I continue to introduce faculty and students at UGA to LiveCode. For a recent workshop, I came up with another first project example, which I call "Follow the Bouncing Ball." This is the one that the attendees voted to have me build for them during the workshop.

Here is a snapshot of the project:

put item 1 of the location of button "ball" into x

put item 2 of the location of button "ball" into y

put line 1 of field "speed" into varSpeedx

put line 2 of field "speed" into varSpeedy

repeat until the mouseclick

if x > 320 then put -1*varSpeedx into varSpeedx

if x < 0 then put -1*varSpeedx into varSpeedx

if y > 480 then put -1*varSpeedy into varSpeedy

if y < 0 then put -1*varSpeedy into varSpeedy

wait 1 millisecond

add varSpeedx to x

add varSpeedy to y

set the location of button "ball" to x, y

end repeat

show me

end mouseUp

It's a very graphical project where an animated soccer ball bounces around the screen based on some information provided by the user. This information is simply the horizontal and vertical speed of the ball.

I made a YouTube video of me demonstrating how to build this project from scratch, so I'm not bothering to go into any detail here on how it works.

Here is a snapshot of the project:

[ Get the free LiveCode Community version. ]

What is rather cool about this project is that it shows some very
fundamental and important physics concepts and principles. It's a fun
way to show the hierarchical relationship between an object's location,
distance traveled, velocity of the object, and acceleration of the
object. The study of a moving object is a great example of rate of change problems. The distance an object travels shows its change in position. The velocity (speed and direction) of an object shows its change in distance over time, and acceleration denotes the change in velocity. This project didn't go as far as demonstrating acceleration, but it did a good job of showing velocity as consisting of both the speed the soccer ball is traveling and direction in which it is moving. Of course, I know I run the risk of alienating people if I go too far with the physics explanations!

(But, the history of the discovery of calculus is closely tied to dynamic problems such as this. Velocity is the first derivative of distance and acceleration is the second derivative of distance. Ergo, acceleration is the first derivative of velocity. How cool is that!)

I built this project only using local variables in order to try to show the difference between global and local variables.

Here is the script of the button "Bounce":

on mouseUp

hide meput item 1 of the location of button "ball" into x

put item 2 of the location of button "ball" into y

put line 1 of field "speed" into varSpeedx

put line 2 of field "speed" into varSpeedy

repeat until the mouseclick

if x > 320 then put -1*varSpeedx into varSpeedx

if x < 0 then put -1*varSpeedx into varSpeedx

if y > 480 then put -1*varSpeedy into varSpeedy

if y < 0 then put -1*varSpeedy into varSpeedy

wait 1 millisecond

add varSpeedx to x

add varSpeedy to y

set the location of button "ball" to x, y

end repeat

show me

end mouseUp

Sir Isaac Newton would be proud.

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