详解Unity3D Shader之Shader Lab框架

笔者介绍：姜雪伟，IT公司技术合伙人，IT高级讲师，CSDN社区专家，特邀编辑，畅销书作者，国家专利发明人;已出版书籍：《手把手教你架构3D游戏引擎》电子工业出版社和《Unity3D实战核心技术详解》电子工业出版社等。CSDN课程视频网址：http://edu.csdn.net/lecturer/144 网上有很多关于Shader的教程，我在这里就不给读者讲解基础知识了，我们直接讲重点，我会结合着C++底层代码一起讲解，帮助读者理解Unity3D引擎内部对于Shader加载的实现原理，下面就结合着Unity3D中的Shader的编写给读者解释，在Unity3D中的每个Shader中都有SubShader代码段。以下面的代码为例：SubShader {

Pass{
// Dont write to the depth buffer
ZWrite off

// Set up alpha blending
Blend SrcAlpha OneMinusSrcAlpha

CGPROGRAM
#pragma vertex vert
#pragma fragment frag
#include "UnityCG.cginc"

sampler2D _MainTex;
float4 _Color;

struct v2f{
float4 pos:SV_POSITION;
float4 texcoord : TEXCOORD0;
};

v2f vert(appdata_base v)
{
v2f o;
o.pos = mul(UNITY_MATRIX_MVP, v.vertex);
o.texcoord = v.texcoord;
return o;
}

half4 frag(v2f i):COLOR0
{
half4 col = _Color * tex2D(_MainTex, i.texcoord.xy);
return col;
}

ENDCG
}

pass
{

}
}

SubShader
{
Pass
{

}
}
SubShader中包含的代码段是核心程序，它中间还有Pass通道，Pass通道包含了定义的输出结构体和处理顶点函数和处理片段函数，在一个Shader中还可以包含多个SubShader，这些SubShader可以根据硬件自行适配，下面结合着C++代码给读者分析一下Unity3D中的Shader。先把DirectX中的Shader代码展示如下：//--------------------------------------------------------------
// 全局变量
//--------------------------------------------------------------
float4x4 matWorldViewProj;
float4x4 matWorld;
float4 vecLightDir;
float4 vecEye;

float4 materialAmbient;
float4 materialDiffuse;
float4 materialSpecular;

//-------------------------------------------------------------
// 顶点渲染器输出结构
//-------------------------------------------------------------
struct VS_OUTPUT
{
float4 Pos : POSITION;
float4 Color : COLOR;
};

//-------------------------------------------------------------
// 顶点渲染器
//-------------------------------------------------------------
VS_OUTPUT VS( float4 Pos: POSITION, float3 Normal: NORMAL,
uniform bool bEnableSelfShadow )
{
VS_OUTPUT Out = (VS_OUTPUT) 0;

//顶点坐标变换
Out.Pos = mul(Pos, matWorldViewProj);

//单位化光照方向向量
float3 LightDir = normalize( vecLightDir );

//计算观察方向
float3 PosWorld = normalize( mul(Pos, matWorld) );
float3 ViewDir = normalize( vecEye - PosWorld );

//计算法向量方向和漫反射强度
float3 NormalWorld = normalize( mul(Normal, matWorld) );
float4 diff = saturate( dot(NormalWorld, LightDir) );

//计算反射光方向( R = 2 * (N.L) * N - L)和镜面反射强度
float3 Reflect = normalize( 2 * diff * NormalWorld - LightDir );
float4 specu = pow( saturate(dot(Reflect, ViewDir)), 0.5 );

//各种光的颜色
float4 ambientColor = { 0.1f, 0.0f, 0.0f, 1.0f};
float4 diffuseColor = { 1.0f, 0.0f, 0.0f, 1.0f};
float4 specularColor = { 1.0f, 0.0f, 0.0f, 1.0f};

//计算顶点颜色
if(bEnableSelfShadow) //启用自阴影
{
float shadow = saturate(4* diff);

