A to Z Scripting: Conditionals - Revision history

Dragofer: /* Next / previous article */

2020-12-23T23:48:02Z

Next / previous article

← Older revision		Revision as of 23:48, 23 December 2020
Line 106:		Line 106:
	*Previous article: [[A to Z Scripting: Practical exercise: subtle teleportation]]		*Previous article: [[A to Z Scripting: Practical exercise: subtle teleportation]]
	*Table of contents: [[A to Z Scripting]]		*Table of contents: [[A to Z Scripting]]

			[[Category:Scripting]]

Dragofer at 17:21, 23 December 2020

2020-12-23T17:21:46Z

← Older revision		Revision as of 17:21, 23 December 2020
Line 1:		Line 1:
	Scripts can check whether conditions have been met before carrying out the associated set of instructions. This is very useful for making dynamic scripts that react to or wait for events in the map.		Scripts can check whether conditions have been met before carrying out the associated set of instructions. This is very useful for making dynamic scripts that react to or wait for events in the map.

			== Basics ==
	If there's only a single line of instructions to carry out, then the instructions can be on the same line as the conditional itself. No extra brackets needed:		If there's only a single line of instructions to carry out, then the instructions can be on the same line as the conditional itself. No extra brackets needed:

Line 31:		Line 31:


	=== Available symbols ===		== Available symbols ==

	{\| class="wikitable"		{\| class="wikitable"
Line 55:		Line 55:


	=== Multiple conditionals ===		== Multiple conditionals ==
	Sometimes you want to check multiple conditionals, i.e. if A and B are true but C is false. Important symbols here are:		Sometimes you want to check multiple conditionals, i.e. if A and B are true but C is false. Important symbols here are:

Line 64:		Line 64:


	==== Example: secret conversation under specific circumstances ====		=== Example: secret conversation under specific circumstances ===
	if ( ( $lord_marlow.getLocation() == $mansion_bedchamber \|\| $mansion_secretchamber ) && ( !$lord_marlow.canSee($player1) ) )		if ( ( $lord_marlow.getLocation() == $mansion_bedchamber \|\| $mansion_secretchamber ) && ( !$lord_marlow.canSee($player1) ) )
	{		{
Line 75:		Line 75:


	=== Chains of conditionals ===		== Chains of conditionals ==
	Other than "if", there are also "else" and "elseif". These only get considered if the preceding "if" has failed.		Other than "if", there are also "else" and "elseif". These only get considered if the preceding "if" has failed.

Line 90:		Line 90:


	==== Example: lever with 3 positions and an inactive state ====		=== Example: lever with 3 positions and an inactive state ===
	void lever() //intended as one of several scripts controlling a lever. Checks which position the lever is in and performs an appropriate action		void lever() //intended as one of several scripts controlling a lever. Checks which position the lever is in and performs an appropriate action
	{		{

Dragofer at 17:20, 23 December 2020

2020-12-23T17:20:26Z

← Older revision		Revision as of 17:20, 23 December 2020
Line 1:		Line 1:
	~~== Conditionals ==~~
	~~=== Basics ===~~
	Scripts can check whether conditions have been met before carrying out the associated set of instructions. This is very useful for making dynamic scripts that react to or wait for events in the map.		Scripts can check whether conditions have been met before carrying out the associated set of instructions. This is very useful for making dynamic scripts that react to or wait for events in the map.

Line 21:		Line 19:
	You can either:		You can either:
	* compare values with each other (i.e. "is an entity's health less than or equal to x?")		* compare values with each other (i.e. "is an entity's health less than or equal to x?")
	* or you can ~~evaluate whether~~ a single value is true or false. ~~You can evaluate any type of variable~~, ~~not just booleans:~~ any ~~non-0 or~~ non-default value counts as "true"~~. So i.e.~~ for an entity ~~variable,~~ $null_entity is considered false, for a string "" is considered false, for a float 0 is false, for a vector '0 0 0' is false.		* or you can check if a single value is true or false. For non-booleans, any non-default value counts as "true", so for an entity $null_entity is considered false, for a string "" is considered false, for a float 0 is false and for a vector '0 0 0' is false. Note that a negative float also counts as true.

	Various examples:		Various examples:
	if (attempts_left) //~~check whether~~ the player has ~~a non-0 number of~~ attempts left (~~note: also~~ negative ~~values~~ count ~~as true~~)		if (attempts_left) //if the player has attempts left... (negative numbers count too, so not ideal in this case)
	if (attempts < max_attempts) //another way of checking whether the player has attempts left		if (attempts < max_attempts) //another way of checking whether the player has attempts left
	if ($lord_marlow.getFloatKey("can_unlock")) //check whether this AI can unlock doors		if ($lord_marlow.getFloatKey("can_unlock")) //check whether this AI can unlock doors

	//If you want to check whether something is false, you need an exclamation mark within the brackets.		//If you want to check whether something is false, you need to begin with an exclamation mark within the brackets.
	if ( !$lord_marlow.canSee($player1) ) //if the AI CAN'T see the player, do the following...		if ( !$lord_marlow.canSee($player1) ) //if the AI CAN'T see the player, do the following...

Line 62:		Line 60:
	&& AND		&& AND
	\|\| OR		\|\| OR

			The OR sign works inclusively: the check is successful if any of the values are true.


