Hi, I was searching for any tutorial about it but didn't find any which would be made using simple language.
There is one here but I found it difficult to understand when I saw it for the first time.
Why is it useful?
Cleo is limited to 31 variables (+2 timers) which may cause some confusion while making complex scripts. By correct usage of 0AB1 it's possible to make a complex script look clean and organised. Each function has its own "internal variables" and changing them doesn't affect the script where the function is called, that's why it's so useful. By using it you can:
-make calculations using a lot of variables without affecting your base script
-pass a result of your calculations back to your base script
-set something (e.g. your position, your car's position)
Example of use:
Script below is using a function to set maximum speed of the car driven by the player. The function not only sets the maximum speed but also passes his current speed back to the base script. (I advise to copy the following code to your sanny builder and analyse it there, it's going to be more clear because of the colours)
0AB1: call_scm_func @set_max_speed 2 carHandle 10@ speedValue 10.0 _returnedSpeedValue 11@
2 - number of parameters you'd like to pass to the function
10@ 10.0 - parameters you're passing to the function, first one becomes 0@(function's internal variable), second becomes 1@
11@ - parameters you return to your base script by using 0AB2: ret 1 31@
0AB2: ret 1 31@
1 - number of parameters you'd like to return back to the base script
31@ - function's "internal variable" you return back to the base script, it becomes 11@ or any variable you wish
Returning boolean
Function can also return "true"/"false" which means that it can be used as a condition. The script below displays a message if the specified actor is driving.
0485: return_true - causes the function to return true
059A: return_false - causes the function to return false
Note that it's still neccessary to use "0AB2: ret" at the end of the function which returns boolean despite of the true/false opcodes above.
How not to use function returning boolean. (For some reason the "if and" condition is true even if only one of the actors is driving)
Additional tips:
1. Sometimes, for example if someone would like to improve his already made function, he might want to add more parameters to it. That's why I used 31@ instead of 2@ to get the speed of the car. It's better to use higher variable than lower within a function when it's not neccessary. If I used 2@ to get the car speed and later added 3rd parameter I'd have to change 2@ variable to any other to get the speed of the car (or use something like "0085: 31@ = 2@" at the begining of the function but personally I think it's better to avoid that and keep it simple)
2. Adding "_" or "_returned" to the titles of returned parameters (e.g. _carSpeed 11@) is a good way to distinguish which ones are which if you'd like to avoid counting them. It's not an issue with simple functions but it can save time and effort while working with functions which have like 15 or more different parameters.
3. Maximum number of parameters that can be passed to a function is 64 (in cleo 4.3, probably it's the same in cleo 4.1 but I'm not sure).
There is one here but I found it difficult to understand when I saw it for the first time.
Why is it useful?
Cleo is limited to 31 variables (+2 timers) which may cause some confusion while making complex scripts. By correct usage of 0AB1 it's possible to make a complex script look clean and organised. Each function has its own "internal variables" and changing them doesn't affect the script where the function is called, that's why it's so useful. By using it you can:
-make calculations using a lot of variables without affecting your base script
-pass a result of your calculations back to your base script
-set something (e.g. your position, your car's position)
Example of use:
Script below is using a function to set maximum speed of the car driven by the player. The function not only sets the maximum speed but also passes his current speed back to the base script. (I advise to copy the following code to your sanny builder and analyse it there, it's going to be more clear because of the colours)
Code:
{$CLEO}
0000: NOP
while true //constantly
wait 0
if 00DF: actor $PLAYER_ACTOR driving //check for driving
then
0811: 10@ = actor $PLAYER_ACTOR used_car //store your car to 10@ variable
0AB1: call_scm_func @set_max_speed 2 carHandle 10@ speedValue 10.0 _returnedSpeedValue 11@ //the code goes now to the ":set_max_speed" label, look there now to see what it does there
//your first returned parameter from the function which was your current speed (31@) becomes 11@
0AD1: show_formatted_text_highpriority "your current speed= %f" time 1000 11@ //your current speed is displayed. If you used here 31@ instead of 11@ it wouldn't work because 31@ is function's internal variable
end
end
:set_max_speed
// your first parameter which is carHandle (10@) becomes 0@
// your second parameter (10.0) becomes 1@
// if you passed any more parameters to this function they would become the following: third-2@, fourth-3@, fifth-4@, sixth-5@ etc...
02E3: 31@ = car 0@ speed //stores current speed to 31@
if 0025: 31@ > 1@
then
04BA: set_car 0@ speed_to 1@
end
0AB2: ret 1 31@ //31@ which is your current speed is sent back to your base script, now the code jumps to the point where the function has been called0AB1: call_scm_func @set_max_speed 2 carHandle 10@ speedValue 10.0 _returnedSpeedValue 11@
2 - number of parameters you'd like to pass to the function
10@ 10.0 - parameters you're passing to the function, first one becomes 0@(function's internal variable), second becomes 1@
11@ - parameters you return to your base script by using 0AB2: ret 1 31@
0AB2: ret 1 31@
1 - number of parameters you'd like to return back to the base script
31@ - function's "internal variable" you return back to the base script, it becomes 11@ or any variable you wish
Returning boolean
Function can also return "true"/"false" which means that it can be used as a condition. The script below displays a message if the specified actor is driving.
Code:
{$CLEO}
0000: NOP
while true
wait 0
if 0AB1: @is_driving 1 $PLAYER_ACTOR
then
print "Specified player is driving" 100
end
end
:is_driving
if 00DF: actor 0@ driving
then
0485: return_true
else
059A: return_false
end
0AB2: ret 0059A: return_false - causes the function to return false
Note that it's still neccessary to use "0AB2: ret" at the end of the function which returns boolean despite of the true/false opcodes above.
How not to use function returning boolean. (For some reason the "if and" condition is true even if only one of the actors is driving)
Code:
if and
0AB1: @is_driving 1 $PLAYER_ACTOR //example of incorrect usage
0AB1: @is_driving 1 0@ //example of incorrect usage
0AB1: @is_driving 1 1@ //example of incorrect usage
then
endAdditional tips:
1. Sometimes, for example if someone would like to improve his already made function, he might want to add more parameters to it. That's why I used 31@ instead of 2@ to get the speed of the car. It's better to use higher variable than lower within a function when it's not neccessary. If I used 2@ to get the car speed and later added 3rd parameter I'd have to change 2@ variable to any other to get the speed of the car (or use something like "0085: 31@ = 2@" at the begining of the function but personally I think it's better to avoid that and keep it simple)
2. Adding "_" or "_returned" to the titles of returned parameters (e.g. _carSpeed 11@) is a good way to distinguish which ones are which if you'd like to avoid counting them. It's not an issue with simple functions but it can save time and effort while working with functions which have like 15 or more different parameters.
3. Maximum number of parameters that can be passed to a function is 64 (in cleo 4.3, probably it's the same in cleo 4.1 but I'm not sure).
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