//计算顶点颜色 = Ambient + Shadow * ( Diffuse + Specular )
Out.Color = ambientColor * materialAmbient + shadow *
(diffuseColor * materialDiffuse * diff +
specularColor * specu * materialSpecular);
}
else //禁用自阴影
{
Out.Color = ambientColor * materialAmbient +
diffuseColor * materialDiffuse * diff +
specularColor * specu * materialSpecular;
}

return Out;
}

//--------------------------------------------------------------
// 技术
//--------------------------------------------------------------
technique TShaderSelfShadow
{
pass P0
{
VertexShader = compile vs_2_0 VS(true);
}
}

technique TShaderNoSelfShadow
{
pass P0
{
VertexShader = compile vs_2_0 VS(false);
}
}
上述Shader定义了输出结构体这个跟Unity3D中的定义的结构体很类似，DirectX中的Shader定义了顶点渲染器VS函数：VS_OUTPUT VS( float4 Pos: POSITION, float3 Normal: NORMAL,
uniform bool bEnableSelfShadow ) 其中，VS函数是结合了顶点着色器和片段着色器一起实现的，另外，它还定义了technique，在technique中也有pass通道，这个technique跟SubShader类似，pass通道跟SubPass中的pass通道类似。因为Unity引擎内部我们是看不到的，那就以DirectX中的C++代码为例给读者解密一下引擎内部是如何实现的，C++完整代码如下所示：/-----------------------------------------------------------------------------
// 全局变量
//-----------------------------------------------------------------------------
ID3DXFont* g_pFont = NULL; //ID3DXFont字体对象
ID3DXSprite* g_pTextSprite = NULL; //ID3DXSprite文本精灵对象
bool g_bShowHelp = true; //标识是否显示简单说明文本

CDXUTDialogResourceManager g_DialogResourceManager; //对话框资源管理器
CD3DSettingsDlg g_SettingsDlg; //Direct3D设备设置对话框
CDXUTDialog g_HUD; //对话框
CDXUTDialog g_SampleUI; //对话框

LPDIRECT3DVERTEXBUFFER9 g_pVB = NULL; //顶点缓冲区
LPD3DXEFFECT g_pEffect = NULL; //效果
bool g_bEnableSelfShadow; //标志是否启用预编译渲染器

//顶点结构和灵活顶点格式
struct CUSTOMVERTEX
{
D3DXVECTOR3 position; //位置
D3DXVECTOR3 normal; //法线
};
#define D3DFVF_CUSTOMVERTEX (D3DFVF_XYZ|D3DFVF_NORMAL)

//-----------------------------------------------------------------------------
// 控件ID
//-----------------------------------------------------------------------------
#define IDC_TOGGLEFULLSCREEN 1
#define IDC_TOGGLEREF 2
#define IDC_CHANGEDEVICE 3
#define IDC_ENABLE_SELFSHADOW 4

//-----------------------------------------------------------------------------
// Desc: 函数声明
//------------------------------------------------------------------------------
bool CALLBACK IsDeviceAcceptable( D3DCAPS9* pCaps, D3DFORMAT AdapterFormat, D3DFORMAT BackBufferFormat, bool bWindowed, void* pUserContext );
bool CALLBACK ModifyDeviceSettings( DXUTDeviceSettings* pDeviceSettings, const D3DCAPS9* pCaps, void* pUserContext );
HRESULT CALLBACK OnCreateDevice( IDirect3DDevice9* pd3dDevice, const D3DSURFACE_DESC* pBackBufferSurfaceDesc, void* pUserContext );
HRESULT CALLBACK OnResetDevice( IDirect3DDevice9* pd3dDevice, const D3DSURFACE_DESC* pBackBufferSurfaceDesc, void* pUserContext );
void CALLBACK OnFrameMove( IDirect3DDevice9* pd3dDevice, double fTime, float fElapsedTime, void* pUserContext );
void CALLBACK OnFrameRender( IDirect3DDevice9* pd3dDevice, double fTime, float fElapsedTime, void* pUserContext );
LRESULT CALLBACK MsgProc( HWND hWnd, UINT uMsg, WPARAM wParam, LPARAM lParam, bool* pbNoFurtherProcessing, void* pUserContext );
void CALLBACK KeyboardProc( UINT nChar, bool bKeyDown, bool bAltDown, void* pUserContext );
void CALLBACK OnGUIEvent( UINT nEvent, int nControlID, CDXUTControl* pControl, void* pUserContext );
void CALLBACK OnLostDevice( void* pUserContext );
void CALLBACK OnDestroyDevice( void* pUserContext );

