* 3D box test 

-----------------------------------------------------------------------
This software comes with ABSOLUTELY NO WARRANTY. This is free software,
and you are welcome to modify and redistribute it under the GPL license
-----------------------------------------------------------------------

* ϸ mz3d, mz3dx 2  ˴ϴ.
 - mz3d  : Frame buffer  3D box ׸ϴ.
 - mz3dx : XFreeR6  3D box ׸ϴ.

*  ȨԴϴ. (minzkn)
 - http://www.minzkn.com:2744/

* TODO
 - Z buffer  
 - ĳ ұ ʿ

-----------------------------------------------------------------------------------------------------------

# 3 ǥ 2 ȯϴ ⺻

1. x' = distance * x / z;
2. y' = distance * y / z;
3. distance   ٰ ġ ؼ ϴ°   z (distance * 2)  ȭ ߾ӿ  ġ  ɰ̴ϴ.

# ȸ ʿ ⺻

1. z ȸ (Front)
* x' = sin(x) - cos(y)
* y' = -(cos(x) + sin(y))
2. x ȸ (Side)
* y' = sin(y) - cos(z)
* z' = -(cos(y) + sin(z))
3. y ȸ (Top)
* z' = sin(z) - cos(x)
* x' = -(cos(z) + sin(x))

# Scale  ʿ ⺻

1. x' = x * scalex;
2. y' = y * scaley;
3. z' = z * scalez;

# z buffer   ?

* 3 ̾ Ӹ ׸ ȴٴ  ִٸ ¥ ϰ ӿ  ̾  ƴ ǻ翡   ݻ Ǽ ̴ϴ. 嵥 ̾ ӿ 鿡  ĸ鵵 ׷ٴ  ˼ ֽϴ. ⼭  ĸ ׸ ʱ ؼ z buffer   ϴ. z buffer     ƴϰ   ̾ ׸ z࿡  ۸ Ѱ     z buffer ϵ˴ϴ. ׷ ϵ z buffer   ׸ ׸ 鿡  ĸ ׷ ʰ Ǵ ̴ϴ.
