Zh/Adding a Dynamic Scope

这篇文章会创建一个动态狙击镜，它使用一个渲染目标的武器模型得出当前玩家的视角。这些代码可以运行在半条命2：第一章的引擎，应该也可以在其他版本引擎工作。
==创建代码==
首先创建两个文件分别命名为tne_RenderTargets.cpp和tne_RenderTargets.h，并添加到cl_dll项目，这些代码能够自定义渲染目标。此外，为了避免未知错误，baseclientrendertargts.cpp（及其头文件）需要添加到cl_dll项目。然而，其他版本的SDK都有这文件。
===tne_RenderTargets.cpp （新文件）===
#include "cbase.h"
#include "tne_RenderTargets.h"
#include "materialsystem\imaterialsystem.h"
#include "rendertexture.h"
 
ITexture* CTNERenderTargets::CreateScopeTexture( IMaterialSystem* pMaterialSystem )
{
//	DevMsg("Creating Scope Render Target: _rt_Scope\n");
	return pMaterialSystem->CreateNamedRenderTargetTextureEx2(
		"_rt_Scope",
		1024, 1024, RT_SIZE_OFFSCREEN,
		pMaterialSystem->GetBackBufferFormat(),
		MATERIAL_RT_DEPTH_SHARED, 
		TEXTUREFLAGS_CLAMPS | TEXTUREFLAGS_CLAMPT,
		CREATERENDERTARGETFLAGS_HDR );
 
}
//-----------------------------------------------------------------------------
// Purpose: Called by the engine in material system init and shutdown.
//			Clients should override this in their inherited version, but the base
//			is to init all standard render targets for use.
// Input : pMaterialSystem - the engine's material system (our singleton is not yet inited at the time this is called)
//			pHardwareConfig - the user hardware config, useful for conditional render target setup
//-----------------------------------------------------------------------------
void CTNERenderTargets::InitClientRenderTargets( IMaterialSystem* pMaterialSystem, IMaterialSystemHardwareConfig* pHardwareConfig )
{ 
	m_ScopeTexture.Init( CreateScopeTexture( pMaterialSystem ) ); 
	// Water effects & camera from the base class (standard HL2 targets) 
	BaseClass::InitClientRenderTargets( pMaterialSystem, pHardwareConfig );
}
 
//-----------------------------------------------------------------------------
// Purpose: Shut down each CTextureReference we created in InitClientRenderTargets.
//			Called by the engine in material system shutdown.
// Input : - 
//-----------------------------------------------------------------------------
void CTNERenderTargets::ShutdownClientRenderTargets()
{ 
	m_ScopeTexture.Shutdown();
 
	// Clean up standard HL2 RTs (camera and water) 
	BaseClass::ShutdownClientRenderTargets();
}
 
//add the interface!
static CTNERenderTargets g_TNERenderTargets;
EXPOSE_SINGLE_INTERFACE_GLOBALVAR( CTNERenderTargets, IClientRenderTargets, CLIENTRENDERTARGETS_INTERFACE_VERSION, g_TNERenderTargets );
CTNERenderTargets* TNERenderTargets = &g_TNERenderTargets;
这段代码类似于CBaseClientRenderTargets。CreateScopeTexture()函数在引擎中被InitClientRenderTargets()函数呼应，为了初始化m_ScopeTexture（就是渲染目标贴图）,他也呼应ShutdownClientRenderTargets()。
===tne_RenderTargets.h （新文件）===
#ifndef TNERENDERTARGETS_H_
#define TNERENDERTARGETS_H_
#ifdef _WIN32
#pragma once
#endif
 
#include "baseclientrendertargets.h" // Base class, with interfaces called by engine and inherited members to init common render targets
 
// externs
class IMaterialSystem;
class IMaterialSystemHardwareConfig;
 
class CTNERenderTargets : public CBaseClientRenderTargets
{ 
	// no networked vars 
	DECLARE_CLASS_GAMEROOT( CTNERenderTargets, CBaseClientRenderTargets );
public: 
	virtual void InitClientRenderTargets( IMaterialSystem* pMaterialSystem, IMaterialSystemHardwareConfig* pHardwareConfig );
	virtual void ShutdownClientRenderTargets();
 
	ITexture* CreateScopeTexture( IMaterialSystem* pMaterialSystem );
private:
	CTextureReference		m_ScopeTexture; 
};
 
extern CTNERenderTargets* TNERenderTargets;
 
