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UiRenderPolicy

Frame-rate and invalidation policy controlling how frequently retained UI trees are rebuilt and rendered.

Overview

UiRenderPolicy dictates whether the runtime redraws the UI on every game tick, only when widget state changes (dirty signal), at a capped FPS, or locked to display VSYNC. This prevents unnecessary GPU and CPU overhead for static interfaces.

Render Modes

  • CONTINUOUS: Rebuilds and renders every frame. Ideal for fluid 60+ FPS animations, procedural shaders, and editor viewports.
  • ON_DIRTY: Renders only when an explicit invalidation/dirty signal is raised. Conserves significant GPU/CPU cycles for static menus and HUDs.
  • FIXED_FPS: Clamps rendering frequency to a specified target frame rate (e.g. 30 FPS).
  • VSYNC: Synchronizes rendering intervals with the window display refresh rate.

Performance and Power Efficiency

Static screens with complex layout trees can cause substantial overhead if re-rendered every tick. Switching to onDirty() reduces draw-call generation to zero during idle states, re-rendering only when user input or data events arrive.

Configuring On-Dirty Rendering for Static Menus

UiRenderPolicy policy = UiRenderPolicy.onDirty();
window.renderPolicy(policy);

Enabling VSYNC for Smooth Animations

UiRenderPolicy policy = UiRenderPolicy.vsync();
window.renderPolicy(policy);

API

UiRenderPolicy::continuous()

continuous()

Returns a policy that renders every frame continuously.

Returns UiRenderPolicy: Continuous rendering policy instance..

UiRenderPolicy::mode()

mode()

Returns the active mode of this render policy.

Returns Mode: Policy mode..

UiRenderPolicy::onDirty()

onDirty()

Returns a policy that renders only upon dirty invalidation signals.

Returns UiRenderPolicy: On-dirty rendering policy instance..

UiRenderPolicy::fixedFps(float)

fixedFps(float)

Creates a policy that limits UI rendering to a fixed target frame rate.

Parameter Type Description
fps float Target frames per second; must be finite and positive.

Returns UiRenderPolicy: Fixed FPS rendering policy instance..

UiRenderPolicy::vsync()

vsync()

Returns a policy synchronized with the window display refresh rate.

Returns UiRenderPolicy: VSYNC-synchronized policy instance..

UiRenderPolicy::fps()

fps()

Returns the target FPS for FIXED_FPS mode, or 0.0 for other modes.

Returns float: Target FPS value..

UiRenderPolicy::intervalNanos()

intervalNanos()

Returns the minimum nanosecond interval between renders in FIXED_FPS mode.

Returns long: Interval in nanoseconds, or 0 if not FIXED_FPS..