Advance M8-M11 parity workflows

web/protocol/viewport-camera.ts

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+export interface ViewportOrbitState {
+  yaw: number;
+  pitch: number;
+  distance: number;
+  target: [number, number, number];
+}
+
+export interface ViewportCameraState extends ViewportOrbitState {
+  position: [number, number, number];
+}
+
+export const VIEWPORT_DEFAULT_ORBIT: Readonly<ViewportOrbitState> = Object.freeze({
+  yaw: -Math.PI / 4,
+  pitch: 0.55,
+  distance: 7,
+  target: [0, 0, 0] as [number, number, number],
+});
+
+export const VIEWPORT_ORBIT_ROTATE_SENSITIVITY = 0.008;
+export const VIEWPORT_ORBIT_ZOOM_SENSITIVITY = 0.001;
+export const VIEWPORT_ORBIT_MIN_DISTANCE = 0.2;
+export const VIEWPORT_ORBIT_MAX_DISTANCE = 500;
+
+export function orbitPosition(state: Pick<ViewportOrbitState, "yaw" | "pitch" | "distance" | "target">): [number, number, number] {
+  const horizontal = state.distance * Math.cos(state.pitch);
+  return [
+    state.target[0] + horizontal * Math.cos(state.yaw),
+    state.target[1] + horizontal * Math.sin(state.yaw),
+    state.target[2] + state.distance * Math.sin(state.pitch),
+  ];
+}
+
+export function cameraState(state: ViewportOrbitState): ViewportCameraState {
+  return { ...state, target: [...state.target] as [number, number, number], position: orbitPosition(state) };
+}
+
+export function orbitStateFromPosition(position: readonly number[], target: readonly number[] = [0, 0, 0]): ViewportOrbitState {
+  const dx = position[0] - target[0];
+  const dy = position[1] - target[1];
+  const dz = position[2] - target[2];
+  const distance = Math.max(VIEWPORT_ORBIT_MIN_DISTANCE, Math.hypot(dx, dy, dz));
+  return {
+    yaw: Math.atan2(dy, dx),
+    pitch: Math.asin(Math.max(-1, Math.min(1, dz / distance))),
+    distance,
+    target: [target[0], target[1], target[2]],
+  };
+}
+
+export function applyOrbitDelta(state: ViewportOrbitState, deltaX: number, deltaY: number, zoom: number): ViewportOrbitState {
+  return {
+    ...state,
+    yaw: state.yaw - deltaX * VIEWPORT_ORBIT_ROTATE_SENSITIVITY,
+    pitch: Math.max(-1.45, Math.min(1.45, state.pitch + deltaY * VIEWPORT_ORBIT_ROTATE_SENSITIVITY)),
+    distance: Math.max(VIEWPORT_ORBIT_MIN_DISTANCE, Math.min(VIEWPORT_ORBIT_MAX_DISTANCE, state.distance * Math.exp(zoom * VIEWPORT_ORBIT_ZOOM_SENSITIVITY))),
+    target: [...state.target] as [number, number, number],
+  };
+}