3.3应用程序

3.3应用程序

程序中我们首先创建一个四边形，然后使用像素着色器进行纹理混合后对其进行渲染。下面是应用程序代码：

…

/*********************顶点格式定义*****************/

struct CUSTOMVERTEX

{

//定点位置坐标

float x,y,z;

//两套纹理坐标；

float tu0, tv0;

float tu1, tv1;

};

#define D3DFVF_CUSTOMVERTEX (D3DFVF_XYZ | D3DFVF_TEX2)

…

/*********************声明变量*****************/

//顶点着色器

LPDIRECT3DPIXELSHADER9 pixelShader = 0;

//常量表

ID3DXConstantTable* pixelConstTable = 0;

//常量句柄

D3DXHANDLE ScalarHandle = 0;

D3DXHANDLE Samp0Handle = 0;

D3DXHANDLE Samp1Handle = 0;

//常量描述结构

D3DXCONSTANT_DESC Samp0Desc;

D3DXCONSTANT_DESC Samp1Desc;

//四边形顶点缓存

LPDIRECT3DVERTEXBUFFER9 quadVB = NULL;

//两个纹理

LPDIRECT3DTEXTURE9 quadTexture0 = NULL;

LPDIRECT3DTEXTURE9 quadTexture1 = NULL;

…

/********************初始化应用程序*****************/

//创建四边形顶点模型

CUSTOMVERTEX quad[] =

// x y z tu0 tv0 tu1 tv1

{{-3.0f, -3.0f, 10.0f, 0.0f, 1.0f, 0.0f, 1.0f},

{ -3.0f, 3.0f, 10.0f, 0.0f, 0.0f, 0.0f, 0.0f},

{ 3.0f, -3.0f, 10.0f, 1.0f, 1.0f, 1.0f, 1.0f},

{ 3.0f, 3.0f, 10.0f, 1.0f, 0.0f, 1.0f, 0.0f}};

//创建顶点缓存

void *ptr = NULL;

g_pd3dDevice->CreateVertexBuffer(sizeof(quad),

D3DUSAGE_WRITEONLY,

0,

D3DPOOL_MANAGED,

&quadVB,

NULL);

quadVB->Lock(0, 0, (void**)&ptr, 0);

memcpy((void*)ptr, (void*)quad, sizeof(quad));

quadVB->Unlock();

//创建纹理

D3DXCreateTextureFromFile(g_pd3dDevice, "porpcart.jpg", &quadTexture0);

D3DXCreateTextureFromFile(g_pd3dDevice, "luoqi.jpg", &quadTexture1);

//检测系统是否支持像素着色器

D3DCAPS9 caps;

g_pd3dDevice->GetDeviceCaps(&caps);

if(caps.PixelShaderVersion < D3DPS_VERSION(1, 1))

{

MessageBox(0, "NotSupport Pixel Shader - FAILED", 0, 0);

exit(0);

}

//创建像素着色器

ID3DXBuffer* codeBuffer = 0;

ID3DXBuffer* errorBuffer = 0;

HRESULT hr = D3DXCompileShaderFromFile("ps.txt",

0,

0,

"PS_Main", // entry point function name

"ps_1_1",

D3DXSHADER_DEBUG,

&codeBuffer,

&errorBuffer,

&pixelConstTable);

// output any error messages

if(errorBuffer)

{

MessageBox(0, (char*)errorBuffer->GetBufferPointer(), 0, 0);

ReleaseCOM(errorBuffer);

}

if(FAILED(hr))

{

MessageBox(0, "D3DXCompileShaderFromFile() - FAILED", 0, 0);

return false;

}

hr = g_pd3dDevice->CreatePixelShader((DWORD*)codeBuffer->GetBufferPointer(), &pixelShader);

if(FAILED(hr))

{

MessageBox(0, "CreatePixelShader - FAILED", 0, 0);

return false;

}

ReleaseCOM(codeBuffer);

ReleaseCOM(errorBuffer);

//得到各常量句柄

ScalarHandle = pixelConstTable->GetConstantByName(0, "Scalar");

Samp0Handle = pixelConstTable->GetConstantByName(0, "Samp0");

Samp1Handle = pixelConstTable->GetConstantByName(0, "Samp1");

//得到对着色器变量Samp0、Samp0的描述

UINT count;

pixelConstTable->GetConstantDesc(Samp0Handle, & Samp0Desc, &count);

pixelConstTable->GetConstantDesc(Samp1Handle, & Samp1Desc, &count);

//设定各着色器变量为初始值

pixelConstTable->SetDefaults(g_pd3dDevice);

…

/********************渲染*****************/

g_pd3dDevice->Clear( 0, NULL, D3DCLEAR_TARGET | D3DCLEAR_ZBUFFER, D3DCOLOR_XRGB(153,153,153), 1.0f, 0 );

g_pd3dDevice->BeginScene();

//为着色器全局变量Scalar赋值

D3DXVECTOR4 scalar(0.5f, 0.5f, 0.0f, 1.0f);

pixelConstTable->SetVector(g_pd3dDevice, ScalarHandle, &scalar);

//设置像素着色器

g_pd3dDevice->SetPixelShader(pixelShader);

//设置定点格式、绑定数据流

g_pd3dDevice->SetFVF(D3DFVF_CUSTOMVERTEX);

g_pd3dDevice->SetStreamSource(0, quadVB, 0, sizeof(CUSTOMVERTEX));

//设置第一、二层纹理

g_pd3dDevice->SetTexture(Samp0Desc.RegisterIndex, quadTexture0);

g_pd3dDevice->SetTexture(Samp1Desc.RegisterIndex, quadTexture1);

//绘制图形

g_pd3dDevice->DrawPrimitive(D3DPT_TRIANGLESTRIP, 0, 2);

g_pd3dDevice->EndScene();

g_pd3dDevice->Present(NULL, NULL, NULL, NULL);

…

程序中像素着色器的使用和之前顶点着色器的使用无二，只是设置着色器中纹理采样器变量Samp0、Samp1和设定着色器其他变量稍有不同：

1. 首先通过变量名称得到变量句柄：

Tex0Handle = pixelConstTable->GetConstantByName(0, " Samp0");

Tex1Handle = pixelConstTable->GetConstantByName(0, " Samp1");

2. 然后通过句柄得到对变量的描述：

UINT count;

pixelConstTable->GetConstantDesc(Samp0Handle, & Samp0Desc, &count);

pixelConstTable->GetConstantDesc(Samp1Handle, & Samp1Desc, &count);

3.最后通过SetTexture配合所得到的描述信息设置纹理：

g_pd3dDevice->SetTexture(Samp0Desc.RegisterIndex, quadTexture0);

g_pd3dDevice->SetTexture(Samp1Desc.RegisterIndex, quadTexture1);

编译运行程序，运行效果如图3.2，这里我们将颜色混合比例设置为0.5，如果读者在渲染过程中不断变换对着色器变量Scalar的赋值，你将会得到一个混合度不断变换的多纹理效果。

D3DXVECTOR4 scalar(0.5f, 0.5f, 0.0f, 1.0f); //读者可以尝试改变混合采用的比例值

pixelConstTable->SetVector(g_pd3dDevice, ScalarHandle, &scalar);

纹理一

纹理二

混合后纹理三

图3.2