alpha混合原理（转）
alpha混合原理
在前面介绍的示例程序中，绘制图形的颜色总是替换当前颜色缓冲区中存在的颜色，这样后面的物体总是覆盖在原有的物体上。但是当想要绘制类似于玻璃、水等具有透明效果的物体时，这种方法显然满足不了要求。通过定义一个表示物体半透明度的alpha值和一个半透明计算公式，可以将要绘制的物体颜色与颜色缓冲区中存在的颜色相混合，从而绘制出具有半透明效果的物体。Direct3D计算alpha颜色混合的方法如下：
Ksrc) OP (RGBdst&* Kdst)
其中color表示alpha混合后的颜色值，RGBsrc表示源颜色值，即将要绘制的图元的颜色值；Ksrc表示源混合系数，通常赋值为表示半透明程度的alpha值，也可以是属于枚举类型D3DBLEND的任意值，用来和RGBsrc相乘。RGBdst表示目标颜色值，即当前颜色缓冲区中的颜色值，Kdst表示目标混合系数，可以是属于枚举D3DBLEND的任意值，用来和RGBdst相乘。OP表示源计算结果与颜色缓冲区计算结果的混合方法，默认状态下OP为D3DBLEND_ADD，即源计算结果与颜色缓冲区计算结果相加。
图形显示中，对alpha混合最普遍的用法是：把Ksrc赋值为D3DBLEND_SRCALPHA，即当前绘制像素的alpha值；把Kdst赋值为D3DBLEND_INVSRCALPHA，即1减去当前绘制像素的alpha值；把OP赋值为D3DBLEND_ADD，使源计算结果和颜色缓冲区计算结果相加，这样一来，alpha混合颜色的公式变为：
Ksrc) + (RGBdst&* Kdst)
上面的设置可以较好地模拟大多数半透明物体的效果。
启用alpha混合
想要绘制半透明物体，首先需要激活Direct3D的alpha混合运算，调用Direct3D渲染状态设置函数IDirect3DDevice9:::SetRenderState()，将第一个参数设置为D3DRS_ALPHABLENDENABLE，第二个参数设置为TRUE，可以激活alpha混合，代码如下：
g_device-&SetRenderState(D3DRS_ALPHABLENDENABLE,
设置alpha混合系数
在上面介绍的alpha混合原理中提到的源混合系数和目标混合系数，也是通过Direct3D渲染状态设置函数IDirect3DDevice9::SetRenderState()设置的。若将第一个参数设置为D3DRS_SRCBLEND，则用于设置源混合系数，若将第一个参数设置为D3DRS_DESTBLEND，则用于设置目标混合系数，第二个参数可以设置为D3DBLEND枚举常量，各具体枚举常量的含义如下：
Defines the
supported blend mode.
typedef enum D3DBLEND
D3DBLEND_ZERO = 1,
D3DBLEND_ONE = 2,
D3DBLEND_SRCCOLOR = 3,
D3DBLEND_INVSRCCOLOR = 4,
D3DBLEND_SRCALPHA = 5,
D3DBLEND_INVSRCALPHA = 6,
D3DBLEND_DESTALPHA = 7,
D3DBLEND_INVDESTALPHA = 8,
D3DBLEND_DESTCOLOR = 9,
D3DBLEND_INVDESTCOLOR = 10,
D3DBLEND_SRCALPHASAT = 11,
D3DBLEND_BOTHSRCALPHA = 12,
D3DBLEND_BOTHINVSRCALPHA = 13,
D3DBLEND_BLENDFACTOR = 14,
D3DBLEND_INVBLENDFACTOR = 15,
D3DBLEND_SRCCOLOR2 = 16,
D3DBLEND_INVSRCCOLOR2 = 17,
D3DBLEND_FORCE_DWORD = 0x7fffffff,
} D3DBLEND, *LPD3DBLEND;
D3DBLEND_ZERO
Blend factor is (0, 0, 0, 0).
D3DBLEND_ONE
Blend factor is (1, 1, 1, 1).
