Mouse scroll never reaches Input on native: Wayland PointerListenerHandleAxis is an empty stub, Win32 lacks WM_MOUSEWHEEL #32

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opened 2026-06-11 14:20:25 +02:00 by catbot · 0 comments

catbot commented

2026-06-11 14:20:25 +02:00

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While wiring 3DForts' scroll-wheel device rotation (3DForts#164) to a MouseScrollBind Axis1D action, we found the wheel input chain (Window::onMouseScroll → MouseScrollBind) only works on the DOM/wasm backend (dom-env.js wheel listener).

Native is dead on both window backends:

Wayland: Device::PointerListenerHandleAxis in implementations/Crafter.Graphics-Device.cpp is an empty stub — the wl_fixed_t value is dropped, so onMouseScroll never fires. Looks like a one-liner: convert with wl_fixed_to_double(value) (vertical axis, axis 0) and invoke the focused window's scroll event with the same sign/scale convention dom-env.js uses (one detent ≈ ±1 after normalization).
Win32: the window proc has no WM_MOUSEWHEEL case, so the same chain is dead there too (GET_WHEEL_DELTA_WPARAM(wParam) / WHEEL_DELTA per detent).

3DForts works around it for now by documenting the gap (scroll actions are rebindable to keys on native; wasm is the verify platform), but the fix belongs here. Happy to provide more detail if useful.

While wiring 3DForts' scroll-wheel device rotation (3DForts#164) to a `MouseScrollBind` Axis1D action, we found the wheel input chain (`Window::onMouseScroll` → `MouseScrollBind`) only works on the DOM/wasm backend (dom-env.js wheel listener). Native is dead on both window backends: - **Wayland**: `Device::PointerListenerHandleAxis` in `implementations/Crafter.Graphics-Device.cpp` is an empty stub — the `wl_fixed_t value` is dropped, so `onMouseScroll` never fires. Looks like a one-liner: convert with `wl_fixed_to_double(value)` (vertical axis, axis 0) and invoke the focused window's scroll event with the same sign/scale convention dom-env.js uses (one detent ≈ ±1 after normalization). - **Win32**: the window proc has no `WM_MOUSEWHEEL` case, so the same chain is dead there too (`GET_WHEEL_DELTA_WPARAM(wParam) / WHEEL_DELTA` per detent). 3DForts works around it for now by documenting the gap (scroll actions are rebindable to keys on native; wasm is the verify platform), but the fix belongs here. Happy to provide more detail if useful.