Synchronized_Skaters

Created by Barbara Lerner

You need to download Java software in order to view this Alice world. Please visit this page: http://www.alice.org/applet/requirements/

Created with Alice, the easy-to-learn programming system. Provided free as a public service by Carnegie Mellon University

When is clicked on anything

Do:

doInOrder {
	// Click on a skater to have her skate.
	world.skate ( ( whatWasPicked() ) );
}

When Left is typed

Do:

doInOrder {
	// When the left arrow is clicked, the 1st skater turns left.
	iceSkater .turn( LEFT , 1 revolution );
}

While Right is pressed

Begin:

doInOrder {
	// When the right arrow is depressed, the first skater speaks.
	iceSkater .say( I like getting dizzy! );
}

During:

doInOrder {
	// While the user is holding the right arrow down, the first skater spins right.
	iceSkater .turn( RIGHT , 1 revolution );
}

End:

doInOrder {
	// When the user releases the right arrow key, the skater falls over from being dizzy.
	iceSkater .roll( RIGHT , 0.25 revolutions );
}

public void my_first_method ( ) { Object[] skaters = ; Number skaterNumber = 1 ;
	// Randomly select a skater to skate.
	skaterNumber .set( value , ( Random.nextDouble() minimum = 1 maximum = 4 integerOnly = true ) );
	world.skate ( ( skaters [ skaterNumber ] ) );
	// Have all the skaters turn consecutively.
	For all skaters , one item_from_skaters at a time {
		item_from_skaters .turn( LEFT , 1 revolution );
	}
	// Remove the 1st skater from the list.
	skaters .remove( 0 );
	// Have the right 3 skaters turn simultaneously.
	For all skaters , every item_from_skaters together {
		item_from_skaters .turn( LEFT , 1 revolution );
	}
}

public void skate ( Object whichSkater) { Object skatersLeftLeg = <None> ; Object skatersRightLeg = <None> ;
	// Get the skater's 2 legs and save them in variables.
	// Notice that if this method is passed an object that is not a skater, like the beach chair, the Alice world will crash with a "null" error.
	skatersLeftLeg .set( value , ( whichSkater .partNamed( leftLeg ) ) );
	skatersRightLeg .set( value , ( whichSkater .partNamed( rightLeg ) ) );
	// Take a skating stroke pushing with the left leg
	doTogether {
		whichSkater .move( FORWARD , 1 meter ); duration = 2 seconds
		doInOrder {
			doTogether {
				skatersLeftLeg .turn( FORWARD , 0.12 revolutions );
				skatersLeftLeg .roll( RIGHT , 0.12 revolutions );
			}
			doTogether {
				skatersLeftLeg .turn( BACKWARD , 0.12 revolutions );
				skatersLeftLeg .roll( LEFT , 0.12 revolutions );
			}
		}
	}
	// Take a skating stroke pushing with the right leg
	doTogether {
		whichSkater .move( FORWARD , 1 meter ); duration = 2 seconds
		doInOrder {
			doTogether {
				skatersRightLeg .turn( FORWARD , 0.12 revolutions );
				skatersRightLeg .roll( LEFT , 0.12 revolutions );
			}
			doTogether {
				skatersRightLeg .turn( BACKWARD , 0.12 revolutions );
				skatersRightLeg .roll( RIGHT , 0.12 revolutions );
			}
		}
	}
}