Implemented simple tests for sync track calculations.

src/SkinnedMesh.h

@@ -27,14 +27,32 @@ struct SyncTrack {
   int m_num_intervals;
   float m_interval_durations[cSyncTrackMaxIntervals];
 
-  float ConvertAbsTimeToSyncTime (float abs_time) {
+  float CalcSyncFromAbsTime (float abs_time) {
     float sync_time = fmodf (abs_time, m_duration) / m_duration;
 
     int interval_index = 0;
-    while (sync_time < m_interval_durations[interval_index]) {
+    while (sync_time >= m_interval_durations[interval_index]) {
       sync_time -= m_interval_durations[interval_index];
       interval_index ++;
     }
+
+    return float(interval_index) + sync_time / m_interval_durations[interval_index];
+  }
+
+  float CalcRatioFromSyncTime (float sync_time) {
+    float interval_ratio = fmodf(sync_time, 1.0f);
+    int interval = int(sync_time - interval_ratio);
+
+    float result = 0.f;
+    int i = 0;
+    while (i < interval) {
+      result += m_interval_durations[i];
+      i++;
+    }
+
+    result += m_interval_durations[i] * interval_ratio;
+
+    return result;
   }
 
   static SyncTrack Blend(float weight, const SyncTrack& track_A, const SyncTrack& track_B) {

tests/SyncTrackTests.cc

@@ -9,15 +9,50 @@
 TEST_CASE("SyncTrackBlendSimple", "[SyncTrackBlend]") {
   SyncTrack track_A;
   track_A.m_num_intervals = 2;
-  track_A.m_duration = 1.0;
+  track_A.m_duration = 2.0;
-  track_A.m_interval_durations[0] = 0.8;
+  track_A.m_interval_durations[0] = 0.7;
-  track_A.m_interval_durations[1] = 0.2;
+  track_A.m_interval_durations[1] = 0.3;
 
   SyncTrack track_B;
   track_B.m_num_intervals = 2;
-  track_B.m_duration = 2.0;
+  track_B.m_duration = 1.5;
-  track_B.m_interval_durations[0] = 0.1;
+  track_B.m_interval_durations[0] = 0.6;
-  track_B.m_interval_durations[1] = 0.9;
+  track_B.m_interval_durations[1] = 0.4;
+
+  WHEN ("Calculating sync time of track_B at 0.5 duration") {
+    float sync_time_at_0_75 = track_B.CalcSyncFromAbsTime(0.5 * track_B.m_duration);
+    REQUIRE(sync_time_at_0_75 == Catch::Detail::Approx(0.83333));
+  }
+
+  WHEN ("Calculating sync time of track_B at 0.6 duration") {
+    float sync_time_at_0_6 = track_B.CalcSyncFromAbsTime(0.6 * track_B.m_duration);
+    REQUIRE(sync_time_at_0_6 == Catch::Detail::Approx(1.0));
+  }
+
+  WHEN ("Calculating sync time of track_B at 0.7 duration") {
+    float sync_time_at_0_7 = track_B.CalcSyncFromAbsTime(0.7 * track_B.m_duration);
+    REQUIRE(sync_time_at_0_7 == Catch::Detail::Approx(1.25));
+  }
+
+  WHEN ("Calculating sync time of track_B at 0.0 duration") {
+    float sync_time_at_1_0 = track_B.CalcSyncFromAbsTime(0.0 * track_B.m_duration);
+    REQUIRE(sync_time_at_1_0 == Catch::Detail::Approx(0.0));
+  }
+
+  WHEN ("Calculating sync time of track_B at 1.0 duration") {
+    float sync_time_at_1_0 = track_B.CalcSyncFromAbsTime(0.9999 * track_B.m_duration);
+    REQUIRE(sync_time_at_1_0 == Catch::Detail::Approx(2.0).epsilon(0.001f));
+  }
+
+  WHEN ("Calculating ratio from sync time on track_A at 0.83333") {
+    float ratio = track_A.CalcRatioFromSyncTime(0.83333333);
+    REQUIRE (ratio == Catch::Detail::Approx(0.5833333));
+  }
+
+  WHEN ("Calculating ratio from sync time on track_A at 0.83333") {
+    float ratio = track_A.CalcRatioFromSyncTime(1.25);
+    REQUIRE (ratio == Catch::Detail::Approx(0.775));
+  }
 
   WHEN("Blending two synctracks with weight 0.") {
     SyncTrack blended = SyncTrack::Blend(0.f, track_A, track_B);