CameraRig

import React, {type CSSProperties, type ReactNode} from "react";
import {useCurrentFrame, useVideoConfig} from "remotion";
import {cameraTransform, focusStyle, inOut, phase, type CameraPose, type MotionTiming} from "./core.js";

export type FocusPullProps = MotionTiming & {children: ReactNode; direction?: "out" | "in"; blur?: number; dim?: number; style?: CSSProperties};
export function FocusPull({children, at = 0, duration = 0.7, direction = "out", blur = 6, dim = 0.45, style}: FocusPullProps) {
  const p = inOut(phase(useCurrentFrame(), useVideoConfig().fps, at, duration));
  if (direction !== "out" && direction !== "in") throw new TypeError("direction must be out or in.");
  return <div style={{...style, ...focusStyle(direction === "out" ? p : 1 - p, blur, dim)}}>{children}</div>;
}

export type CameraRigProps = MotionTiming & {children: ReactNode; from: CameraPose; to: CameraPose; style?: CSSProperties};
/** The point in each pose is the world coordinate to place at the viewport center. */
export function CameraRig({children, from, to, at = 0, duration = 1.2, style}: CameraRigProps) {
  const frame = useCurrentFrame(), {fps, width, height} = useVideoConfig();
  const p = inOut(phase(frame, fps, at, duration));
  return <div style={{position: "absolute", inset: 0, ...style, transform: cameraTransform(from, to, p, width, height), transformOrigin: "0 0"}}>{children}</div>;
}

import {Easing} from "remotion";

/** All motion is evaluated from the local Remotion frame, including frames before a Sequence. */
export type MotionTiming = {at?: number; duration?: number};
export type Point = {x: number; y: number};
export type CameraPose = Point & {zoom: number};
export const out = Easing.bezier(0.16, 1, 0.3, 1);
export const inOut = Easing.bezier(0.65, 0, 0.35, 1);

export function finite(value: number, name: string): number {
  if (!Number.isFinite(value)) throw new TypeError(`${name} must be finite.`);
  return value;
}
export function positive(value: number, name: string): number {
  if (finite(value, name) <= 0) throw new RangeError(`${name} must be greater than zero.`);
  return value;
}
export function nonNegative(value: number, name: string): number {
  if (finite(value, name) < 0) throw new RangeError(`${name} must be zero or greater.`);
  return value;
}
export function unit(value: number, name = "progress"): number {
  return Math.min(1, Math.max(0, finite(value, name)));
}
export function lerp(from: number, to: number, p: number): number {
  finite(from, "from"); finite(to, "to");
  const t = unit(p);
  return finite(from * (1 - t) + to * t, "interpolated value");
}
export function phase(frame: number, fps: number, at = 0, duration = 0.6): number {
  finite(frame, "frame"); positive(fps, "fps"); finite(at, "at"); positive(duration, "duration");
  return unit((frame / fps - at) / duration);
}
export function reveal(frame: number, fps: number, at = 0, duration = 0.6): number {
  return out(phase(frame, fps, at, duration));
}
export function staggerAt(at: number, index: number, interval: number): number {
  finite(at, "at"); nonNegative(index, "index"); nonNegative(interval, "stagger");
  return at + index * interval;
}
export function swapState(progress: number): {side: "from" | "to"; opacity: number} {
  const p = unit(progress);
  return {side: p < 0.5 ? "from" : "to", opacity: Math.min(1, Math.abs(p - 0.5) * 4)};
}
export function cameraTransform(from: CameraPose, to: CameraPose, p: number, width: number, height: number): string {
  positive(from.zoom, "from.zoom"); positive(to.zoom, "to.zoom");
  positive(width, "width"); positive(height, "height");
  const x = lerp(from.x, to.x, p), y = lerp(from.y, to.y, p), zoom = lerp(from.zoom, to.zoom, p);
  const tx = finite(width / 2 - x * zoom, "camera translation x");
  const ty = finite(height / 2 - y * zoom, "camera translation y");
  return `translate(${tx}px, ${ty}px) scale(${zoom})`;
}
export function focusStyle(progress: number, blur: number, dim: number): {filter: string; opacity: number} {
  nonNegative(blur, "blur");
  if (finite(dim, "dim") < 0 || dim > 1) throw new RangeError("dim must be between zero and one.");
  const p = unit(progress);
  return {filter: `blur(${blur * p}px)`, opacity: lerp(1, dim, p)};
}
export function connectorGeometry(from: Point, to: Point, bend: number): {path: string; point: (p: number) => Point} {
  finite(from.x, "from.x"); finite(from.y, "from.y"); finite(to.x, "to.x"); finite(to.y, "to.y"); finite(bend, "bend");
  const middle = {x: lerp(from.x, to.x, 0.5), y: finite(lerp(from.y, to.y, 0.5) - bend, "curve midpoint")};
  return {
    path: `M ${from.x} ${from.y} Q ${middle.x} ${middle.y} ${to.x} ${to.y}`,
    point(p) { const t = unit(p); return {x: lerp(lerp(from.x, middle.x, t), lerp(middle.x, to.x, t), t), y: lerp(lerp(from.y, middle.y, t), lerp(middle.y, to.y, t), t)}; },
  };
}