weird jumping problem - GameCreators Forum

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Night Giant

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Posted: 15th Nov 2003 21:49

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hey all,
ok, i am trying to make a platformer and for some reason the jumping is all screwed up, the model just goes up a bit (like 3 units) and back down really quick (like 1/2 second). it doesn't even go as high as it should. i have no idea what the problem is, here's the relevant code if anyone thinks they can help me, this is so damn frustrating, well thanks all.

+ Code Snippet

rem normal direction testing
for t=1 to numberoftiles
xt#=tile#(t,1)
yt#=tile#(t,2)
h#=tile#(t,4)
w#=tile#(t,3)
und#=(yt#+h#/2)-.5
lnd#=(xt#-w#/2)+.25
dnd#=(yt#-h#/2)+.5
rnd#=(xt#+w#/2)-.25
ny#=y_normal#(lx#,rx#,fy#,hy#,und#,dnd#,xt#,yt#,h#,w#)
if ny#=1 then t=numberoftiles+1
next t

rem activate variables for jumping
oldjumpkey=jumpkey
jumpkey=keystate(57)
if jumpkey=1 and oldjumpkey=0 and ny#=1
   gosub jump
endif

rem the actual code to modify the y# value
if ny#=1
   y#=yt#+h#/2 : yi#=y#
   if jumpkey=1 and oldjumpkey=0
      gosub jump
   endif
else
   timer#=timer#+.1
   y#=yi#+(vy#*timer#+.5*gravity#*timer#^2)
endif

and here's the y_normal function:

+ Code Snippet

function y_normal#(lx#,rx#,fy#,hy#,und#,dnd#,x#,y#,h#,w#)
   if fy#<y#+h#/2 and fy#>und# and rx#>x#-w#/2 and lx#<x#+w#/2
      y_normal#=1
   endif
endfunction y_normal#

thanx all.

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Jess T

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Posted: 16th Nov 2003 05:07

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In your for next loop, do you realise tha tyou are reseeding the value for xt# and yt# over and over...?

I think what you're trying to do is something like set the value for x1# up to x4# or whatever aren't you?

If so... you can't do it like that... you have to use an array...

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Night Giant

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Posted: 16th Nov 2003 05:17

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well, the for next loop reseeds the xt# and yt# values like you said, but not to increment them. maybe i should've explained the tile# array, what that is an array to keep track of the x and y positions of each object in the level. what the for next loop does is assign the values for the current tile being checked (t) to the variables, and then check whether a normal force is produced by the current tile (t). and if there is an upward normal force (1) it breaks out of the loop, with the current values for the variables set in the loop for that object/tile. at least i hope that's what it does, heh. hopefully that'll help to understand my code and perhaps my problem. thanx Jess.

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Jess T

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Posted: 16th Nov 2003 12:24 Edited at: 16th Nov 2003 12:28

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Quote: "it breaks out of the loop"

Hmmm, i think your coding is a bit dodgy then... lol... (I don't mean to be harsh, it was a joke...)

Where you have;

if ny#=1 then t=numberoftiles+1

I am assuming that is where you are meant to be brakeing from the loop?
If so ( i may be wrong in my assumption again here ), that will not work...

Ok... here is the lengthy explination that i wrote out, which is indeed completely wrong... lol:

#### Start incorrect explination ####

What the For...Next Loop does, is it takes the variable, gives a value equal to the starting value that you provide ( in your case, the variable is t and the value is 1 ).
It then goes through the code to the next Loop command ( in this case, Next ), using that variable the entire way through it...

Once it hits that Next Loop command, the "read head" ( the part of the code that is being executed ) returns to the last For command that was read.

When it get's to this command, it incriments the variable by a value of one, checks to see if it exceedes the limit value of your To command ( in your case the limit is equal to the value of numberoftiles ), and if it does, it skips the code untill after the Next command, and continues from there.
If it doesn't exceed the value of the limit you asigned then it does the loop again...

Where you have assigned the variable t = numberoftiles + 1 , the For...Next Command will ignore that when it comes time to incriment the value of t for the next loop, it will incriment t compared to the last value it was incrimented to at the start of the loop.

