响应式

响应式层对齐 Manim 的 ValueTracker + add_updater + always_redraw（design.md §8）。

Signal 与 computed

import { signal, computed } from "@intermact/core";

const radius = signal(1);
const area = computed(() => Math.PI * radius.get() * radius.get());

构建期在 createProgram 内创建的信号会通过 setSignalRegistrar 自动注册到 ReactiveEngine。

derived

几何工厂，依赖信号变化时最小重算：

import { derived, circle } from "@intermact/core";

const disk = derived(
  () =>
    circle({
      radius: radius.get(),
      style: { stroke: "#38bdf8", fill: "rgba(56,189,248,0.2)" },
    }),
  [radius],
);

scene.register(disk, { position: xy(0, 0) });

valueTracker 与 tweenSignal

import { valueTracker, tweenSignal } from "@intermact/core";

const t = valueTracker(0);
await scene.play(tweenSignal(t, 1, { duration: 2 }));

tweenSignal 编译为可 seek 的 SignalTrack。

bindSignal 与 useSignal

• bindSignal：把外部源（如 Leva）绑定到 signal
• useSignal（@intermact/react）：在 React 组件中订阅 signal

import { useSignal } from "@intermact/react";

function Panel({ freq }: { freq: Signal<number> }) {
  const f = useSignal(freq);
  return <span>f = {f.toFixed(2)}</span>;
}

帧循环

Player.prepareFrame → ReactiveEngine.flush → 重算 derived / 运行 addUpdater → 再生成 RenderSnapshot。

相关示例

• reactive/value-tracker — §8.2 双曲线内接矩形
• reactive/leva-binding — §19.2 交互正弦曲线
• l1/interactive-sine — L1 闸口演示