DirectX 2D Tilebased games part III

Author: James McCue
Author's e-mail: aloiterer@juno.com
Author's homepage: Jim the loiterer's PC games, programming, & stuff

This one was a pain
Then it crashed
Plotting the pixels and the source of my DirectAngst
How I got my RGB values from bitmaps
Rotating sprites in software
Dhonn's superfast timer
My New Game_Main()
ALT + TAB
Running the demo
Building the project

void PlotPixel(int x, int y, WORD pixel, DDSURFACEDESC *ddsd)
{
 WORD *pixels = (WORD *)ddsd->lpSurface;
 DWORD pitch = ddsd->dwWidth; 
 pixels[y*pitch + x] = pixel; 
}

void PlotPixel (int x, int y, WORD pixel)
{
	*((WORD *)(double_buffer + y * lpitch + (x<<1))) = pixel;
}

    sprite_data = (HBITMAP)LoadImage(NULL, szPlayer1, IMAGE_BITMAP, SHIP_WIDTH, SHIP_HEIGHT, LR_LOADFROMFILE);
    smelly = DDCopyBitmap(lpddsplayer, sprite_data, 0, 0,   SHIP_WIDTH, SHIP_HEIGHT);

    if (smelly!=DD_OK)
    {
        MessageBox(main_window_handle,"couldn't load bitmap PLAY1.BMP, please check the directory tiled3.exe is in, if the file isn't there, download tiled3.zip again, if it is, contact aloiterer@juno.com, thank you!","Bitmap loading error",MB_OK);
        PostQuitMessage(0);

    }

    // lock the lpddsplayer surface, and use double_buffer as a word
    // pointer, for ease of access

    memset(&ddsd,0,sizeof(ddsd));
    ddsd.dwSize = sizeof(ddsd);
    lpddsplayer->Lock(NULL,&ddsd,DDLOCK_SURFACEMEMORYPTR,NULL);
    double_buffer = (unsigned char *)ddsd.lpSurface;

    // here's the pitch acquisition

    lpitch = ddsd.lPitch;

    // loop across surface, storing values I'll use to draw with
    // in a WORD buffer called SpriteRGB16

    for (y_index=0; y_indexUnlock(NULL);

    // Don't need this hbitmap anymore

    DeleteObject(sprite_data);

typedef struct poly_typ
{
	float x,y;
	vertex vertices_local_original[4];
	vertex vertices_local_rotated[4];
} polygon, *polygon_ptr;

void Rotate_Ship(polygon_ptr poly, int angle)
{
	int index;

	float si,cs,
		  rx,ry;

	// there's a little trigonometry going on here
	// your new x coordinate for a vertex is:
	//  oldx * cos(angle in radians) + oldy * sin(angle in radians)
	// and your new y coordinate for a vertex is:
	//  oldy * cos(angle in radians) + oldx * sin(angle in radians)

	si = sin_look[angle];
	cs = cos_look[angle];

	// loop through all 4 polygon vertices

	for (index=0; index<4; index++)
	{
		rx = poly->vertices_local_original[index].x *
			cs - poly->vertices_local_original[index].y * si;

		ry = poly->vertices_local_original[index].y *
			cs + poly->vertices_local_original[index].x * si;

		// put the info into vertices_local_rotated

		poly->vertices_local_rotated[index].x = rx;
		poly->vertices_local_rotated[index].y = ry;
	} // end for index
} // end Rotate_Ship

double ftime(void) 
{
    // by dividing by its rate you get accurate seconds

    __int64 endclock;

    QueryPerformanceCounter((LARGE_INTEGER*)&endclock);

    return (double)(endclock-startclock)*rate_inv;

    // note: I recommend that you multiply but the inverse of a constant.
    // (speed reasons)
}

BOOL initftime(void) 
{
    __int64 rate;

    // we need the accuracy
    if(!QueryPerformanceFrequency((LARGE_INTEGER*)&rate)) 
	{
        return FALSE; // win errors
    }

    // usually the rate will be 1193180
    if(!rate) 
	{
        return FALSE;
    }

    rate_inv=1.0/(double)rate;

    if(!QueryPerformanceCounter((LARGE_INTEGER*)&startclock)) 
	{
        return FALSE; // win errors
    }

    return TRUE; // there is a clock
}

    do 
	{
        // get the time till its not equal to start frame time, it should,
        // never loop at the rate of this timer, but if it does then
        // it will cap to the frame rate to the rate of this timer which
        // is 1193180 hz
	    start_time = ftime();

