# 1.13 Game 2302-0135: venturing into a 3d world  (Page 8/30)

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• GM01.Point3D.draw
• GM01.Vector3D.draw
• GM01.Line3D.draw

## The method named GM01.Point3D.draw

Recall that a point simply represents a location in space and has no width, height, or depth. Therefore a point is not visible to the human eye.However, it is sometimes useful to draw a small circle around a point to mark its location for human consumption. That is the purpose of the draw method of the GM01.Point3D class, which is shown in its entirety in Listing 4 .

Listing 4 . The method named GM01.Point3D.draw.
```public void draw(Graphics2D g2D){//Get 2D projection coordinate values. ColMatrix2D temp = convert3Dto2D(point);drawOval(g2D,temp.getData(0)-3, temp.getData(1)+3,6, 6);}//end draw```

Purpose of the method

This method draws a small circle around the location of a point in 3D space. The 3D location of the circle is projected onto the 2D plane of the specifiedgraphics context for display later on a 2D screen. The code in Listing 4 projects that location in 3D space onto the 2D plane by calling the staticmethod named convert3Dto2D .

Behavior of the GM01.Point3D.draw method

The location of a point in 3D space, as represented by an object of the GM01.Point3D class, is actually stored in an object of the GM01.ColMatrix3D class. A reference to that ColMatrix3D object is stored in the instance variable named point belonging to the Point3D object. This reference is passed as a parameter to the convert3Dto2D method in Listing 4 .

Recall from Listing 1 that the convert3Dto2D method receives an incoming reference to an object of the class GM01.ColMatrix3D and returns a reference to an object of the class GM01.ColMatrix2D , which contains the horizontal and vertical components of the projection of the 3D point onto a2D plane.

Using the returned GM01.ColMatrix2D object

Listing 4 uses the horizontal and vertical components stored in the returned ColMatrix2D object to construct the proper parameters and call the wrapper method named GM01.drawOval . This wrapper method doesn't know that it is receiving parameters that were originally derived from an objectin 3D space. The world of the wrapper method is confined to 2D space. The wrapper method named GM01.drawOval performs the following actions:

• casts the four incoming numeric parameters to type int ,
• flips the sign on the vertical component to resolve the issue regarding the positive value for the y-axis, and
• passes the parameters to the drawOval method of the standard Graphics class to cause a small circle to be drawn at the correct location on the 2D off-screen image.

The small circle is not converted to an ellipse

Note that even though the location of the point in 3D space is projected onto the 2D plane, the shape of the small circle is not converted to an ellipse toreflect the 3D to 2D conversion nature of the operation. Thus, if the circle were large, it wouldn't necessarily look right. However, in thiscase, the only purpose of the circle is to mark the location of a point in 3D space. Therefore, I didn't consider the actual shape of the marker to betoo important. Figure 1 shows examples of circles marking points in 3D space at the corners of the box and at the ends of the axes.

Is there any normative that regulates the use of silver nanoparticles?
what king of growth are you checking .?
Renato
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
why we need to study biomolecules, molecular biology in nanotechnology?
?
Kyle
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
why?
what school?
Kyle
biomolecules are e building blocks of every organics and inorganic materials.
Joe
anyone know any internet site where one can find nanotechnology papers?
research.net
kanaga
sciencedirect big data base
Ernesto
Introduction about quantum dots in nanotechnology
what does nano mean?
nano basically means 10^(-9). nanometer is a unit to measure length.
Bharti
do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
absolutely yes
Daniel
how to know photocatalytic properties of tio2 nanoparticles...what to do now
it is a goid question and i want to know the answer as well
Maciej
Abigail
for teaching engĺish at school how nano technology help us
Anassong
Do somebody tell me a best nano engineering book for beginners?
there is no specific books for beginners but there is book called principle of nanotechnology
NANO
what is fullerene does it is used to make bukky balls
are you nano engineer ?
s.
fullerene is a bucky ball aka Carbon 60 molecule. It was name by the architect Fuller. He design the geodesic dome. it resembles a soccer ball.
Tarell
what is the actual application of fullerenes nowadays?
Damian
That is a great question Damian. best way to answer that question is to Google it. there are hundreds of applications for buck minister fullerenes, from medical to aerospace. you can also find plenty of research papers that will give you great detail on the potential applications of fullerenes.
Tarell
what is the Synthesis, properties,and applications of carbon nano chemistry
Mostly, they use nano carbon for electronics and for materials to be strengthened.
Virgil
is Bucky paper clear?
CYNTHIA
carbon nanotubes has various application in fuel cells membrane, current research on cancer drug,and in electronics MEMS and NEMS etc
NANO
so some one know about replacing silicon atom with phosphorous in semiconductors device?
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
Harper
Do you know which machine is used to that process?
s.
how to fabricate graphene ink ?
for screen printed electrodes ?
SUYASH
What is lattice structure?
of graphene you mean?
Ebrahim
or in general
Ebrahim
in general
s.
Graphene has a hexagonal structure
tahir
On having this app for quite a bit time, Haven't realised there's a chat room in it.
Cied
what is biological synthesis of nanoparticles
how did you get the value of 2000N.What calculations are needed to arrive at it
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