先看看微软对这个头文件的定义：////// Copyright (C) Microsoft Corporation. All Rights Reserved.//// File: d3dx9.h// Content: D3DX utility library////#ifdef __D3DX_INTERNAL__#error Incorrect D3DX header used#endif#ifndef __D3DX9_H__#define __D3DX9_H__// Defines#include <limits.h>#define D3DX_DEFAULT ((UINT) -1)#define D3DX_DEFAULT_NONPOW2 ((UINT) -2)#define D3DX_DEFAULT_FLOAT FLT_MAX#define D3DX_FROM_FILE ((UINT) -3)#define D3DFMT_FROM_FILE ((D3DFORMAT) -3)#ifndef D3DXINLINE#ifdef _MSC_VER#if (_MSC_VER >= 1200)#define D3DXINLINE __forceinline#else#define D3DXINLINE __inline#endif#else#ifdef __cplusplus#define D3DXINLINE inline#else#define D3DXINLINE#endif#endif#endif// Includes#include "d3d9.h"#include "d3dx9math.h"#include "d3dx9core.h"#include "d3dx9xof.h"#include "d3dx9mesh.h"#include "d3dx9shader.h"#include "d3dx9effect.h"#include "d3dx9tex.h"#include "d3dx9shape.h"#include "d3dx9anim.h"// Errors#define _FACDD 0x876#define MAKE_DDHRESULT( code ) MAKE_HRESULT( 1, _FACDD, code )enum _D3DXERR {D3DXERR_CANNOTMODIFYINDEXBUFFER = MAKE_DDHRESULT(2900),D3DXERR_INVALIDMESH = MAKE_DDHRESULT(2901),D3DXERR_CANNOTATTRSORT = MAKE_DDHRESULT(2902),D3DXERR_SKINNINGNOTSUPPORTED = MAKE_DDHRESULT(2903),D3DXERR_TOOMANYINFLUENCES = MAKE_DDHRESULT(2904),D3DXERR_INVALIDDATA = MAKE_DDHRESULT(2905),D3DXERR_LOADEDMESHASNODATA = MAKE_DDHRESULT(2906),D3DXERR_DUPLICATENAMEDFRAGMENT = MAKE_DDHRESULT(2907),D3DXERR_CANNOTREMOVELASTITEM = MAKE_DDHRESULT(2908),};#endif //__D3DX9_H__
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我们可以看出，其实这就是一个包含d3dx9XXX.h头文件的大礼包。
需要注意的是，当我们已经包了d3dx9.h 头文件的时候，就无需再包含d3d9.h 头文件了。