void InitApp();
void RenderText();

//-----------------------------------------------------------------------------
// Desc: 入口函数
//-----------------------------------------------------------------------------
INT WINAPI WinMain( HINSTANCE, HINSTANCE, LPSTR, int )
{
//为Debug配置启用运行时内存检查功能
#if defined(DEBUG) | defined(_DEBUG)
_CrtSetDbgFlag( _CRTDBG_ALLOC_MEM_DF | _CRTDBG_LEAK_CHECK_DF );
#endif

//设置回调函数
DXUTSetCallbackDeviceCreated( OnCreateDevice );
DXUTSetCallbackDeviceReset( OnResetDevice );
DXUTSetCallbackDeviceLost( OnLostDevice );
DXUTSetCallbackDeviceDestroyed( OnDestroyDevice );
DXUTSetCallbackMsgProc( MsgProc );
DXUTSetCallbackKeyboard( KeyboardProc );
DXUTSetCallbackFrameRender( OnFrameRender );
DXUTSetCallbackFrameMove( OnFrameMove );

//应用程序相关的初始化
InitApp();

//初始化DXUT, 创建窗口, 创建Direct3D设备对象
DXUTInit( true, true, true );
DXUTSetCursorSettings( true, true );
DXUTCreateWindow( L"HLSLSelfShadowing" );
DXUTCreateDevice( D3DADAPTER_DEFAULT, true, 640, 480,
IsDeviceAcceptable, ModifyDeviceSettings );

//进入消息循环和场景渲染
DXUTMainLoop();

//在此进行应用程序相关的清除工作

return DXUTGetExitCode();
}

//-----------------------------------------------------------------------------
// Desc: 应用程序相关初始化
//-----------------------------------------------------------------------------
void InitApp()
{
//初始化对话框
g_SettingsDlg.Init( &g_DialogResourceManager );
g_HUD.Init( &g_DialogResourceManager );
g_SampleUI.Init( &g_DialogResourceManager );

//为g_HUD对话框设置消息处理函数,添加控件
g_HUD.SetCallback( OnGUIEvent ); int iY = 10;
g_HUD.AddButton( IDC_TOGGLEFULLSCREEN, L"Toggle full screen", 35, iY, 125, 22 );
g_HUD.AddButton( IDC_TOGGLEREF, L"Toggle REF (F3)", 35, iY += 24, 125, 22 );
g_HUD.AddButton( IDC_CHANGEDEVICE, L"Change device (F2)", 35, iY += 24, 125, 22, VK_F2 );

//为g_SampleUI对话框设置消息处理函数,添加控件
g_SampleUI.SetCallback( OnGUIEvent ); iY = 0;
g_bEnableSelfShadow = true;
g_SampleUI.AddCheckBox( IDC_ENABLE_SELFSHADOW, L"Enable preshaders", 35, iY, 125, 22, true );
}

//-----------------------------------------------------------------------------
// Desc: 设备能力检查
//-----------------------------------------------------------------------------
bool CALLBACK IsDeviceAcceptable( D3DCAPS9* pCaps, D3DFORMAT AdapterFormat,
D3DFORMAT BackBufferFormat, bool bWindowed,
void* pUserContext )
{
//检查后台缓冲区格式是否支持Alpha混合等操作(post pixel blending operations)
IDirect3D9* pD3D = DXUTGetD3DObject();
if( FAILED( pD3D->CheckDeviceFormat( pCaps->AdapterOrdinal, pCaps->DeviceType,
AdapterFormat, D3DUSAGE_QUERY_POSTPIXELSHADER_BLENDING,
D3DRTYPE_TEXTURE, BackBufferFormat ) ) )
return false;

