Pic.New doesn't work

[who cares?]

Hello,

I am trying to make a Pong game, and I am trying to use the Pic. New command in order to take a picture of the place where the ball is going to be, before it gets there and then paste it after the ball passes the place, so that I get a smooth motion, without having to clear the screen every time the ball moves. The problem is that when I use the Pic.New command, I get the message "Illegal pictured ID number '0'. (Probable cause: picture was not succesfully created.)." Here is my program:

-----------------------------------------------

setscreen ("graphics")

var x, y : int
var xchange, ychange : int
var pic1 : int

x := 0
y := 0
xchange := 1
ychange := 1

Draw.FillBox (0, 0, maxx, maxy, black)

loop
if
x > 639
then
xchange := -xchange
elsif
x < 0
then
xchange := -xchange
end if
if
y > 399
then
ychange := -ychange
elsif
y < 0
then
ychange := -ychange
end if
x := x + xchange
y := y + ychange
pic1 := Pic.New (x - 4, y - 4, x + 4, y + 4)
Draw.FillBox (x - 4, y - 4, x + 4, y + 4, white)
Pic.Draw (pic1, x, y, picCopy)
delay (5)
end loop

-----------------------------------------------

Any help would be appreciated. Thank you very much.

[krishon]

which version of turing are u using? that might be the problem, tho i doubt it

[who cares?]

I'm using version 4.0.4 c of Turing. I have the latest updates installed.

[Asok]

k Pic.New shouldn't be in the loop, because the picture is a constant. only the location (Pic.Draw) changes.

The whole thing needs to be restructured. Store the pic then draw it.

[krishon]

maybe it'll help if u put a procedure...i dunno if its necessary tho

[Tony]

might be faster if you keep the whole background in the memory, this way you dont have to use Pic.New inside the loop and should also speed up your game.

[PaddyLong]

well unless you are going to have something in the background other than just black, it would likely be easier to simply draw a small black box over it rather than using Pic

any way... here is what you want if you want to use the Pic method
(also note I started the ball at 10,10 rather than 0,0 this is because you are trying to take a pic at x - 4 and y - 4 so it would be trying to take a pic from -4,-4 to 4,4) I also modified your if statements for changing the directions so that they'll work better and also commented the stuff for the drawing/erasing so hopefully you can understand what is going on with it

code:

setscreen ("graphics") var x, y : int var xchange, ychange : int var pic1 : int x := 10 y := 10 xchange := 1 ychange := 1 Draw.FillBox (0, 0, maxx, maxy, black) pic1 := Pic.New (x - 4, y - 4, x + 4, y + 4) Draw.FillBox (x - 4, y - 4, x + 4, y + 4, white) loop     if x >= maxx - 4 then         xchange := -xchange     elsif x <= 4 then         xchange := -xchange     end if     if y >= maxy - 4 then         ychange := -ychange     elsif y <= 4 then         ychange := -ychange     end if     Pic.Draw (pic1, x - 4, y - 4, picCopy) %erase the ball BEFORE changing the x and y     x := x + xchange     y := y + ychange     Pic.Free (pic1) %free the old image     pic1 := Pic.New (x - 4, y - 4, x + 4, y + 4) %take a new image     Draw.FillBox (x - 4, y - 4, x + 4, y + 4, white) %draw the ball     delay (5) end loop

[PaddyLong]

also, if you want it to run smoother add in setscreen("offscreenonly")
and after

code:

  pic1 := Pic.New (x - 4, y - 4, x + 4, y + 4) %take a new image     Draw.FillBox (x - 4, y - 4, x + 4, y + 4, white) %draw the ball

but before the delay put in View.Update

this will elminate the small flickering of the ball that you notice

[AsianSensation]

doesn't turing only allow so many pics to be declared? then if you declare it in a loop, then it's going to run out of space, and you get an error that way...

[who cares?]

Thank you all for your help. I have found a way to do it, but your code is better. Thank you for it. Oh well, I am just a begginer in Turing. Thank you all for your help.

[PaddyLong]

yes Asian, that's why the Pic.Free is there

[AsianSensation]

oh, heh heh, didn't see it....

oh well, sorry about that