D3DBLEND_SRCCOLOR
Blend factor is (Rs, Gs, Bs, As).
D3DBLEND_INVSRCCOLOR
Blend factor is (1 - Rs, 1 - Gs, 1 - Bs, 1 - As).
D3DBLEND_SRCALPHA
Blend factor is (As, As, As, As).
D3DBLEND_INVSRCALPHA
Blend factor is ( 1 - As, 1 - As, 1 - As, 1 - As).
D3DBLEND_DESTALPHA
Blend factor is (Ad&Ad&Ad&Ad).
D3DBLEND_INVDESTALPHA
Blend factor is (1 - Ad&1 - Ad&1 - Ad&1 - Ad).
D3DBLEND_DESTCOLOR
Blend factor is (Rd, Gd, Bd, Ad).
D3DBLEND_INVDESTCOLOR
Blend factor is (1 - Rd, 1 - Gd, 1 - Bd, 1 - Ad).
D3DBLEND_SRCALPHASAT
Blend factor is (f, f, f, 1); where f =
min(As, 1 - Ad).
D3DBLEND_BOTHSRCALPHA
Obsolete. Starting with DirectX 6, you can
achieve the same effect by setting the source and destination blend
factors to D3DBLEND_SRCALPHA and D3DBLEND_INVSRCALPHA in separate
D3DBLEND_BOTHINVSRCALPHA
Source blend factor is (1 - As, 1 - As, 1 - As, 1 - As), and destination blend factor is
(As, As, As, As); the destination blend selection is
overridden. This blend mode is supported only for the
D3DRS_SRCBLEND render state.
D3DBLEND_BLENDFACTOR
Constant color blending factor used by the
frame-buffer blender. This blend mode is supported only if
D3DPBLENDCAPS_BLENDFACTOR is set in
the&SrcBlendCaps&or&DestBlendCaps&members
of D3DCAPS9.
D3DBLEND_INVBLENDFACTOR
Inverted constant color-blending factor used
by the frame-buffer blender. This blend mode is supported only if
the D3DPBLENDCAPS_BLENDFACTOR bit is set in
the&SrcBlendCaps&or&DestBlendCapsmembers
of&D3DCAPS9.
D3DBLEND_SRCCOLOR2
Blend factor is (PSOutColor[1]r, PSOutColor[1]g, PSOutColor[1]b, not used). See Render Target
Differences between Direct3D 9 and Direct3D
This flag is
available in Direct3D 9Ex only.
D3DBLEND_INVSRCCOLOR2
Blend factor is (1 - PSOutColor[1]r, 1 - PSOutColor[1]g, 1 - PSOutColor[1]b, not used)). See Render Target
Differences between Direct3D 9 and Direct3D
This flag is
available in Direct3D 9Ex only.
D3DBLEND_FORCE_DWORD
Forces this enumeration to compile to 32 bits
in size. Without this value, some compilers would allow this
enumeration to compile to a size other than 32 bits. This value is
In the preceding
member descriptions, the RGBA values of the source and destination
are indicated by the&s&andd&subscripts.
The values in this
enumerated type are used by the following render states:
D3DRS_DESTBLEND
D3DRS_SRCBLEND
D3DRS_DESTBLENDALPHA
D3DRS_SRCBLENDALPHA
D3DRENDERSTATETYPE
Render Target Blending
Direct3D 9Ex has
improved text rendering capabilities. Rendering clear-type fonts
would normally require two passes. To eliminate the second pass, a
pixel shader can be used to output two colors, which we can call
PSOutColor[0] and PSOutColor[1]. The first color would contain the
standard 3 color components (RGB). The second color would contain 3
alpha components (one for each component of the first
These new blending
modes are only used for text rendering on the first render
设置alpha混合系数的代码示例如下：
g_device-&SetRenderState(D3DRS_SRCBLEND,
D3DBLEND_SRCALPHA);
g_device-&SetRenderState(D3DRS_DESTBLEND,
D3DBLEND_INVSRCALPHA);
设置alpha混合方法
alpha混合方法指定源颜色和目标颜色的混合方法，通过Direct3D渲染状态设置函数IDirect3DDevice9::SetRenderState()设置，其中第一个参数设置为
D3DRS_BLENDOP，第二个参数设置为D3DBLENDOP枚举常量，各常量的含义如下：
Defines the supported blend
operations. See Remarks for definitions of terms.