//检查当前设备支持的顶点渲染器版本
if( pCaps->VertexShaderVersion < D3DVS_VERSION(2,0) )
return FALSE;

return true;
}

//-----------------------------------------------------------------------------
// Desc: 修改Direct3D渲染设备设置
//-----------------------------------------------------------------------------
bool CALLBACK ModifyDeviceSettings( DXUTDeviceSettings* pDeviceSettings,
const D3DCAPS9* pCaps, void* pUserContext )
{
//如果不支持硬件顶点处理则使用软件顶点处理
if( (pCaps->DevCaps & D3DDEVCAPS_HWTRANSFORMANDLIGHT) == 0)
{
pDeviceSettings->BehaviorFlags = D3DCREATE_SOFTWARE_VERTEXPROCESSING;
}

//调试顶点渲染器需要参考设备或软件顶点处理
#ifdef DEBUG_VS
if( pDeviceSettings->DeviceType != D3DDEVTYPE_REF )
{
pDeviceSettings->BehaviorFlags &= ~D3DCREATE_HARDWARE_VERTEXPROCESSING;
pDeviceSettings->BehaviorFlags &= ~D3DCREATE_PUREDEVICE;
pDeviceSettings->BehaviorFlags |= D3DCREATE_SOFTWARE_VERTEXPROCESSING;
}
#endif

//调试像素渲染器需要参考设备
#ifdef DEBUG_PS
pDeviceSettings->DeviceType = D3DDEVTYPE_REF;
#endif

//如果使用参考设备,则弹出警告对话框
static bool s_bFirstTime = true;
if( s_bFirstTime )
{
s_bFirstTime = false;
if( pDeviceSettings->DeviceType == D3DDEVTYPE_REF )
DXUTDisplaySwitchingToREFWarning();
}

return true;
}

//-----------------------------------------------------------------------------
// Desc: 在此创建管理内存资源对象
//-----------------------------------------------------------------------------
HRESULT CALLBACK OnCreateDevice( IDirect3DDevice9* pd3dDevice,
const D3DSURFACE_DESC* pBackBufferSurfaceDesc,
void* pUserContext )
{
HRESULT hr;

V_RETURN( g_DialogResourceManager.OnCreateDevice( pd3dDevice ) );
V_RETURN( g_SettingsDlg.OnCreateDevice( pd3dDevice ) );

//创建字体
V_RETURN( D3DXCreateFont( pd3dDevice, 15, 0, FW_BOLD, 1, FALSE, DEFAULT_CHARSET,
OUT_DEFAULT_PRECIS, DEFAULT_QUALITY, DEFAULT_PITCH | FF_DONTCARE,
L"Arial", &g_pFont ) );

//创建顶点缓冲区
V_RETURN( pd3dDevice->CreateVertexBuffer( 50*2*sizeof(CUSTOMVERTEX),
0, D3DFVF_CUSTOMVERTEX,
D3DPOOL_MANAGED, &g_pVB, NULL ));
//填充顶点缓冲区
CUSTOMVERTEX* pVertices;
V_RETURN( g_pVB->Lock( 0, 0, (void**)&pVertices, 0 ) );
for( DWORD i=0; i<50; i++ )
{
FLOAT theta = (2*D3DX_PI*i)/(50-1);
pVertices[2*i+0].position = D3DXVECTOR3( sinf(theta),-1.0f, cosf(theta) );
pVertices[2*i+0].normal = D3DXVECTOR3( sinf(theta), 0.0f, cosf(theta) );
pVertices[2*i+1].position = D3DXVECTOR3( sinf(theta), 1.0f, cosf(theta) );
pVertices[2*i+1].normal = D3DXVECTOR3( sinf(theta), 0.0f, cosf(theta) );
}
g_pVB->Unlock();

