DirectX9:基础篇 纹理

一.简介

纹理映射是一种为三角形赋予图像数据的技术

在 Direct3D 中一个纹理是通过 IDirect3DTexture9 接口来表示,一个纹理是一个像素矩阵的表面被映射到三角形上

 

二.纹理坐标

Direct3D 使用一个纹理坐标系统,它是由水平方向的 u 轴(向右为正)和竖直方向 v 轴(向下为正)构成

 

// 纹理坐标系统表示

struct Vertex

{

　　float _x, _y, _z;

　　float _nx, _ny, _nz;

　　float _u, _v;

　　static const DWORD FVF;
};

const DWORD Vertex::FVF = D3DFVF_XYZ | D3DFVF_NORMAL | D3DFVF_TEX1;

 

三.创建纹理

1.D3DXCreateTextureFromFile()

纹理数据可以从存储在磁盘中的图片文件中读取,放入 IDirect3DTexture9 抽象纹理类型

支持的图片格式有: BMP DDS  DIB JPG  PNG  TGA

 

HRESULT D3DXCreateTextureFromFile(

　　LPDIRECT3DDEVICE9 pDevice,

　　LPCSTR pSrcFile,

　　LPDIRECT3DTEXTURE9* ppTexture

);

 

HRESULT IDirect3DDevice9::SetTexture(

　　DWORD Stage,

　　IDirect3DBaseTexture9* pTexture

);

 

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// 创建纹理
IDirect3Dtexture9* _stonewall;
D3DXCreateTextureFromFile(_device, "stonewall.bmp", &_stonewall);
 
// 设置纹理
Device->SetTexture(0, _stonewall);

 

四.过滤器

纹理被映射到屏幕中的三角形上,有可能纹理和三角形不一样大,当出现需要对纹理进行变形的时候,就要用过滤(Filtering)来让变形平滑的技术

Direct3D提供了三种不同的过滤器,每种的品质级别和速度各不相同

 

1.Nearest point sampling

默认的过滤方法,品质最差,速度最快

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Device->SetSamplerState(0, D3DSAMP_MAGFILTER, D3DTEXF_POINT);
Device->SetSamplerState(0, D3DSAMP_MINFILTER, D3DTEXF_POINT);

 

2.Linear filtering

推荐使用,过滤产生的效果好

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Device->SetSamplerState(0, D3DSAMP_MAGFILTER, D3DTEXF_LINEAR);
Device->SetSamplerState(0, D3DSAMP_MINFILTER, D3DTEXF_LINEAR);

 

3.Anisotropic filtering

过滤产生的品质最好,处理时间最长

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Device->SetSamplerState(0, D3DSAMP_MAGFILTER, D3DTEXF_ANISOTROPIC);
Device->SetSamplerState(0, D3DSAMP_MINFILTER, D3DTEXF_ANISOTROPIC);

 

4.Mipmaps过滤器

如果显卡支持Mipmaps,Direct3D会自动选择与三角形最匹配的Mipmap

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Device->SetSamplerState(0, D3DSAMP_MIPFILTER, D3DTEXF_NONE);  // 不使用 mipmap<br>Device->SetSamplerState(0, D3DSAMP_MIPFILTER, D3DTEXF_POINT); <br>Device->SetSamplerState(0, D3DSAMP_MIPFILTER, D3DTEXF_LINEAR);

 

五.寻址模式

纹理坐标必须指定在[0, 1]之间

Direct3D的寻址模式有四种: 环绕纹理寻址模式 边框颜色纹理寻址模式  截取纹理寻址模式 镜像纹理寻址模式

1.环绕纹理寻址模式(wrap address mode)

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if (::GetAsyncKeyState('W') & 0x8000f)
{
    Device->SetSamplerState(0, D3DSAMP_ADDRESSU, D3DTADDRESS_WRAP);
    Device->SetSamplerState(0, D3DSAMP_ADDRESSV, D3DTADDRESS_WRAP);  
}

 

2.边框颜色纹理寻址模式(border color address mode)

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if (::GetAsyncKeyState('B') & 0x8000f)
{
    Device>SetSamplerState(0, D3DSAMP_ADDRESSU, D3DTADDRESS_BORDER);
    Device->SetSamplerState(0, D3DSAMP_ADDRESSV, D3DTADDRESS_BORDER);
    Device->SetSamplerState(0, D3DSAMP_BORDERCOLOR, 0x000000ff);
}

 

3.截取纹理寻址模式(clamp address mode)

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if (::GetAsyncKeyState('C') & 0x8000f)
{
    Device->SetSamplerState(0, D3DSAMP_ADDRESSU, D3DTADDRESS_CLAMP);
    Device->SetSamplerState(0, D3DSAMP_ADDRESSV, D3DTADDRESS_CLAMP);
}

 

4.镜像纹理寻址模式(mirror address mode)

