DirectX 基础学习系列5 纹理映射

1 纹理坐标
类似BMP图像坐标系，左上为原点
纹理坐标为了规范化，范围限定在[0,1]之间，使用纹理的时候，需要修改顶点结构
struct ColorVetex
{
float x, y,z;
float _nx,_ny,_nz ;
float _u,_y ;
static const DWORD FVF;
}
const DWORD ColorVetex::FVF = D3DFVF_XYZ | D3DFVF_NORMAL|D3DFVF_TEX1;
2创建并启用纹理
从文件中加载纹理数据
HRESULT D3DXCreateTextureFromFile(
  LPDIRECT3DDEVICE9 pDevice,
  LPCTSTR pSrcFile,
  LPDIRECT3DTEXTURE9 * ppTexture
);
从内存中加载
HRESULT D3DXCreateTextureFromFileInMemory(
LPDIRECT3DDEVICE9 pDevice,  LPCVOID
pSrcData,  UINT SrcDataSize,
LPDIRECT3DTEXTURE9 * ppTexture);
从资源加载
HRESULT D3DXCreateTextureFromResource(
  LPDIRECT3DDEVICE9 pDevice,
  HMODULE hSrcModule,
  LPCTSTR pSrcResource,
  LPDIRECT3DTEXTURE9 * ppTexture);
设置问题。，DX最多可以设置8层纹理，从而组合得到更细致的图片
SetTexture(0,&_stonewall);
禁用纹理
SetTexture(0,0);
3 纹理过滤器
纹理三角形和屏幕三角形大小不适合的时候，通过这项技术，让二者适应
DX提供三种纹理过滤器：
最近点采样：默认情况，速度快，效果差
setsamplerstate(0,D3DSAMP_MAGFILTER,D3DTEXT_POINT);
setsamplerstate(0,D3DSAMP_MINFILTER,D3DTEXT_POINT);
线性纹理过滤器：线性插值，可以分为 放大和缩小
SetSamplerState(0,D3DSAMP_MAGFILTER,D3DTEXT_LINEAR);
SetSamplerState(0,D3DSAMP_MINFILTER,D3DTEXT_LINEAR);
各向异性纹理过滤器：多线条采样技术，
setsamplerstate(0,D3DSAMP_MAGFILTER,D3DTEXT_ANISOTROPIC);
setsamplerstate(0,D3DSAMP_MINFILTER, D3DTEXT_ANISOTROPIC);
使用anisotropic filter时，需要对D3DSAMP_MAXANISOTROPIC 水平进行设置
4 多级渐进纹理
消除纹理和三角尺寸不一致的问题，创建多级渐进纹理，
多级渐进纹理过滤器：
Device->SetSamplerState(0,D3D_MIPFILTER,flag);
flag:D3DTEXT_NONE  ：不适用
D3DTEXF_POINT    选族最近接的一级纹理，选择后使用指定的纹理过滤器进行处理
D3DTEXF_LINEAR  选择最近的两极纹理，用指定纹理过滤器过滤后，再对两极纹理进行线性融合
使用多级渐进纹理之后 DX会自动选用合适的尺寸纹理
5 寻址模式 ：处理纹理坐标超过[0,1]范围的问题
有四种扩展模式：
重复寻址模式
Device->SetSamplerState(0,D3DSAMP_ADDRESSU,D3DTADDRESS_WRAP);
Device->SetSamplerState(0, D3DSAMP_ADDRESSV, D3DTADDRESS_WRAP);
边界颜色模式
Device->SetSamplerState(0,D3DSAMP_ADDRESSU,D3DTADDRESS_BORDER);
Device->SetSamplerState(0, D3DSAMP_ADDRESSV, D3DTADDRESS_BORDER);
Device->SetSamplerState(0, D3DSAMP_BORDERCOLOR,0x000000FF);
嵌位寻址模式
Device->SetSamplerState(0,D3DSAMP_ADDRESSU,D3DTADDRESS_CLAMP);
Device->SetSamplerState(0, D3DSAMP_ADDRESSV, D3DTADDRESS_CLAMP);
镜像寻址模式
Device->SetSamplerState(0,D3DSAMP_ADDRESSU,D3DTADDRESS_MIRROR);
Device->SetSamplerState(0, D3DSAMP_ADDRESSV, D3DTADDRESS_MIRROR);
6纹理映射的过程
（1）构建具有纹理坐标的顶点
（2）读取纹理数据
（3）设置 缩小 放大过滤器，多级渐进纹理过滤器
（4）将纹理与物体关

下列代码为《directx9.0c游戏开发基础教程》第六章的代码：配合光源 纹理 ，物理的旋转采用更改观察者视角

 
 
#include "d3dUtility.h"
#include "cube.h"
#include "vertex.h"
 
//
// Globals
//
 
IDirect3DDevice9*     Device = 0; 
 
const int Width  = 640;
const int Height = 480;
 
