Found: `CameraController::setMoveScale()` is a dead knob

Read gui_client/CameraController.h and .cpp, then inspect MainWindow.cpp:5826 and the three processMove* functions in gui_client/PlayerPhysics.cpp. Confirm whether move_speed_scale should affect movement or whether the setter and startup call should be removed. Done means the API is no longer misleading and the intended movement-speed behavior is covered by the relevant existing checks.

Found: CameraController::setMoveScale() is a dead knob

What we were doing

Adding a "Camera speed" multiplier slider to the Photo Mode UI, backed by
CameraController::setMoveScale(). Slider changes speed live while walking
around a splat scene, log-scale, 0.001× - 10×.

How we noticed

The slider was wired to setMoveScale(), but dragging it did nothing to the
camera's actual movement speed. Investigating why revealed the surprise below.

The finding

CameraController::move_speed_scale is written but never read.

• Set once at app startup:
  MainWindow.cpp:5826 cam_controller.setMoveScale(0.3f);
• Set by CameraController::setMoveScale() on demand.
• Read: nowhere in substrata/gui_client or glare-core. PlayerPhysics.cpp
  (which is what actually turns key-presses into move_desired_vel) uses a
  local static const float move_speed = 3; and never consults the
  CameraController for a scale.

So the setMoveScale(0.3f) call at startup is a no-op — the effective
in-game speed for every user has always been the raw move_speed = 3 in
PlayerPhysics.cpp, unaffected by the 0.3. The setMoveScale() API looks
functional from the outside (has a setter, has a member, header comment
"Adjust camera movement speed based on world scale"), so an author landing
new UI on it — as we did — quite reasonably assumes it works.

Why it looks strange

Either:

• The 0.3× was meant to apply and something later refactored it out
  accidentally, in which case the whole app has silently been walking at 3.3×
  the intended speed for however long.
• Or the scale mechanism was intended but never finished, in which case the
  startup call and the setter should probably be removed to stop misleading
  future contributors.

Either way, current state is a "ghost knob": present, documented, and inert.

Relevant source files

All paths relative to the substrata repo root.

• gui_client/CameraController.h — declares setMoveScale() (line ~41) and
  the private move_speed_scale field.
• gui_client/CameraController.cpp — the setter body (writes the field), the
  constructor default (move_speed_scale = 1;). No reader.
• gui_client/MainWindow.cpp:5826 — the only in-repo call site of
  setMoveScale() before this change (setMoveScale(0.3f) at app startup).
• gui_client/PlayerPhysics.cpp — the read side that isn't there. The three
  processMove* functions (processMoveForwards, processStrafeRight,
  processMoveUp) compute move_desired_vel from a hardcoded
  static const float move_speed = 3; and never consult the
  CameraController for a scale. This is the file where a one-line
  * cam.getMoveScale() on each of the three additions would make the setter
  do what its name suggests.

What we did about it in our own build

To make the Photo Mode slider work at all, we:

1. Multiplied move_desired_vel by cam.getMoveScale() in the three
   PlayerPhysics::processMove* functions (Forwards, StrafeRight, MoveUp).
2. Added a CameraController::getMoveScale() const getter alongside the
   existing setter.
3. Kept the startup setMoveScale(0.3f) untouched so default in-game speed
   does not change for existing users — the slider's "1×" label reflects
   that baseline (slider multiplier × 0.3 → the move_speed_scale field).