basic advanced example

Content/Python/ue_workshop/root_motion.py

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+"""Transfer horizontal root motion to Sequencer actor keys without changing source clips."""
+import math
+import hashlib
+
+import unreal
+
+from .paths import GENERATED
+
+
+def prepare(clip, child, scene_name):
+    component = child.skeletal_mesh_component
+    bone = component.get_bone_name(0)
+    count = int(clip.get_editor_property("number_of_sampled_keys"))
+    duration = clip.get_play_length()
+    if count < 2 or duration <= 0:
+        raise ValueError("keep_end_position wymaga animacji z co najmniej dwiema probkami.")
+    poses = [unreal.AnimationLibrary.get_bone_pose_for_time(
+        clip, bone, duration * index / (count - 1), False) for index in range(count)]
+    first = poses[0].translation
+    # Extract only horizontal travel. Keep vertical motion (jumps/bobbing),
+    # every root rotation and scale, and all other bone tracks unchanged.
+    positions = [unreal.Vector(first.x, first.y, pose.translation.z) for pose in poses]
+    folder = f"{GENERATED}/{scene_name}/RootMotion"
+    identity = hashlib.sha1(clip.get_path_name().encode("utf-8")).hexdigest()[:8]
+    name = clip.get_name() + "_" + identity + "_InPlace"
+    path = folder + "/" + name
+    if unreal.EditorAssetLibrary.does_asset_exist(path):
+        # This path contains only our generated derivative for this scene.
+        if not unreal.EditorAssetLibrary.delete_asset(path):
+            raise RuntimeError("Nie mozna odswiezyc wygenerowanego klipu " + path)
+    copy = unreal.AssetToolsHelpers.get_asset_tools().duplicate_asset(name, folder, clip)
+    if copy is None:
+        raise RuntimeError("Nie mozna utworzyc kopii animacji dla keep_end_position.")
+    controller = copy.get_editor_property("controller")
+    if not controller.set_bone_track_keys(bone, positions, [pose.rotation for pose in poses],
+                                          [pose.scale3d for pose in poses], should_transact=False):
+        raise RuntimeError("Nie mozna przeniesc ruchu kosci glownej do Transform.")
+    unreal.EditorAssetLibrary.save_loaded_asset(copy)
+    return copy, poses, duration
+
+
+def displacement(poses, duration, elapsed, reverse=False):
+    """Interpolate horizontal root travel, accumulating complete playback loops."""
+    elapsed = max(0.0, elapsed)
+    loops = math.floor(elapsed / duration)
+    time = elapsed - loops * duration
+    if reverse:
+        time = duration - time
+    index = min(time / duration * (len(poses) - 1), len(poses) - 1)
+    lower = int(index)
+    upper = min(lower + 1, len(poses) - 1)
+    alpha = index - lower
+    a, b = poses[lower].translation, poses[upper].translation
+    start, end = poses[0].translation, poses[-1].translation
+    if reverse:
+        start, end = end, start
+    return unreal.Vector(a.x + (b.x - a.x) * alpha - start.x + loops * (end.x - start.x),
+                         a.y + (b.y - a.y) * alpha - start.y + loops * (end.y - start.y), 0)