Pong

[upthescale]

<h1>i wanna make a pong game, but how do i do it so when the ball withs the edge of the screen, it will bounce away randomly, liek i don't want to set coordinates for the wohle game i want it no random</h1>

[do_pete]

You would multiply your X speed variable by -1

[upthescale]

can u make a program quicktime of a ball bouncing randomoy arond the screen?

[Cervantes]

"Randomness" can be achieved by using the Rand.Int function.

Do you really want it to bounce randomly off a wall, though? That's not how collision works in this universe of ours. It's not random.

The angle of incidence equals the angle of reflection. This is most easily achieved if you have x and y components to your ball's position and velocity, and if the wall it is bouncing off of is parallel to either the x or y axis.

pseudo:

If it bounces of a horizontal wall then     reverse the y velocity else if it bounces off a vertical wall then     reverse the x velocity end if

[do_pete]

Huh? What are you trying to say?

[upthescale]

doesn't werk

code:

var x, y : int randint (x, 1, 500) randint (y, 1, 200) loop     drawfillbox (x, y, x + 30, y + 30, 7)     delay (12)     drawfillbox (x, y, x + 30, y + 30, 0)     x := x + 2     y := y + 2     if y > 420 then         exit     end if end loop loop  drawfillbox (x, y, x + 30, y + 30, 7)     delay (12)     drawfillbox (x, y, x + 30, y + 30, 0)     x := -x end loop

[Cervantes]

It works. You've just done it wrong.

Why did you exit your loop when the ball collides with a horizontal wall? That's not what you want to do. You want to reverse it's vertical velocity.

Furthermore, in the last portion of your code (the second loop), x := -x is not going to reverse the velocity of the ball. It's going to flip the ball from one side of the y axis to the other.

Finally, your code exits the first loop when it bounces off a horizontal wall, then you go in the second loop attempting to modify the horizontal velcoity. The horizontal velocity doesn't change when a ball bounces off a horizontal wall.

Really, this isn't hard. Put a little thought into it, and I'm sure you'll understand it a whole lot better. Feeding you the answers isn't going to help you understand anything as much as if you figured it out mostly on your own.

[upthescale]

i've been trying fer weeks now can u plz just fix it and paste it

[do_pete]

We don't do people's homework

[upthescale]

im done turing i finished it last semester

[Cervantes]

Trying for weeks, but on what? You've already been told basically how to do it.

Begging for people to tell you the answers is a terrible attitude.

[upthescale]

but when i puty x:=-x like u told me, the box just stays n the same position ttwitching like a mad man

[[Gandalf]]

Create a vx and vy variable (velocity in x direction, velocity in y direction), and work with those instead of directly with the x and y vars.