Cube*              Box = 0;
IDirect3DTexture9* Tex = 0;
 
//
// Framework Functions
//
bool Setup()
{
    //
    // Create the cube.
    //
 
    Box = new Cube(Device);
 
    //
    // Set a directional light.
    //
 
    D3DLIGHT9 light;
    ::ZeroMemory(&light, sizeof(light));
    light.Type      = D3DLIGHT_DIRECTIONAL;
    light.Ambient   = D3DXCOLOR(0.1f, 0.8f, 0.8f, 1.0f);
    light.Diffuse   = D3DXCOLOR(0.9f, 1.0f, 1.0f, 1.0f);
    light.Specular  = D3DXCOLOR(0.0f, 0.2f, 1.0f, 1.0f);
    light.Direction = D3DXVECTOR3(1.0f, 0.0f, 0.0f);
    Device->SetLight(0, &light);
    Device->LightEnable(0, true);
 
    Device->SetRenderState(D3DRS_NORMALIZENORMALS, true);
    Device->SetRenderState(D3DRS_SPECULARENABLE, true);
 
    //
    // Create texture.
    //
    D3DXCreateTextureFromFile(
        Device,
        "crate.jpg",
        &Tex);
 
    // 
    // Set Texture Filter States.
    //
 
    Device->SetSamplerState(0, D3DSAMP_MAGFILTER, D3DTEXF_LINEAR);
    Device->SetSamplerState(0, D3DSAMP_MINFILTER, D3DTEXF_LINEAR);
    Device->SetSamplerState(0, D3DSAMP_MIPFILTER, D3DTEXF_LINEAR);
 
    //
    // Set the projection matrix.
    //
 
    D3DXMATRIX proj;
    D3DXMatrixPerspectiveFovLH(
            &proj,
            D3DX_PI * 0.5f, // 90 - degree
            (float)Width / (float)Height,
            1.0f,
            1000.0f);
    Device->SetTransform(D3DTS_PROJECTION, &proj);
 
    return true;
}
 
void Cleanup()
{
    d3d::Delete<Cube*>(Box);
    d3d::Release<IDirect3DTexture9*>(Tex);
}
 
bool Display(float timeDelta)
{
    if( Device )
    {
        // 
        // Update the scene: update camera position.
        //
 
        static float angle  = (3.0f * D3DX_PI) / 2.0f;
        static float height = 2.0f;
    
        if( ::GetAsyncKeyState(VK_LEFT) & 0x8000f )
            angle -= 0.5f * timeDelta;
 
        if( ::GetAsyncKeyState(VK_RIGHT) & 0x8000f )
            angle += 0.5f * timeDelta;
 
        if( ::GetAsyncKeyState(VK_UP) & 0x8000f )
            height += 5.0f * timeDelta;
 
        if( ::GetAsyncKeyState(VK_DOWN) & 0x8000f )
            height -= 5.0f * timeDelta;
 
        D3DXVECTOR3 position( cosf(angle) * 3.0f, height, sinf(angle) * 3.0f );
        D3DXVECTOR3 target(0.0f, 0.0f, 0.0f);
        D3DXVECTOR3 up(0.0f, 1.0f, 0.0f);
        D3DXMATRIX V;
        D3DXMatrixLookAtLH(&V, &position, &target, &up);
 
        Device->SetTransform(D3DTS_VIEW, &V);
 
        //
        // Draw the scene:
        //
 
        Device->Clear(0, 0, D3DCLEAR_TARGET | D3DCLEAR_ZBUFFER, 0xffffffff, 1.0f, 0);
        Device->BeginScene();
 
        Device->SetMaterial(&d3d::RED_MTRL);
        Device->SetTexture(0, Tex);
 
        Box->draw(0, 0, 0);
 
        Device->EndScene();
        Device->Present(0, 0, 0, 0);
    }
    return true;
}
 
//
// WndProc
//
LRESULT CALLBACK d3d::WndProc(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam)
{
    switch( msg )
    {
    case WM_DESTROY:
        ::PostQuitMessage(0);
        break;
        
    case WM_KEYDOWN:
        if( wParam == VK_ESCAPE )
            ::DestroyWindow(hwnd);
        break;
    }
    return ::DefWindowProc(hwnd, msg, wParam, lParam);
}
 
//
// WinMain
//
int WINAPI WinMain(HINSTANCE hinstance,
                   HINSTANCE prevInstance, 
                   PSTR cmdLine,
                   int showCmd)
{
    if(!d3d::InitD3D(hinstance,
        Width, Height, true, D3DDEVTYPE_HAL, &Device))
    {
        ::MessageBox(0, "InitD3D() - FAILED", 0, 0);
        return 0;
    }
        
    if(!Setup())
    {
        ::MessageBox(0, "Setup() - FAILED", 0, 0);
        return 0;
    }
 
    d3d::EnterMsgLoop( Display );
 
    Cleanup();
 
    Device->Release();
 
    return 0;
}

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