Line 79:		Line 79:

	"Else" will always get carried out, while "elseif" checks whether its conditions are met.		"Else" will always get carried out, while "elseif" checks whether its conditions are met.

			{\| class="wikitable"
			\|-
			\| if
			\|-
			\| elseif (alternative: else if)
			\|-
			\| else
			\|}


Line 86:		Line 95:
	if ( lever_position == "inactive" ) return; //if lever is inactive, stop processing this script		if ( lever_position == "inactive" ) return; //if lever is inactive, stop processing this script

	if ( lever_position == 1 ) sys.trigger($door1); //check for lever position 1		if ( lever_position == 1 ) sys.trigger($door1); //check for lever position 1
	elseif ( lever_position == 2 ) sys.trigger($door2); //otherwise check for lever position 2		elseif ( lever_position == 2 ) sys.trigger($door2); //otherwise check for lever position 2
	else sys.trigger($door3); //only remaining possibility is the lever is in position 3		else sys.trigger($door3); //only remaining possibility is the lever is in position 3

Dragofer: /* Next / previous article */

2020-12-23T15:04:15Z

Next / previous article

← Older revision		Revision as of 15:04, 23 December 2020
Line 95:		Line 95:

	*Next article: [[A to Z Scripting: Looping a script]]		*Next article: [[A to Z Scripting: Looping a script]]
	*Previous article: [[A to Z Scripting: ~~Scripts that use input variables~~]]		*Previous article: [[A to Z Scripting: Practical exercise: subtle teleportation]]
	*Table of contents: [[A to Z Scripting]]		*Table of contents: [[A to Z Scripting]]

Dragofer: Created page with "== Conditionals == === Basics === Scripts can check whether conditions have been met before carrying out the associated set of instructions. This is very useful for making dyn..."

2020-12-21T11:03:09Z

Created page with "== Conditionals == === Basics === Scripts can check whether conditions have been met before carrying out the associated set of instructions. This is very useful for making dyn..."

New page

== Conditionals ==
=== Basics ===
Scripts can check whether conditions have been met before carrying out the associated set of instructions. This is very useful for making dynamic scripts that react to or wait for events in the map.

If there's only a single line of instructions to carry out, then the instructions can be on the same line as the conditional itself. No extra brackets needed:

if($player1.getHealth == 100) sys.println("player1 has full health");

If you have a set of instructions, use curly brackets. Note that the line with the conditional needs no semicolon:

if($player1.getHealth != 100)
{
sys.println("player1 doesn't have full health");
$player1.setHealth(100);
sys.println("player1 has now been restored to full health");
}

You can either:
* compare values with each other (i.e. "is an entity's health less than or equal to x?")
* or you can evaluate whether a single value is true or false. You can evaluate any type of variable, not just booleans: any non-0 or non-default value counts as "true". So i.e. for an entity variable, $null_entity is considered false, for a string "" is considered false, for a float 0 is false, for a vector '0 0 0' is false.

Various examples:
if (attempts_left) //check whether the player has a non-0 number of attempts left (note: also negative values count as true)
if (attempts < max_attempts) //another way of checking whether the player has attempts left
if ($lord_marlow.getFloatKey("can_unlock")) //check whether this AI can unlock doors

//If you want to check whether something is false, you need an exclamation mark within the brackets.
if ( !$lord_marlow.canSee($player1) ) //if the AI CAN'T see the player, do the following...

=== Available symbols ===

{| class="wikitable"
|-
| ==, != || equal, not equal
|-
| <, > || less than, greater than
|-
| <=, >= || less or equal to, greater or equal to
|}

An easy mistake is to use only a single equals sign in a conditional:

= means "set to this value"

== means "equal to this value"

Example:
attempts = 3; //translation: set "attempts" to 3
if (attempts == 3) //translation: check if "attempts" is equal to 3

=== Multiple conditionals ===
Sometimes you want to check multiple conditionals, i.e. if A and B are true but C is false. Important symbols here are:

&& AND
|| OR

==== Example: secret conversation under specific circumstances ====
if ( ( $lord_marlow.getLocation() == $mansion_bedchamber || $mansion_secretchamber ) && ( !$lord_marlow.canSee($player1) ) )
{
$lord_marlow.bark("snd_secretconversation"); //say a secret pass phrase if he believes no one's nearby
}

In other words: if (Lord Marlow is either in his bed chamber or his secret chamber) and (he can't see the player), make him say a secret line.

Getting the right number of brackets in the right place can be tricky. It can be helpful to write each conditional on its own line first, then combine them one by one into a single line.

=== Chains of conditionals ===
Other than "if", there are also "else" and "elseif". These only get considered if the preceding "if" has failed.

"Else" will always get carried out, while "elseif" checks whether its conditions are met.

==== Example: lever with 3 positions and an inactive state ====
void lever() //intended as one of several scripts controlling a lever. Checks which position the lever is in and performs an appropriate action
{
if ( lever_position == "inactive" ) return; //if lever is inactive, stop processing this script

if ( lever_position == 1 ) sys.trigger($door1); //check for lever position 1
elseif ( lever_position == 2 ) sys.trigger($door2); //otherwise check for lever position 2
else sys.trigger($door3); //only remaining possibility is the lever is in position 3
}

== Next / previous article ==

*Next article: [[A to Z Scripting: Looping a script]]
*Previous article: [[A to Z Scripting: Scripts that use input variables]]
*Table of contents: [[A to Z Scripting]]