//创建效果
V_RETURN(D3DXCreateEffectFromFile( pd3dDevice, L"HLSLSelfShadowing.fx", NULL, NULL,
D3DXSHADER_DEBUG, NULL, &g_pEffect, NULL ));

return S_OK;
}

//-----------------------------------------------------------------------------
// Desc: 在此创建默认内存类型资源对象
//-----------------------------------------------------------------------------
HRESULT CALLBACK OnResetDevice( IDirect3DDevice9* pd3dDevice,
const D3DSURFACE_DESC* pBackBufferSurfaceDesc,
void* pUserContext )
{
HRESULT hr;

V_RETURN( g_DialogResourceManager.OnResetDevice() );
V_RETURN( g_SettingsDlg.OnResetDevice() );

//设置对话框位置和尺寸
g_HUD.SetLocation( pBackBufferSurfaceDesc->Width-170, 0 );
g_HUD.SetSize( 170, 170 );
g_SampleUI.SetLocation( pBackBufferSurfaceDesc->Width-170,
pBackBufferSurfaceDesc->Height-50 );
g_SampleUI.SetSize( 170, 50 );

//恢复字体
if( g_pFont )
V_RETURN( g_pFont->OnResetDevice() );

//创建ID3DXSprite接口对象
V_RETURN( D3DXCreateSprite( pd3dDevice, &g_pTextSprite ) );

//恢复效果对象
if( g_pEffect )
V_RETURN( g_pEffect->OnResetDevice() );

//构造世界矩阵
D3DXMATRIX matWorld;
D3DXMatrixIdentity( &matWorld );

//构造观察矩阵
D3DXMATRIXA16 matView;
D3DXVECTOR3 vEyePt( 0.0f, 3.0f,-5 );
D3DXVECTOR3 vLookatPt( 0.0f, 0.0f, 0.0f );
D3DXVECTOR3 vUpVec( 0.0f, 1.0f, 0.0f );
D3DXMatrixLookAtLH( &matView, &vEyePt, &vLookatPt, &vUpVec );

//构造投影矩阵
D3DXMATRIXA16 matProj;
float fAspectRatio = (float)pBackBufferSurfaceDesc->Width / pBackBufferSurfaceDesc->Height;
D3DXMatrixPerspectiveFovLH( &matProj, D3DX_PI/4, fAspectRatio, 1.0f, 100.0f );

//为效果设置组合变换矩阵和世界矩阵
D3DXMATRIX mWorldViewProj = matWorld * matView * matProj;
g_pEffect->SetMatrix( "matWorldViewProj", &mWorldViewProj );
g_pEffect->SetMatrix( "matWorld", &matWorld );

//为效果设置观察点位置
D3DXVECTOR4 vecEyeInEffect = D3DXVECTOR4(vEyePt.x, vEyePt.y, vEyePt.z, 0);
g_pEffect->SetVector( "vecEye", &vecEyeInEffect );

//为效果设置材质反射系数
D3DXVECTOR4 mtrlAmbientInEffect = D3DXVECTOR4( 0.5f, 0.5f, 0.0f, 1.0f );
D3DXVECTOR4 mtrlDiffuseInEffect = D3DXVECTOR4( 1.0f, 1.0f, 0.0f, 1.0f );
D3DXVECTOR4 mtrlSpecularInEffect = D3DXVECTOR4( 1.0f, 1.0f, 1.0f, 1.0f );
g_pEffect->SetVector( "materialAmbient", &mtrlAmbientInEffect );
g_pEffect->SetVector( "materialDiffuse", &mtrlDiffuseInEffect );
g_pEffect->SetVector( "materialSpecular", &mtrlSpecularInEffect);