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if (::GetAsyncKeyState('M') & 0x8000f)
{
    Device->SetSamplerState(0, D3DSAMP_ADDRESSU, D3DTADDRESS_MIRROR);
    Device->SetSamplerState(0, D3DSAMP_ADDRESSV, D3DTADDRESS_MIRROR);
}

 

六.例子

1.不过滤纹理

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#include "d3dUtility.h"
 
IDirect3DDevice9* Device = 0;
 
const int Width = 640;
const int Height = 480;
 
IDirect3DVertexBuffer9* Quad = 0;
IDirect3DTexture9* Tex = 0;
 
struct Vertex
{
    Vertex(){}
 
    float _x, _y, _z;
    float _nx, _ny, _nz;
    float _u, _v;
 
    Vertex(float x, float y, float z,
          float nx, float ny, float nz,
          float u, float v)
    {
        _x = x; _y = y; _z = z;
        _nx = nx; _ny = ny; _nz = nz;
        _u = u; _v = v;
    }
 
    static const DWORD FVF;
};
 
const DWORD Vertex::FVF = D3DFVF_XYZ | D3DFVF_NORMAL | D3DFVF_TEX1;
 
bool Setup()
{
    Device->CreateVertexBuffer(
        6 * sizeof(Vertex),
        D3DUSAGE_WRITEONLY,
        Vertex::FVF,
        D3DPOOL_MANAGED,
        &Quad,
        0);
 
    Vertex* v;
    Quad->Lock(0, 0, (void**)&v, 0);
 
    v[0] = Vertex(-1.0f, -1.0f, 1.25f, 0.0f, 0.0f, -1.0f, 0.0f, 1.0f);
    v[1] = Vertex(-1.0f, 1.0f, 1.25f, 0.0f, 0.0f, -1.0f, 0.0f, 0.0f);
    v[2] = Vertex(1.0f, 1.0f, 1.25f, 0.0f, 0.0f, -1.0f, 1.0f, 0.0f);
 
    v[3] = Vertex(-1.0f, -1.0f, 1.25f, 0.0f, 0.0f, -1.0f, 0.0f, 1.0f);
    v[4] = Vertex(1.0f, 1.0f, 1.25f, 0.0f, 0.0f, -1.0f, 1.0f, 0.0f);
    v[5] = Vertex(1.0f, -1.0f, 1.25f, 0.0f, 0.0f, -1.0f, 1.0f, 1.0f);
 
    Quad->Unlock();
 
    // 加载纹理文件
    D3DXCreateTextureFromFile(Device, "a.bmp", &Tex);
    Device->SetTexture(0, Tex);
 
    Device->SetSamplerState(0, D3DSAMP_MAGFILTER, D3DTEXF_LINEAR);
    Device->SetSamplerState(0, D3DSAMP_MINFILTER, D3DTEXF_LINEAR);
    Device->SetSamplerState(0, D3DSAMP_MIPFILTER, D3DTEXF_POINT);
 
    Device->SetRenderState(D3DRS_LIGHTING, false);
 
    D3DXMATRIX proj;
    D3DXMatrixPerspectiveFovLH(
        &proj,
        D3DX_PI * 0.5f,
        (float)Width / (float)Height,
        1.0f,
        1000.0f);
    Device->SetTransform(D3DTS_PROJECTION, &proj);
 
    return true;
}
 
void Cleanup()
{
    d3d::Release<IDirect3DVertexBuffer9*>(Quad);
    d3d::Release<IDirect3DTexture9*>(Tex);
}
 
bool Display(float timeDelta)
{
    if (Device)
    {
 
        Device->Clear(0, 0, D3DCLEAR_TARGET | D3DCLEAR_ZBUFFER, 0xffffffff, 1.0f, 0);
        Device->BeginScene();
 
        Device->SetStreamSource(0, Quad, 0, sizeof(Vertex));
        Device->SetFVF(Vertex::FVF);
        Device->DrawPrimitive(D3DPT_TRIANGLELIST, 0, 2);
 
        Device->EndScene();
        Device->Present(0, 0, 0, 0);
    }
    return true;
}

 

 

2.过滤处理纹理

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#include "d3dUtility.h"
 
//
// Globals
//
 
IDirect3DDevice9* Device = 0;
 
const int Width = 640;
const int Height = 480;
 
IDirect3DVertexBuffer9* Quad = 0;
IDirect3DTexture9* Tex = 0;
 
 
// 顶点格式
struct Vertex
{
    Vertex(){}
    Vertex(
        float x, float y, float z,
        float nx, float ny, float nz,
        float u, float v)
    {
        _x = x; _y = y; _z = z;
        _nx = nx; _ny = ny; _nz = nz;
        _u = u; _v = v;
    }
 
    float _x, _y, _z;
    float _nx, _ny, _nz;
    float _u, _v;
 
    static const DWORD FVF;
};
 
const DWORD Vertex::FVF = D3DFVF_XYZ | D3DFVF_NORMAL | D3DFVF_TEX1;
 
