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Since the earliest days of animation, two-dimensional (2D) animation has been created by presenting a series of drawings to the viewer in rapid succession where each drawing was similar to but slightlydifferent from the previous drawing. Because of the property of human vision to blur one Image Into the next, if the images are sufficiently similar and theyare presented in rapid succession, the human mind perceives the series of images as continuous motion. This is how motion pictures work, and it is also how thecartoons that you see on television work.


Animation can be created in a couple of different ways in Scratch. One way is through the use of something called costumes . For example, when you createa new project in Scratch, an image of a cat having two costumes is automatically added to the project. Image D shows a screen shot of the center panel in the user interface for a new project with the Costumes tab selected.

Image d. the costumes tab for a new scratch project.

Missing image.
Image D. The costumes tab for a new Scratch project.

Image D shows a lot more than just the current costumes. The current costumes are shown in the upper-left corner of Image D .

The cat sprite has two costumes

As you can see, the cat sprite has two costumes, which are really two different images of the cat. The images are designed to make it look like thecat is walking if the two images are repeated in rapid succession. You can also see that each costume has a name, with the default names in this case being:

  • costume1
  • costume2

If you choose to do so, you can click in the boxes containing the names and modify them. Also, if you choose to do so, you can use the built-in drawing program to modifythe drawing. However, most of that is beyond the scope of this module so we won't get into it here.

With only two costumes for the cat, the walking motion is not very smooth. Somewhere on the Scratch website, I saw a project that had sixteendifferent costumes for the cat. When those sixteen different costumes are displayed in succession, the cat appears to walk very smoothly.

Loop blocks

If you click the tan Control button in the Scratch user interface, you will expose a large number of blocks that are generally used to control the flow of the program. The following control blocks that areexposed by that button can be used to construct loops:

repeat (numeric value) - (see

The repeat (numeric value) block

The repeat (numeric value) block (referred to hereafter simply as the repeat block) provides the mechanism by which you can cause a set of actions to be executed a specified number of times. (See Image E .)

You create a repeat block that will do something useful by inserting programming blocks into the mouth of a repeat block. When you drag a raw repeat block into the center panel, it looks like the tan image shown in Image E .

Image e. various scratch blocks.

Missing image.
Image E. Various Scratch blocks.

Setting the number of repeats (iterations)

By default, the white box in the repeat block contains a literal numeric value. You can modify that value and specify the number of times thatthe code in the repeat block will be executed. When you use a literal value, the code will be executed the same number of times every time you run theprogram.

Questions & Answers

Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
Stoney Reply
why we need to study biomolecules, molecular biology in nanotechnology?
Adin Reply
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
what school?
biomolecules are e building blocks of every organics and inorganic materials.
anyone know any internet site where one can find nanotechnology papers?
Damian Reply
sciencedirect big data base
Introduction about quantum dots in nanotechnology
Praveena Reply
what does nano mean?
Anassong Reply
nano basically means 10^(-9). nanometer is a unit to measure length.
do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
Damian Reply
absolutely yes
how to know photocatalytic properties of tio2 nanoparticles...what to do now
Akash Reply
it is a goid question and i want to know the answer as well
characteristics of micro business
for teaching engĺish at school how nano technology help us
Do somebody tell me a best nano engineering book for beginners?
s. Reply
there is no specific books for beginners but there is book called principle of nanotechnology
what is fullerene does it is used to make bukky balls
Devang Reply
are you nano engineer ?
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.
what is the actual application of fullerenes nowadays?
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.
what is the Synthesis, properties,and applications of carbon nano chemistry
Abhijith Reply
Mostly, they use nano carbon for electronics and for materials to be strengthened.
is Bucky paper clear?
carbon nanotubes has various application in fuel cells membrane, current research on cancer drug,and in electronics MEMS and NEMS etc
so some one know about replacing silicon atom with phosphorous in semiconductors device?
s. Reply
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.
Do you know which machine is used to that process?
how to fabricate graphene ink ?
for screen printed electrodes ?
What is lattice structure?
s. Reply
of graphene you mean?
or in general
in general
Graphene has a hexagonal structure
On having this app for quite a bit time, Haven't realised there's a chat room in it.
what is biological synthesis of nanoparticles
Sanket Reply
Berger describes sociologists as concerned with
Mueller Reply
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Source:  OpenStax, Teaching beginners to code. OpenStax CNX. May 27, 2013 Download for free at http://cnx.org/content/col11498/1.20
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