Release Healer Man 0.1.9

src/scene/frameRateGovernor.ts

@@ -0,0 +1,86 @@
+export type FrameRateGovernorMode = number | "display";
+
+export interface FrameRateGovernorState {
+  readonly mode: FrameRateGovernorMode;
+  readonly lastTimestampMs: number | null;
+  readonly nextDeadlineMs: number | null;
+  readonly elapsedSeconds: number;
+}
+
+export interface FrameRateGovernorStep {
+  readonly state: FrameRateGovernorState;
+  readonly shouldRender: boolean;
+  readonly elapsedSeconds: number;
+}
+
+function frameIntervalMs(mode: FrameRateGovernorMode): number | null {
+  if (mode === "display") return null;
+  return Number.isFinite(mode) && mode > 0 ? 1_000 / mode : 1_000 / 60;
+}
+
+export function createFrameRateGovernor(
+  mode: FrameRateGovernorMode,
+  elapsedSeconds = 0,
+): FrameRateGovernorState {
+  return {
+    mode,
+    lastTimestampMs: null,
+    nextDeadlineMs: null,
+    elapsedSeconds: Math.max(0, elapsedSeconds),
+  };
+}
+
+export function resetFrameRateGovernor(
+  state: FrameRateGovernorState,
+  mode: FrameRateGovernorMode = state.mode,
+): FrameRateGovernorState {
+  return createFrameRateGovernor(mode, state.elapsedSeconds);
+}
+
+export function stepFrameRateGovernor(
+  state: FrameRateGovernorState,
+  rawTimestampMs: number,
+): FrameRateGovernorStep {
+  const fallbackTimestamp = state.lastTimestampMs ?? 0;
+  const finiteTimestamp = Number.isFinite(rawTimestampMs) ? rawTimestampMs : fallbackTimestamp;
+  const timestampMs = Math.max(fallbackTimestamp, finiteTimestamp);
+  const intervalMs = frameIntervalMs(state.mode);
+
+  if (state.lastTimestampMs === null) {
+    const nextState: FrameRateGovernorState = {
+      ...state,
+      lastTimestampMs: timestampMs,
+      nextDeadlineMs: intervalMs === null ? null : timestampMs + intervalMs,
+    };
+    return { state: nextState, shouldRender: true, elapsedSeconds: nextState.elapsedSeconds };
+  }
+
+  const elapsedSeconds = state.elapsedSeconds + (timestampMs - state.lastTimestampMs) / 1_000;
+  if (intervalMs === null) {
+    const nextState: FrameRateGovernorState = {
+      ...state,
+      lastTimestampMs: timestampMs,
+      elapsedSeconds,
+    };
+    return { state: nextState, shouldRender: true, elapsedSeconds };
+  }
+
+  const deadlineMs = state.nextDeadlineMs ?? timestampMs;
+  if (timestampMs < deadlineMs) {
+    const nextState: FrameRateGovernorState = {
+      ...state,
+      lastTimestampMs: timestampMs,
+      elapsedSeconds,
+    };
+    return { state: nextState, shouldRender: false, elapsedSeconds };
+  }
+
+  const missedIntervals = Math.floor(Math.max(0, timestampMs - deadlineMs) / intervalMs);
+  const nextState: FrameRateGovernorState = {
+    ...state,
+    lastTimestampMs: timestampMs,
+    nextDeadlineMs: deadlineMs + (missedIntervals + 1) * intervalMs,
+    elapsedSeconds,
+  };
+  return { state: nextState, shouldRender: true, elapsedSeconds };
+}