//设置剔出模式,为不剔出任何面
hr = pd3dDevice->SetRenderState( D3DRS_CULLMODE, D3DCULL_NONE );

return S_OK;
}

//-----------------------------------------------------------------------------
// Desc: 更新场景
//-----------------------------------------------------------------------------
void CALLBACK OnFrameMove( IDirect3DDevice9* pd3dDevice, double fTime,
float fElapsedTime, void* pUserContext )
{
//为效果设置光的方向
D3DXVECTOR4 lightDir = D3DXVECTOR4( cosf(timeGetTime()/350.0f), 1.0f,
sinf(timeGetTime()/350.0f), 1.0f );
g_pEffect->SetVector( "vecLightDir", &lightDir );
}

//-----------------------------------------------------------------------------
// Desc: 渲染场景
//-----------------------------------------------------------------------------
void CALLBACK OnFrameRender( IDirect3DDevice9* pd3dDevice, double fTime,
float fElapsedTime, void* pUserContext )
{
HRESULT hr;

//如果正在利用Direct3D设备设置对话框进行设置, 则不渲染场景
if( g_SettingsDlg.IsActive() )
{
g_SettingsDlg.OnRender( fElapsedTime );
return;
}

//清除后台颜色缓冲区和深度缓冲区
V( pd3dDevice->Clear(0, NULL, D3DCLEAR_TARGET | D3DCLEAR_ZBUFFER,
D3DCOLOR_ARGB(0, 45, 50, 170), 1.0f, 0) );

//渲染场景
if( SUCCEEDED( pd3dDevice->BeginScene() ) )
{
//使用效果渲染图形
if(g_bEnableSelfShadow)
{
V(g_pEffect->SetTechnique( "TShaderSelfShadow" ));
}
else
{
V(g_pEffect->SetTechnique( "TShaderNoSelfShadow" ));
}

UINT nPasses;
g_pEffect->Begin( &nPasses, 0 );
for( UINT iPass = 0; iPass < nPasses; iPass ++ )
{
V(g_pEffect->BeginPass( iPass ));
V(pd3dDevice->SetStreamSource( 0, g_pVB, 0, sizeof(CUSTOMVERTEX) ));
V(pd3dDevice->SetFVF( D3DFVF_CUSTOMVERTEX ));
V(pd3dDevice->DrawPrimitive( D3DPT_TRIANGLESTRIP, 0, 2*50-2 ));
V(g_pEffect->EndPass());
}
g_pEffect->End();

//渲染文本和控件
DXUT_BeginPerfEvent( DXUT_PERFEVENTCOLOR, L"HUD / Stats" );
RenderText();
V( g_HUD.OnRender( fElapsedTime ) );
V( g_SampleUI.OnRender( fElapsedTime ) );
DXUT_EndPerfEvent();

V( pd3dDevice->EndScene() );
}
}

//-----------------------------------------------------------------------------
// Desc: 渲染文本
//-----------------------------------------------------------------------------
void RenderText()
{
CDXUTTextHelper txtHelper( g_pFont, g_pTextSprite, 15 );

//显示当前Direct3D设备状态和渲染帧速率
txtHelper.Begin();
txtHelper.SetInsertionPos( 5, 5 );
txtHelper.SetForegroundColor( D3DXCOLOR( 1.0f, 1.0f, 0.0f, 1.0f ) );
txtHelper.DrawTextLine( DXUTGetFrameStats(true) );
txtHelper.DrawTextLine( DXUTGetDeviceStats() );

//显示其他简要信息
txtHelper.SetForegroundColor( D3DXCOLOR( 1.0f, 1.0f, 1.0f, 1.0f ) );
txtHelper.DrawTextLine( L"通过HLSL编程实现自遮蔽阴影" );

