光照

使用光照时,我们无需自行指定顶点的颜色。Direct3D会将顶点送入光照的计算引擎，依据光源类型，材质以及物体表面相对光源的朝向，计算出每个顶点的颜色值。

1.光照的组成

在Direct3D的光照模型中，有3种类型的光。

1.1环境光。这种类型的光经其他表面反射到达物体表面，并照亮整个场景。

1.2漫射光。当光到达某一表面时，将沿着各个方向均匀反射。从各个方向观察，亮度均相同。

1.3镜面光。当光到达某一表面时，将沿着特定方向反射。只能在一定的角度才能看到高亮度。镜面光计算量较大，默认情况下Direct3D禁用镜面反射。启用镜面光的方法：

Device->SetRenderState（D3DRS_SPECULARENABLE，true）；

每一种类型的光都可以用结构D3DCOLORVALUE和D3DXCOLOR来表示。这些类型描述了光线的颜色。描述光线颜色时，D3DXCOLOR结构中的Alpha值都将被忽略。

D3DXCOLOR WhiteCo（1.0f，1.0f, 1.0f, 1.0f）

2.材质

在现实世界中物体的颜色是由物体所反射的光的颜色决定的。例如红色的球会反射所有的红色入射光，并吸收非红色的光。在Direct3D中，通过定义物体的材质来模拟此现象。

typedef struct D3DMATERIAL9 {
    D3DCOLORVALUE Diffuse;  //材质多漫射光的反射率
    D3DCOLORVALUE Ambient;   //材质对环境光的反射率
    D3DCOLORVALUE Specular;  //材质对镜面光的反射率
    D3DCOLORVALUE Emissive;   //用于增强物体的亮度
    float Power; //指定镜面高光点的锐度。
} D3DMATERIAL9, *LPD3DMATERIAL9;
顶点结构中不含有材质属性，我们可以用函数对材质进行设定。
HRESULT  IDirect3DDevice9::SetMaterial(
  CONST D3DMATERIAL9 * pMaterial
);
3.顶点法线
顶点法线描述的是构成多边形的各个顶点的法线。顶点法线的FVF标志D3DFVF_NORMAL.
使顶点法向量重新规范化：Device->SetRenderState(D3DRS_NORMALIZENORMALS,true)；

4.光源。Direct3D支持3种类型的光源

4.1点光源 在世界坐标系中有固定位置，向各个方向发射光线。

4.2方向光 光源没有位置信息，发射的光线平行的沿某一方向走。

4.3聚光灯 光源有位置信息，光源锥形的沿特定方向传播。有内部锥形，外部锥形。

光源用D3DLIGHT9表示。

typedef struct D3DLIGHT9 {
 D3DLIGHTTYPE Type; //光源类型 D3DLIGHT_POINT,D3DLIGHT_SPOT,D3DLIGHT_DIRECTIONAL
    D3DCOLORVALUE Diffuse; //光源发出的漫射光的颜色
    D3DCOLORVALUE Specular; //光源发出的镜面光的颜色
    D3DCOLORVALUE Ambient; //光源发出的环境光的颜色
    D3DVECTOR Position;  //光源在世界坐标系中的位置向量，对方向光无意义
    D3DVECTOR Direction; //光在世界坐标系中传播方向的向量，对点光源无意义。
    float Range; //光线消亡前所能到达的最大光程。最大取值(FLT_MAX开平方), 对方向光无意义
    float Falloff; //仅用于聚光灯。定义光强从内锥形到外锥形的衰减。一般取值1.0f.
    float Attenuation0; //紧接着的3个参数定义了光强随距离的衰减方式
    float Attenuation1;
    float Attenuation2;
    float Theta; //仅用于聚光灯，定义了内锥形的圆锥角，单位弧度
    float Phi; //仅用于聚光灯，定义了外锥形的圆锥角，单位弧度。
} D3DLIGHT9, *LPD3DLIGHT;
 