    } while(start_time==end_time);

	// the total time it took to put together the last frame and
	// get back here...

	frametime = start_time-end_time;
    end_time = start_time;

	// slow-poke rules are in effect... if your machine is running my
	// demo at less than 5 frames per second - aside from telling you
	// that I stink, this will keep my program from becoming unbelievably
	// choppy. ACTUALLY - I should set this value to 0.1 (representing
	// 10 fps)

	if (frametime>(double)0.2)
	    frametime = 0.2;

	// store the framerate for the last frame in the char buffer, which
	// I'll print below

	sprintf(buffer,"last fps rate: %4d ",(int)((double)1/frametime));

        // here is where we use frametime to get the amount of
		// of translation/rotation we can move this frame

// NOTE: you want to keep floating point precision here, for computers that will run this
//   at the high end of possible framerate (pageflipping caps us at the refresh rates
//   of people's monitors)

        movementspeed = ((double)magnitude_per_second*frametime);
        anglespeed = ((double)angles_per_second*frametime);

		// which way is player moving and/or rotating

		if (KEY_DOWN(VK_RIGHT))
		{
			angle -= anglespeed;
			if (angle < 0.0f) 
				angle+=360.0f;

			Rotate_Ship((polygon_ptr)&ship, (int)angle);
		}

		if (KEY_DOWN(VK_LEFT))
		{

			angle += anglespeed;
			if (angle >= 360.0f) 
				angle -= 360.0f;

			Rotate_Ship((polygon_ptr)&ship, (int)angle);
		}

		Translate_Other_Objects();

		Wind_Effects_All();

		// also move ship by our own power

		ship.x += (float)cos(angle*3.14159/180)*movementspeed;
		ship.y += (float)sin(angle*3.14159/180)*movementspeed;

        // FINALLY - draw the polygon ship!
		// LOCK the backbuffer surface so we can 
		// draw directly to it

		memset(&ddsd,0,sizeof(ddsd));
		ddsd.dwSize = sizeof(ddsd);
		
		while((lpddsback->Lock(NULL,&ddsd,DDLOCK_SURFACEMEMORYPTR,NULL)) != DD_OK);

		double_buffer = (unsigned char *)ddsd.lpSurface;

		// here's the pitch acquisition, I think I redundantly get this value
		// in PlotPixel

		lpitch = ddsd.lPitch;
    

		Draw_Ship((polygon_ptr)&ship,sprite_mid_x,sprite_mid_y);

		// don't forget to unlock the surface!

	    while((lpddsback->Unlock(NULL))!=DD_OK);

		// print a message on the backbuffer

		while ((lpddsback->GetDC(&hdc)) != DD_OK);

		SetBkColor( hdc, RGB( 0, 0, 255 ) );
		SetTextColor( hdc, RGB( 255, 255, 0 ) );
		TextOut( hdc, 0, 0, "Keys: LEFT, RIGHT, UP, DOWN, .. and ESC... OH - and M Music (on), N (off).", 74 );
        TextOut( hdc, 0, iScreenHeight-25, buffer, 20 ); 
		
		while ((lpddsback->ReleaseDC(hdc)) != DD_OK);

		// flip back buffer to primary buffer
		lpddsprimary->Flip(NULL,DDFLIP_WAIT);

	// return and let windows have some time - NO WAY, since I'm not checking
	// for "lost" surfaces, I don't let you switch to other applications while
	// this is running, we'll cros that bridge when we come to it...
    } // end if NOT paused

} // end Game_Main

		case WM_ACTIVATEAPP:
		{
			fActive = (BOOL)wparam;           // activation flag 

			if (fActive)
			{
				if (fActive!=lastwparam)
				{
					Restore_Surfaces();
					Reload_Bitmaps();
					game_is_running = TRUE;
				}
			}
			else
			{
				Stop_Music();
				game_is_running = FALSE;
				paused=TRUE;
            }
			lastwparam = fActive;
		}
		break;

tiled3.cpp
polydraw.cpp
ddutil.cpp
tiled3.rc (I'm a little iffy about whether you have to make your own dialog resource for this project)
ddraw.lib (from your directX sdk\lib folder)
winmm.lib (from your MSDEVSTD\LIB folder)

Download the demo and source code

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