Adding a Dynamic Scope

This article will deal with creating a dynamic scope, which uses a render target on weapon model to draw the current players view. This code was created and run on the Episode One source code, but it should work in other versions too.

Note:There can apparently only be one render target on a model at a time. If you try to use this code and overlay it with another effect (e.g. refraction to simulate a lens), only one of the targets will be drawn.

Note:The modified crossbow model as seen on the right is available for download here.

The Code

Firstly, create two new files - in the code they are called tne_RenderTargets.cpp and tne_RenderTargets.h. Add them to cl_dll project. They deal with the custom render targets interface. Moreover, baseclientrendertargts.cpp needs to be added (and subsequently the header of it) to the cl_dll project in order to avoid unresolved externals. Although, other versions of SDK might already have it in.

Here's what should be pasted in each, with proper explanation.

tne_RenderTargets.cpp (new file)

#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;

This class derives from CBaseClientRenderTargets, an interface made by Valve. CreateScopeTexture() function is called by the engine in InitClientRenderTargets(), in order to Init m_ScopeTexture (our scope render target texture) and it is also released in ShutdownClientRenderTargets().

tne_RenderTargets.h (new file)

#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_

This is the header file, it's pretty self-explanatory - it overrides virtual functions from its 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;
}

Put this somewhere near GetCameraTexture function. It provides as a function which finds&returns Render Target Texture;

//Release the scope render target too
s_pScopeTexture.Shutdown();

Add this code to void ReleaseRenderTargets( void ). It handles the removal of render target.

rendertexture.h

ITexture *GetScopeTexture();

Add this line after GetCameraTexture.

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 );
}

This code is very similar to DrawCamera one. Basically, it copies the current view, assigns the render target to a texture pointer, then sets some basic options for scopeView like width, height, position, etc. The FOV is set here with reference to a value set in weapon script file and be elaborated upon.

viewrender.h

void	DrawScope( const CViewSetup &cameraView );

Put this after DrawCamera.

view_scene.cpp

//Draw the scope too
if(g_pMaterialSystemHardwareConfig->GetDXSupportLevel() >= 70 )
{
	DrawScope( view );
}

It draws the scope vision if you have a DirectX 7 capable card (lowers are not supported). Put this code in RenderViewEx() just after #ifdef USE_MONITORS #endif block in the beginning of the function.

The .vmt file

Created a new .vmt file that will setup the texture and allow it to be attached to a gun. Put inside:

UnlitGeneric { $basetexture _rt_Scope $model 1 }

It takes the newly created _rt_Scope texture and sets it up to be useable for texturing models. Then just put the _rt_Scope texture on your weapon model!

Episode 2 Engine Fixes

viewrender.cpp

Place the DrawScope function in viewrender.cpp after DrawMonitors, instead of in view.cpp.

Change:

	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 );

To:

	//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 );

Change:

scopeView.fov = localPlayer->GetActiveWeapon()->GetZoomFOV();

To:

scopeView.fov = 45;

(GetZoomFOV() isn't a default float function. It needs to be added to C_BaseCombatWeapon in order to work, or hardcoded as shown above.)

Place this in viewrender.cpp at the end of CViewRender::RenderView

		if(g_pMaterialSystemHardwareConfig->GetDXSupportLevel() >= 70 )
		{
			DrawScope( view );
		}

Right above

	render->PopView( GetFrustum() );
	g_WorldListCache.Flush();

instead of view_scene.cpp

The scopes should now work in any Episode 2 based Game.

Special thanks to omega from hlcoders mailing list, who shared his code and pointed the writer in the right direction.