object direction_marker {
	void			destroy();

	void			Create( float index, string entityDef, vector position, vector direction );
	void			Fade( float sec, float duration, float start, float end );
	void			Remove();
	void			Update( float sec );

	entity			marker;
	vector			markerOrigin;
	vector			markerNormal;
	
	float			arrowJoint;
	
	float			bobStartSec;
	
	// fade
	float			fadeStartSec;
	float			fadeDurationSec;
	float			fadeStart;
	float			fadeEnd;
};

void direction_marker::destroy() {
	Remove();
}

void direction_marker::Create( float index, string entityDef, vector position, vector direction ) {
	float fraction = sys.tracePoint( position, position + ( vec3_down * MAX_WORLD_SIZE ), CONTENTS_SOLID | CONTENTS_OPAQUE | CONTENTS_WATER, $null_entity );
	
	if ( fraction == 1.0f ) {
		return;
	}
	
	bobStartSec = index * 0.025f;
	
	fadeStartSec = 0.0f;
	fadeDurationSec = 0.0f;
	fadeStart = 1.0f;
	fadeEnd = 1.0f;

	marker = sys.spawnClient( entityDef );
	marker.playCycle( ANIMCHANNEL_ALL, "locking" );
	
	arrowJoint = marker.getJointHandle( "arrow" );
	
	markerOrigin = sys.getTraceEndPos();
	markerNormal = sys.getTraceNormal();

	markerOrigin = markerOrigin + markerNormal * 4.0f;

	marker.setOrigin( markerOrigin );

	vector right = sys.crossProduct( markerNormal, direction );
	right = sys.vecNormalize( right );
	vector forward = sys.crossProduct( markerNormal, right );
	forward = sys.vecNormalize( forward );
	
	marker.setWorldAxis( forward, right, markerNormal );
}

void direction_marker::Fade( float sec, float duration, float start, float end ) {
	if ( marker == $null_entity ) {
		return;
	}

	fadeStartSec = sec;
	fadeDurationSec = duration;
	fadeStart = start;
	fadeEnd = end;
}

void direction_marker::Remove() {
	if ( marker != $null_entity ) {
		marker.remove();
		marker = $null_entity;
	}
}

void direction_marker::Update( float sec ) {
	if ( marker == $null_entity ) {
		return;
	}
	
	// fading
	float fade;
	if ( sec < fadeStartSec ) {
		fade = fadeStart;
	} else if ( sec > fadeStartSec + fadeDurationSec ) {
		fade = fadeEnd;
	} else if ( fadeDurationSec > 0.0f ) {
		fade = fadeStart + ( ( ( sec - fadeStartSec ) / fadeDurationSec ) * ( fadeEnd - fadeStart ) );
	} else {
		fade = fadeStart;
	}
	marker.setShaderParms( fade, fade, fade, 1.0f );

	// bobbing
	float secInCycle = sys.fmod( sec, 0.6f );	// was 1.0f
	float bobDuration = 0.3f;//0.2f;

	if ( secInCycle < bobStartSec ) {
		// not starting bob yet
		return;
	} else if ( secInCycle > bobStartSec + bobDuration ) {
		// finished bob
		return;
	}

	// in bob
	float secInBob = secInCycle - bobStartSec;
	float fractionInBob = secInBob / bobDuration;
	float verticalBobFraction = ( -0.5f * sys.cos( fractionInBob * 360.0f ) ) + 0.5f;
	
	//vector offset = verticalBobFraction * markerNormal * 36.0f;
	vector offset = verticalBobFraction * vec3_up * 36.0f;

	//marker.setOrigin( markerOrigin + offset );
	marker.setJointPos( arrowJoint, JOINTMOD_LOCAL, offset );
}