#endif //TNERENDERTARGETS_H_
这是头文件，它重写一个虚函数来自CBaseClientRenderTargets。
===rendertexture.cpp===
static CTextureReference s_pScopeTexture;
ITexture *GetScopeTexture( void )
{ 
	if ( !s_pScopeTexture )
	{
		s_pScopeTexture.Init( materials->FindTexture( "_rt_Scope", TEXTURE_GROUP_RENDER_TARGET ) );
		Assert( !IsErrorTexture( s_pScopeTexture ) );
		AddReleaseFunc();
	}
	return s_pScopeTexture;
}
把这段代码放到GetCameraTexture函数附近，它的作用是返回渲染目标贴图。
===rendertexture.h===
ITexture *GetScopeTexture();
把这行代码放到GetCameraTexture之后。
===view.cpp===
void CViewRender::DrawScope( const CViewSetup &viewSet )
{
	C_BasePlayer *localPlayer = C_BasePlayer::GetLocalPlayer();
	if(!localPlayer)
		return;
	if( !localPlayer->GetActiveWeapon() )
		return;
	if( !localPlayer->GetActiveWeapon()->GetViewModel() )
		return;
	//Copy our current View.
	CViewSetup scopeView = viewSet;
	//Get our camera render target.
	ITexture *pRenderTarget = GetScopeTexture();
	if( pRenderTarget == NULL )
		return;
	if( !pRenderTarget->IsRenderTarget() )
		Msg(" not a render target");
	//Our view information, Origin, View Direction, window size
	//	location on material, and visual ratios.
	scopeView.width = pRenderTarget->GetActualWidth();
	scopeView.height = pRenderTarget->GetActualHeight();
	scopeView.x = 0;
	scopeView.y = 0;
	scopeView.fov = localPlayer->GetActiveWeapon()->GetZoomFOV();
	scopeView.m_bOrtho = false;
	scopeView.m_flAspectRatio = 1.0f;
	int nClearFlags = VIEW_CLEAR_DEPTH | VIEW_CLEAR_COLOR;
	bool bDrew3dSkybox = false;	// bDrew3dSkybox = true turns the skybox OFF. DO NOT SET IT TO TRUE.
	bool bSkyboxVisible = true;
	//Set the view up and output the scene to our RenderTarget (Scope Material).
	render->Push3DView( scopeView, VIEW_CLEAR_DEPTH | VIEW_CLEAR_COLOR, true, pRenderTarget, m_Frustum );
	Draw3dSkyboxworld( scopeView, nClearFlags, bDrew3dSkybox, bSkyboxVisible);
	ViewDrawScene( bDrew3dSkybox, bSkyboxVisible, scopeView, 0, VIEW_MONITOR );
	
	render->PopView( m_Frustum );
}
这段代码有点像DrawCamera，基本上，它复制当前的视角，分配渲染目标到贴图，然后设置一些基本属性给scopeView例如高度、宽度、位置等等，FOV在这里参考了武器脚本的值。
===viewrender.h===
void	DrawScope( const CViewSetup &cameraView );
把这行代码放在DrawCamera之后。
===view_scene.cpp===
//Draw the scope too
if(g_pMaterialSystemHardwareConfig->GetDXSupportLevel() >= 70 )
{
	DrawScope( view );
}
如果你是DirectX 7的显卡它的作用是切出瞄准镜，把这段代码放到RenderViewEx()，在#ifdef USE_MONITORS #endif这块代码之前。
==vmt文件==
创建一个新的vmt文件来创建贴图，并用它来与相关的武器对应。把以下文字放到此文件：
UnlitGeneric
{
	$basetexture _rt_Scope
	 $model 1
}
它创建_rt_Scope贴图并应用于可用的武器，然后把_rt_Scope放到你的武器模型！
== 半条命第二章引擎文件修复 ==
=== viewrender.cpp ===
在viewrender.cpp文件，在DrawMonitors之后，更换DrawScope函数，代替view.cpp。
更换：
	int nClearFlags = VIEW_CLEAR_DEPTH | VIEW_CLEAR_COLOR;
	bool bDrew3dSkybox = false;	// bDrew3dSkybox = true turns the skybox OFF. DO NOT SET IT TO TRUE.
	bool bSkyboxVisible = true;
	//Set the view up and output the scene to our RenderTarget (Scope Material).
	render->Push3DView( scopeView, VIEW_CLEAR_DEPTH | VIEW_CLEAR_COLOR, true, pRenderTarget, m_Frustum );
	Draw3dSkyboxworld( scopeView, nClearFlags, bDrew3dSkybox, bSkyboxVisible);
	ViewDrawScene( bDrew3dSkybox, bSkyboxVisible, scopeView, 0, VIEW_MONITOR );
	render->PopView( m_Frustum );
到：
	//Set the view up and output the scene to our RenderTarget (Scope Material).
	render->Push3DView( scopeView, VIEW_CLEAR_DEPTH | VIEW_CLEAR_COLOR, pRenderTarget, GetFrustum() );
	SkyboxVisibility_t nSkyboxVisible = SKYBOX_NOT_VISIBLE;
	int ClearFlags = 0;
	CSkyboxView *pSkyView = new CSkyboxView( this );
	if( pSkyView->Setup( scopeView, &ClearFlags, &nSkyboxVisible ) != false )
		AddViewToScene( pSkyView );
	SafeRelease( pSkyView );
	ViewDrawScene( false, SKYBOX_3DSKYBOX_VISIBLE, scopeView, VIEW_CLEAR_DEPTH, VIEW_MONITOR );
	
	render->PopView( m_Frustum );
更换：
scopeView.fov = localPlayer->GetActiveWeapon()->GetZoomFOV();
到
scopeView.fov = 45;
（GetZoomFOV()不是默认浮点函数，它需要C_BaseCombatWeapon的命令才能工作。）
更换viewrender.cpp的末尾CViewRender::RenderView
		if(g_pMaterialSystemHardwareConfig->GetDXSupportLevel() >= 70 )
		{
			DrawScope( view );
		}
右上方
	render->PopView( GetFrustum() );
	g_WorldListCache.Flush();
view_scene.cpp
现在动态狙击镜可以在半条命第二章引擎工作了。