typedef enum D3DBLENDOP
D3DBLENDOP_ADD = 1,
D3DBLENDOP_SUBTRACT = 2,
D3DBLENDOP_REVSUBTRACT = 3,
D3DBLENDOP_MIN = 4,
D3DBLENDOP_MAX = 5,
D3DBLENDOP_FORCE_DWORD = 0x7fffffff,
} D3DBLENDOP, *LPD3DBLENDOP;
D3DBLENDOP_ADD
The result
is the destination added to the source. Result = Source +
Destination
D3DBLENDOP_SUBTRACT
The result
is the destination subtracted from to the source. Result = Source -
Destination
D3DBLENDOP_REVSUBTRACT
The result
is the source subtracted from the destination. Result = Destination
D3DBLENDOP_MIN
The result
is the minimum of the source and destination. Result = MIN(Source,
Destination)
D3DBLENDOP_MAX
The result
is the maximum of the source and destination. Result = MAX(Source,
Destination)
D3DBLENDOP_FORCE_DWORD
Forces this
enumeration to compile to 32 bits in size. Without this value, some
compilers would allow this enumeration to compile to a size other
than 32 bits. This value is not used.
Source, Destination, and
Result are defined as:
Description
Color of the
source pixel before the operation.
Destination
Color of the
pixel in the destination buffer before the operation.
value that is the blended color resulting from the
operation.
This enumerated type defines
values used by the following render states:
D3DRS_BLENDOP
D3DRS_BLENDOPALPHA
示例程序：
该示例程序模拟了直升飞机螺旋桨的半透明效果。在程序的初始化阶段，载入Heli.x文件，它是一个包含直升飞机的三维模型文件，其中螺旋桨的材质漫反射属性为（R,
G, B, A） = (0....500000;
)，可以用文本方式打开Heli.x查看它的材质属性，Heli.x是一个文本格式的.x文件。
示例程序中没有设置alpha混合方法，所以应用程序将采用默认的alpha混合方法D3DBLEND_ADD，即将源计算结果与颜色缓冲区计算结果相加。由于直升机螺旋桨的材质的alpha值为0.5f，因此它的最终颜色就是50%的玻璃颜色加上50%的背景颜色。
按下数字键"1"，激活alpha混合。
按下数字键"0"，禁用alpha混合。
设置alpha混合方法为D3DBLENDOP_SUBTRACT的效果图，启用alpha混合时。
g_device-&SetRenderState(D3DRS_BLENDOP,
D3DBLENDOP_SUBTRACT);
设置以下代码时的效果图，可以看到直升机变亮了，启用alpha混合：
g_device-&SetRenderState(D3DRS_SRCBLEND,
D3DBLEND_ONE);
g_device-&SetRenderState(D3DRS_DESTBLEND,
D3DBLEND_DESTCOLOR);
设置以下代码时的效果图，可以看到直升机变暗了，启用alpha混合：
g_device-&SetRenderState(D3DRS_SRCBLEND,
D3DBLEND_ONE);
