Skip to content

PCAM-24: A Phase-Centric Action Model

For Deterministic Interactive Simulation

Abstract

This paper introduces PCAM-24, a simulation model in which discrete phase—rather than continuous time—is the authoritative coordinate for action progression. By elevating phase to a first-class primitive, PCAM-24 eliminates timing inference between subsystems, simplifies deterministic networking, and provides a shared semantic language for animation, combat, and AI.

📄 YAML Data Standard v1.0 Available

Ready to implement PCAM-24? See the YAML Data Standard for the engine-agnostic schema that defines combat actions, phase windows, and interaction resolution.

1. Introduction

Modern interactive simulations—especially games—coordinate multiple subsystems that each operate on their own notion of time. Animation advances clip time, combat evaluates frame-based windows, and networking reconciles wall-clock deltas. This fragmentation produces: * Desynchronization between animation and gameplay * Brittle timing logic (floats/frames) * Ambiguous interaction adjudication

PCAM-24 proposes a different foundation: replace time as the primary semantic coordinate with discrete phase. Rather than asking "when did something happen?", PCAM-24 asks "what stage of the action is occurring?"

2. Core Concept

2.1 Phase Space

PCAM-24 defines a fixed, cyclic phase space:

\[Phase \in \mathbb{Z}_{24} = \{0,1,\dots,23\}\]

Phase advances discretely and wraps modulo 24.

The choice of 24 phases reflects a balance between expressive resolution and cognitive tractability. It provides sufficient granularity to model nuanced action stages while remaining small enough to reason about as a complete cycle.

2.2 Actions

An action is the atomic unit of interactive intent. Each action owns: * A current phase value * A phase progression rule * A set of named phase windows * Deterministic transition rules

3. Phase Windows and Semantics

A phase window is a named subset of the phase space \(W \subseteq \mathbb{Z}_{24}\). * ACTIVE: Phases where an attack deals damage. * INVULN: Phases where damage is negated. * PARRY_PERFECT: Phases where a parry succeeds.

4. Phase Authority (The Axioms)

PCAM-24 enforces several non-negotiable axioms:

  1. Phase is Authoritative: It is the sole coordinate for ordering and adjudication.
  2. Discrete Semantics: All logic must be expressible as phase membership.
  3. Monotonic Progression: No rewinds. Corrections occur by snapping phase.
  4. Subsystem Subscription: Animation/Audio observe phase but do not drive it.
  5. Interaction by Phase: Cross-entity interactions are resolved by phase rules, not wall-clock time.

5. Action Lifecycles

  • Impulse: Progress once and terminate (e.g., Melee Attack).
  • Sustained: Loop while input is held (e.g., Block).
  • Reactive: Narrow success window (e.g., Parry).
  • Evasive: Invulnerability window + movement (e.g., Dodge).

6. Transitions & Buffering

  • Cancels are allowed only within defined windows.
  • Inputs are buffered and consumed deterministically.
  • Priority rules resolve simultaneous transition eligibility.

7. Interaction Adjudication

PCAM-24 requires explicit precedence for contested interactions: 1. Evasion (e.g., INVULN) 2. Perfect Defense 3. Mitigating Defense 4. Hit

8. Networking and Determinism

PCAM-24 is inherently network-friendly. * Replication: Transmits Action ID + Phase. * Prediction: Clients predict by advancing phase. * Reconciliation: Snap to authoritative phase (no complex time rewinding).

10. Benefits

Why use PCAM-24?

  • Consistency: All systems share a single semantic clock.
  • Determinism: Eliminates floating-point drift.
  • Explainability: Bugs are inspectable state, not vague timing artifacts.
  • Authorability: Designers reason in stages, not milliseconds.

12. Conclusion

PCAM-24 reframes interactive simulation timing from a question of when to a question of what stage. It is not an optimization of existing timing systems. It is a replacement of their underlying assumption.