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我们继续上次的话题。
上一讲中，我们介绍了一下具体的步骤。下面的清单 1.0 包含了所有的功能以及一个展示如何操作显存和键盘的例子。我们简单地将它作为一个演示。
// LISTING 1.0 - DIRECT X 5.0 GAME CONSOLE ////////////////////////////////////
// INCLUDES ///////////////////////////////////////////////////////////////////
#define WIN32_LEAN_AND_MEAN // make sure certain headers are included correctly
#include <windows.h> // include the standard windows stuff
#include <windowsx.h> // include the 32 bit stuff
#include <mmsystem.h> // include the multi media stuff
// note you need winmm.lib also
#include <ddraw.h> // include direct draw components
#include <stdlib.h> // include all the good stuff
#include <stdio.h>
#include <math.h>
#include <float.h>
// DEFINES ////////////////////////////////////////////////////////////////////
#define WINDOW_CLASS_NAME "WINDOW_CLASS" // this is the name of the window class
// defines for screen parameters
#define SCREEN_WIDTH 640 // the width of the viewing surface
#define SCREEN_HEIGHT 480 // the height of the viewing surface
#define SCREEN_BPP 8 // the bits per pixel
#define MAX_COLORS 256 // the maximum number of colors
// TYPES //////////////////////////////////////////////////////////////////////
typedef unsigned char UCHAR;
// MACROS /////////////////////////////////////////////////////////////////////
// these query the keyboard in real-time
#define KEY_DOWN(vk_code) ((GetAsyncKeyState(vk_code) & 0x8000) ? 1 : 0)
#define KEY_UP(vk_code) ((GetAsyncKeyState(vk_code) & 0x8000) ? 0 : 1)
// PROTOTYPES /////////////////////////////////////////////////////////////////
int DD_Init(HWND hwnd);
int DD_Shutdown(void);
int Set_Pal_Entry(int index, int red, int green, int blue);
void Game_Init(void);
void Game_Main(void);
void Game_Shutdown(void);
// DIRECTDRAW GLOBALS ////////////////////////////////////////////////////////
LPDIRECTDRAW lpdd = NULL; // dd object
LPDIRECTDRAWSURFACE lpddsprimary = NULL; // dd primary surface
LPDIRECTDRAWPALETTE lpddpal = NULL; // a pointer to the created dd palette
PALETTEENTRY color_palette[256]; // holds the shadow palette entries
DDSURFACEDESC ddsd; // a direct draw surface description struct
DDSCAPS ddscaps; // a direct draw surface capabilities struct
HRESULT ddrval; // result back from dd calls
HWND main_window_handle = NULL; // used to store the window handle
UCHAR *video_buffer = NULL; // pointer to video ram
// GAME GLOBALS GO HERE /////////////////////////////////////////////////////
// DIRECT X FUNCTIONS /////////////////////////////////////////////////////////
int DD_Init(HWND hwnd)
{
// this function is responsible for initializing direct draw, it creates a
// primary surface
int index; // looping index
// now that the windows portion is complete, start up direct draw
if (DirectDrawCreate(NULL,&lpdd,NULL)!=DD_OK)
{
// shutdown any other dd objects and kill window
DD_Shutdown();
return(0);
} // end if
// now set the coop level to exclusive and set for full screen and mode x
if (lpdd->SetCooperativeLevel(hwnd, DDSCL_ALLOWREBOOT | DDSCL_EXCLUSIVE |
DDSCL_FULLSCREEN | DDSCL_ALLOWMODEX)!=DD_OK)
{
// shutdown any other dd objects and kill window
DD_Shutdown();
return(0);
} // end if
// now set the display mode
if (lpdd->SetDisplayMode(SCREEN_WIDTH,SCREEN_HEIGHT,SCREEN_BPP)!=DD_OK)
{
// shutdown any other dd objects and kill window
DD_Shutdown();
return(0);
} // end if
// Create the primary surface
ddsd.dwSize = sizeof(ddsd);
ddsd.dwFlags = DDSD_CAPS;
ddsd.ddsCaps.dwCaps = DDSCAPS_PRIMARYSURFACE;
if
(lpdd->CreateSurface(&ddsd,&lpddsprimary,NULL)!=DD_OK)
{
// shutdown any other dd objects and kill window
DD_Shutdown();
return(0);
} // end if
// create the palette and attach it to the primary surface
// clear all the palette entries to RGB 0,0,0
memset(color_palette,0,256*sizeof(PALETTEENTRY));
// set all of the flags to the correct value
for (index=0; index<256; index++)
{
// create the GRAY/RED/GREEN/BLUE palette, 64 shades of each
if ((index / 64)==0)
{
color_palette[index].peRed = index*4;
