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2017-04-08T11:01:37Z

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''This page contains text copied from the ZDoom wiki.''

Constants are values that are always the same when executed. An example of a constant would be 1, "Hello", etc. Constants can also be #define'd.

The syntax of defining a constant is as follows
#define NAME VALUE

==Numbers==
These constants can be used as values and also as script numbers.

For example:
#define SNUM 1
#define VAL 3131

script SNUM (void)
{
int x = VAL;
}

Here SNUM would be replaced with '''1''' and VAL would be replaced with '''3131'''.

This is useful for a constant that is used a lot. If something like the spawn numbers were to be changed, you'd only need to change the constant for the defined spawn numbers.

==Use of operators==
Constants can be used to define other constants.

For example:
#define WEAPON_FIST 0
#define WEAPON_CHAINSAW WEAPON_FIST + 1

script "Test" Enter
{
print(i:WEAPON_FIST);
print(i:WEAPON_CHAINSAW);
}

This prints the values '''0''' and '''1''' as messages.

You can also make more complex operations.
#define HUD_WIDTH 1024
#define HUD_HEIGHT 768
#define HUD_FWIDTH HUD_WIDTH * 1.0
#define HUD_FCENTERX HUD_FWIDTH / 2
#define HUD_FHEIGHT HUD_HEIGHT * 1.0
#define HUD_FCENTERY HUD_FHEIGHT / 2

script "Test2" Enter
{
print(f:HUD_FWIDTH);
print(i:HUD_HEIGHT);
}

This logs the values '''1024.0''' and '''768''' to the console.

==String Constants==
You can define string constants as well.

First example:
script 1 Open
{
print(s:"err");
print(s:"err");
}

Second example:
#define STR_err "err"

script 1 Open
{
print(s:STR_err);
print(s:STR_err);
}

Both examples produce identical output.

==Library Constants==
You can also place constants in your [[ACS libraries|Libraries]]. This can be especially useful when, say, applying a [[TID]] to the player, or numbers you may want handy for [[ACS functions|custom functions]].

The syntax is much the same as a normal constant, with one change.
#libdefine NAME VALUE

Here is an example of some other useful constants. These constants provide quick shortcuts to cardinal directions for [[Polyobject|PolyObjects]] and [[SetActorAngle]].

#libdefine POLY_NORTH 64
#libdefine POLY_SOUTH 192
#libdefine POLY_WEST 128
#libdefine POLY_EAST 0

#libdefine ACTOR_FACE_NORTH 0.25
#libdefine ACTOR_FACE_WEST 0.5
#libdefine ACTOR_FACE_EAST 1.0
#libdefine ACTOR_FACE_SOUTH 0.75

[[category:ACS]]
[[category:Editing reference]]

ACS constants - Revision history

Printz: Created page with "''This page contains text copied from the ZDoom wiki.'' Constants are values that are always the same when executed. An example of a constant would be 1, "Hello", etc. Consta..."