Lesson 9:全屏
课程预览
让你的游戏全屏很简单，但是需要在程序中改变一些细节，同时添加几行代码。
本课我们将介绍两个事情。首先我们将介绍如何全局化你的屏幕分辨率。第二，我们介绍使窗口全屏和退出全屏模式的技术细节。
设置屏幕大小
纵观你的DirectX体验和游戏开发你会碰到很多函数和结构需要你的屏幕尺寸。这在你稍后决定改变分辨率的时候会是个麻烦，尤其是你决定在运行时改变它。
现在，我们介绍一个简单的方法标准化你的屏幕尺寸。
首先，我们必须在程序顶部添加两个指令。这些东西代表了屏幕的宽和高。
// define the screen resolution
#define SCREEN_WIDTH 800
#define SCREEN_HEIGHT 600下一步就是浏览你的程序指定在哪里放置窗口的宽和高。改变的代码粗体显示：
hWnd = CreateWindowEx(NULL,
L"WindowClass",
L"Our Direct3D Program",
WS_OVERLAPPEDWINDOW,
300, 300,
SCREEN_WIDTH, SCREEN_HEIGHT, // set window to new resolution
NULL,
NULL,
hInstance,
NULL);还有这里：
viewport.TopLeftX = 0;
viewport.TopLeftY = 0;
viewport.Width = SCREEN_WIDTH;
viewport.Height = SCREEN_HEIGHT;后面的课程我们会介绍在运行中改变窗口如何维护屏幕尺寸。
常见的PC屏幕尺寸如下表：
改变到全屏模式
尽管大部分游戏都在全局模式下玩耍，还是有很多游戏支持窗口模式和全屏模式间转换。通常用Alt+Enter键做到这点。
更新到全屏有几件事情必须做：
1.窗口修改为无背景。
2.设置后台缓冲为一个特定的大小。
3.设置当按下Alt-Enter键时自动切换DirectX.
4.修改CleanD3D（）函数在关闭的时候关掉全屏。
1.窗口修改为无背景
移除窗口背景只需要注释掉WINDOWCLASSEX结构的一个成员（那个用来设置背景颜色的家伙）。这意味着在游戏开始时窗口有一两秒是看不到的。
// wc.hbrBackground = (HBRUSH)COLOR_WINDOW;2.设置后台缓冲为一个特定的大小
下一步是告诉DirectX关于我们的新屏幕的分辨率。这点我们通过在scd结构中做一些修来达到。
void initD3D(HWND hWnd)
{
DXGI_SWAP_CHAIN_DESC scd; // create a struct to hold various swap chain information
ZeroMemory(&scd, sizeof(DXGI_SWAP_CHAIN_DESC)); // clear out the struct for use
scd.BufferCount = 1; // one back buffer
scd.BufferDesc.Format = DXGI_FORMAT_R8G8B8A8_UNORM; // use 32-bit color
scd.BufferDesc.Width = SCREEN_WIDTH; // set the back buffer width
scd.BufferDesc.Height = SCREEN_HEIGHT; // set the back buffer height
scd.BufferUsage = DXGI_USAGE_RENDER_TARGET_OUTPUT; // how swap chain is to be used
scd.OutputWindow = hWnd; // the window to be used
scd.SampleDesc.Count = 1; // how many multisamples
scd.SampleDesc.Quality = 0; // multisample quality level
scd.Windowed = TRUE; // windowed/full-screen mode
// ...3.设置当按下Alt-Enter键时自动切换DirectX
这步很简单，只要在scd结构中添加一个标记。在Flags成员的位置填上DXGI_SWAP_CHAIN_DESC。
void initD3D(HWND hWnd)
{
DXGI_SWAP_CHAIN_DESC scd; // create a struct to hold various swap chain information
ZeroMemory(&scd, sizeof(DXGI_SWAP_CHAIN_DESC)); // clear out the struct for use
scd.BufferCount = 1; // one back buffer
scd.BufferDesc.Format = DXGI_FORMAT_R8G8B8A8_UNORM; // use 32-bit color
scd.BufferDesc.Width = SCREEN_WIDTH; // set the back buffer width
scd.BufferDesc.Height = SCREEN_HEIGHT; // set the back buffer height
scd.BufferUsage = DXGI_USAGE_RENDER_TARGET_OUTPUT; // how swap chain is to be used
scd.OutputWindow = hWnd; // the window to be used
scd.SampleDesc.Count = 1; // how many multisamples
scd.SampleDesc.Quality = 0; // multisample quality level
scd.Windowed = TRUE; // windowed/full-screen mode
scd.Flags = DXGI_SWAP_CHAIN_FLAG_ALLOW_MODE_SWITCH; // allow full-screen switching
