Add a "time offset" option to the SpiceRotation and SpiceTranslation (#3544)

Lets SpiceTranslation and SpiceRotation compute the transformation with a given time offset compared to the simulation time (or fixed date if one is configured)

data/assets/examples/rotation/spicerotation/timeoffset.asset

@@ -0,0 +1,37 @@
+-- Time offset
+-- This asset creates a rotation provided by a SPICE kernel and applies it to a
+-- SceneGraphNode that only displays coordinate axes. The rotation of the coordinate axes
+-- are determined by SPICE, in this case pretending that the coordinate axes are rotating
+-- at the same rate as Earth. In this specific example, the orientation is offset 8h back
+-- compared to the actual in-game time in OpenSpace.
+
+-- Load the default SPICE kernels, which is the planetary constants and the DE430 kernel
+asset.require("spice/core")
+
+local Node = {
+  Identifier = "SpiceRotation_Example_TimeOffset",
+  Transform = {
+    Rotation = {
+      Type = "SpiceRotation",
+      SourceFrame = "IAU_EARTH",
+      DestinationFrame = "GALACTIC",
+      TimeOffset = -8 * 60 * 60
+    }
+  },
+  Renderable = {
+    Type = "RenderableCartesianAxes"
+  },
+  GUI = {
+    Name = "SpiceRotation - Time Offset",
+    Path = "/Examples"
+  }
+}
+
+asset.onInitialize(function()
+  openspace.addSceneGraphNode(Node)
+end)
+
+asset.onDeinitialize(function()
+  openspace.removeSceneGraphNode(Node)
+end)
+

data/assets/examples/translation/spicetranslation/timeoffset.asset

@@ -0,0 +1,37 @@
+-- Fixed Date
+-- This asset creates a time-varying translation with information from a SPICE kernel and
+-- applies it to a SceneGraphNode that only displays coordinate axes. The position of the
+-- coordinate axes are determined by SPICE, in this case pretending that the axes are
+-- orbiting the same way the Moon does around Earth. In this specific example, the position
+-- is offset 8h back compared to the actual in-game time in OpenSpace.
+-- For more information about SPICE see: https://naif.jpl.nasa.gov/naif/
+
+-- Load the default SPICE kernels, which are the planetary constants and the DE430 kernel
+asset.require("spice/core")
+
+local Node = {
+  Identifier = "SpiceTranslation_Example_TimeOffset",
+  Transform = {
+    Translation = {
+      Type = "SpiceTranslation",
+      Target = "MOON",
+      Observer = "EARTH",
+      TimeOffset = -8 * 60 * 60
+    }
+  },
+  Renderable = {
+    Type = "RenderableCartesianAxes"
+  },
+  GUI = {
+    Name = "SpiceTranslation - Time Offset",
+    Path = "/Examples"
+  }
+}
+
+asset.onInitialize(function()
+  openspace.addSceneGraphNode(Node)
+end)
+
+asset.onDeinitialize(function()
+  openspace.removeSceneGraphNode(Node)
+end)

modules/space/rotation/spicerotation.cpp

@@ -63,6 +63,14 @@ namespace {
         openspace::properties::Property::Visibility::AdvancedUser
     };
 
+    constexpr openspace::properties::Property::PropertyInfo TimeOffsetInfo = {
+        "TimeOffset",
+        "Time Offset",
+        "A time offset, in seconds, added to the simulation time (or Fixed Date if any), "
+        "at which to compute the rotation.",
+        openspace::properties::Property::Visibility::User
+    };
+
     struct [[codegen::Dictionary(SpiceRotation)]] Parameters {
         // [[codegen::verbatim(SourceInfo.description)]]
         std::string sourceFrame
@@ -80,6 +88,9 @@ namespace {
         // [[codegen::verbatim(FixedDateInfo.description)]]
         std::optional<std::string> fixedDate
             [[codegen::annotation("A time to lock the rotation to")]];
+
+        // [[codegen::verbatim(TimeOffsetInfo.description)]]
+        std::optional<float> timeOffset;
     };
 #include "spicerotation_codegen.cpp"
 } // namespace
@@ -94,6 +105,7 @@ SpiceRotation::SpiceRotation(const ghoul::Dictionary& dictionary)
     : _sourceFrame(SourceInfo)
     , _destinationFrame(DestinationInfo)
     , _fixedDate(FixedDateInfo)
+    , _timeOffset(TimeOffsetInfo)
 {
     const Parameters p = codegen::bake<Parameters>(dictionary);
 
@@ -111,6 +123,9 @@ SpiceRotation::SpiceRotation(const ghoul::Dictionary& dictionary)
     _fixedDate = p.fixedDate.value_or(_fixedDate);
     addProperty(_fixedDate);
 
