Help me with my pong game

[shoobyman]

Hey, i need help with my program cuz this is my final exam!
I need to make the ball bounce of the both platforms but i cant pick the right code :/ . PLS help! ty...

code:

var x, y, b, t, r, x1, y1 : int var chars : array char of boolean var x3, y3, button : int var objectVX, objectVY, x2, y2 : int objectVY := 10 objectVX := 10 x2 := maxx div 2 y2 := maxy div 2 x := 100 y := 200 x1 := 300 y1 := 400 setscreen ("graphics:500;500") colorback (green) setscreen ("offscreenonly") loop     Input.KeyDown (chars)     drawfillbox (x, 100, y, 120, black)     if chars (KEY_RIGHT_ARROW) then         y := y + 15         x := x + 15     end if     if chars (KEY_LEFT_ARROW) then         x := x - 15         y := y - 15     end if     drawfillbox (x1, 400, y1, 380, black)     if chars ('d') then         y1 := y1 + 15         x1 := x1 + 15     end if     if chars ('a') then         x1 := x1 - 15         y1 := y1 - 15     end if     drawline (150, 70, 150, 1, black)     drawline (300, 70, 300, 1, black)     drawline (300, 500, 300, 430, black)     drawline (450, 500, 450, 430, black)     const ballRad : int := 7     mousewhere (x3, y3, button)     drawfilloval (x2, y2, ballRad, ballRad, black)     x2 += objectVX     y2 += objectVY     delay (15)     if x2 > maxx - 5 then         objectVX := -objectVX + 2     elsif x2 < 5 then         objectVX := -objectVX + 1     elsif y2 > maxx - 5 then         objectVY := -objectVY + 1     elsif y2 < 5 then         objectVY := -objectVY + 1     elsif x2<=x and y2<=y and x2<=400 and y2>=380 then     objectVY:= -objectVY+1     end if             View.Update     delay (5)     cls end loop

[Albrecd]

Quote:

code:

if chars (KEY_RIGHT_ARROW) then         y := y + 15         x := x + 15

First of all, you can do this much more simply by using:

code:

y += 15

(It means the same thing)

Second of all, why do you have a mousewhere? You don't use it...

And third of all, in order to make the ball bounce, you need to put something along the lines of:

code:

if x2 >= x and x2 <= y and y2 < 120 then     %change the ball direction

Then do the same for the other paddle. Note that when I said < 120, you could put = 120 or something else to make the impact look better (or change 120 to 130 or something). The reason I put < 120 is that, since the ball does not move one pixel each frame, it will not nessessarily appear at 120 Y.

(And Fourth of all... Constants should be entirely capitals... Ex: BALLRAD... but that's just me being picky...)

[Delos]

Albrecd wrote:

(And Fourth of all... Constants should be entirely capitals... Ex: BALLRAD... but that's just me being picky...)

Eh? No, that's likely just your teacher's own paradigm. No such rule, perhaps a suggestion (similar to "Reserve variable names with captial first letters for Classes only"). Perhaps a way of easing legibility.
But not a rule.

[shoobyman]

thnx a lot

[Albrecd]

Quote:

No, that's likely just your teacher's own paradigm. No such rule

Like I said, that's just me being picky.

[shoobyman]

Dont get why it doesnt bounce and shakes every time? I thought i got the coordinated right but still... PLS help again

code:

var x, y, b, t, r, x1, y1 : int var chars : array char of boolean var x3, y3, button : int var objectVX, objectVY, x2, y2 : int objectVY := 10 objectVX := 10 x2 := maxx div 2 y2 := maxy div 2 x := 100 y := 200 x1 := 300 y1 := 400 setscreen ("graphics:500;500") colorback (green) setscreen ("offscreenonly") loop     Input.KeyDown (chars)     drawfillbox (x, 0, y, 20, black)     if chars (KEY_RIGHT_ARROW) then         y := y + 15         x := x + 15     end if     if chars (KEY_LEFT_ARROW) then         x := x - 15         y := y - 15     end if     drawfillbox (x1, 499, y1, 479, black)     if chars ('d') then         y1 := y1 + 15         x1 := x1 + 15     end if     if chars ('a') then         x1 := x1 - 15         y1 := y1 - 15     end if     const ballRad : int := 7     drawfilloval (x2, y2, ballRad, ballRad, black)     x2 += objectVX     y2 += objectVY     delay (15)     if x2 > maxx - 5 then         objectVX := -objectVX     elsif x2 < 5 then         objectVX := -objectVX     elsif y2 > maxx - 5 then         objectVY := -objectVY     elsif y2 < 5 then         objectVY := -objectVY     elsif x2 >= x and x2 <= y and y2 < 20 then         objectVY := -objectVY     elsif x2 >= x1 and x2 <= y1 and y2 < 479 then         objectVY := -objectVY     end if     View.Update     delay (5)     cls end loop

[pavol]

first, i think that you shouldn't have : if...elsif...elsif etc. because this way only one of the conditions may be true, so put each of the conditions in a seperate if statement. second, your collision detection for the paddle looks wrong.
you have

code:

elsif x2 >= x and x2 <= y and y2 < 20 then         objectVY := -objectVY

you should have something like:

code:

if x2>= x- (paddlewidth div 2) and x2 <= x+(paddlewidth div 2) and y2 <= 20 then     objectVY := -objectVY end if

do that for the other paddle as well and it should help at least a bit

[Clayton]

i got your ball to bounce properly now you have to figure it out your self, u should have something like this

code:

if x2 - radius <= 0 then         objectVX := -objectVX     end if     if x2 + radius >= maxx then         objectVX := -objectVX     end if     if y2 + radius >= maxy - 21 and x2 - radius >= x and x2 + radius <= y then         objectVY := -objectVY     end if     if y2 - radius <= 21 and x2 - radius >= x1 and x2 + radius <= y1 then         objectVY := -objectVY     end if     if y2 + radius >= maxy or y2 - radius <= 0 then         objectVY := 0         objectVX := 0     end if

something like that eliminates the really weird jumpy movement of the ball, but you need to figure out how to bounce off of the paddle