// ...4.修改CleanD3D（）函数
实际上Direct3D在全屏模式下是无法关闭的。这归咎于某些线程问题发生在幕后。为了正确关闭，我们必须确保我们处于窗口模式。我们可以使用SetFullscreenState()函数做到这点。下面是新的CleanD3D（）函数：
// this is the function that cleans up Direct3D and COM
void CleanD3D(void)
{
swapchain->SetFullscreenState(FALSE, NULL); // switch to windowed mode
// close and release all existing COM objects
swapchain->Release();
backbuffer->Release();
dev->Release();
devcon->Release();
}函数的第一个参数FALSE是指窗口模式，TRUE表示全屏模式。
第二个参数一个特征，可以允许你选择使用什么显示适配器。
这在特定情况下很有用，例如你使用多显示器，但是对于几乎所有的游戏你只需要设置这个值为NULL，它就会选择正确的适配器了。
完整项目
// include the basic windows header files and the Direct3D header files
#include <windows.h>
#include <windowsx.h>
#include <d3d11.h>
#include <d3dx11.h>
#include <d3dx10.h>
// include the Direct3D Library file
#pragma comment (lib, "d3d11.lib")
#pragma comment (lib, "d3dx11.lib")
#pragma comment (lib, "d3dx10.lib")
// define the screen resolution
#define SCREEN_WIDTH 800
#define SCREEN_HEIGHT 600
// global declarations
IDXGISwapChain *swapchain; // the pointer to the swap chain interface
ID3D11Device *dev; // the pointer to our Direct3D device interface
ID3D11DeviceContext *devcon; // the pointer to our Direct3D device context
ID3D11RenderTargetView *backbuffer; // the pointer to our back buffer
// function prototypes
void InitD3D(HWND hWnd); // sets up and initializes Direct3D
void RenderFrame(void); // renders a single frame
void CleanD3D(void); // closes Direct3D and releases memory
// the WindowProc function prototype
LRESULT CALLBACK WindowProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam);
// the entry point for any Windows program
int WINAPI WinMain(HINSTANCE hInstance,
HINSTANCE hPrevInstance,
LPSTR lpCmdLine,
int nCmdShow)
{
HWND hWnd;
WNDCLASSEX wc;
ZeroMemory(&wc, sizeof(WNDCLASSEX));
wc.cbSize = sizeof(WNDCLASSEX);
wc.style = CS_HREDRAW | CS_VREDRAW;
wc.lpfnWndProc = WindowProc;
wc.hInstance = hInstance;
wc.hCursor = LoadCursor(NULL, IDC_ARROW);
// wc.hbrBackground = (HBRUSH)COLOR_WINDOW; // no longer needed
wc.lpszClassName = L"WindowClass";
RegisterClassEx(&wc);
RECT wr = {0, 0, SCREEN_WIDTH, SCREEN_HEIGHT};
AdjustWindowRect(&wr, WS_OVERLAPPEDWINDOW, FALSE);
hWnd = CreateWindowEx(NULL,
L"WindowClass",
L"Our First Direct3D Program",
WS_OVERLAPPEDWINDOW,
300,
300,
wr.right - wr.left,
wr.bottom - wr.top,
NULL,
NULL,
hInstance,
NULL);
ShowWindow(hWnd, nCmdShow);
// set up and initialize Direct3D
InitD3D(hWnd);
// enter the main loop:
MSG msg;
while(TRUE)
{
if(PeekMessage(&msg, NULL, 0, 0, PM_REMOVE))
{
TranslateMessage(&msg);
DispatchMessage(&msg);
if(msg.message == WM_QUIT)
break;
}
RenderFrame();
}
// clean up DirectX and COM
CleanD3D();
return msg.wParam;
}
