fix: interpolator in cpp runtime (#10752) 01c1b43af9

* fix: interpolator in cpp runtime

Co-authored-by: hernan <hernan@rive.app>

.rive_head

@@ -1 +1 @@
-a3f6433c00cac824852ba6eb383ce8a8d53fcf3c
+01c1b43af9ac51debb54e99a326405460b873fda

src/data_bind/converters/data_converter_interpolator.cpp

@@ -70,6 +70,7 @@ void InterpolatorAdvancer::advanceAnimationData(float elapsedTime)
         }
         return;
     }
+    animationData->elapsedSeconds += elapsedTime;
     float f =
         std::fmin(1.0f,
                   m_converter->duration() > 0
@@ -80,21 +81,23 @@ void InterpolatorAdvancer::advanceAnimationData(float elapsedTime)
         f = m_converter->interpolator()->transform(f);
     }
     animationData->interpolate(f, m_currentValue);
-
-    animationData->elapsedSeconds += elapsedTime;
 }
 
 bool InterpolatorAdvancer::advance(float elapsedTime)
 {
     auto animationData = currentAnimationData();
-    if (animationData->to->compare(m_currentValue))
+    if (animationData->to->compare(m_currentValue) || elapsedTime == 0)
     {
         return false;
     }
+    auto prevTime = animationData->elapsedSeconds;
     advanceAnimationData(elapsedTime);
-    if (animationData->elapsedSeconds < m_converter->duration())
+    if (prevTime < m_converter->duration())
     {
         m_converter->markConverterDirty();
+    }
+    if (animationData->elapsedSeconds < m_converter->duration())
+    {
         return true;
     }
     return false;
@@ -142,10 +145,6 @@ bool DataConverterInterpolator::advance(float elapsedTime)
     {
         return false;
     }
-    if (elapsedTime == 0)
-    {
-        return false;
-    }
     // Advance can be called multiple times in a single frame.
     // We want to make sure that two advances with time > 0 have elapsed before
     // considering the state as second frame.

tests/unit_tests/runtime/serialized_rendering_test.cpp

@@ -883,7 +883,7 @@ TEST_CASE("Reset randomization only once", "[silver]")
         artboard->draw(renderer.get());
     }
 
-    // Random generation hasn't been called again
+    // Random generation has been called again
     REQUIRE(RandomProvider::totalCalls() == 1);
     RandomProvider::clearRandoms();
     CHECK(silver.matches("formula_random-once"));
@@ -920,7 +920,6 @@ TEST_CASE("Reset randomization on every change", "[silver]")
 
     silver.addFrame();
 
-    RandomProvider::addRandomValue(1.0f);
     numProp->propertyValue(500);
     stateMachine->advanceAndApply(0.1f);
     artboard->draw(renderer.get());
@@ -1048,4 +1047,44 @@ TEST_CASE("interactive and non interactive scrolling", "[silver]")
     artboard->draw(renderer.get());
 
     CHECK(silver.matches("interactive_scrolling"));
+}
+
+TEST_CASE("Interpolator returns advance status as true until it settles",
+          "[silver]")
+{
+    SerializingFactory silver;
+    auto file = ReadRiveFile("assets/interpolate_to_end.riv", &silver);
+
+    auto artboard = file->artboardNamed("child");
+
+    silver.frameSize(artboard->width(), artboard->height());
+
+    REQUIRE(artboard != nullptr);
+    auto stateMachine = artboard->stateMachineAt(0);
+    int viewModelId = artboard.get()->viewModelId();
+
+    auto vmi = viewModelId == -1
+                   ? file->createViewModelInstance(artboard.get())
+                   : file->createViewModelInstance(viewModelId, 0);
+
+    auto numProp = vmi->propertyValue("num")->as<ViewModelInstanceNumber>();
+
+    stateMachine->bindViewModelInstance(vmi);
+    stateMachine->advanceAndApply(0.1f);
+
+    auto renderer = silver.makeRenderer();
+    artboard->draw(renderer.get());
+
+    numProp->propertyValue(1000);
+    stateMachine->advanceAndApply(0.001f);
+
+    auto shouldAdvance = true;
+    while (shouldAdvance)
+    {
+        silver.addFrame();
+        shouldAdvance = stateMachine->advanceAndApply(0.25f);
+        artboard->draw(renderer.get());
+    }
+
+    CHECK(silver.matches("interpolate_to_end"));
 }