g_device-&SetRenderState(D3DRS_DESTBLEND,
D3DBLEND_INVDESTCOLOR);
可以根据需要自己修改设置，以实现不同的颜色混合效果。
由于alpha混合是当前绘制的像素颜色与颜色缓冲区中存在的颜色的混合运算，因此，在绘制半透明物体前，必须保证位于半透明物体后的物体先于半透明物体绘制，也就是说，先绘制不透明物体，再绘制半透明物体。
有些计算机硬件由于功能的限制，可能不支持某些混合方法，这时Direct3D会自动使用alpha混合方法D3DBLENDOP_ADD。
#include&&d3dx9.h&
#pragma&warning(disable&:&4127)
#define&CLASS_NAME&&&&"GameApp"
#define&release_com(p)&&&&do&{&if(p)&{&(p)-&Release();&(p)&=&NULL;&}&}&while(0)
IDirect3D9*&&&&&&&&&&&&&&&&g_d3d;
IDirect3DDevice9*&&&&&&&&g_
ID3DXMesh*&&&&&&&&&&&&&&&&g_
D3DMATERIAL9*&&&&&&&&&&&&g_mesh_
IDirect3DTexture9**&&&&&&&&g_mesh_
DWORD&&&&&&&&&&&&&&&&&&&&g_num_
void&setup_world_matrix()
&&&&D3DXMATRIX&mat_
&&&&D3DXMatrixRotationY(&mat_world,&timeGetTime()&/&1000.0f);
&&&&g_device-&SetTransform(D3DTS_WORLD,&&mat_world);
void&setup_view_proj_matrices()
&&&&//&setup&view&matrix
&&&&D3DXVECTOR3&eye(0.0f,&15.0f,&-20.0f);
&&&&D3DXVECTOR3&at(0.0f,&&0.0f,&&&0.0f);
&&&&D3DXVECTOR3&up(0.0f,&&1.0f,&&&0.0f);
&&&&D3DXMATRIX&mat_
&&&&D3DXMatrixLookAtLH(&mat_view,&&eye,&&at,&&up);
&&&&g_device-&SetTransform(D3DTS_VIEW,&&mat_view);
&&&&//&setup&projection&matrix
&&&&D3DXMATRIX&mat_
&&&&D3DXMatrixPerspectiveFovLH(&mat_proj,&D3DX_PI/4,&1.0f,&1.0f,&500.0f);
&&&&g_device-&SetTransform(D3DTS_PROJECTION,&&mat_proj);
bool&init_geometry()
&&&&ID3DXBuffer*&material_
&&&&if(FAILED(D3DXLoadMeshFromX("heli.x",&D3DXMESH_SYSTEMMEM,&g_device,&NULL,&&material_buffer,&NULL,
&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&g_num_materials,&&g_mesh)))
&&&&&&&&MessageBox(NULL,&"Could&not&find&heli.x",&"ERROR",&MB_OK);
&&&&&&&&return&false;
&&&&D3DXMATERIAL*&xmaterials&=&(D3DXMATERIAL*)&material_buffer-&GetBufferPointer();
&&&&g_mesh_materials&=&new&D3DMATERIAL9[g_num_materials];
&&&&g_mesh_textures&&&&&=&new&IDirect3DTexture9*[g_num_materials];
&&&&for(DWORD&i&=&0;&i&&&g_num_&i++)
&&&&&&&&g_mesh_materials[i]&=&xmaterials[i].MatD3D;
&&&&&&&&//&set&ambient&reflected&coefficient,&because&.x&file&do&not&set&it.