#ifndef __d3dUtilityH__
#define __d3dUtilityH__

#include <d3dx9.h>
#include <string>

namespace d3d
{
    bool InitD3D(
        HINSTANCE hInstance,       // [in] Application instance.
        int width, int height,     // [in] Backbuffer dimensions.
        bool windowed,             // [in] Windowed (true)or full screen (false).
        D3DDEVTYPE deviceType,     // [in] HAL or REF
        IDirect3DDevice9** device);// [out]The created device.

    int EnterMsgLoop( 
        bool (*ptr_display)(float timeDelta));

    LRESULT CALLBACK WndProc(
        HWND hwnd,
        UINT msg, 
        WPARAM wParam,
        LPARAM lParam);

    template<class T> void Release(T t)
    {
        if( t )
        {
            t->Release();
            t = 0;
        }
    }
        
    template<class T> void Delete(T t)
    {
        if( t )
        {
            delete t;
            t = 0;
        }
    }

    const D3DXCOLOR      WHITE( D3DCOLOR_XRGB(255, 255, 255) );
    const D3DXCOLOR      BLACK( D3DCOLOR_XRGB(  0,   0,   0) );
    const D3DXCOLOR        RED( D3DCOLOR_XRGB(255,   0,   0) );
    const D3DXCOLOR      GREEN( D3DCOLOR_XRGB(  0, 255,   0) );
    const D3DXCOLOR       BLUE( D3DCOLOR_XRGB(  0,   0, 255) );
    const D3DXCOLOR     YELLOW( D3DCOLOR_XRGB(255, 255,   0) );
    const D3DXCOLOR       CYAN( D3DCOLOR_XRGB(  0, 255, 255) );
    const D3DXCOLOR    MAGENTA( D3DCOLOR_XRGB(255,   0, 255) );

    D3DMATERIAL9 InitMtrl(D3DXCOLOR a,D3DXCOLOR d,D3DXCOLOR s,D3DXCOLOR e,float p);

    const D3DMATERIAL9 White_Mtrl=InitMtrl(WHITE,WHITE,WHITE,BLACK,8.0f);
    const D3DMATERIAL9 Red_Mtrl=InitMtrl(RED,RED,RED,BLACK,8.0f);
    const D3DMATERIAL9 Green_Mtrl=InitMtrl(GREEN,GREEN,GREEN,BLACK,8.0f);
    const D3DMATERIAL9 Blue_Mtrl=InitMtrl(BLUE,BLUE,BLUE,BLACK,8.0f);

    D3DLIGHT9 InitDirectionalLight(D3DVECTOR* direction,D3DXCOLOR * color);
    D3DLIGHT9 InitPointLight(D3DXVECTOR3* position,D3DXCOLOR * color);
    D3DLIGHT9 InitSpotLight(D3DXVECTOR3* position, D3DXVECTOR3* direction, D3DXCOLOR* color);
}

#endif // __d3dUtilityH__
d3dUtility.h
#include "d3dUtility.h"

bool d3d::InitD3D(
    HINSTANCE hInstance,
    int width, int height,
    bool windowed,
    D3DDEVTYPE deviceType,
    IDirect3DDevice9** device)
{ 
    WNDCLASS wc;

    wc.style         = CS_HREDRAW | CS_VREDRAW;
    wc.lpfnWndProc   = (WNDPROC)d3d::WndProc; 
    wc.cbClsExtra    = 0;
    wc.cbWndExtra    = 0;
    wc.hInstance     = hInstance;
    wc.hIcon         = LoadIcon(0, IDI_APPLICATION);
    wc.hCursor       = LoadCursor(0, IDC_ARROW);
    wc.hbrBackground = (HBRUSH)GetStockObject(WHITE_BRUSH);
    wc.lpszMenuName  = 0;
    wc.lpszClassName = "Direct3D9App";

    if( !RegisterClass(&wc) ) 
    {
        ::MessageBox(0, "RegisterClass() - FAILED", 0, 0);
        return false;
    }
        
    HWND hwnd = 0;
    hwnd = ::CreateWindow("Direct3D9App", "Direct3D9App", 
        WS_EX_TOPMOST,
        0, 0, width, height,
        0 /*parent hwnd*/, 0 /* menu */, hInstance, 0 /*extra*/); 

    if( !hwnd )
    {
        ::MessageBox(0, "CreateWindow() - FAILED", 0, 0);
        return false;
    }

    ::ShowWindow(hwnd, SW_SHOW);
    ::UpdateWindow(hwnd);

    //
    // Init D3D: 
    //

    HRESULT hr = 0;

    // Step 1: Create the IDirect3D9 object.

