Smooth scrolling (pixel-precise UI scrolling, eased wheel) and smooth camera zoom #727

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opened 2026-10-12 17:57:20 +00:00 by sky_line · 1 comment

sky_line commented

2026-10-12 17:57:20 +00:00

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Today: the UI only understands whole wheel notches. The window passes integer clicks (handleScrollWheel(S32 clicks)), and every widget moves a fixed amount per click (scroll lists a line, scroll containers a step, text editors lines). Touchpads and free-spinning or high-resolution wheels can only produce discrete jumps. (45ac9a1723 made the stepping symmetric -- fractional deltas accumulate into whole steps -- but it is still stepped.)

Wanted: smooth scrolling

Fractional deltas through the input chain: a float scroll path from LLWindowSDL through LLViewerWindow to LLView::handleScrollWheel. The integer path stays for widgets that only understand notches, and as the fallback.
Pixel scrolling in the scrolling widgets: scroll containers, scroll lists, text editors / chat history, folder views (inventory), the web / media floater. Each moves by delta x line height in pixels, not whole lines; scrollbars follow.
Eased motion for notched wheels: one notch animates over about 100 ms instead of jumping (browser-style), behind a setting, on by default if it feels right.

Wanted: smooth camera zoom

The mouse wheel's camera zoom (third person / orbit, and the mouselook FOV zoom if it uses the wheel) eases toward the target distance instead of stepping, and uses fractional deltas from touchpads and high-resolution wheels. Behind a setting, with a speed / smoothing control.
Coordinate with the camera options already in Move & View (the Beta 5 middle-mouse camera and speed-based FOV).

Testing: touchpad, free-spinning wheel, regular notched wheel; Linux (Wayland / X11) and Windows; long inventories, chat history, scroll lists, web floater; camera zoom in / out at various distances.

**Today:** the UI only understands whole wheel notches. The window passes integer clicks (`handleScrollWheel(S32 clicks)`), and every widget moves a fixed amount per click (scroll lists a line, scroll containers a step, text editors lines). Touchpads and free-spinning or high-resolution wheels can only produce discrete jumps. (45ac9a1723 made the stepping symmetric -- fractional deltas accumulate into whole steps -- but it is still stepped.) **Wanted: smooth scrolling** 1. **Fractional deltas through the input chain:** a float scroll path from LLWindowSDL through LLViewerWindow to `LLView::handleScrollWheel`. The integer path stays for widgets that only understand notches, and as the fallback. 2. **Pixel scrolling** in the scrolling widgets: scroll containers, scroll lists, text editors / chat history, folder views (inventory), the web / media floater. Each moves by delta x line height in pixels, not whole lines; scrollbars follow. 3. **Eased motion for notched wheels:** one notch animates over about 100 ms instead of jumping (browser-style), behind a setting, on by default if it feels right. **Wanted: smooth camera zoom** - The mouse wheel's camera zoom (third person / orbit, and the mouselook FOV zoom if it uses the wheel) eases toward the target distance instead of stepping, and uses fractional deltas from touchpads and high-resolution wheels. Behind a setting, with a speed / smoothing control. - Coordinate with the camera options already in Move & View (the Beta 5 middle-mouse camera and speed-based FOV). **Testing:** touchpad, free-spinning wheel, regular notched wheel; Linux (Wayland / X11) and Windows; long inventories, chat history, scroll lists, web floater; camera zoom in / out at various distances.

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2026-10-12 17:57:20 +00:00

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