color_palette[index].peGreen = index*4;
color_palette[index].peBlue = index*4;
} // end if
else
if ((index / 64)==1)
color_palette[index].peRed = (index%64)*4;
else
if ((index / 64)==2)
color_palette[index].peGreen = (index%64)*4;
else
if ((index / 64)==3)
color_palette[index].peBlue = (index%64)*4;
// set the no collapse flag
color_palette[index].peFlags = PC_NOCOLLAPSE;
} // end for index
// now create the palette object, note that it is a member of the dd object itself
if (lpdd->CreatePalette((DDPCAPS_8BIT | DDPCAPS_INITIALIZE),color_palette,&lpddpal,NULL)!=DD_OK)
{
// shutdown any other dd objects and kill window
DD_Shutdown();
return(0);
} // end if
// now attach the palette to the primary surface
lpddsprimary->SetPalette(lpddpal);
// return success if we got this far
return(1);
} // end DD_Init
///////////////////////////////////////////////////////////////////////////////
int DD_Shutdown(void)
{
// this function tests for dd components that have been created and releases
// them back to the operating system
// test if the dd object exists
if (lpdd)
{
// test if there is a primary surface
if(lpddsprimary)
{
// release the memory and set pointer to NULL
lpddsprimary->Release();
lpddsprimary = NULL;
} // end if
// now release the dd object itself
lpdd->Release();
lpdd = NULL;
// return success
return(1);
} // end if
else
return(0);
} // end DD_Shutdown
//////////////////////////////////////////////////////////////////////////////
int Set_Pal_Entry(int index, int red, int green, int blue)
{
// this function sets a palette entry with the sent color
PALETTEENTRY color; // used to build up color
// set RGB value in structure
color.peRed = (BYTE)red;
color.peGreen = (BYTE)green;
color.peBlue = (BYTE)blue;
color.peFlags = PC_NOCOLLAPSE;
// set the color palette entry
lpddpal->SetEntries(0,index,1,&color);
// make copy in shadow palette
memcpy(&color_palette[index],
&color,
sizeof(PALETTEENTRY));
// return success
return(1);
} // end Set_Pal_Entry
// WINDOWS CALLBACK FUNCTION //////////////////////////////////////////////////
LRESULT CALLBACK WindowProc(HWND hwnd, UINT msg, WPARAM wparam, LPARAM lparam)
{
// this is the main message handler of the system
HDC hdc; // handle to graphics context
PAINTSTRUCT ps; // used to hold the paint info
// what is the message?
switch(msg)
{
case WM_CREATE:
{
// do windows inits here
return(0);
} break;
case WM_PAINT:
{
// this message occurs when your window needs repainting
hdc = BeginPaint(hwnd,&ps);
EndPaint(hwnd,&ps);
return(0);
} break;
case WM_DESTROY:
{
// this message is sent when your window is destroyed
PostQuitMessage(0);
return(0);
} break;
default:break;
} // end switch
// let windows process any messages that we didn't take care of
return (DefWindowProc(hwnd, msg, wparam, lparam));
} // end WinProc
// WINMAIN ////////////////////////////////////////////////////////////////////
int WINAPI WinMain( HINSTANCE hinstance,
HINSTANCE hprevinstance,
LPSTR lpcmdline,
int ncmdshow)
{
WNDCLASSEX winclass; // this holds the windows class info
HWND hwnd; // this holds the handle of our new window
MSG msg; // this holds a generic message
// first fill in the window class stucture
winclass.cbSize = sizeof(WNDCLASSEX);
winclass.style = CS_DBLCLKS | CS_OWNDC | CS_HREDRAW | CS_VREDRAW;
winclass.lpfnWndProc = WindowProc;
winclass.cbClsExtra = 0;
winclass.cbWndExtra = 0;
winclass.hInstance = hinstance;
winclass.hIcon = LoadIcon(NULL, IDI_APPLICATION);
winclass.hIconSm = LoadIcon(NULL, IDI_APPLICATION);
winclass.hCursor = LoadCursor(NULL, IDC_ARROW);
winclass.hbrBackground = (HBRUSH)GetStockObject(BLACK_BRUSH);
winclass.lpszMenuName = NULL;
winclass.lpszClassName = WINDOW_CLASS_NAME;
// register the window class
if (!RegisterClassEx(&winclass))
return(0);
// create the window
if (!(hwnd = CreateWindowEx(WS_EX_TOPMOST,
WINDOW_CLASS_NAME, // class
"You can't See This!", // title
WS_VISIBLE | WS_POPUP,
0,0, // x,y
GetSystemMetrics(SM_CXSCREEN),
GetSystemMetrics(SM_CYSCREEN),
NULL, // parent