    IDirect3D9* d3d9 = 0;
    d3d9 = Direct3DCreate9(D3D_SDK_VERSION);

    if( !d3d9 )
    {
        ::MessageBox(0, "Direct3DCreate9() - FAILED", 0, 0);
        return false;
    }

    // Step 2: Check for hardware vp.

    D3DCAPS9 caps;
    d3d9->GetDeviceCaps(D3DADAPTER_DEFAULT, deviceType, &caps);

    int vp = 0;
    if( caps.DevCaps & D3DDEVCAPS_HWTRANSFORMANDLIGHT )
        vp = D3DCREATE_HARDWARE_VERTEXPROCESSING;
    else
        vp = D3DCREATE_SOFTWARE_VERTEXPROCESSING;

    // Step 3: Fill out the D3DPRESENT_PARAMETERS structure.
 
    D3DPRESENT_PARAMETERS d3dpp;
    d3dpp.BackBufferWidth            = width;
    d3dpp.BackBufferHeight           = height;
    d3dpp.BackBufferFormat           = D3DFMT_A8R8G8B8;
    d3dpp.BackBufferCount            = 1;
    d3dpp.MultiSampleType            = D3DMULTISAMPLE_NONE;
    d3dpp.MultiSampleQuality         = 0;
    d3dpp.SwapEffect                 = D3DSWAPEFFECT_DISCARD; 
    d3dpp.hDeviceWindow              = hwnd;
    d3dpp.Windowed                   = windowed;
    d3dpp.EnableAutoDepthStencil     = true; 
    d3dpp.AutoDepthStencilFormat     = D3DFMT_D24S8;
    d3dpp.Flags                      = 0;
    d3dpp.FullScreen_RefreshRateInHz = D3DPRESENT_RATE_DEFAULT;
    d3dpp.PresentationInterval       = D3DPRESENT_INTERVAL_IMMEDIATE;

    // Step 4: Create the device.

    hr = d3d9->CreateDevice(
        D3DADAPTER_DEFAULT, // primary adapter
        deviceType,         // device type
        hwnd,               // window associated with device
        vp,                 // vertex processing
        &d3dpp,             // present parameters
        device);            // return created device

    if( FAILED(hr) )
    {
        // try again using a 16-bit depth buffer
        d3dpp.AutoDepthStencilFormat = D3DFMT_D16;
        
        hr = d3d9->CreateDevice(
            D3DADAPTER_DEFAULT,
            deviceType,
            hwnd,
            vp,
            &d3dpp,
            device);

        if( FAILED(hr) )
        {
            d3d9->Release(); // done with d3d9 object
            ::MessageBox(0, "CreateDevice() - FAILED", 0, 0);
            return false;
        }
    }

    d3d9->Release(); // done with d3d9 object
    
    return true;
}

int d3d::EnterMsgLoop( bool (*ptr_display)(float timeDelta) )
{
    MSG msg;
    ::ZeroMemory(&msg, sizeof(MSG));

    static float lastTime = (float)timeGetTime(); 

    while(msg.message != WM_QUIT)
    {
        if(::PeekMessage(&msg, 0, 0, 0, PM_REMOVE))
        {
            ::TranslateMessage(&msg);
            ::DispatchMessage(&msg);
        }
        else
        {    
            float currTime  = (float)timeGetTime();
            float timeDelta = (currTime - lastTime)*0.001f;

            ptr_display(timeDelta);

            lastTime = currTime;
        }
    }
    return msg.wParam;
}

D3DMATERIAL9 d3d::InitMtrl(D3DXCOLOR a,D3DXCOLOR d,D3DXCOLOR s,D3DXCOLOR e,float p)
{
    D3DMATERIAL9 mtrl;
    mtrl.Ambient=a;
    mtrl.Diffuse =d;
    mtrl.Emissive =e;
    mtrl.Power =p;
    mtrl.Specular=s;
    return mtrl;
}

