//This function initializes the game and DirectX----------------------------------------------

void GameInit(int screen_width, int screen_height)
{
	// Initialize Direct Draw

	DDSURFACEDESC2	surfaceDesc;		//Surface description

	DDSCAPS2		surfaceCaps;		//Surface capabilities


	// Create Direct Draw object and set it''s cooperation level with windows 

	DirectDrawCreateEx(NULL, (VOID** )&directDraw, IID_IDirectDraw7, NULL);
	directDraw->SetCooperativeLevel(main_window_handle, DDSCL_EXCLUSIVE | DDSCL_FULLSCREEN | DDSCL_ALLOWREBOOT);
	
	// Set the display to the screen width and height specified, and 16-bit color

	directDraw->SetDisplayMode(screen_width, screen_height, 16, 0, 0);
	
	// clean out the surface description struct and set it''s size

	DDRAW_INIT_STRUCT(surfaceDesc)
	
	// Set all primary surfaces capabilities and prepare it for a backbuffer

	surfaceDesc.dwFlags = DDSD_CAPS | DDSD_BACKBUFFERCOUNT;
	surfaceDesc.ddsCaps.dwCaps = DDSCAPS_PRIMARYSURFACE | DDSCAPS_FLIP | DDSCAPS_COMPLEX;
	surfaceDesc.dwBackBufferCount = 1;
	
	// Create the primary surface

	directDraw->CreateSurface(&surfaceDesc, &primary_surface, NULL);

	// clean out the surface capabilites struct

	ZeroMemory(&surfaceCaps, sizeof(surfaceCaps));

	// Set primary surface''s capabilites to accept an attached surface

	surfaceCaps.dwCaps = DDSCAPS_BACKBUFFER;

	// Attach the backbuffer (back_buffer) to the primary surface

	primary_surface->GetAttachedSurface(&surfaceCaps, &back_buffer);

	//Create a clipper, and atach it to the back_buffer

	directDraw->CreateClipper(0,&clipper,NULL);
	clipper->SetHWnd(0, main_window_handle);
	back_buffer->SetClipper(clipper);
    clipper->Release();
				
	//Set up an offscreen plain system memory scratch buffer surface

	DDSURFACEDESC2   temp_desc;
	DDRAW_INIT_STRUCT(temp_desc)

	temp_desc.dwFlags = DDSD_CAPS | DDSD_HEIGHT | DDSD_WIDTH;
   	temp_desc.dwWidth = 640;
	temp_desc.dwHeight = 480;
	temp_desc.ddsCaps.dwCaps = DDSCAPS_OFFSCREENPLAIN | DDSCAPS_SYSTEMMEMORY;	
	if(FAILED(directDraw->CreateSurface(&temp_desc, &scratch_buffer, NULL)));
		return;	

	//Calculate the lookuptable for y values, for Plot_Pixel

	//Lock the back buffer

	DDRAW_INIT_STRUCT(ddsurface) //Clear ddsurface and set size, never assume it''s clean	

	if (FAILED(back_buffer->Lock(NULL, &ddsurface, DDLOCK_SURFACEMEMORYPTR | DDLOCK_WAIT, NULL)))
		return;
	lpitch16 = (ddsurface.lPitch >> 1);
	for (int counter = 0; counter <= 480; counter++)
	{
		ylookup[counter] = lpitch16 * counter;
	}
	//Unlock the Back buffer

	if (FAILED(back_buffer->Unlock(NULL)))
	return;

	// Load the bitmaps to their surfaces here

	Load_Bmp(background,1, "background.bmp", backrect);
	Load_Bmp(particles, 1, "particles2.bmp", partrect);
	Load_Bmp(gnome, 0, "gnome.bmp", gnomerect);
	Load_Bmp(alpha_bmp, 0, "alpha1.bmp", alpharect);

	// Set the position for the bitmap to draw at

	bitmapX = 320;
	bitmapY = 240;

	//Calculate rects for the Particles, each one is 8*8 pixels in size.

	for (int i = 0; i < 8; i++)
	{
		particle_rect[i].left = i * 8;
		particle_rect[i].right = i * 8 + 8;
		particle_rect[i].top = 0;
		particle_rect[i].bottom = 8;
	}
	Init_Particles();
	Init_Starfield();
	
	//Calculates lookup tables for sin and cos functions

	for (int angle = 0; angle <= 360; angle++)
	{
		double rad_angle = angle * (3.141592654/180);
		sin_look[angle] = sin(rad_angle);
		cos_look[angle] = cos(rad_angle);
	}
	
	ShowCursor(FALSE); //Hide the mouse cursor

}