&&&&&&&&g_mesh_materials[i].Ambient&=&g_mesh_materials[i].D
&&&&&&&&g_mesh_textures[i]&=&NULL;
&&&&&&&&if(xmaterials[i].pTextureFilename&!=&NULL&&&&strlen(xmaterials[i].pTextureFilename)&&&0)&&&&
&&&&&&&&&&&&D3DXCreateTextureFromFile(g_device,&xmaterials[i].pTextureFilename,&&g_mesh_textures[i]);&&&&
&&&&material_buffer-&Release();
&&&&return&true;
bool&init_d3d(HWND&hwnd)
&&&&g_d3d&=&Direct3DCreate9(D3D_SDK_VERSION);
&&&&if(g_d3d&==&NULL)
&&&&&&&&return&false;
&&&&D3DPRESENT_PARAMETERS&d3
&&&&ZeroMemory(&d3dpp,&sizeof(d3dpp));
&&&&d3dpp.Windowed&&&&&&&&&&&&&&&&&&&&=&TRUE;
&&&&d3dpp.SwapEffect&&&&&&&&&&&&&&&&=&D3DSWAPEFFECT_DISCARD;
&&&&d3dpp.BackBufferFormat&&&&&&&&&&&&=&D3DFMT_UNKNOWN;
&&&&d3dpp.EnableAutoDepthStencil&&&&=&TRUE;
&&&&d3dpp.AutoDepthStencilFormat&&&&=&D3DFMT_D16;
&&&&if(FAILED(g_d3d-&CreateDevice(D3DADAPTER_DEFAULT,&D3DDEVTYPE_HAL,&hwnd,&D3DCREATE_SOFTWARE_VERTEXPROCESSING,
&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&d3dpp,&&g_device)))
&&&&&&&&return&false;
&&&&if(!&init_geometry())
&&&&&&&&return&false;
&&&&setup_view_proj_matrices();&&&&
&&&&g_device-&SetRenderState(D3DRS_ALPHABLENDENABLE,&TRUE);
&&&&g_device-&SetRenderState(D3DRS_SRCBLEND,&&&&&&&&&D3DBLEND_SRCALPHA);
&&&&g_device-&SetRenderState(D3DRS_DESTBLEND,&&&&&&&&&D3DBLEND_INVSRCALPHA);&&&&
&&&&//g_device-&SetRenderState(D3DRS_SRCBLEND,&&&&&&&&&D3DBLEND_ONE);
&&&&//g_device-&SetRenderState(D3DRS_DESTBLEND,&&&&&&&&&D3DBLEND_INVDESTCOLOR);&&&&
&&&&//g_device-&SetRenderState(D3DRS_BLENDOP,&&&&&&&&&&&&&D3DBLENDOP_SUBTRACT);&&&&&&&&
&&&&g_device-&SetRenderState(D3DRS_ZENABLE,&&&&&&&&&TRUE);
&&&&g_device-&SetRenderState(D3DRS_ZFUNC,&&&&&&&&&D3DCMP_LESS);
&&&&g_device-&SetRenderState(D3DRS_ZWRITEENABLE,&TRUE);
&&&&g_device-&SetRenderState(D3DRS_AMBIENT,&0xFFFFBB55);
&&&&return&true;
void&cleanup()
&&&&delete[]&g_mesh_
&&&&if(g_mesh_textures)
&&&&&&&&for(DWORD&i&=&0;&i&&&g_num_&i++)
&&&&&&&&&&&&release_com(g_mesh_textures[i]);
&&&&&&&&delete[]&g_mesh_
&&&&release_com(g_mesh);
&&&&release_com(g_device);
&&&&release_com(g_d3d);
void&render()
&&&&g_device-&Clear(0,&NULL,&D3DCLEAR_TARGET&|&D3DCLEAR_ZBUFFER,&D3DCOLOR_XRGB(5,&5,&5),&1.0f,&0);
&&&&g_device-&BeginScene();
&&&&setup_world_matrix();
&&&&//&render&opaque&object&first
&&&&for(DWORD&i&=&0;&i&&&g_num_&i++)
&&&&&&&&if(g_mesh_materials[i].Diffuse.a&==&1.0f)
&&&&&&&&&&&&g_device-&SetMaterial(&g_mesh_materials[i]);
&&&&&&&&&&&&g_device-&SetTexture(0,&g_mesh_textures[i]);
&&&&&&&&&&&&g_mesh-&DrawSubset(i);
&&&&&&&&}&&&&&&&&
&&&&}&&&&&&&&
&&&&//&render&transparent&object&second
&&&&for(DWORD&i&=&0;&i&&&g_num_&i++)
&&&&&&&&if(g_mesh_materials[i].Diffuse.a&!=&1.0f)
&&&&&&&&&&&&g_device-&SetMaterial(&g_mesh_materials[i]);
&&&&&&&&&&&&g_device-&SetTexture(0,&g_mesh_textures[i]);
&&&&&&&&&&&&g_mesh-&DrawSubset(i);
&&&&&&&&}&&&&&&&&
&&&&}&&&&&&&&
&&&&g_device-&EndScene();
&&&&g_device-&Present(NULL,&NULL,&NULL,&NULL);
LRESULT&WINAPI&WinProc(HWND&hwnd,&UINT&msg,&WPARAM&wParam,&LPARAM&lParam)
&&&&switch(msg)
&&&&case&WM_KEYDOWN:
&&&&&&&&switch(wParam)
&&&&&&&&case&48:&//&press&key&"0",&disable&alpha&blend.
