point3.cpp

<B>DirectX9.0 3D游戏编程</B>

/*******************************************************************
 *         Advanced 3D Game Programming using DirectX 9.0
 * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
 * copyright (c) 2003 by Peter A Walsh and Adrian Perez
 * See license.txt for modification and distribution information
 ******************************************************************/

#include "point3.h"
#include "point4.h"

const point3 point3::Zero( 0.f,0.f,0.f );

const point3 point3::i( 1.f, 0.f, 0.f );
const point3 point3::j( 0.f, 1.f, 0.f );
const point3 point3::k( 0.f, 0.f, 1.f );

point3::point3( const point4& in )
{
	/**
	 * If the homogenous coordinate isn't 1, normalize the point.
	 */
	if( in.w != 1.f )
	{
		float inv = 1/in.w;
		x = in.x * inv;
		y = in.y * inv;
		z = in.z * inv;
	}
	else
	{
		x = in.x;
		y = in.y;
		z = in.z;
	}
}