NULL, // menu
hinstance, // instance
NULL))) // creation parms
return(0);
// hide the mouse cursor
ShowCursor(0);
// save the window handle
main_window_handle = hwnd;
// initialize direct draw
if (!DD_Init(hwnd))
{
DestroyWindow(hwnd);
return(0);
} // end if
// initialize game
Game_Init();
// enter main event loop
while(1)
{
if (PeekMessage(&msg,NULL,0,0,PM_REMOVE))
{
// test if this is a quit
if (msg.message == WM_QUIT)
break;
// translate any accelerator keys
TranslateMessage(&msg);
// send the message to the window proc
DispatchMessage(&msg);
} // end if
else
{
// do asynchronous processing here
// acquire pointer to video ram, note it is always linear
memset(&ddsd,0,sizeof(ddsd));
ddsd.dwSize = sizeof(ddsd);
lpddsprimary->Lock(NULL,&ddsd,DDLOCK_SURFACEMEMORYPTR,NULL);
video_buffer = (UCHAR *)ddsd.lpSurface;
// call main logic module
Game_Main();
// release pointer to video ram
lpddsprimary->Unlock(ddsd.lpSurface);
} // end else
} // end while
// shut down direct draw
DD_Shutdown();
// shutdown game
Game_Shutdown();
// return to Windows
return(msg.wParam);
} // end WinMain
// HERE ARE OUR GAME CONSOLE FUNCTIONS ///////////////////////////////////////////////////////
void Game_Init(void)
{
// do any initialization here
} // end Game_Init
/////////////////////////////////////////////////////////////////////////////////////////////
void Game_Shutdown(void)
{
// cleanup and release all resources here
} // end Game_Shutdown
/////////////////////////////////////////////////////////////////////////////////////////////
void Game_Main(void)
{
// process your game logic and draw next frame
// this function must exit each frame and return back to windows
// also this function is responsible for controlling the frame rate
// therefore, if you want the game to run at 30fps, then the function should
// take 1/30th of a second before returning
static int px = SCREEN_WIDTH/2, // position of player
py = SCREEN_HEIGHT/2,
color = 0; // color of blob 0..3, gray, red, green, blue
// on entry video_buffer is valid
// get input, note how keyboard is accessed with constants
//"VK_"
// these are defined in "winuser.h" are basically the
//scan codes
// for letters just use capital ASCII codes
if (KEY_DOWN(VK_ESCAPE))
PostMessage(main_window_handle,WM_CLOSE,0,0); // this is how you exit you game
// which way is player moving
if (KEY_DOWN(VK_RIGHT))
if (++px>SCREEN_WIDTH-8) px=8;
if (KEY_DOWN(VK_LEFT))
if (--px<8) px=SCREEN_WIDTH-8;
if (KEY_DOWN(VK_UP))
if (--py<8) py=SCREEN_HEIGHT-8;
if (KEY_DOWN(VK_DOWN))
if (++py>SCREEN_HEIGHT-8) py=8;
// adjust color, notice
if (KEY_DOWN('C'))
{
if (++color>=4)
color=0;
Sleep(100);
} // end if
// draw graphics
for (int pixels=0; pixels<32; pixels++)
video_buffer[(px-4+rand()%8)+(py-4+rand()%8)*SCREEN_WIDTH] = (color*64)+rand()%64;
// sync time (optional)
// use sleep to slow system down to 70ish fps
Sleep(14); // note that Sleep is extremly inaccurate, IRL you would use something more robust
// return and let windows have some time
} // end Game_Main
要编译这个程序并且运行它，你需要在工程中包括库文件 DDRAW.LIB ，和头文件 DDRAW.H 。他们通过设置搜索路径存在于你的 IDE 中或者是直接加到工程中去。你的目标程序，应该是一个标准的 Windows 程序。在建立了程序后，运行它，你应该可以看到一个炽热的水滴，并且可以通过方向键来移动它，<C> 键可以更改色彩，按 <ESC> 可以退出程序。现在你拥有了开始体验 DirectX 基础的所有东西了。你可以通过常量 SCREEN_WIDTH 和 SCREEN_HEIGHT 来尝试双缓冲、不同分辨率，甚至是调色板颜色变换。
现在，只剩下一个可能引起的问题了。如果你的显卡不能简单地为 DirectX 创建一个线形的显存模式的话，你必须直接仔细得操作显卡了。举个简单的例子，如果你创建了一个 640 象素每行，即在 640x480x256 色模式中，操作下一行的显存的话，你必须加上 640，或者是一般地操作一个象素点，你可以这样写：
video_buffer[x + y*640] = pixel;
无论如何，如果你的显卡无法支持线形内存的话，那么，你必须去修改一下，以便能直接真正地操作显存的“线形内存跨度”。这个值会比象素值大。举个例子，它在 640 个象素每行的模式中甚至可能是 1024 个象素的值。这个线形跨度能够通过锁定一个 DirectDraw 表面的描述来访问，像这样：
// 我们可以这样锁定
lpddsprimary->Lock(NULL,&ddsd,DDLOCK_SURFACEMEMORYPTR,NULL);
video_buffer = (UCHAR *)ddsd.lpSurface;
// 这里就是我们可以用于操作的值
int lpitch = ddsd.lPitch;
那么，我们可以通过下面的方法来直接操作显存了：
video_buffer[x + y*lpitch] = pixel;
因此，最安全的方法是去经常使用我们修改后得到的值。但是，这个方法牺牲了极大的性能。因此，你可能会去测试他们是否会是一个相等的值，然后使用一个不同的基于此原理的渲染函数。
[本文例子的源代码下载]
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