#### End incorrect explination ####

Ok, to hopefuly fix your problem.. change this:

+ Code Snippet

for t=1 to numberoftiles
xt#=tile#(t,1)
yt#=tile#(t,2)
h#=tile#(t,4)
w#=tile#(t,3)
und#=(yt#+h#/2)-.5
lnd#=(xt#-w#/2)+.25
dnd#=(yt#-h#/2)+.5
rnd#=(xt#+w#/2)-.25
ny#=y_normal#(lx#,rx#,fy#,hy#,und#,dnd#,xt#,yt#,h#,w#)
if ny#=1 then t=numberoftiles+1
next t

To this:

+ Code Snippet

for t=1 to numberoftiles
xt#=tile#(t,1)
yt#=tile#(t,2)
h#=tile#(t,4)
w#=tile#(t,3)
und#=(yt#+h#/2)-.5
lnd#=(xt#-w#/2)+.25
dnd#=(yt#-h#/2)+.5
rnd#=(xt#+w#/2)-.25
ny#=y_normal#(lx#,rx#,fy#,hy#,und#,dnd#,xt#,yt#,h#,w#)
if ny#=1 then exit
next t

Hope I Helped...

Team EOD :: Programmer/Logical Engineer/All-Round Nice Guy

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Night Giant

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Posted: 16th Nov 2003 23:09

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ahh, fantastic. thank you, i haven't tried it yet, but it seems like it should help. i was looking for something like that in the help files, actually i was looking for a break command and when i couldn't find it i figured it would have to jimmy-rig something. thanks again. i shall tell you if it works.

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Night Giant

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Posted: 17th Nov 2003 03:09

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alas, no luck, it still has the same problem. this is very frustrating, i hope i don't have to go back and rework my entire way of constructing levels and testing for collisions.

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Jess T

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Posted: 17th Nov 2003 09:03

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Having another look over your code, i can't realy see anythign wrong with it.

There is a small point, which shouldn't make any difference, but ill mentuion it anyway,
Where you have:

+ Code Snippet

function y_normal#(lx#,rx#,fy#,hy#,und#,dnd#,x#,y#,h#,w#)
   if fy#<y#+h#/2 and fy#>und# and rx#>x#-w#/2 and lx#<x#+w#/2
      y_normal#=1
   endif
endfunction y_normal#

Try changing that to:

+ Code Snippet

function y_normal(lx#,rx#,fy#,hy#,und#,dnd#,x#,y#,h#,w#)
   if fy#<y#+h#/2 and fy#>und# and rx#>x#-w#/2 and lx#<x#+w#/2
      y_normal#=1
   endif
endfunction ny

and in the other section, change:

+ Code Snippet

rnd#=(xt#+w#/2)-.25
ny#=y_normal#(lx#,rx#,fy#,hy#,und#,dnd#,xt#,yt#,h#,w#)
if ny#=1 then t=numberoftiles+1
next t

To:

+ Code Snippet

rnd#=(xt#+w#/2)-.25
y_normal(lx#,rx#,fy#,hy#,und#,dnd#,xt#,yt#,h#,w#)
if ny=1 then t=numberoftiles+1
next t

Then, at the start of your program, declare ny as a global, by putting this in:

+ Code Snippet

Global ny = 1

Note:
You will notice that i have chenged the variable of ny# to ny. I did this for two reasons. 1) becasue the number is never going to need a decimal point, it is wiser to declare it as an integer rather than a Floating point, mainly because floating points take up more memory (only minutely though, but still worth it in the long run); and 2) When i personally set GLobals, it has a fit if i put in a # symbol, dunno what's up with that...

Second Note:
The global commandmay not work ( i am assuming you are useing DrakEDIT which has support for Globals, but doesn't always work )
To get by this (if it doesn't work) just change:

+ Code Snippet

Global ny = 1

To:

+ Code Snippet

Dim ny(1)
ny(1) = 1

And change the other instances of ny to ny(1)...

