Authoring a Model Entity/Code

//===== Copyright © 1996-2005, Valve Corporation, All rights reserved. ========
//
// Purpose: Simple model entity that randomly moves and changes direction
//			when activated.
//
//=============================================================================

#include "cbase.h"

class CMyModelEntity : public CBaseAnimating
{
public:
	DECLARE_CLASS( CMyModelEntity, CBaseAnimating );
	DECLARE_DATADESC();

	CMyModelEntity()
	{
		m_bActive = false;
	}

	void Spawn( void );
	void Precache( void );

	void MoveThink( void );

	// Input function
	void InputToggle( inputdata_t &inputData );

private:

	bool	m_bActive;
	float	m_flNextChangeTime;
};

LINK_ENTITY_TO_CLASS( my_model_entity, CMyModelEntity );

// Start of our data description for the class
BEGIN_DATADESC( CMyModelEntity )
	
	// Save/restore our active state
	DEFINE_FIELD( m_bActive, FIELD_BOOLEAN ),
	DEFINE_FIELD( m_flNextChangeTime, FIELD_TIME ),

	// Links our input name from Hammer to our input member function
	DEFINE_INPUTFUNC( FIELD_VOID, "Toggle", InputToggle ),

	// Declare our think function
	DEFINE_THINKFUNC( MoveThink ),

END_DATADESC()

// Name of our entity's model
#define	ENTITY_MODEL	"models/gibs/airboat_broken_engine.mdl"

//-----------------------------------------------------------------------------
// Purpose: Precache assets used by the entity
//-----------------------------------------------------------------------------
void CMyModelEntity::Precache( void )
{
	PrecacheModel( ENTITY_MODEL );

	BaseClass::Precache();
}

//-----------------------------------------------------------------------------
// Purpose: Sets up the entity's initial state
//-----------------------------------------------------------------------------
void CMyModelEntity::Spawn( void )
{
	Precache();

	SetModel( ENTITY_MODEL );
	SetSolid( SOLID_BBOX );
	UTIL_SetSize( this, -Vector(20,20,20), Vector(20,20,20) );
}

//-----------------------------------------------------------------------------
// Purpose: Think function to randomly move the entity
//-----------------------------------------------------------------------------
void CMyModelEntity::MoveThink( void )
{
	// See if we should change direction again
	if ( m_flNextChangeTime < gpGlobals->curtime )
	{
		// Randomly take a new direction and speed
		Vector vecNewVelocity = RandomVector( -64.0f, 64.0f );
		SetAbsVelocity( vecNewVelocity );

		// Randomly change it again within one to three seconds
		m_flNextChangeTime = gpGlobals->curtime + random->RandomFloat( 1.0f, 3.0f );
	}

	// Snap our facing to where we're heading
	Vector velFacing = GetAbsVelocity();
	QAngle angFacing;
	VectorAngles( velFacing, angFacing );
 	SetAbsAngles( angFacing );

	// Think every 20Hz
	SetNextThink( gpGlobals->curtime + 0.05f );
}

//-----------------------------------------------------------------------------
// Purpose: Toggle the movement of the entity
//-----------------------------------------------------------------------------
void CMyModelEntity::InputToggle( inputdata_t &inputData )
{
	// Toggle our active state
	if ( !m_bActive )
	{
		// Start thinking
		SetThink( &CMyModelEntity::MoveThink );

		SetNextThink( gpGlobals->curtime + 0.05f );
		
		// Start moving
		SetMoveType( MOVETYPE_FLY );

		// Force MoveThink() to choose a new speed and direction immediately
		m_flNextChangeTime = gpGlobals->curtime;

		// Update m_bActive to reflect our new state
		m_bActive = true;
	}
	else
	{
		// Stop thinking
		SetThink( NULL );
		
		// Stop moving
		SetAbsVelocity( vec3_origin );
 		SetMoveType( MOVETYPE_NONE );
		
		m_bActive = false;
	}
}

See also

• Authoring a Model Entity