// this is the main message handler for the program
LRESULT CALLBACK WindowProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
{
switch(message)
{
case WM_DESTROY:
{
PostQuitMessage(0);
return 0;
} break;
}
return DefWindowProc (hWnd, message, wParam, lParam);
}
// this function initializes and prepares Direct3D for use
void InitD3D(HWND hWnd)
{
// create a struct to hold information about the swap chain
DXGI_SWAP_CHAIN_DESC scd;
// clear out the struct for use
ZeroMemory(&scd, sizeof(DXGI_SWAP_CHAIN_DESC));
// fill the swap chain description struct
scd.BufferCount = 1; // one back buffer
scd.BufferDesc.Format = DXGI_FORMAT_R8G8B8A8_UNORM; // use 32-bit color
scd.BufferDesc.Width = SCREEN_WIDTH; // set the back buffer width
scd.BufferDesc.Height = SCREEN_HEIGHT; // set the back buffer height
scd.BufferUsage = DXGI_USAGE_RENDER_TARGET_OUTPUT; // how swap chain is to be used
scd.OutputWindow = hWnd; // the window to be used
scd.SampleDesc.Count = 4; // how many multisamples
scd.Windowed = TRUE; // windowed/full-screen mode
scd.Flags = DXGI_SWAP_CHAIN_FLAG_ALLOW_MODE_SWITCH; // allow full-screen switching
// create a device, device context and swap chain using the information in the scd struct
D3D11CreateDeviceAndSwapChain(NULL,
D3D_DRIVER_TYPE_HARDWARE,
NULL,
NULL,
NULL,
NULL,
D3D11_SDK_VERSION,
&scd,
&swapchain,
&dev,
NULL,
&devcon);
// get the address of the back buffer
ID3D11Texture2D *pBackBuffer;
swapchain->GetBuffer(0, __uuidof(ID3D11Texture2D), (LPVOID*)&pBackBuffer);
// use the back buffer address to create the render target
dev->CreateRenderTargetView(pBackBuffer, NULL, &backbuffer);
pBackBuffer->Release();
// set the render target as the back buffer
devcon->OMSetRenderTargets(1, &backbuffer, NULL);
// Set the viewport
D3D11_VIEWPORT viewport;
ZeroMemory(&viewport, sizeof(D3D11_VIEWPORT));
viewport.TopLeftX = 0;
viewport.TopLeftY = 0;
viewport.Width = SCREEN_WIDTH;
viewport.Height = SCREEN_HEIGHT;
devcon->RSSetViewports(1, &viewport);
}
// this is the function used to render a single frame
void RenderFrame(void)
{
// clear the back buffer to a deep blue
devcon->ClearRenderTargetView(backbuffer, D3DXCOLOR(0.0f, 0.2f, 0.4f, 1.0f));
// do 3D rendering on the back buffer here
// switch the back buffer and the front buffer
swapchain->Present(0, 0);
}
// this is the function that cleans up Direct3D and COM
void CleanD3D(void)
{
swapchain->SetFullscreenState(FALSE, NULL); // switch to windowed mode
// close and release all existing COM objects
swapchain->Release();
backbuffer->Release();
dev->Release();
devcon->Release();
}
你的程序应该像这个样子：一个蓝色矩形
Ready...Set...
棒极了！
练习
1.改变程序的分辨率直到你对各种可选的分辨率都熟悉了。
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