Debug

LittleJS Debug System

  • Press Esc to show debug overlay with mouse pick
  • Number keys toggle debug functions
  • +/- apply time scale
  • Debug primitive rendering
  • Save a 2d canvas as a png image
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Members

(static, constant) debug :boolean

True if debug is enabled

Type:
  • boolean
Default Value
  • true
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(static) debugKey :string

Key code used to toggle debug mode, Esc by default

Type:
  • string
Default Value
  • Escape
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(static) debugOverlay :boolean

True if the debug overlay is active, always false in release builds

Type:
  • boolean
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(static, constant) debugPointSize :number

Size to render debug points by default

Type:
  • number
Default Value
  • 0.5
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(static) showWatermark :boolean

True if watermark with FPS should be shown, false in release builds

Type:
  • boolean
Default Value
  • true
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Methods

(static) ASSERT(assert, …outputopt)

Asserts if the expression is false, does nothing in release builds Halts execution if the assert fails and throws an error

Parameters:
NameTypeAttributesDescription
assertboolean
outputObject<optional>
<repeatable>

error message output

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(static) LOG(…outputopt)

Log to console if debug is enabled, does nothing in release builds

Parameters:
NameTypeAttributesDescription
outputObject<optional>
<repeatable>

message output

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(static) debugCircle(pos, sizeopt, coloropt, timeopt, fillopt, screenSpaceopt)

Draw a debug circle in world space

Parameters:
NameTypeAttributesDefaultDescription
posVector2
sizenumber<optional>
0

diameter

colorColor | string<optional>
timenumber<optional>
0
fillboolean<optional>
false
screenSpaceboolean<optional>
false
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(static) debugClear()

Clear all debug primitives in the list

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(static) debugLine(posA, posB, coloropt, widthopt, timeopt, screenSpaceopt)

Draw a debug line in world space

Parameters:
NameTypeAttributesDefaultDescription
posAVector2
posBVector2
colorColor | string<optional>
widthnumber<optional>
0.1
timenumber<optional>
screenSpaceboolean<optional>
false
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(static) debugOverlap(posA, sizeA, posB, sizeB, coloropt, timeopt, screenSpaceopt)

Draw a debug combined axis aligned bounding box in world space

Parameters:
NameTypeAttributesDefaultDescription
posAVector2
sizeAVector2
posBVector2
sizeBVector2
colorColor | string<optional>
timenumber<optional>
screenSpaceboolean<optional>
false
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(static) debugPoint(pos, coloropt, timeopt, angleopt, screenSpaceopt)

Draw a debug point in world space

Parameters:
NameTypeAttributesDefaultDescription
posVector2
colorColor | string<optional>
timenumber<optional>
anglenumber<optional>
screenSpaceboolean<optional>
false
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(static) debugPoly(pos, points, coloropt, timeopt, angleopt, fillopt, screenSpaceopt)

Draw a debug poly in world space

Parameters:
NameTypeAttributesDefaultDescription
posVector2
pointsArray.<Vector2>
colorColor | string<optional>
timenumber<optional>
0
anglenumber<optional>
0
fillboolean<optional>
false
screenSpaceboolean<optional>
false
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(static) debugRect(pos, sizeopt, coloropt, timeopt, angleopt, fillopt, screenSpaceopt)

Draw a debug rectangle in world space

Parameters:
NameTypeAttributesDefaultDescription
posVector2
sizeVector2<optional>
Vector2()
colorColor | string<optional>
timenumber<optional>
0
anglenumber<optional>
0
fillboolean<optional>
false
screenSpaceboolean<optional>
false
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(static) debugSaveCanvas(canvas, filenameopt, typeopt)

Save a canvas to disk

Parameters:
NameTypeAttributesDefaultDescription
canvasHTMLCanvasElement | OffscreenCanvas
filenamestring<optional>
screenshot
typestring<optional>
image/png
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(static) debugSaveDataURL(dataURL, filename)

Save a data url to disk

Parameters:
NameTypeDescription
dataURLstring
filenamestring
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(static) debugSaveText(text, filenameopt, typeopt)

Save a text file to disk

Parameters:
NameTypeAttributesDefaultDescription
textstring
filenamestring<optional>
text
typestring<optional>
text/plain
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(static) debugScreenshot()

Trigger debug system to take a screenshot

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(static) debugShowErrors()

Breaks on all asserts/errors, hides the canvas, and shows message in plain text This is a good function to call at the start of your game to catch all errors In release builds this function has no effect

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(static) debugText(text, pos, sizeopt, coloropt, timeopt, angleopt, fontopt, screenSpaceopt)

Draw a debug axis aligned bounding box in world space

Parameters:
NameTypeAttributesDefaultDescription
textstring | number
posVector2
sizenumber<optional>
1
colorColor | string<optional>
timenumber<optional>
0
anglenumber<optional>
0
fontstring<optional>
monospace
screenSpaceboolean<optional>
false
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(static) debugVideoCaptureIsActive()

Check if video capture is active

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(static) debugVideoCaptureStart()

Start capturing video

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(static) debugVideoCaptureStop()

Stop capturing video and save to disk

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(static) setDebugKey(key)

Set key code used to toggle debug mode, Esc by default

Parameters:
NameTypeDescription
keystring
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(static) setShowWatermark(show)

Set if watermark with FPS should be shown

Parameters:
NameTypeDescription
showboolean
Source