Supporting the 'step' button in the editor (#294)

* Supporting the 'step' button in the editor.

* Update CHANGELOG.md

* Adding informational log message when frame step is used.

com.unity.perception/CHANGELOG.md

 ### Known Issues
 
 ### Added
+Added support for 'step' button in editor.
 
 ### Changed
 Increased color variety in instance segmentation images
 ### Removed
 
 ### Fixed
+Fixed keypoint labeling bug when visualizations are disabled.
 
 Fixed an issue where Simulation Delta Time values larger than 100 seconds (in Perception Camera) would cause incorrect capture scheduling behavior.
 

com.unity.perception/Runtime/GroundTruth/PerceptionCamera.cs

             // Ignore the subsequent calls.
             if (lastFrameCalledThisCallback == Time.frameCount)
                 return false;
-#if UNITY_EDITOR
-            if (UnityEditor.EditorApplication.isPaused)
-                return false;
-#endif
+
             return true;
         }
 

com.unity.perception/Runtime/GroundTruth/SimulationState.cs

             {
                 var sensorData = m_Sensors[activeSensor];
 
+#if UNITY_EDITOR
+                if (UnityEditor.EditorApplication.isPaused)
+                {
+                    //When the user clicks the 'step' button in the editor, frames will always progress at .02 seconds per step.
+                    //In this case, just run all sensors each frame to allow for debugging
+                    Debug.Log($"Frame step forced all sensors to synchronize, changing frame timings.");
+
+                    sensorData.sequenceTimeOfNextRender = UnscaledSequenceTime;
+                    sensorData.sequenceTimeOfNextCapture = UnscaledSequenceTime;
+                }
+#endif
+
                 if (Mathf.Abs(sensorData.sequenceTimeOfNextRender - UnscaledSequenceTime) < k_SimulationTimingAccuracy)
                 {
                     //means this frame fulfills this sensor's simulation time requirements, we can move target to next frame.
                         sensorData.sequenceTimeOfNextCapture += sensorData.renderingDeltaTime * (sensorData.framesBetweenCaptures + 1);
                         Debug.Assert(sensorData.sequenceTimeOfNextCapture > UnscaledSequenceTime,
                             $"Next scheduled capture should be after {UnscaledSequenceTime} but is {sensorData.sequenceTimeOfNextCapture}");
+                        while (sensorData.sequenceTimeOfNextCapture <= UnscaledSequenceTime)
+                            sensorData.sequenceTimeOfNextCapture += sensorData.renderingDeltaTime * (sensorData.framesBetweenCaptures + 1);
                     }
                     else if (sensorData.captureTriggerMode.Equals(CaptureTriggerMode.Manual))
                     {

com.unity.perception/Tests/Editor/DatasetCaptureEditorTests.cs

 using System.Collections;
 using System.IO;
 using NUnit.Framework;
+using UnityEditor;
 using UnityEngine;
 using UnityEngine.Perception.GroundTruth;
 using UnityEngine.TestTools;
             expectedDatasetPath = DatasetCapture.OutputDirectory;
             yield return new ExitPlayMode();
             FileAssert.Exists(Path.Combine(expectedDatasetPath, "sensors.json"));
+        }
+        [UnityTest]
+        public IEnumerator StepFunction_OverridesSimulationDeltaTime_AndRunsSensors()
+        {
+            yield return new EnterPlayMode();
+            DatasetCapture.ResetSimulation();
+            var ego = DatasetCapture.RegisterEgo("ego");
+            var sensor = DatasetCapture.RegisterSensor(ego, "camera", "", 0, CaptureTriggerMode.Scheduled, 2f, 0);
+            yield return null;
+            var timeBeforeStep = Time.time;
+            EditorApplication.isPaused = true;
+            EditorApplication.Step();
+            Assert.True(Time.time - timeBeforeStep < .3f);
+            Assert.True(sensor.ShouldCaptureThisFrame);
+            yield return new ExitPlayMode();
         }
     }
 }