//显示简单帮助文本
const D3DSURFACE_DESC* pd3dsdBackBuffer = DXUTGetBackBufferSurfaceDesc();
if( g_bShowHelp )
{
txtHelper.SetInsertionPos( 10, pd3dsdBackBuffer->Height-15*6 );
txtHelper.SetForegroundColor( D3DXCOLOR( 1.0f, 0.75f, 0.0f, 1.0f ) );
txtHelper.DrawTextLine( L"Controls (F1 to hide):" );

txtHelper.SetInsertionPos( 40, pd3dsdBackBuffer->Height-15*5 );
txtHelper.DrawTextLine( L"Quit: ESC" );
}
else
{
txtHelper.SetInsertionPos( 10, pd3dsdBackBuffer->Height-15*2 );
txtHelper.SetForegroundColor( D3DXCOLOR( 1.0f, 1.0f, 1.0f, 1.0f ) );
txtHelper.DrawTextLine( L"Press F1 for help" );
}
txtHelper.End();
}

//-----------------------------------------------------------------------------
// Desc: 消息处理
//-----------------------------------------------------------------------------
LRESULT CALLBACK MsgProc( HWND hWnd, UINT uMsg, WPARAM wParam, LPARAM lParam,
bool* pbNoFurtherProcessing, void* pUserContext )
{
*pbNoFurtherProcessing = g_DialogResourceManager.MsgProc( hWnd, uMsg, wParam, lParam );
if( *pbNoFurtherProcessing )
return 0;

if( g_SettingsDlg.IsActive() )
{
g_SettingsDlg.MsgProc( hWnd, uMsg, wParam, lParam );
return 0;
}

*pbNoFurtherProcessing = g_HUD.MsgProc( hWnd, uMsg, wParam, lParam );
if( *pbNoFurtherProcessing )
return 0;

*pbNoFurtherProcessing = g_SampleUI.MsgProc( hWnd, uMsg, wParam, lParam );
if( *pbNoFurtherProcessing )
return 0;

return 0;
}

//-----------------------------------------------------------------------------
// Desc: 键盘消息处理
//-----------------------------------------------------------------------------
void CALLBACK KeyboardProc( UINT nChar, bool bKeyDown, bool bAltDown, void* pUserContext )
{
if( bKeyDown )
{
switch( nChar )
{
case VK_F1: g_bShowHelp = !g_bShowHelp; break;
}
}
}

//-----------------------------------------------------------------------------
// Desc: 处理各种控件消息
//-----------------------------------------------------------------------------
void CALLBACK OnGUIEvent( UINT nEvent, int nControlID, CDXUTControl* pControl,
void* pUserContext )
{
switch( nControlID )
{
case IDC_TOGGLEFULLSCREEN:
DXUTToggleFullScreen();
break;

case IDC_TOGGLEREF:
DXUTToggleREF();
break;

case IDC_CHANGEDEVICE:
g_SettingsDlg.SetActive( !g_SettingsDlg.IsActive() );
break;

case IDC_ENABLE_SELFSHADOW:
g_bEnableSelfShadow = g_SampleUI.GetCheckBox( IDC_ENABLE_SELFSHADOW )->GetChecked();
break;
}
}

//-----------------------------------------------------------------------------
// Desc: 释放在OnResetDevice()中创建的资源
//-----------------------------------------------------------------------------
void CALLBACK OnLostDevice( void* pUserContext )
{
g_DialogResourceManager.OnLostDevice();
g_SettingsDlg.OnLostDevice();
if( g_pFont )
g_pFont->OnLostDevice();
SAFE_RELEASE( g_pTextSprite );

if( g_pEffect )
g_pEffect->OnLostDevice();
}

//------------------------------------------------------------------------------
// Desc: 释放在OnCreateDevice()中创建的资源
//------------------------------------------------------------------------------
void CALLBACK OnDestroyDevice( void* pUserContext )
{
g_DialogResourceManager.OnDestroyDevice();
g_SettingsDlg.OnDestroyDevice();
SAFE_RELEASE( g_pFont );