&&&&&&&&&&&&g_device-&SetRenderState(D3DRS_ALPHABLENDENABLE,&FALSE);
&&&&&&&&&&&&break;
&&&&&&&&case&49:&//&press&key&"1",&enable&alpha&blend.
&&&&&&&&&&&&g_device-&SetRenderState(D3DRS_ALPHABLENDENABLE,&TRUE);
&&&&&&&&&&&&break;
&&&&&&&&case&VK_ESCAPE:
&&&&&&&&&&&&DestroyWindow(hwnd);
&&&&&&&&&&&&break;
&&&&&&&&}&&&&
&&&&&&&&break;
&&&&case&WM_DESTROY:
&&&&&&&&PostQuitMessage(0);
&&&&&&&&return&0;
&&&&return&DefWindowProc(hwnd,&msg,&wParam,&lParam);
int&WINAPI&WinMain(HINSTANCE&inst,&HINSTANCE,&LPSTR,&INT)
&&&&WNDCLASSEX&
&&&&wc.cbSize&&&&&&&&&&&&=&sizeof(WNDCLASSEX);
&&&&wc.style&&&&&&&&&&&&=&CS_CLASSDC;
&&&&wc.lpfnWndProc&&&&&&&&=&WinP
&&&&wc.cbClsExtra&&&&&&&&=&0;
&&&&wc.cbWndExtra&&&&&&&&=&0;
&&&&wc.hInstance&&&&&&&&=&
&&&&wc.hIcon&&&&&&&&&&&&=&NULL;
&&&&wc.hCursor&&&&&&&&&&&&=&NULL;
&&&&wc.hbrBackground&&&&=&NULL;
&&&&wc.lpszMenuName&&&&&&&&=&NULL;
&&&&wc.lpszClassName&&&&=&CLASS_NAME;
&&&&wc.hIconSm&&&&&&&&&&&&=&NULL;
&&&&if(!&RegisterClassEx(&wc))
&&&&&&&&return&-1;
&&&&HWND&hwnd&=&CreateWindow(CLASS_NAME,&"Direct3D&App",&WS_OVERLAPPEDWINDOW,&200,&100,&640,&480,
&&&&&&&&&&&&&&&&&&&&&&&&&&&&&NULL,&NULL,&wc.hInstance,&NULL);&&&&
&&&&if(hwnd&==&NULL)
&&&&&&&&return&-1;
&&&&if(init_d3d(hwnd))
&&&&&&&&ShowWindow(hwnd,&SW_SHOWDEFAULT);
&&&&&&&&UpdateWindow(hwnd);
&&&&&&&&MSG&
&&&&&&&&ZeroMemory(&msg,&sizeof(msg));
&&&&&&&&while(msg.message&!=&WM_QUIT)
&&&&&&&&&&&&if(PeekMessage(&msg,&NULL,&0,&0,&PM_REMOVE))
&&&&&&&&&&&&{
&&&&&&&&&&&&&&&&TranslateMessage(&msg);
&&&&&&&&&&&&&&&&DispatchMessage(&msg);
&&&&&&&&&&&&}
&&&&&&&&&&&&&&&&
&&&&&&&&&&&&render();
&&&&cleanup();
&&&&UnregisterClass(CLASS_NAME,&wc.hInstance);&&&&
&&&&return&0;
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如何使用STL中的transform这个algorithm
提问者采纳
;int&algorithm& }int main () {
vector& &#47。函数原型: 10 20 30 40 50
second: 21 41 61 81 101
cout &lt, class UnaryFunction& &iostream&
cout &#include &&#47: 11 21 31 41 51
transform (first.resize( i&lt,
InputIterator1 _Last1:template& *it,using namespace std, class InputIterator2,
class BinaryFunction& template&
for (it=first,
InputIterator _Last1:
for (int i=1;&class InputI/ i++)&
return 0:;vector& &quot,
OutputIterator _Result, class OutputI.end().begin(); &lt.begin();class InputIterator1;
OutputIterator transform(
InputIterator _First1.size());/&#47.begin();&#47, op_increase),
OutputIterator _Result.end();first contains,6;int& ++it)
UnaryFunction _Func
BinaryFunction _Func
); }int op_sum (int i, it, class OutputIterator.end(); endl.push_back (i*10);int& second.begin(); allocate space