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Night Giant

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Posted: 18th Nov 2003 05:21

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hm, well, the globals don't work, i am using DarkEdit, not DrakEdit (or maybe that was typo?). and changing

+ Code Snippet

function y_normal#(lx#,rx#,fy#,hy#,und#,dnd#,x#,y#,h#,w#)
   if fy#<y#+h#/2 and fy#>und# and rx#>x#-w#/2 and lx#<x#+w#/2
      y_normal#=1
   endif
endfunction y_normal#

to

+ Code Snippet

function y_normal(lx#,rx#,fy#,hy#,und#,dnd#,x#,y#,h#,w#)
   if fy#<y#+h#/2 and fy#>und# and rx#>x#-w#/2 and lx#<x#+w#/2
      y_normal#=1
   endif
endfunction ny

did not work, ny just stays zero because nothing is changing it in the function. well, i changed the function back to what it was, and changed the reals back to integers. still the same problem. arrghh! thanks for trying to help me, i really appreciate it.

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Jess T

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Posted: 18th Nov 2003 09:09 Edited at: 18th Nov 2003 09:10

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Sorry, sorry, my fault, i made a couple-a mistakes... lol.

It was meant to be DarkEDIT, lol, damn typo's, i need a new keyboard, really...

and the function, i stuffed up...

This should be what you need to have (just cut and paste into the appropriate sections of your code):

+ Code Snippet

rem normal direction testing
for t=1 to numberoftiles
xt#=tile#(t,1)
yt#=tile#(t,2)
h#=tile#(t,4)
w#=tile#(t,3)
und#=(yt#+h#/2)-.5
lnd#=(xt#-w#/2)+.25
dnd#=(yt#-h#/2)+.5
rnd#=(xt#+w#/2)-.25
y_normal(lx#,rx#,fy#,hy#,und#,dnd#,xt#,yt#,h#,w#)
if ny=1 then exit
next t


rem activate variables for jumping
oldjumpkey=jumpkey
jumpkey=keystate(57)
if jumpkey=1 and oldjumpkey=0 and ny#=1
   gosub jump
endif

rem the actual code to modify the y# value
if ny#=1
   y#=yt#+h#/2 : yi#=y#
   if jumpkey=1 and oldjumpkey=0
      gosub jump
   endif
else
   timer#=timer#+.1
   y#=yi#+(vy#*timer#+.5*gravity#*timer#^2)
endif




function y_normal(lx#,rx#,fy#,hy#,und#,dnd#,x#,y#,h#,w#)
   if fy#<y#+h#/2 and fy#>und# and rx#>x#-w#/2 and lx#<x#+w#/2
      ny=1
   endif
endfunction ny

Also, seen as your function cal is really long, why not do away with the function, and just put the code straight in?... Like:

+ Code Snippet

rem normal direction testing
for t=1 to numberoftiles
xt#=tile#(t,1)
yt#=tile#(t,2)
h#=tile#(t,4)
w#=tile#(t,3)
und#=(yt#+h#/2)-.5
lnd#=(xt#-w#/2)+.25
dnd#=(yt#-h#/2)+.5
rnd#=(xt#+w#/2)-.25
if fy#<y#+h#/2 and fy#>und# and rx#>x#-w#/2 and lx#<x#+w#/2 Then ny = 1 : Exit
next t


rem activate variables for jumping
oldjumpkey=jumpkey
jumpkey=keystate(57)
if jumpkey=1 and oldjumpkey=0 and ny#=1
   gosub jump
endif

rem the actual code to modify the y# value
if ny#=1
   y#=yt#+h#/2 : yi#=y#
   if jumpkey=1 and oldjumpkey=0
      gosub jump
   endif
else
   timer#=timer#+.1
   y#=yi#+(vy#*timer#+.5*gravity#*timer#^2)
endif

That way, you know that there is not a problem with the function call, and the code is now only one line rather than 7 (including the function, and calling it)...

Hope I Helped...

Team EOD :: Programmer/Logical Engineer/All-Round Nice Guy

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Night Giant

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Posted: 19th Nov 2003 04:35

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*laughs maniacally* it works! haha! i am very grateful Jess, i think it was getting rid of that function call that did it. Thank you, you will be in my credits for all the help. Hazzah! um, thanks again, heh.

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Jess T

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Posted: 19th Nov 2003 09:10

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lol... You're a killer (funny)...

Glad to help NightGiant, i seriously must be in about ten people's credits by now... lol... i keep helping people... i should start charging for such quality services... lol...

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DarkBASIC Discussion / weird jumping problem