SAFE_RELEASE(g_pVB);
SAFE_RELEASE(g_pEffect);
}

C++代码可以直接在程序中运行，但是需要安装Direct SDK，代码中都有注释，这里就不一一讲解了，如果对此还不清楚，自己可以查看一下Direct SDK文档。在这里只把重点代码解释一下，首先是加载Shader脚本文件到内存中，代码函数如下所示： //创建效果
V_RETURN(D3DXCreateEffectFromFile( pd3dDevice, L"HLSLSelfShadowing.fx", NULL, NULL,
D3DXSHADER_DEBUG, NULL, &g_pEffect, NULL ));
接下来开始对Shader文件中的矩阵和声明的变量进行赋值操作： //构造投影矩阵
D3DXMATRIXA16 matProj;
float fAspectRatio = (float)pBackBufferSurfaceDesc->Width / pBackBufferSurfaceDesc->Height;
D3DXMatrixPerspectiveFovLH( &matProj, D3DX_PI/4, fAspectRatio, 1.0f, 100.0f );

//为效果设置组合变换矩阵和世界矩阵
D3DXMATRIX mWorldViewProj = matWorld * matView * matProj;
g_pEffect->SetMatrix( "matWorldViewProj", &mWorldViewProj );
g_pEffect->SetMatrix( "matWorld", &matWorld );

//为效果设置观察点位置
D3DXVECTOR4 vecEyeInEffect = D3DXVECTOR4(vEyePt.x, vEyePt.y, vEyePt.z, 0);
g_pEffect->SetVector( "vecEye", &vecEyeInEffect );

//为效果设置材质反射系数
D3DXVECTOR4 mtrlAmbientInEffect = D3DXVECTOR4( 0.5f, 0.5f, 0.0f, 1.0f );
D3DXVECTOR4 mtrlDiffuseInEffect = D3DXVECTOR4( 1.0f, 1.0f, 0.0f, 1.0f );
D3DXVECTOR4 mtrlSpecularInEffect = D3DXVECTOR4( 1.0f, 1.0f, 1.0f, 1.0f );
g_pEffect->SetVector( "materialAmbient", &mtrlAmbientInEffect );
g_pEffect->SetVector( "materialDiffuse", &mtrlDiffuseInEffect );
g_pEffect->SetVector( "materialSpecular", &mtrlSpecularInEffect);
这些参数是需要传到shader脚本文件中的，由于Unity3D它有自己的UnityCG库，它是已经实现了直接调用接口即可。在Direct3D中通过调用函数SetTechnique执行Technique技术，也就是执行GPU渲染，代码段如下所示： //渲染场景
if( SUCCEEDED( pd3dDevice->BeginScene() ) )
{
//使用效果渲染图形
if(g_bEnableSelfShadow)
{
V(g_pEffect->SetTechnique( "TShaderSelfShadow" ));
}
else
{
V(g_pEffect->SetTechnique( "TShaderNoSelfShadow" ));
}

UINT nPasses;
g_pEffect->Begin( &nPasses, 0 );
for( UINT iPass = 0; iPass < nPasses; iPass ++ )
{
V(g_pEffect->BeginPass( iPass ));
V(pd3dDevice->SetStreamSource( 0, g_pVB, 0, sizeof(CUSTOMVERTEX) ));
V(pd3dDevice->SetFVF( D3DFVF_CUSTOMVERTEX ));
V(pd3dDevice->DrawPrimitive( D3DPT_TRIANGLESTRIP, 0, 2*50-2 ));
V(g_pEffect->EndPass());
}
g_pEffect->End();

//渲染文本和控件
DXUT_BeginPerfEvent( DXUT_PERFEVENTCOLOR, L"HUD / Stats" );
RenderText();
V( g_HUD.OnRender( fElapsedTime ) );
V( g_SampleUI.OnRender( fElapsedTime ) );
DXUT_EndPerfEvent();

V( pd3dDevice->EndScene() );
} 其实，以上利用Direct3D的原理帮助读者理解Unity3D引擎内部实现原理，它们都是相通的，我在博客中也做了关于3D游戏引擎系列文章讲解，在这里也是为了帮助读者理解。文字写的比较少，但是代码都有注释希望读者能够理解。