Function init

packages/shader-transitions/src/hyper-shader.ts:809–2220

(config: HyperShaderConfig)

}

export function init(config: HyperShaderConfig): GsapTimeline {
  const { bgColor, scenes, transitions } = config;

  if (scenes.length !== transitions.length + 1) {
    throw new Error(
      `[HyperShader] init(): expected scenes.length === transitions.length + 1, got scenes=${scenes.length}, transitions=${transitions.length}`,
    );
  }

  // Verify each scene id resolves to an element with the `.scene` class.
  // Capture and compositing later assume both — without this guard the
  // texture map gets stale ids and transitions silently no-op.
  if (typeof document !== "undefined") {
    const missing: string[] = [];
    const notScene: string[] = [];
    for (const id of scenes) {
      const el = document.getElementById(id);
      if (!el) {
        missing.push(id);
      } else if (!el.classList.contains("scene")) {
        notScene.push(id);
      }
    }
    if (missing.length > 0) {
      throw new Error(`[HyperShader] init(): scene ids not found in DOM: ${missing.join(", ")}`);
    }
    if (notScene.length > 0) {
      throw new Error(
        `[HyperShader] init(): elements found but missing .scene class: ${notScene.join(", ")}`,
      );
    }
  }

  // Locally redeclared (not imported) because @hyperframes/shader-transitions
  // ships as a standalone CDN bundle and must not depend on @hyperframes/engine.
  // Keep this in sync with HfTransitionMeta in packages/engine/src/types.ts.
  interface HfTransitionMeta {
    time: number;
    duration: number;
    shader?: string; // undefined = CSS crossfade (no WebGL required)
    ease: string;
    fromScene: string;
    toScene: string;
  }
  type HfWindowWrite = { __hf?: { transitions?: HfTransitionMeta[] } };
  if (typeof window !== "undefined") {
    const hfWin = window as unknown as HfWindowWrite;
    if (hfWin.__hf) {
      hfWin.__hf.transitions = transitions.map((t: TransitionConfig, i: number) => ({
        time: t.time,
        duration: t.duration ?? DEFAULT_DURATION,
        shader: t.shader,
        ease: t.ease ?? DEFAULT_EASE,
        fromScene: scenes[i] ?? "",
        toScene: scenes[i + 1] ?? "",
      }));
    }
  }