Add frame-based RVB animation snapshots

include/gc/RvbLayout.hpp

@@ -4,6 +4,7 @@
 
 #include <array>
 #include <cstdint>
+#include <limits>
 #include <string>
 #include <unordered_map>
 #include <vector>
@@ -25,6 +26,12 @@ struct RvbImageDraw {
 // root timeline). Clips not mentioned here remain on their first FRAM.
 struct RvbSnapshotState {
     std::unordered_map<std::string, std::string> frameByPath;
+    // Frame offset after a labeled play() entry point. The default resolves
+    // to the following stop(), preserving the static snapshot behavior.
+    uint32_t animationFrame = std::numeric_limits<uint32_t>::max();
+    // Optional per-clip overrides allow a transition to advance while child
+    // loops and unrelated state clips remain at their authored stop frames.
+    std::unordered_map<std::string, uint32_t> animationFrameByPath;
     bool includeRootOther = false;
 };
 
@@ -46,6 +53,14 @@ bool BuildRvbSnapshot(const std::vector<uint8_t>& bytes,
                       std::vector<RvbImageDraw>* draws,
                       std::string* error = nullptr);
 
+// Returns the longest play()..stop() span selected by this state. The result
+// includes the labeled entry frame and can be converted to seconds with the
+// scene frame rate.
+uint32_t MeasureRvbSnapshotAnimationFrames(const std::vector<uint8_t>& bytes,
+                                           const RvbScene& scene,
+                                           const RvbSnapshotState& state,
+                                           std::string* error = nullptr);
+
 // Builds an exported/linkage MovieClip without requiring it to be placed on
 // the root timeline. game471.exe uses this path for the twelve dynamically
 // instantiated select-music rows (mc_music_link / mc_index_link).