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This object provides rendering options that you can tweak in-game, usually to provide your players graphics settings.


The target framerate for the game. You can use it to cap the framerate to preserve battery life or to provide smoother but lower FPS than the maximum a player's screen can support.

Example: Setting a framerate cap to 30fps

settings.targetFps = 30


The viewport mode you usually set in project's render options. You may need to change it, for example, to provide a user a choice between fast and quality scaling, or to toggle letterboxing.

The property can be set to one of these values:

  • 'asIs' — disables any viewport management; the rendered canvas
    will be placed as is in the top-left corner.
  • 'fastScale' — the viewport will proportionally fill the screen
    without changing the resolution.
  • 'fastScaleInteger' — the viewport will be positioned at the middle
    of the screen, and will be scaled by whole numbers (x2, x3, x4 and so on).
  • 'expand' — the viewport will fill the whole screen. The camera will
    expand to accommodate the new area.
  • 'scaleFit' — the viewport will proportionally fill the screen, leaving letterboxes
    around the base viewport. The resolution is changed to match the screen.
  • 'scaleFill' — the viewport fills the screen, expanding the camera to avoid letterboxing.
    The resolution is changed to match the screen.

Example: switching between fast and quality scaling

if (settings.viewMode === 'fastScale') {
    settings.viewMode = 'scaleFit';
} else {
    settings.viewMode = 'fastScale';


A boolean property that can be set to true to enable high-DPI support in the game. Defaults to the value you set in the ct.js IDE, in the project's render settings.

High-DPI support is only visible if your screen is high-DPI one. If it is, a player will get a higher resolution that matches the actual pixel density of the screen. You may want to toggle it off or provide a choice for players to ease the load on mobile devices, as they usually have hight-DPI screens.

Example: Toggling high pixel density support

settings.highDensity = !settings.highDensity


A boolean property that can be changed to exit or enter fullscreen mode. It always defaults to false as web games cannot enter fullscreen voluntarily — only through user interaction. Desktop and mobile builds work differently, with mobile builds being always in fullscreen mode and desktop builds having an option in your project's render settings.


Always add a way to exit fullscreen mode, or you risk getting your players stuck in a window they can't escape!