Drawing coordinates system axes in corner of screen

void CDEMView::DrawSomeBox()
{
	// Define the needed matrices - object world, view and project 
	D3DXMATRIX matObjectWorld;
        D3DXMatrixIdentity (&matObjectWorld);	// object world matrix
	D3DXMATRIX matView;				
        D3DXMatrixIdentity (&matView);		// view matrix
	D3DXMATRIX matProjection;	
        D3DXMatrixIdentity (&matProjection);	// projection matrix
	
	// Get the needed matrices
	_device->GetTransform(D3DTS_VIEW, &matView);
	_device->GetTransform(D3DTS_PROJECTION, &matProjection);

	// Get the viewport
	D3DVIEWPORT9 viewport;
	_device->GetViewport(&viewport);

	// Get the center point of the object		
	D3DXVECTOR3* p_centerPoint = BoxCenterVector; // this is from an external variable

	// Get the point on the creen that is the screen projection of the object
	D3DXVECTOR3 projectPoint;
	D3DXVec3Project(&projectPoint, p_centerPoint ,&viewport, &matProjection, &matView, &matObjectWorld);

	// choose the screen point where the object is to be drawn, relative to the Viewport's dimensions
	D3DXVECTOR3 screenPoint;
	screenPoint.x = 0.1*viewport.Width;	// x position (horizontal) is 10% of the width of the screen (0% is left, 100% is right)
	screenPoint.y = 0.9*viewport.Height;	// y position (vertical) is 90% of the height of the screen (0% is top, 100% is bottom)
	screenPoint.z = projectPoint.z;		// 1-projectPoint.z*60/(-zoom);

	//transform the screen position to a world position
	D3DXVECTOR3 worldPoint;
	D3DXVec3Unproject( &worldPoint, &screenPoint, &viewport, &matProjection, &matView, &matObjectWorld );

	// now define how much to translate the box in order to get it to the point we want it to be (WorldPoint)
	float transX, transY, transZ;
	transX = worldPoint.x;
	transY = worldPoint.y;
	transZ = worldPoint.z;
	
	// define a mesh to store the object into and create the object
	ID3DXMesh* _SomeBox;
	float boxSize = 2.0f;
	D3DXCreateBox(_device,boxSize,boxSize,boxSize,&_SomeBox,NULL);

	// define a material and set its color
	D3DMATERIAL9 mat;

	// Set the RGBA for diffuse reflection.
	mat.Diffuse.r = 255;
	mat.Diffuse.g = 0;
	mat.Diffuse.b = 0;
	mat.Diffuse.a = 0.5;

	_device->SetMaterial(&mat);
	_device->SetRenderState(D3DRS_FILLMODE, D3DFILL_WIREFRAME); // D3DFILL_SOLID

	// apply the translation matrix
	D3DXMatrixTranslation(&matObjectWorld, transX, transY, transZ);
	_device->SetTransform(D3DTS_WORLD, &matObjectWorld);

	// draw the object
	_SomeBox->DrawSubset(0);
	// release the mesh
	_SomeBox->Release();

	// some debugging variables
	debug1 = transX;
	debug2 = transY;
	debug3 = transZ;
	debug4 = boxSize;
	//debug5 = scaleFactor;
	manole = 0;
}