System expressions

This section outlines the expressions in the built-in System object in Construct 2. Many are common mathematical operators, and they can be listed with descriptions in the Expressions panel, but they are included here for completeness.

This section does not list the operators or syntax that can be used in expressions - just the expressions specific to the System object. For more general information on how to use expressions in Construct 2, see Expressions.

Display

WindowWidth
WindowHeight
Get the size of the window. Useful with the Fullscreen in browser property of the project, since these enable a variable window size. See also Supporting multiple screen sizes.

Layers

In expressions where a layer is required, either its name (as a string) or index (as a number) can be entered.

layeropacity
Get the opacity (or semitransparency) of a layer, from 0 (transparent) to 100 (opaque).

layerscale
Get the current scale of the layer, not including the overall layout scale.

layerscalerate
Get the current scale rate of the layer, which defines how quickly it scales (if at all).

layoutscale
Get the current scale of the entire layout set by the Set layout scale action. This does not include the scaling of individual layers.

Layout

LayoutWidth
LayoutHeight
Get the size of the current layout in pixels.

LayoutName
Get the name of the current layout.

scrollx
scrolly
Get the current position the view is centered on.

Math

These expressions are simply ordinary math functions like you find on calculators. However, note that all functions using an angle take it in degrees, not radians. Angles start with 0 degrees facing right and increment clockwise.

sin(x), cos(x), tan(x), asin(x), acos(x), atan(x) Trigonometric functions using angles in degrees.

abs(x) Absolute value of x e.g. abs(-5) = 5
angle(x1, y1, x2, y2) Calculate angle between two points
anglelerp(a, b, x) Linearly interpolate the angle a to b by x. Unlike the standard lerp, this takes in to account the cyclical nature of angles.
anglediff(a1, a2) Return the smallest difference between two angles
anglerotate(start, end, step) Rotate angle start towards end by the angle step, all in degrees. If start is less than step degrees away from end, it returns end.
ceil(x) Round up x e.g. ceil(5.1) = 6
distance(x1, y1, x2, y2) Calculate distance between to points
exp(x) Calculate e^x
floor(x) Round down x e.g. floor(5.9) = 5
lerp(a, b, x) Linear interpolation of a to b by x.
ln(x) Log to base e of x.
log10(x) Log to base 10 of x.
max(a, b [, c...]), min(a, b [, c...]) Calculate maximum or minimum of the given numbers. Any number of parameters can be used as long as there are at least two.
pi The mathematical constant pi (3.14159...)
round(x) Round x to the nearest whole number e.g. round(5.6) = 6
sqrt(x) Calculate square root of x e.g. sqrt(25) = 5

System

loopindex
Get the index (number of repeats so far) in any currently running loop.

loopindex(name)
Get the index (number of repeats so far) of the loop with the given name. Useful for getting indices in nested loops.

objectcount
The total number of objects currently created.

projectversion
Return the version entered in to Project Properties. Note that this is always returned as a string, not a number.

renderer
The name of the renderer used to draw the game, currently either canvas2d or webgl. See Technology for more information on canvas renderers.

Text

find(src, text)
Find the first index within src that text occurs, else returns -1.

left(text, count)
Return the first count characters of text.

len(text)
Return the number of characters in text.

lowercase(text)
Convert the given text to all lowercase.

mid(text, index, count)
Return the count characters starting from index in text.

newline
A string containing a line break. Use to insert line breaks in to strings, e.g. "Hello" & newline & "World"

replace(src, find, rep)
Find all occurrences of find in src and replace them with rep.

right(text, count)
Return the last count characters of text.

tokenat(src, index, separator)
Return the Nth token from src, splitting the string by separator. For example, tokenat("apples|oranges|bananas", 1, "|") returns oranges.

tokencount(src, separator)
Count how many tokens occur in src using separator. For example, tokencount("apples|oranges|bananas", "|") returns 3.

trim(src)
Return src with all whitespace (spaces, tabs etc.) removed from the beginning and end of the string.

uppercase(text)
Convert the given text to all uppercase.

Time

dt
Delta-time in seconds. See Delta-time and framerate independence.

fps
The current frames per second (FPS) rate, which is how many times the screen is being drawn every second. Most computers run at 60 fps if they are fast enough.

tickcount
The number of ticks that have run since the game started.

time
The number of seconds since the game started, taking in to account the time scale.

timescale
The current time scale.

wallclocktime
The number of seconds since the game started, not taking in to account the time scale (i.e. the real-world time).

Values

choose(a, b [, c...])
Choose one of the given parameters at random. E.g. choose(1, 3, 9, 20) randomly picks one of the four numbers and returns that. This also works with strings, e.g. choose("Hello", "Hi") returns either Hello or Hi. Any number of parameters can be used as long as there are at least two.

clamp(x, lower, upper)
Return lower if x is less than lower, upper if x is greater than upper, else return x.

float(x)
Convert the integer or text x to a float (fractional number).

int(x)
Convert the float or text x to an integer (whole number).

random(x)
Generate a random float from 0 to x, not including x. E.g. random(4) can generate 0, 2.5, 3.29293, but not 4. Use floor(random(4)) to generate just the whole numbers 0, 1, 2, 3.

random(a, b)
Generate a random float between a and b, including a but not including b.

rgb(r, g, b)
Generate a single number containing a color in RGB format. This is useful for conditions or actions taking a color parameter.

str(x)
Convert the integer or float x to a string. Generally not necessary since strings can be built using the & operator, e.g. "Your score is " & score