transform (
OutputIterator transform(
InputIterator1 _First1;
vector&int op_increase (int i) { return ++i,
InputIterator2 _First2;
&#47,#include &lt, second:#include &&lt, op_sum);
first, int j) { return i+j; &
&#47。.begin().begin();
&#47:&quot。;&lt网上例子挺多的!= set some values
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/*////////////////////////////////
template & class InputIterator, class OutputIterator, class UnaryOperator &
OutputIterator transform ( InputIterator first1,
// 源容器的起始地址
InputIterator last1,
// 源容器的终止地址
OutputIterator result,
// 目标容器的起始地址
UnaryOperator op );
// 函数指针
// typedef 目标容器元素类型 (*UnaryOperator)(源容器元素类型);
template & class InputIterator1, class InputIterator2,
class OutputIterator, class BinaryOperator &
OutputIterator transform ( InputIterator1 first1,
// 源容器1的起始地址
InputIterator1 last1,
// 源容器1的终止地址
InputIterator2 first2,
// 源容器2的起始地址，元素个数与1相同
OutputIterator result,
// 目标容器的起始地址，元素个数与1相同
BinaryOperator binary_op ); // 函数指针
// typedef 目标容器元素类型 (*BinaryOperator)(源容器1元素类型，源容器2元素类型);
//*////////////////////////////////
#include &iostream&
#include &algorithm&
#include &vector&
#include &string&
using namespace
int op_increase (int i)
return i+1;
int op_sum (int i, int j)
return i+j;
int to_upper(int c)
if (islower(c))
return (c-32);
int to_lower(int c)
if (isupper(c))
return c+32;
int main () {
vector&int&
vector&int&
vector&int&::
// set some values:
for (int i=1; i&6; i++) first.push_back (i*10); //
first: 10 20 30 40 50
///将first容器的元素加1赋值给second容器
second.resize(first.size());
// allocate space !!!必须预先设置一个大小与first相同
transform (first.begin(), first.end(), second.begin(), op_increase); // second: 11 21 31 41 51
cout && "second contains:";
for (it=second.begin(); it!=second.end(); ++it)
cout && " " && *
//*////////////////////////////////////////////
///将first容器的元素与second容器的元素相加，并将得到的结果重新赋值给first
transform (first.begin(), first.end(), second.begin(), first.begin(), op_sum); //
first: 21 41 61 81 101
cout && "first contains:";
for (it=first.begin(); it!=first.end(); ++it)
cout && " " && *
//*//////////////////////////////////////////////////////////////////////////
///大小写转换/////////////////////////////////////
string strsrc("Hello, World!");
strdest.resize(strsrc.size());
// !!!必须预先设置一个大小与strsrc相同
transform(strsrc.begin(), strsrc.end(), strdest.begin(), to_upper); // 转换为大写
cout && strdest &&
transform(strsrc.begin(), strsrc.end(), strdest.begin(), to_lower); // 转换为小写
cout && strdest &&
//*/////////////////////////////////////////
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