Moon lighting

CesiumGS · May 22, 2024 · 39485e0 · 39485e0
1 parent 65a1951
commit 39485e0
Show file tree

Hide file tree

Showing 4 changed files with 100 additions and 23 deletions.
diff --git a/Apps/Sandcastle/gallery/Moon.html b/Apps/Sandcastle/gallery/Moon.html
@@ -37,13 +37,10 @@
         Cesium.Ion.defaultAccessToken =
           "eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJqdGkiOiJhZDUyNTc2YS1hMmQyLTQ2NGUtYmE2Ny01ZmQ5MmRmNGEyOGQiLCJpZCI6MTQsInNjb3BlcyI6WyJhc3IiLCJnYyJdLCJpYXQiOjE1ODgxODAxNDB9.q3KJVaTTtaMs404afZYo2RQSbYglE09Xfrm7BkZP694";
 
+        Cesium.Ellipsoid.default = Cesium.Ellipsoid.MOON;
         const moonOptions = {
-          ellipsoid: Cesium.Ellipsoid.MOON,
           terrainProvider: await Cesium.CesiumTerrainProvider.fromIonAssetId(
-            1238,
-            {
-              ellipsoid: Cesium.Ellipsoid.MOON,
-            }
+            1238
           ),
           baseLayer: Cesium.ImageryLayer.fromProviderAsync(
             Cesium.IonImageryProvider.fromAssetId(1208)
@@ -53,12 +50,17 @@
         const viewer = new Cesium.Viewer("cesiumContainer", {
           ...moonOptions,
           useBrowserRecommendedResolution: false,
-          timeline: false,
-          animation: false,
+          //timeline: false,
+          //animation: false,
           baseLayerPicker: false,
           geocoder: false,
         });
-        viewer.scene.msaaSamples = 4;
+        viewer.clock.multiplier = 3 * 60 * 60 * 24;
+        viewer.clock.shouldAnimate = true;
+
+        const scene = viewer.scene;
+        scene.msaaSamples = 4;
+        scene.globe.enableLighting = true;
 
         // Positions courtesy of https://www.sciencedirect.com/science/article/abs/pii/S0019103516301518?via%3Dihub
         const pointsOfInterest = [

diff --git a/packages/engine/Source/Core/Simon1994PlanetaryPositions.js b/packages/engine/Source/Core/Simon1994PlanetaryPositions.js
@@ -627,6 +627,7 @@ const axesTransformation = new Matrix3(
   0.9174820620691819
 );
 let translation = new Cartesian3();
+
 /**
  * Computes the position of the Sun in the Earth-centered inertial frame
  *
@@ -662,7 +663,7 @@ Simon1994PlanetaryPositions.computeSunPositionInEarthInertialFrame = function (
 /**
  * Computes the position of the Moon in the Earth-centered inertial frame
  *
- * @param {JulianDate} [julianDate] The time at which to compute the Sun's position, if not provided the current system time is used.
+ * @param {JulianDate} [julianDate] The time at which to compute the Moon's position, if not provided the current system time is used.
  * @param {Cartesian3} [result] The object onto which to store the result.
  * @returns {Cartesian3} Calculated moon position
  */
@@ -681,11 +682,11 @@ Simon1994PlanetaryPositions.computeMoonPositionInEarthInertialFrame = function (
 };
 
 /**
- * Computes the position of the Sun in the Moon-centered inertial frame
+ * Computes the position of the Sun in the Moon-centered fixed frame
  *
  * @param {JulianDate} [julianDate] The time at which to compute the Sun's position, if not provided the current system time is used.
  * @param {Cartesian3} [result] The object onto which to store the result.
- * @returns {Cartesian3} Calculated sun position
+ * @returns {Cartesian3} Calculated Sun position
  */
 Simon1994PlanetaryPositions.computeSunPositionInMoonInertialFrame = function (
   julianDate,
@@ -707,7 +708,8 @@ Simon1994PlanetaryPositions.computeSunPositionInMoonInertialFrame = function (
   computeSimonMoon(julianDate, translation);
 
   Cartesian3.subtract(result, translation, result);
-  Matrix3.multiplyByVector(axesTransformation, result, result);
+
+  //Matrix3.multiplyByVector(rotation, result, result); TODO: ?
 
   return result;
 };

diff --git a/packages/engine/Source/Core/Transforms.js b/packages/engine/Source/Core/Transforms.js
@@ -726,6 +726,77 @@ Transforms.computeIcrfToFixedMatrix = function (date, result) {
   return Matrix3.transpose(fixedToIcrfMtx, result);
 };
 
