关于Directly Mapping Texels to Pixels的例子

原文：http://msdn.microsoft.com/en-us/library/bb219690%28v=vs.85%29.aspx

是关于在direct3d9中，对于屏幕空间中，将贴图映射到像素的问题

以下是pixel shader源代码（aaa.ps.txt）

texture MyTexture;sampler2D MySampler = sampler_state { Texture = <MyTexture>;MinFilter = LINEAR;MagFilter = LINEAR;AddressU = Clamp;AddressV = Clamp;};float4 TextureLookupPS(float2 vTexCoord : TEXCOORD0) : COLOR{return tex2D(MySampler, vTexCoord);} 

以下是主程序代码（main.cpp）

#include <d3d9.h>#include <d3dx9.h>#pragma comment(lib, "d3d9.lib")#pragma comment(lib, "d3dx9.lib")LPDIRECT3D9 g_pD3D = NULL;LPDIRECT3DDEVICE9 g_pd3dDevice = NULL;LPDIRECT3DTEXTURE9 g_pTexture = NULL;LPDIRECT3DPIXELSHADER9 g_pPS = NULL;LPD3DXCONSTANTTABLE g_pPSConstantTable;#define SAFE_RELEASE(p) if(p) {p->Release();}struct CUSTOMVERTEX{FLOAT x, y, z, rhw;FLOAT tu, tv;};#define D3DFVF_CUSTOMVERTEX (D3DFVF_XYZRHW|D3DFVF_TEX1)HRESULT Init(HWND hWnd){if(NULL == (g_pD3D = Direct3DCreate9(D3D_SDK_VERSION)))return E_FAIL;D3DPRESENT_PARAMETERS d3dpp = {0};d3dpp.Windowed = TRUE;d3dpp.SwapEffect = D3DSWAPEFFECT_DISCARD;d3dpp.BackBufferFormat = D3DFMT_UNKNOWN;if(FAILED(g_pD3D->CreateDevice(D3DADAPTER_DEFAULT, D3DDEVTYPE_HAL, hWnd, D3DCREATE_SOFTWARE_VERTEXPROCESSING, &d3dpp, &g_pd3dDevice)))return E_FAIL;if(FAILED(D3DXCreateTextureFromFile(g_pd3dDevice, L"aaa.bmp", &g_pTexture)))return E_FAIL;LPD3DXBUFFER pShader;LPD3DXBUFFER pErrorMsgs;if(FAILED(D3DXCompileShaderFromFile(L"aaa.ps.txt", NULL, NULL, "TextureLookupPS", "ps_2_0", 0, &pShader, &pErrorMsgs, &g_pPSConstantTable))){MessageBoxA(NULL, (LPSTR)pErrorMsgs->GetBufferPointer(), "Error", MB_OK);SAFE_RELEASE(pErrorMsgs);return E_FAIL;}if(FAILED(g_pd3dDevice->CreatePixelShader((DWORD *)pShader->GetBufferPointer(), &g_pPS)))return E_FAIL;SAFE_RELEASE(pShader);SAFE_RELEASE(pErrorMsgs);return S_OK;}VOID Render(void){HRESULT hres;hres = g_pd3dDevice->Clear(0, NULL, D3DCLEAR_TARGET, D3DCOLOR_XRGB( 0, 0, 255 ), 1.0f, 0);if(SUCCEEDED(hres = g_pd3dDevice->BeginScene())){CUSTOMVERTEX vertices[] ={{0.0f, 0.0f, 0.5f, 1.0f, 0.0f, 0.0f},{4.0f, 0.0f, 0.5f, 1.0f, 1.0f, 0.0f},{4.0f, 4.0f, 0.5f, 1.0f, 1.0f, 1.0f},{0.0f, 0.0f, 0.5f, 1.0f, 0.0f, 0.0f},{4.0f, 4.0f, 0.5f, 1.0f, 1.0f, 1.0f},{0.0f, 4.0f, 0.5f, 1.0f, 0.0f, 1.0f},};//for(int i = 0; i < sizeof(vertices) / sizeof(CUSTOMVERTEX); i++)//{//vertices[i].x -= 0.5f;//vertices[i].y -= 0.5f;//}hres = g_pd3dDevice->SetPixelShader(g_pPS);UINT TextureSamplerIndex = g_pPSConstantTable->GetSamplerIndex("MySampler");hres = g_pd3dDevice->SetTexture(TextureSamplerIndex, g_pTexture);hres = g_pd3dDevice->SetSamplerState(TextureSamplerIndex, D3DSAMP_MINFILTER, D3DTEXF_LINEAR);hres = g_pd3dDevice->SetSamplerState(TextureSamplerIndex, D3DSAMP_MAGFILTER, D3DTEXF_LINEAR);        hres = g_pd3dDevice->SetFVF(D3DFVF_CUSTOMVERTEX);        hres = g_pd3dDevice->DrawPrimitiveUP(D3DPT_TRIANGLELIST, 2, vertices, sizeof(CUSTOMVERTEX));hres = g_pd3dDevice->EndScene();}hres = g_pd3dDevice->Present(NULL, NULL, NULL, NULL);}VOID Cleanup(void){SAFE_RELEASE(g_pPSConstantTable);SAFE_RELEASE(g_pPS);SAFE_RELEASE(g_pTexture);SAFE_RELEASE(g_pd3dDevice);SAFE_RELEASE(g_pD3D);}LRESULT WINAPI MsgProc(HWND hWnd, UINT msg, WPARAM wParam, LPARAM lParam){switch( msg ){case WM_DESTROY:Cleanup();PostQuitMessage( 0 );return 0;}return DefWindowProc(hWnd, msg, wParam, lParam);}INT WINAPI wWinMain(HINSTANCE hInst, HINSTANCE, LPWSTR, INT){WNDCLASSEX wc = {sizeof( WNDCLASSEX ), CS_CLASSDC, MsgProc, 0L, 0L, GetModuleHandle( NULL ), NULL, NULL, NULL, NULL, L"MappingTexels", NULL};RegisterClassEx(&wc);HWND hWnd = CreateWindow(L"MappingTexels", L"MappingTexels", WS_OVERLAPPEDWINDOW, 100, 100, 300, 300, NULL, NULL, wc.hInstance, NULL);if(SUCCEEDED(Init(hWnd))){ShowWindow(hWnd, SW_SHOWDEFAULT);UpdateWindow(hWnd);MSG msg = {0};while(msg.message != WM_QUIT){if(PeekMessage(&msg, NULL, 0U, 0U, PM_REMOVE)){TranslateMessage(&msg);DispatchMessage(&msg);}elseRender();}}UnregisterClass(L"MappingTexels", wc.hInstance);return 0;}