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Focused controller actions (V12)

IVPrismaUI12 lets a mod map controller buttons to UI actions without installing its own raw Fallout controller sink. It derives from V11, so the existing V1-V11 ABI prefix remains unchanged.

Availability: include the canonical PrismaUI_F4_API.h SDK header and request IVPrismaUI12 at runtime. Always null-check the request. Older installed providers may expose only earlier interface versions.

Public API​

virtual bool BindControllerAction(
    PrismaView view,
    const char* canonicalButton,
    const char* action) noexcept = 0;

virtual bool UnbindControllerAction(
    PrismaView view,
    const char* canonicalButton) noexcept = 0;

virtual void ClearControllerActions(PrismaView view) noexcept = 0;

BindControllerAction replaces the mapping for that view and button. It returns false until the target view is DOM-ready. UnbindControllerAction removes one mapping. ClearControllerActions removes every controller mapping owned by the view.

Action identifiers are copied into framework storage and must contain 1-64 ASCII letters, digits, _, -, ., or :.

Canonical buttons​

The accepted button names are:

A, B, X, Y, LB, RB, LT, RT, LS, RS, Back, Start, DUp, DDown, DLeft, DRight.

These match the canonical names used by GetGamepadButtonName() and Prisma controller glyph rendering. PlayStation mode changes presentation only. Your code still registers the canonical names above.

Request V12​

#include "PrismaUI_F4_API.h"

static PRISMA_UI_API::IVPrismaUI12* g_prisma = nullptr;
static PrismaView g_view = 0;

// During/after kGameDataReady:
g_prisma = PRISMA_UI_API::RequestPluginAPI<PRISMA_UI_API::IVPrismaUI12>();
if (!g_prisma) {
    logger::warn("PrismaUI V12 unavailable; controller actions disabled");
}

Request the lowest API version your mod actually requires. If controller actions are optional, keep a fallback path when V12 is unavailable.

Bind after DOM-ready​

Controller actions should normally be registered from your DOM-ready callback. Binding before the final page context is ready returns false.

static void OnDomReady(PrismaView view) {
    if (!g_prisma) return;

    g_prisma->BindControllerAction(view, "X", "scrap");
    g_prisma->BindControllerAction(view, "Y", "favorite");
    g_prisma->BindControllerAction(view, "LB", "category_prev");
    g_prisma->BindControllerAction(view, "RB", "category_next");
}

Duplicate registration for the same view/button replaces the previous action deterministically.

JavaScript event​

The focused page receives one stable browser event:

window.addEventListener('prisma-controller-action', ({ detail }) => {
  console.log(detail.action); // registered action identifier
  console.log(detail.button); // canonical button name
  console.log(detail.state);  // pressed, repeat, or released
});

Example:

window.addEventListener('prisma-controller-action', ({ detail }) => {
  if (detail.state !== 'pressed') return;

  switch (detail.action) {
    case 'scrap':
      scrapSelectedItem();
      break;
    case 'favorite':
      toggleFavorite();
      break;
    case 'category_prev':
      selectPreviousCategory();
      break;
    case 'category_next':
      selectNextCategory();
      break;
  }
});

Delivery runs in the view's Ultralight JavaScript context and is intended for UI work. If JavaScript needs to mutate Fallout-owned state, route that mutation through a native listener registered with V11 BindGameThreadUIEvent, or dispatch native work with DispatchToGameThread.

Focus and event consumption​

A mapped controller event is eligible only when:

  • it is a gamepad button event;
  • the mapped view still exists;
  • that exact view owns PrismaUI focus; and
  • the button has a live mapping for that view.

An admitted pressed, repeat, or released event is marked kStop on the Fallout input chain so the same physical input does not also activate a menu or gameplay action underneath the Prisma view.

kStop means the mapped event was accepted for asynchronous dispatch to the exact focused live view. It does not mean JavaScript synchronously acknowledged or handled the event.

Unmapped, unfocused, keyboard/mouse, idle, and invalid-view events are not consumed by the V12 controller-action path.

Legacy D-pad, A, and B behavior​

PrismaUI already provides automatic controller navigation for focused views:

  • D-pad -> Arrow keys
  • A -> Enter
  • B -> Escape

That behavior remains unchanged when those buttons are not explicitly registered through V12.

If a view explicitly maps A, B, DUp, DDown, DLeft, or DRight, the V12 action replaces the legacy synthetic-key route for that button. One physical event is not delivered through both paths.

This makes migration incremental: map only the actions your UI needs and leave normal keyboard-style navigation alone.

LT and RT hysteresis​

Triggers are analog values, so V12 uses deterministic hysteresis:

  • press at 0.55 or above;
  • remain held through the middle band;
  • release at 0.45 or below.

This avoids trigger drift creating noisy press/release edges. Trigger state is reset when focus is successfully acquired so returning to a view does not inherit stale trigger state.

LS and RS refer to the stick-click buttons. Thumbstick movement itself is outside this API.

Lifecycle​

Mappings are owned per PrismaView.

  • UnbindControllerAction removes one button.
  • ClearControllerActions removes all mappings for a view.
  • Destroy(view) clears the view's mappings before backend destruction.
  • A destroyed view cannot leak mappings into a later view.

For long-lived views, it is fine to bind once after DOM-ready and keep the mappings until destruction. For screens whose control scheme changes, rebind or clear mappings when the mode changes.

Removing a mapping​

g_prisma->UnbindControllerAction(g_view, "X");

Clear all mappings:

g_prisma->ClearControllerActions(g_view);

Controller prompts​

V12 handles actions, while the existing V9 prompt API handles presentation. Use them together:

char prompt[32]{};
if (g_prisma->GetButtonPrompt("Activate", prompt, sizeof(prompt))) {
    // Show prompt in the page.
}

For a direct gamepad code, GetGamepadButtonName() returns the same canonical naming family used by V12.

Migrating an existing mod​

If your mod currently installs its own menu/player controller sink only to catch X/Y/LB/RB/etc. for a Prisma view:

  1. Include PrismaUI_F4_API.h and request IVPrismaUI12.
  2. Remove the duplicate raw controller sink for UI actions now owned by PrismaUI.
  3. Bind actions after DOM-ready.
  4. Handle prisma-controller-action in the page.
  5. Keep V9 prompt/glyph APIs for visual button prompts.
  6. Keep engine mutations behind the V11 game-thread APIs.

This avoids multiple mods independently consuming the same Fallout controller events.

Fallout 4 VR​

V12 follows the current V11 flat-provider boundary. The VR provider may compile shared controller policy, but it does not advertise V11 or V12. Do not assume the desktop V12 interface exists in Fallout 4 VR.

See also​