Support starting playback at a specified frame

Author: appgurueu

doc/lua_api.md

@@ -8662,8 +8662,9 @@ Track numbers start at 1.
 * `play_animation(track, [animation])`
       `.x` and `.b3d` models only have a single animation track.
     * `animation` is an optional table with the following optional fields:
-      * `start_frame = 0.0`, `end_frame = math.huge`, animation range in frames (seconds);
+      * `min_frame = 0.0`, `max_frame = math.huge`, animation range in frames (seconds);
          clamped on the client to first and last frame in the corresponding track.
+      * `frame`, where to start playing the animation, defaults to `min_frame` if `speed >= 0`, `max_frame` otherwise.
       * `speed = 1.0`, animation speed in frames per second.
         (Recall that glTF frames are typically just timetamps in seconds.)
         A negative speed plays the animation backwards.

src/client/content_cao.cpp

@@ -1673,14 +1673,10 @@ void GenericCAO::processMessage(const std::string &data)
 		v2f range = readV2F32(is);
 		anim.min_frame = std::min(range.X, range.Y);
 		anim.max_frame = std::max(range.X, range.Y);
-
 		anim.fps = readF32(is);
-		if (anim.fps >= 0) {
-			anim.cur_frame = anim.min_frame;
-		} else {
-			anim.cur_frame = anim.max_frame;
-		}
+		anim.cur_frame = anim.fps >= 0 ? anim.min_frame : anim.max_frame;
 		anim.blend = readF32(is);
+
 		// these are sent inverted so we get true when the server sends nothing
 		anim.loop = !readU8(is);
 
@@ -1691,6 +1687,7 @@ void GenericCAO::processMessage(const std::string &data)
 		}
 		if (!is.eof()) {
 			anim.priority = readS32(is);
+			anim.cur_frame = readF32(is);
 		}
 
 		// Apply animation

src/script/lua_api/l_object.cpp

@@ -491,6 +491,8 @@ static void readTrackAnimSpec(lua_State *L, int tidx,
 	anim.max_frame = getfloatfield_default(L, tidx, "max_frame",
 			std::numeric_limits<f32>::infinity());
 	anim.fps = getfloatfield_default(L, tidx, "speed", 1.0f);
+	anim.cur_frame = getfloatfield_default(L, tidx, "frame",
+			anim.fps >= 0 ? anim.min_frame : anim.max_frame);
 	anim.blend = getfloatfield_default(L, tidx, "blend", 0.0f);
 	anim.loop = getboolfield_default(L, tidx, "loop", true);
 	anim.priority = getintfield_default(L, tidx, "priority", 0);
@@ -502,6 +504,7 @@ static void pushTrackAnimSpec(lua_State *L,
 	lua_newtable(L);
 	setfloatfield(L, -1, "min_frame", anim.min_frame);
 	setfloatfield(L, -1, "max_frame", anim.max_frame);
+	setfloatfield(L, -1, "frame", anim.cur_frame);
 	setfloatfield(L, -1, "speed", anim.fps);
 	setfloatfield(L, -1, "blend", anim.blend);
 	setboolfield(L, -1, "loop", anim.loop);

src/server/unit_sao.cpp

@@ -392,11 +392,12 @@ std::string UnitSAO::generateUpdateAnimationCommand(const scene::TrackId &track)
 	writeF32(os, anim.max_frame);
 	writeF32(os, anim.fps);
 	writeF32(os, anim.blend);
-	// these are sent inverted so we get true when the server sends nothing
+	// sent inverted so we get true when the server sends nothing
 	writeU8(os, !anim.loop);
 
 	writeTrackIdentifier(os, track);
 	writeS32(os, anim.priority);
+	writeF32(os, anim.cur_frame);
 
 	return os.str();
 }