Crosshair Source Code ...

Variant 1:
/*This down here create the function with the name "DrawXHair", so for use you'll write: DrawXHair(pDevice, D3DCOLOR_XRGB(0, 0, 0); //for example. The color can be as in the example but also hex (0xFFFFFFFF), and in ARGB.*/

Code:
void DrawXHair(LPDIRECT3DDEVICE9 pDevice, D3DCOLOR color)

{

D3DVIEWPORT9 viewP; //this create a D3DVIEWPORT9 variable

pDevice->GetViewport( &viewP ); //put the values of screen resolution, viewport coords, in viewP

DWORD ScreenCenterX = viewP.Width / 2; //Create a DWORD that represent the screen center X // STUDY CARTESIAN AXES AND ALGEBRA

DWORD ScreenCenterY = viewP.Height / 2; // Same as up there, but for Y



D3DRECT rect1 = {ScreenCenterX-25, ScreenCenterY, ScreenCenterX+ 25, ScreenCenterY+1}; //Create a D3DRECT variable that contains the coord of where we are going to draw a line

D3DRECT rect2 = {ScreenCenterX, ScreenCenterY-25, ScreenCenterX+ 1, ScreenCenterY+25}; //Same as up there



pDevice->Clear( 1, &rect1, D3DCLEAR_TARGET, color, 0, 0 ); //This function draw a line on determinated coords

pDevice->Clear( 1, &rect2, D3DCLEAR_TARGET, color, 0, 0 ); //Same as up there

}


here another way to draw a crosshair:
void CrossHair(LPDIRECT3DDEVICE9 pDevice, int size, int strong, D3DCOLOR xcolor){

int iCenterX = GetSystemMetrics( 0 ) / 2;

int iCenterY = GetSystemMetrics( 1 ) / 2;

if( iCenterX < 20 && iCenterY < 20 )

{

iCenterX = ( GetSystemMetrics( 0 ) / 2 );

iCenterY = ( GetSystemMetrics( 1 ) / 2 );

}

D3DRECT rec2 = { iCenterX- size, iCenterY, iCenterX+ size, iCenterY+ strong};

D3DRECT rec3 = { iCenterX, iCenterY- size, iCenterX+ strong,iCenterY+ size};

pDevice->Clear(1, &rec2, D3DCLEAR_TARGET, xcolor, 1000, 0);

pDevice->Clear(1, &rec3, D3DCLEAR_TARGET, xcolor, 100, 0);

}