+const TdtMinusTai = 32.184;
+const J2000d = 2451545;
+const scratchHpr = new HeadingPitchRoll();
+const scratchRotationMatrix = new Matrix3();
+const dateScratch = new JulianDate();
+Transforms.computeMoonFixedToIcrfMatrix = function (date, result) {
+  //>>includeStart('debug', pragmas.debug);
+  if (!defined(date)) {
+    throw new DeveloperError("date is required.");
+  }
+  //>>includeEnd('debug');
+
+  if (!defined(result)) {
+    result = new Matrix3();
+  }
+
+  // Converts TAI to TT
+  const secondsTT = JulianDate.addSeconds(date, TdtMinusTai, dateScratch);
+
+  // Converts TT to TDB, interval in days since the standard epoch
+  const d = JulianDate.totalDays(secondsTT) - J2000d;
+
+  // Compute the approximate rotation, using https://articles.adsabs.harvard.edu//full/1980CeMec..22..205D/0000209.000.html
+  const e1 = CesiumMath.toRadians(12.112) - CesiumMath.toRadians(0.052992) * d;
+  const e2 = CesiumMath.toRadians(24.224) - CesiumMath.toRadians(0.105984) * d;
+  const e3 = CesiumMath.toRadians(227.645) + CesiumMath.toRadians(13.012) * d;
+  const e4 =
+    CesiumMath.toRadians(261.105) + CesiumMath.toRadians(13.340716) * d;
+  const e5 = CesiumMath.toRadians(358.0) + CesiumMath.toRadians(0.9856) * d;
+
+  scratchHpr.heading =
+    CesiumMath.toRadians(270.0) -
+    CesiumMath.toRadians(3.878) * Math.sin(e1) -
+    CesiumMath.toRadians(0.12) * Math.sin(e2) +
+    CesiumMath.toRadians(0.07) * Math.sin(e3) -
+    CesiumMath.toRadians(0.017) * Math.sin(e4);
+  scratchHpr.pitch =
+    CesiumMath.toRadians(66.534) +
+    CesiumMath.toRadians(1.543) * Math.cos(e1) +
+    CesiumMath.toRadians(0.24) * Math.cos(e2) -
+    CesiumMath.toRadians(0.028) * Math.cos(e3) +
+    CesiumMath.toRadians(0.007) * Math.cos(e4);
+  scratchHpr.roll =
+    CesiumMath.toRadians(244.375) +
+    CesiumMath.toRadians(13.17635831) * d +
+    CesiumMath.toRadians(3.558) * Math.sin(e1) +
+    CesiumMath.toRadians(0.121) * Math.sin(e2) -
+    CesiumMath.toRadians(0.064) * Math.sin(e3) +
+    CesiumMath.toRadians(0.016) * Math.sin(e4) +
+    CesiumMath.toRadians(0.025) * Math.sin(e5);
+  return Matrix3.fromHeadingPitchRoll(scratchHpr, scratchRotationMatrix);
+};
+
+Transforms.computeIcrfToMoonFixedMatrix = function (date, result) {
+  //>>includeStart('debug', pragmas.debug);
+  if (!defined(date)) {
+    throw new DeveloperError("date is required.");
+  }
+  //>>includeEnd('debug');
+  if (!defined(result)) {
+    result = new Matrix3();
+  }
+
+  const fixedToIcrfMtx = Transforms.computeMoonFixedToIcrfMatrix(date, result);
+  if (!defined(fixedToIcrfMtx)) {
+    return undefined;
+  }
+
+  return Matrix3.transpose(fixedToIcrfMtx, result);
+};
+
 const xysScratch = new Iau2006XysSample(0.0, 0.0, 0.0);
 const eopScratch = new EarthOrientationParametersSample(
   0.0,

diff --git a/packages/engine/Source/Renderer/UniformState.js b/packages/engine/Source/Renderer/UniformState.js
@@ -1305,19 +1305,21 @@ function setCamera(uniformState, camera) {
   );
 }
 
-let transformMatrix = new Matrix3();
+const transformMatrix = new Matrix3();
 const sunCartographicScratch = new Cartographic();
 function setSunAndMoonDirections(uniformState, frameState) {
-  if (
-    !defined(
-      Transforms.computeIcrfToFixedMatrix(frameState.time, transformMatrix)
-    )
-  ) {
-    transformMatrix = Transforms.computeTemeToPseudoFixedMatrix(
-      frameState.time,
-      transformMatrix
-    );
-  }
+  // if (
+  //   !defined(
+  //     Transforms.computeIcrfToFixedMatrix(frameState.time, transformMatrix)
+  //   )
+  // ) {
+  //   transformMatrix = Transforms.computeTemeToPseudoFixedMatrix(
+  //     frameState.time,
+  //     transformMatrix
+  //   );
+  // }
+
+  Transforms.computeIcrfToMoonFixedMatrix(frameState.time, transformMatrix);
 
   let position = Simon1994PlanetaryPositions.computeSunPositionInMoonInertialFrame(
     frameState.time,