feat(timeline): 支持逐切点机位过渡与概览轨编辑

src/editor/schema/timeline.ts

@@ -152,6 +152,8 @@ export interface CameraTimelineKeyframe {
   value: CameraKeyframeValue;
   /** 该关键帧「出去的那一段」使用的缓动曲线；不填或 "linear" 即线性插值 */
   easing?: EasingKind;
+  /** 该关键帧成为激活机位时的切点过渡（硬切 / 平滑运镜）；不填则退回时间轴全局默认 cameraTransition */
+  transition?: CameraTransition;
 }
 export interface CameraTimelineTrack {
   cameraId: string; // 对应 DirectorCameraShot.id
@@ -401,6 +403,57 @@ export function getActiveCameraIdAtTime(
   return getActiveCameraSegmentAtTime(cameraTracks, fallbackCameraId, time).cameraId;
 }
 
+/**
+ * 时间轴上「激活机位发生变化」的切点序列，用于把多机位切换过渡画在概览轨上：
+ * 遍历所有相机轨道的关键帧（按时间排序），每当某关键帧使其所属机位成为新的激活机位（与上一刻不同），
+ * 即记为一个切换点。该切换点的过渡优先取切点关键帧上的 transition，否则退回全局默认。
+ * 注意：最早期关键帧建立的是时间轴「初始机位」，其前没有任何关键帧，不算一次切换（即便与当前激活机位不同），
+ * 因此只有当该切点之前已存在其它关键帧时才记为切换，避免 0s 处出现一条无关的镜头切换。
+ */
+export interface CameraCutSegment {
+  /** 切换发生的时刻（= 切点关键帧的时间） */
+  time: number;
+  /** 切换前的激活机位（紧邻切点之前）；时间轴开头无关键帧时为 fallback */
+  fromCameraId: string | null;
+  /** 切换后的激活机位（切点关键帧所属机位） */
+  toCameraId: string;
+  /** 切点关键帧（过渡就挂在它上面，编辑时按它定位） */
+  keyframe: CameraTimelineKeyframe;
+  /** 解析后的过渡：切点关键帧 transition ?? 全局默认 */
+  transition: CameraTransition;
+}
+
+export function getCameraCutSegments(
+  cameraTracks: CameraTimelineTrack[],
+  globalTransition: CameraTransition,
+  fallbackCameraId: string | null
+): CameraCutSegment[] {
+  const items = cameraTracks
+    .flatMap((track) => track.keyframes.map((kf) => ({ cameraId: track.cameraId, kf })))
+    .sort((a, b) => a.kf.time - b.kf.time);
+  const segments: CameraCutSegment[] = [];
+  let prevCameraId = fallbackCameraId;
+  for (const { cameraId, kf } of items) {
+    const activeCameraId = getActiveCameraIdAtTime(cameraTracks, fallbackCameraId, kf.time);
+    // 仅当该切点之前已存在其它关键帧时才记为一次切换：最早期关键帧（无前序关键帧）是时间轴初始机位，
+    // 即便与当前激活机位不同也不算一次切换，不画在概览轨上（也避免 0s 处出现无关切换）
+    const hasPriorKeyframe = cameraTracks.some((track) =>
+      track.keyframes.some((k) => k.time < kf.time - 1e-6)
+    );
+    if (activeCameraId !== null && activeCameraId !== prevCameraId && hasPriorKeyframe) {
+      segments.push({
+        time: kf.time,
+        fromCameraId: prevCameraId,
+        toCameraId: activeCameraId,
+        keyframe: kf,
+        transition: kf.transition ? normalizeCameraTransition(kf.transition) : globalTransition,
+      });
+    }
+    prevCameraId = activeCameraId;
+  }
+  return segments;
+}
+
 export interface CameraViewAtTime {
   cameraId: string | null;
   pose: CameraKeyframeValue;
@@ -425,12 +478,28 @@ export function evaluateCameraViewAtTime(
   const incomingPose = evaluateCameraTrackAtTime(incomingTrack, time);
   if (!incomingPose) return null;
 
-  if (transition.type !== "smooth" || transition.duration <= 0) {
+  // 切点之前没有任何关键帧：这是时间轴的「初始机位」，不算一次切换，直接落位（与概览轨一致，避免 0s 处出现无关切换）
+  const hasPriorKeyframe = cameraTracks.some((track) =>
+    track.keyframes.some((k) => k.time < segment.cutTime - 1e-6)
+  );
+  if (!hasPriorKeyframe) {
+    return { cameraId: segment.cameraId, pose: incomingPose };
+  }
+
+  // 本切点的过渡：优先用切点关键帧上挂的逐个过渡，否则退回全局默认 cameraTransition
+  const cutKeyframe = incomingTrack.keyframes.find(
+    (kf) => Math.abs(kf.time - segment.cutTime) < KEYFRAME_TIME_TOLERANCE
+  );
+  const effectiveTransition = cutKeyframe?.transition
+    ? normalizeCameraTransition(cutKeyframe.transition)
+    : transition;
+
+  if (effectiveTransition.type !== "smooth" || effectiveTransition.duration <= 0) {
     return { cameraId: segment.cameraId, pose: incomingPose };
   }
 
   const elapsed = time - segment.cutTime;
-  if (elapsed >= transition.duration) {
+  if (elapsed >= effectiveTransition.duration) {
     return { cameraId: segment.cameraId, pose: incomingPose };
   }
 
@@ -446,7 +515,7 @@ export function evaluateCameraViewAtTime(
   const outgoingPose = evaluateCameraTrackAtTime(prevTrack, segment.cutTime);
   if (!outgoingPose) return { cameraId: segment.cameraId, pose: incomingPose };
 
-  const progress = applyEasing("easeInOutCubic", elapsed / transition.duration);
+  const progress = applyEasing("easeInOutCubic", elapsed / effectiveTransition.duration);
   return { cameraId: segment.cameraId, pose: lerpCameraValue(outgoingPose, incomingPose, progress) };
 }
 
@@ -600,6 +669,30 @@ export function updateCameraKeyframeEasing(
   };
 }
 
+/** 设置 / 清除某个运镜关键帧上的「切点过渡」覆盖（transition 为 null = 清除，退回全局默认 cameraTransition） */
+export function setCameraKeyframeTransition(
+  timeline: Timeline,
+  cameraId: string,
+  keyframeId: string,
+  transition: CameraTransition | null
+): Timeline {
+  return {
+    ...timeline,
+    cameraTracks: timeline.cameraTracks.map((track) =>
+      track.cameraId !== cameraId
+        ? track
+        : {
+            ...track,
+            keyframes: track.keyframes.map((kf) =>
+              kf.id === keyframeId
+                ? { ...kf, transition: transition ? normalizeCameraTransition(transition) : undefined }
+                : kf
+            ),
+          }
+    ),
+  };
+}
+
 // ===== 运镜片段时间（时间轴上的「片段条 + 右端把手」） =====
 /** 运镜片段里相邻关键帧之间允许的最小时间间隔（秒），保证时间严格递增 */
 export const CAMERA_KEYFRAME_MIN_GAP = 0.05;