Added initial support for blending of SyncTracks with differing numbers of intervals.

Not sure that the resulting blends are correct, but leave it for now.

blendalot_animation_node.cpp

@@ -385,6 +385,10 @@ StringName BLTAnimationNodeSampler::get_animation() const {
 	return animation_name;
 }
 
+AnimationPlayer *BLTAnimationNodeSampler::get_animation_player() const {
+	return animation_player;
+}
+
 TypedArray<StringName> BLTAnimationNodeSampler::get_animations_as_typed_array() const {
 	TypedArray<StringName> typed_arr;
 
@@ -417,6 +421,7 @@ TypedArray<StringName> BLTAnimationNodeSampler::get_animations_as_typed_array()
 void BLTAnimationNodeSampler::_bind_methods() {
 	ClassDB::bind_method(D_METHOD("set_animation", "name"), &BLTAnimationNodeSampler::set_animation);
 	ClassDB::bind_method(D_METHOD("get_animation"), &BLTAnimationNodeSampler::get_animation);
+	ClassDB::bind_method(D_METHOD("get_animation_player"), &BLTAnimationNodeSampler::get_animation_player);
 
 	ADD_PROPERTY(PropertyInfo(Variant::STRING_NAME, "animation"), "set_animation", "get_animation");
 

blendalot_math_helper.h

@@ -0,0 +1,22 @@
+//
+// Created by martin on 20.02.26.
+//
+
+#ifndef MASTER_BLENDALOT_MATH_HELPER_H
+#define MASTER_BLENDALOT_MATH_HELPER_H
+
+inline int greatest_common_divisor(int a, int b) {
+	while (b != 0) {
+		int temp = b;
+		b = a % b;
+		a = temp;
+	}
+
+	return a;
+}
+
+inline int least_common_multiple(int a, int b) {
+	return (a / greatest_common_divisor(a, b)) * b;
+}
+
+#endif //MASTER_BLENDALOT_MATH_HELPER_H

sync_track.h

@@ -2,6 +2,7 @@
 
 #include "core/templates/local_vector.h"
 
+#include "blendalot_math_helper.h"
 #include <cassert>
 #include <cmath>
 
@@ -21,7 +22,7 @@
  *  duration. Blended SyncTracks always have their first interval start at t = 0.0s.
  */
 struct SyncTrack {
-	static constexpr int cSyncTrackMaxIntervals = 8;
+	static constexpr int cSyncTrackMaxIntervals = 32;
 
 	SyncTrack() :
 			duration(0.f), num_intervals(1) {
@@ -59,6 +60,12 @@ struct SyncTrack {
 	}
 
 	double calc_ratio_from_sync_time(double sync_time) const {
+		// When blending SyncTracks with differing numbers of intervals the resulting SyncTrack may have
+		// additional repeats of the animation (=> "virtual sync periods", https://youtu.be/Jkv0pbp0ckQ?t=8178).
+		//
+		// Therefore, we first have to transform it back to the numbers of intervals we actually have.
+		sync_time = fmod(sync_time, num_intervals);
+
 		float interval_ratio = fmod(sync_time, 1.0f);
 		int interval = int(sync_time - interval_ratio);
 
@@ -126,19 +133,32 @@ struct SyncTrack {
 	 */
 	static SyncTrack
 	blend(float weight, const SyncTrack &track_A, const SyncTrack &track_B) {
-		assert(track_A.num_intervals == track_B.num_intervals);
+		if (Math::is_zero_approx(weight)) {
+			return track_A;
+		}
+
+		if (Math::is_zero_approx(1.0 - weight)) {
+			return track_B;
+		}
 
 		SyncTrack result;
+
+		if (track_A.num_intervals != track_B.num_intervals) {
+			result.num_intervals = least_common_multiple(track_A.num_intervals, track_B.num_intervals);
+		} else {
 			result.num_intervals = track_A.num_intervals;
+		}
+		assert(result.num_intervals < cSyncTrackMaxIntervals);
 