+    _timeOffset = p.timeOffset.value_or(_timeOffset);
+    addProperty(_timeOffset);
+
     if (p.timeFrame.has_value()) {
         _timeFrame = TimeFrame::createFromDictionary(*p.timeFrame);
         addPropertySubOwner(_timeFrame.get());
@@ -127,14 +142,10 @@ glm::dmat3 SpiceRotation::matrix(const UpdateData& data) const {
     if (_timeFrame && !_timeFrame->isActive(data.time)) {
         return glm::dmat3(1.0);
     }
-    double time = data.time.j2000Seconds();
-    if (_fixedEphemerisTime.has_value()) {
-        time = *_fixedEphemerisTime;
-    }
     return SpiceManager::ref().positionTransformMatrix(
         _sourceFrame,
         _destinationFrame,
-        time
+        _fixedEphemerisTime.value_or(data.time.j2000Seconds()) + _timeOffset
     );
 }
 

modules/space/rotation/spicerotation.h

@@ -28,6 +28,7 @@
 #include <openspace/scene/rotation.h>
 
 #include <openspace/properties/stringproperty.h>
+#include <openspace/properties/scalar/floatproperty.h>
 #include <openspace/scene/timeframe.h>
 #include <optional>
 
@@ -48,6 +49,7 @@ private:
     properties::StringProperty _sourceFrame;
     properties::StringProperty _destinationFrame;
     properties::StringProperty _fixedDate;
+    properties::FloatProperty _timeOffset;
 
     ghoul::mm_unique_ptr<TimeFrame> _timeFrame;
     std::optional<double> _fixedEphemerisTime;

modules/space/translation/spicetranslation.cpp

@@ -77,6 +77,14 @@ namespace {
         openspace::properties::Property::Visibility::User
     };
 
+    constexpr openspace::properties::Property::PropertyInfo TimeOffsetInfo = {
+        "TimeOffset",
+        "Time Offset",
+        "A time offset, in seconds, added to the simulation time (or Fixed Date if any), "
+        "at which to compute the translation.",
+        openspace::properties::Property::Visibility::User
+    };
+
     struct [[codegen::Dictionary(SpiceTranslation)]] Parameters {
         // [[codegen::verbatim(TargetInfo.description)]]
         std::variant<std::string, int> target;
@@ -89,6 +97,9 @@ namespace {
 
         // [[codegen::verbatim(FixedDateInfo.description)]]
         std::optional<std::string> fixedDate;
+
+        // [[codegen::verbatim(TimeOffsetInfo.description)]]
+        std::optional<float> timeOffset;
     };
 #include "spicetranslation_codegen.cpp"
 } // namespace
@@ -104,6 +115,7 @@ SpiceTranslation::SpiceTranslation(const ghoul::Dictionary& dictionary)
     , _observer(ObserverInfo)
     , _frame(FrameInfo, "GALACTIC")
     , _fixedDate(FixedDateInfo)
+    , _timeOffset(TimeOffsetInfo)
     , _cachedFrame("GALACTIC")
 {
     const Parameters p = codegen::bake<Parameters>(dictionary);
@@ -140,6 +152,9 @@ SpiceTranslation::SpiceTranslation(const ghoul::Dictionary& dictionary)
     _fixedDate = p.fixedDate.value_or(_fixedDate);
     addProperty(_fixedDate);
 
+    _timeOffset = p.timeOffset.value_or(_timeOffset);
+    addProperty(_timeOffset);
+
     if (std::holds_alternative<std::string>(p.target)) {
         _target = std::get<std::string>(p.target);
     }
@@ -166,7 +181,7 @@ glm::dvec3 SpiceTranslation::position(const UpdateData& data) const {
         _cachedObserver,
         _cachedFrame,
         {},
-        _fixedEphemerisTime.value_or(data.time.j2000Seconds()),
+        _fixedEphemerisTime.value_or(data.time.j2000Seconds()) + _timeOffset,
         lightTime
     ) * 1000.0;
 }

modules/space/translation/spicetranslation.h

@@ -28,6 +28,7 @@
 #include <openspace/scene/translation.h>
 
 #include <openspace/properties/stringproperty.h>
+#include <openspace/properties/scalar/floatproperty.h>
 #include <optional>
 
 namespace openspace {
@@ -45,6 +46,7 @@ private:
     properties::StringProperty _observer;
     properties::StringProperty _frame;
     properties::StringProperty _fixedDate;
+    properties::FloatProperty _timeOffset;
 
     // We are accessing these values every frame and when retrieving a string from the
     // StringProperty, it allocates some new memory, which we want to prevent. Until the