//
// Framework Functions
//
 
bool Setup()
{
 
 
    // 创建顶点缓存
    Device->CreateVertexBuffer(
        6 * sizeof(Vertex),
        D3DUSAGE_WRITEONLY,
        Vertex::FVF,
        D3DPOOL_MANAGED,
        &Quad,
        0);
 
    Vertex* v;
    Quad->Lock(0, 0, (void**)&v, 0);
 
    v[0] = Vertex(-1.0f, -1.0f, 1.25f, 0.0f, 0.0f, -1.0f, 0.0f, 3.0f);
    v[1] = Vertex(-1.0f,  1.0f, 1.25f, 0.0f, 0.0f, -1.0f, 0.0f, 0.0f);
    v[2] = Vertex( 1.0f,  1.0f, 1.25f, 0.0f, 0.0f, -1.0f, 3.0f, 0.0f);
 
    v[3] = Vertex(-1.0f, -1.0f, 1.25f, 0.0f, 0.0f, -1.0f, 0.0f, 3.0f);
    v[4] = Vertex( 1.0f,  1.0f, 1.25f, 0.0f, 0.0f, -1.0f, 3.0f, 0.0f);
    v[5] = Vertex( 1.0f, -1.0f, 1.25f, 0.0f, 0.0f, -1.0f, 3.0f, 3.0f);
 
    Quad->Unlock();
 
    //
    // Create the texture and set texture
    //
 
    D3DXCreateTextureFromFile(
        Device,
        "a.bmp",
        &Tex);
 
    Device->SetTexture(0, Tex);
 
    Device->SetSamplerState(0, D3DSAMP_MAGFILTER, D3DTEXF_LINEAR);
    Device->SetSamplerState(0, D3DSAMP_MINFILTER, D3DTEXF_LINEAR);
    Device->SetSamplerState(0, D3DSAMP_MIPFILTER, D3DTEXF_POINT);
 
    //
    // Don't use lighting for this sample
    //
 
    Device->SetRenderState(D3DRS_LIGHTING, false);
 
    //
    // Set the projection matrix
    //
 
    D3DXMATRIX proj;
    D3DXMatrixPerspectiveFovLH(
        &proj,
        D3DX_PI * 0.5f,
        (float)Width / (float)Height,
        1.0f,
        1000.0f);
    Device->SetTransform(D3DTS_PROJECTION, &proj);
 
    return true;
}
 
void Cleanup()
{
    d3d::Release<IDirect3DVertexBuffer9*>(Quad);
    d3d::Release<IDirect3DTexture9*>(Tex);
}
 
bool Display(float timeDelta)
{
    if (Device)
    {
        //
        // Update the scene
        //
 
        // set wrap address mode
        if (::GetAsyncKeyState('W') & 0x8000f)
        {
            Device->SetSamplerState(0, D3DSAMP_ADDRESSU, D3DTADDRESS_WRAP);
            Device->SetSamplerState(0, D3DSAMP_ADDRESSV, D3DTADDRESS_WRAP);
        }
 
        // set border color address mode
        if (::GetAsyncKeyState('B') & 0x8000f)
        {
            Device->SetSamplerState(0, D3DSAMP_ADDRESSU, D3DTADDRESS_BORDER);
            Device->SetSamplerState(0, D3DSAMP_ADDRESSV, D3DTADDRESS_BORDER);
            Device->SetSamplerState(0, D3DSAMP_BORDERCOLOR, 0x000000ff);
        }
 
        // set clamp address mode
        if (::GetAsyncKeyState('C') & 0x8000f)
        {
            Device->SetSamplerState(0, D3DSAMP_ADDRESSU, D3DTADDRESS_CLAMP);
            Device->SetSamplerState(0, D3DSAMP_ADDRESSV, D3DTADDRESS_CLAMP);
        }
 
        // set mirror address mode
        if (::GetAsyncKeyState('M') & 0x8000f)
        {
            Device->SetSamplerState(0, D3DSAMP_ADDRESSU, D3DTADDRESS_MIRROR);
            Device->SetSamplerState(0, D3DSAMP_ADDRESSV, D3DTADDRESS_MIRROR);
        }
 
        //
        // Draw the scene
        //
 
        Device->Clear(0, 0, D3DCLEAR_TARGET | D3DCLEAR_ZBUFFER, 0xffffffff, 1.0f, 0);
        Device->BeginScene();
 
        Device->SetStreamSource(0, Quad, 0, sizeof(Vertex));
        Device->SetFVF(Vertex::FVF);
        Device->DrawPrimitive(D3DPT_TRIANGLELIST, 0, 2);
 
        Device->EndScene();
        Device->Present(0, 0, 0, 0);
 
    }
    return true;
}

 

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