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Fortunately, the value of delta can often be used to give the appearance of running at the target frame rate even though the actual frame rate may be belowthe target. I will show you how to do that in this module.

Discussion and sample code

A program with a relatively constant frame rate - Slick0150a

I will begin by discussing a case with a relatively constant frame rate. The program for this case, Slick0150a , is shown in Listing 9 .

The screen output for Slick0150a

Before getting into the coding details, I will show you some output. Figure 3 shows a screen shot of the game window while the program is running.

Figure 3 . Screen shot of the program named Slick0150a.
Missing image

The screen shot in Figure 3 caught the ladybug in mid flight. As mentioned earlier, the next time it collides with one of the edges of the gamewindow, it will bounce off and move in the opposite direction like a pool ball striking the cushion on the edge of a pool table.

The FPS output

As you learned in an earlier module, the text in the upper-left corner is the frame rate in frames per second computed and automatically displayed by the gameengine. You will see later that a target frame rate of 60 frames per second was requested by calling the method named setTargetFrameRate and passing 60 as a parameter.

At 60 frames per second, a time interval of 16.6666 milliseconds would be required to complete each frame. It appears that the setTargetFrameRate method truncates this value to an integer value of 16 milliseconds, which represents a framerate of 62.5 frames per second. It also appears that the code that displays the frame rate converts the actual frame rate to an integer for display. Hence you see an FPSvalue of 62 in Figure 3 .

The traversalTime output

The traversalTime output that you see in Figure 3 is computed and displayed by the program that we will examine shortly. This is the time required for the sprite to complete one round tripfrom the right edge to the left edge and back to the right edge.

If you compile and run this program, you will see that the traversalTime value is reasonably stable at around 3015 milliseconds.

The theoretical traversalTime

Although it isn't shown here, a separate output on the command-line window reported the width of the background image to be 414 pixels and the width of thesprite to be 48 pixels. The sprite is never allowed to go outside the boundaries of the game window, so the one-way distance from the left edge to the right edgeis 366 pixels. (This is the distance that the upper-left corner of the sprite travels during the one-way trip.) The round-trip distance is twice that, or 732 pixels.

You will see later that the sprite is caused to move horizontally by four pixels during each frame. At 62 frames per second, this represents a horizontalspeed for the sprite of 248 pixels per second. At that speed, the sprite should complete the round trip in 2952 milliseconds. That is close enough to thetypical reported time of 3015 milliseconds to validate the theoretical considerations.

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
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
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Source:  OpenStax, Anatomy of a game engine. OpenStax CNX. Feb 07, 2013 Download for free at https://legacy.cnx.org/content/col11489/1.13
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