-		result.duration =
+		float track_A_repeats = static_cast<float>(result.num_intervals / track_A.num_intervals);
-				(1.0f - weight) * track_A.duration + weight * track_B.duration;
+		float track_B_repeats = static_cast<float>(result.num_intervals / track_B.num_intervals);
 
+		result.duration = (1.0f - weight) * (track_A.duration * track_A_repeats) + weight * (track_B.duration * track_B_repeats);
 		result.interval_start_ratio[0] = 0.f;
 
 		for (int i = 0; i < result.num_intervals; i++) {
-			float interval_duration_A = track_A.interval_duration_ratio[i];
+			float interval_duration_A = track_A.interval_duration_ratio[i % track_A.num_intervals] / track_A_repeats;
-			float interval_duration_B = track_B.interval_duration_ratio[i];
+			float interval_duration_B = track_B.interval_duration_ratio[i % track_B.num_intervals] / track_B_repeats;
 			result.interval_duration_ratio[i] =
 					(1.0f - weight) * interval_duration_A + weight * interval_duration_B;
 
@@ -152,8 +172,6 @@ struct SyncTrack {
 			}
 		}
 
-		assert(result.num_intervals < cSyncTrackMaxIntervals);
-
 		return result;
 	}
 };

tests/test_sync_track.h

@@ -203,4 +203,47 @@ TEST_CASE("[Blendalot][SyncTrack] Sync Track blending") {
 	}
 }
 
-} //namespace TestSyncedAnimationGraph
+TEST_CASE("[Blendalot][SyncTrack] Sync Track blending non-matching interval count") {
+	SyncTrack track_a = SyncTrack::create_from_markers(2.0, { 0., 0.6, 1.8 });
+	SyncTrack track_b = SyncTrack::create_from_markers(1.5f, { 1.05 });
+
+	WHEN("Blending two synctracks with weight 0.") {
+		SyncTrack blended = SyncTrack::blend(0.f, track_a, track_b);
+
+		blended.duration = track_a.duration;
+		blended.interval_start_ratio[0] = 0.0;
+		for (int i = 0; i < track_a.num_intervals; i++) {
+			CHECK(blended.interval_duration_ratio[i] == track_a.interval_duration_ratio[i]);
+		}
+	}
+	WHEN("Blending two synctracks with weight 1.") {
+		SyncTrack blended = SyncTrack::blend(1.f, track_a, track_b);
+
+		blended.duration = track_b.duration;
+		blended.interval_start_ratio[0] = 0.0;
+		for (int i = 0; i < track_b.num_intervals; i++) {
+			CHECK(blended.interval_duration_ratio[i] == track_b.interval_duration_ratio[i]);
+		}
+	}
+
+	WHEN("Blending with weight 0.2") {
+		float weight = 0.2f;
+		SyncTrack blended = SyncTrack::blend(weight, track_a, track_b);
+
+		float track_a_repeats = static_cast<float>(blended.num_intervals / track_a.num_intervals);
+		float track_b_repeats = static_cast<float>(blended.num_intervals / track_b.num_intervals);
+
+		CHECK(
+				blended.duration == doctest::Approx(2.5));
+		CHECK(
+				blended.interval_start_ratio[0] == 0.0);
+		CHECK(
+				blended.interval_duration_ratio[0] == doctest::Approx((1.0 - weight) * track_a.interval_duration_ratio[0] / track_a_repeats + weight * track_b.interval_duration_ratio[0] / track_b_repeats));
+		CHECK(
+				blended.interval_duration_ratio[1] == doctest::Approx((1.0 - weight) * track_a.interval_duration_ratio[1] / track_a_repeats + weight * track_b.interval_duration_ratio[0] / track_b_repeats));
+		CHECK(
+				blended.interval_duration_ratio[2] == doctest::Approx((1.0 - weight) * track_a.interval_duration_ratio[2] / track_a_repeats + weight * track_b.interval_duration_ratio[0] / track_b_repeats));
+	}
+}
+
+} //namespace TestBlendalotAnimationGraph