Download and unzip the zip file and you will see an ExampleProgram folder. Open the ExampleProgram
folder, the EXE folder contains the compiled program and you can double click on the .sln
file to work with the source code.
When the game starts, you'll see a screen that
looks similar to this:
The program is nearly identical to the earlier tutorial,
260.PongSoccerWithArray. The only change for this tutorial is that
we're doing our linear search using a while loop, rather than a for loop.
2. Examining The Program:
Let's examine the
C# source code that produces the behavior we see on-screen
BounceOffBlocks() (called from UpdateWorld() ):
///
<summary>
///
Test for collision with the blocks, if collision occurs,
///
flip the sign of the x-component of the velocity.
///
</summary>
private
void
BounceOffBlocks()
//
EchoToTopStatus("Last block collision:" + i + "-Block");
//
PlayACue("Break");
//
}
//
}
#endregion
// now
while loop solution
bool found =
false;
int
i = 0;
while ((!found) && (i<m_Blocks.Length)
)
{
if
(m_Blocks[i].Collided(m_TheSoccer)) {
//
found!
found =
true;
m_TheSoccer.VelocityX = -m_TheSoccer.VelocityX;
EchoToTopStatus(
"Last
block collision:" + i +
"-Block");
PlayACue(
"Break");
}
else
i = i + 1;
}
}
As you can see, the while loop can also be used to do a linear search.
This particular while loop uses the 'set found to true' trick that will
end the loop early, once we find a block that overlaps the soccer ball.
FURTHER EXERCISES:
Start from a blank starter project (1000.201, if you need it), and re-do
the code from memory as much as possible. On your first try, do what
you can, and keep the above code open so that when you get stuck, you can
quickly look up what you forgot (and that after you finish a line, so that
you can compare your line to the 'correct' line). On the next try, do
the same thing, but try to use the finished code less. Repeat this
until you can type everything, without refering the tutorial's code.
Repeat this exercise daily for several days, so that you really get the
hang of this. As you go on, periodically review this by re-doing this
exercise.
Listing All Matches
For this exercise, you should use the same project that was explained in the
above tutorial.
Modify the program so that instead of displaying the contents of the
m_NumbersToSearchThrough array
along the top, you instead display all the rectangles that the soccer ball
overlaps. If the soccer ball is overlapping no rectangles, then
display a message like "No overlapping rectangles". If the soccer ball
only overlaps rectangle #5, then display something like "Overlap with #5",
and if the soccer ball overlaps #5 and #6, display something like "Overlap
with #5, #6".
While it is impossible for the soccer ball to overlap more than 2
squares, you should still write your code so that the program displays a
list of all overlapping rectangles - if the soccer ball was large enough
to overlap all of the rectangles, then your code should display a list of
all the rectangles.
