bmWidth,bi.bmHeight,&bmDC,0,0,SRCCOPY);
	}

	bmDC.SelectObject(pOldbmp);
}

It all works but I don''t think I can do collision detection going about it this way. Everything I have read suggests using a two dimensional array. The only problem is i have no clue as to what to put in the array. Since I am using MFC I would probably create my own CArray class, something along the lines of CArray< CBitmap, CBitmap& > if that is even right I don''t know, I''ve also read about ImageLists. They seem as though they might come in handy but again I have no idea of what to put in them. Of course any help would be appreciated.

AlienCharm

Nov 23, 2003 at 12:56 AM

well heres what i''ve came up with. i made a 2d array:


bool m_blArray[5] [10];

then I set it all to true:


for( int i = 0; i < 5; i++ )
		for( int j = 0; j < 10; j++ )
			m_blArray[ i ] [ j ] = true;

then when i called my *draw invader* functions i just tested if the element was true or false. if its true i draw it if its false i dont.


for( int i = 0; i < 1; i++ )
		for( int j = 0; j < 10; j++ )
			if( m_blArray[ i ] [ j ] == true )
			{	
				dc.BitBlt(( 5 + x ) + m_nMoveInvaderX,60 + m_nMoveInvaderY,bi.bmWidth,bi.bmHeight,&bmDC,0,0,SRCCOPY);
				x += 50;
			}

i''m not sure if this is the fastest/easiest/most efficient way. but its the only thing i could come up with so i went with it.

now on to figure out the whole collision detection thing and to see if i can get it to work with this array.....

SelethD

Nov 24, 2003 at 12:44 AM

You have the right idea, about making a class, but it needs to be a generic type class that will work for each invader, with variables describing which one to draw.

class cInvader
{
public:
int row;
int x;
int y;
int active;
int type;
int image;
};

cInvader Invaders[50];

then use for loops to set up inital information in class

for (r=0;r<5;r++)
for (c=0;c<10;c++)
Invaders[r*10+c].type = r;
Invaders[r*10+c].active = 1; (or TRUE)
and so on...

then when drawing, use loop for all, such as
for (i=0;i<50;i++)
if (Invaders.active==TRUE)
//load bitmap according to Invaders[i].image
//draw certain frame from bitmap accoring to
Invaders[i].type
//position image at Invaders[i].x, .y

once you have this setup working collision detection will be easier

KurtCPP

Nov 24, 2003 at 8:26 AM

Hi. BTW, when setting the whole array with two imbricated for loops, ain''t you ever been told memset(array,1,50); was still keeping working fine, too? ;-)

Prog, Hex & Rock''n''Roll :
I don''t like the Prog but the Prog likes me.
Some nice poetry to sweeten your spirit and relax a bit before programming

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