D3DLIGHT9 d3d::InitDirectionalLight(D3DVECTOR* direction,D3DXCOLOR* color)
{
    D3DLIGHT9 light;
    memset(&light,0,sizeof(light));
    light.Type=D3DLIGHT_DIRECTIONAL;
    light.Ambient=*color * 0.4f;
    light.Diffuse=*color;
    light.Specular=*color * 0.6f;
    light.Direction= *direction;
   return light;
}

D3DLIGHT9 d3d::InitPointLight(D3DXVECTOR3* position,D3DXCOLOR * color)
{    
    D3DLIGHT9 light;
    memset(&light,0,sizeof(light));
    light.Type=D3DLIGHT_POINT;
    light.Ambient=*color * 0.4f;
    light.Diffuse=*color;
    light.Specular=*color * 0.6f; 
    light.Position=*position;
    light.Range        = 1000.0f;
    light.Falloff      = 1.0f;
    light.Attenuation0 = 1.0f;
    light.Attenuation1 = 0.0f;
    light.Attenuation2 = 0.0f;
   return light;
}

D3DLIGHT9 d3d::InitSpotLight(D3DXVECTOR3* position, D3DXVECTOR3* direction, D3DXCOLOR* color)
{
    D3DLIGHT9 light;
    memset(&light,0,sizeof(light));
    light.Type=D3DLIGHT_SPOT;
    light.Ambient   = *color * 0.0f;
    light.Diffuse   = *color;
    light.Specular  = *color * 0.6f;
    light.Position  = *position;
    light.Direction = *direction;
    light.Range        = 1000.0f;
    light.Falloff      = 1.0f;
    light.Attenuation0 = 1.0f;
    light.Attenuation1 = 0.0f;
    light.Attenuation2 = 0.0f;
    light.Theta        = 0.4f;
    light.Phi          = 0.9f;
   return light;}
d3dUtility.cpp
#include "d3dUtility.h"

IDirect3DDevice9* Device = 0; 

const int Width  = 640;
const int Height = 480;

IDirect3DVertexBuffer9* vb = 0; 
D3DXMATRIX WorldMatrix;

struct Vertex //顶点结构：位置和顶点法线
{
    Vertex(){}

    Vertex(float x, float y, float z,float nx,float ny,float nz)
    {
        _x = x;     _y = y;  _z = z;
        _nx=nx;_ny=ny;_nz=nz;
    }

    float _x, _y, _z;
    float _nx,_ny,_nz;

    static const DWORD FVF;
};
const DWORD Vertex::FVF = D3DFVF_XYZ | D3DFVF_NORMAL;

//
// Framework Functions
//
bool Setup()
{
    Device->SetRenderState(D3DRS_LIGHTING, true);  //设置光照可用
    Device->CreateVertexBuffer(               //创建顶点缓存
        12 * sizeof(Vertex), // size in bytes
        D3DUSAGE_WRITEONLY, // flags
        Vertex::FVF,        // vertex format
        D3DPOOL_MANAGED,    // managed memory pool
        &vb,          // return create vertex buffer
        0);                 // not used - set to 0

    Vertex* vertices;
    vb->Lock(0, 0, (void**)&vertices, 0);        //获取指向顶点缓存内容的指针

    vertices[0] = Vertex(-1.0f, 0.0f, -1.0f,0.0f,0.707f,-0.707f);
    vertices[1] = Vertex( 0.0f, 1.0f, 0.0f,0.0f,0.707f,-0.707f);
    vertices[2] = Vertex( 1.0f, 0.0f, -1.0f,0.0f,0.707f,-0.707f);

    vertices[3] = Vertex(-1.0f, 0.0f, 1.0f,-0.707f,0.707f,0.0f);
    vertices[4] = Vertex( 0.0f, 1.0f, 0.0f,-0.707f,0.707f,0.0f);
    vertices[5] = Vertex( -1.0f, 0.0f, -1.0f,-0.707f,0.707f,0.0f);

    vertices[6] = Vertex( 1.0f, 0.0f, -1.0f, 0.707f, 0.707f, 0.0f);
    vertices[7] = Vertex( 0.0f, 1.0f,  0.0f, 0.707f, 0.707f, 0.0f);
    vertices[8] = Vertex( 1.0f, 0.0f,  1.0f, 0.707f, 0.707f, 0.0f);
 
    vertices[9]  = Vertex( 1.0f, 0.0f,  1.0f, 0.0f, 0.707f, 0.707f);
    vertices[10] = Vertex( 0.0f, 1.0f,  0.0f, 0.0f, 0.707f, 0.707f);
    vertices[11] = Vertex(-1.0f, 0.0f,  1.0f, 0.0f, 0.707f, 0.707f);

    vb->Unlock();

    D3DMATERIAL9 Mtrl;  //定义材质，设置材质对各种光的反射率
    Mtrl.Ambient =d3d::RED;
    Mtrl.Diffuse=d3d::BLUE;
    Mtrl.Specular=d3d::CYAN;
    Mtrl.Emissive=d3d::BLACK;
    Mtrl.Power=5.0f;

    Device->SetMaterial(&Mtrl); 

    D3DLIGHT9 light;   //设置方向光，并对其值赋值
    memset(&light,0,sizeof(light));
    light.Type=D3DLIGHT_DIRECTIONAL;
    light.Diffuse=d3d::BLUE;
    light.Specular=d3d::BLUE;
    light.Ambient=d3d::BLUE;
    light.Direction=D3DXVECTOR3(1.0f,0.0f,0.0f);
    Device->SetLight(0,&light);
    Device->LightEnable(0,true);
    Device->SetRenderState(D3DRS_NORMALIZENORMALS,true); //使顶点法向量重新规范化
    Device->SetRenderState(D3DRS_SPECULARENABLE,true); //启用镜面光

    D3DXVECTOR3 pos(0.0f, 1.0f, -3.0f);
    D3DXVECTOR3 target(0.0f, 0.0f, 0.0f);
    D3DXVECTOR3 up(0.0f, 1.0f, 0.0f);
    D3DXMATRIX V;
    D3DXMatrixLookAtLH(&V, &pos, &target, &up); //取景变换矩阵，设置摄像机在时间坐标系中位置，界坐标系的被观察点，世界坐标系中表示“向上”方向的向量
    Device->SetTransform(D3DTS_VIEW, &V); //转换成观察者坐标系

    //
    // 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); //投影
    return true;
}
void Cleanup()
{
    d3d::Release<IDirect3DVertexBuffer9*>(vb);
}

bool Display(float timeDelta)
{
    if( Device )
    {
        D3DXMATRIX yRot;

        static float y = 0.0f;

        D3DXMatrixRotationY(&yRot, y);
        y += timeDelta;

        if( y >= 6.28f )
            y = 0.0f;

        Device->SetTransform(D3DTS_WORLD, &yRot);

        Device->Clear(0, 0, D3DCLEAR_TARGET | D3DCLEAR_ZBUFFER, 0xffffffff, 1.0f, 0);
        Device->BeginScene();

        Device->SetStreamSource(0, vb, 0, sizeof(Vertex));
        Device->SetFVF(Vertex::FVF);
        Device->DrawPrimitive(D3DPT_TRIANGLELIST, 0, 4); //画出顶点缓存
        Device->SetFVF(Vertex::FVF); 

        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;
}
main.cpp
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原文地址：https://www.cnblogs.com/hometown/p/3654838.html