Merge pull request #8934 from easternmotors/master

Exposing Transforms.rotationMatrixFromPositionVelocity

Author: mramato

CHANGES.md

@@ -5,6 +5,7 @@
 ##### Additions :tada:
 
 - Add a `toString` method to the `Resource` class in case an instance gets logged as a string. [#8722](https://github.com/CesiumGS/cesium/issues/8722)
+- Exposed `Transforms.rotationMatrixFromPositionVelocity` method from Cesium's private API. [#8927](https://github.com/CesiumGS/cesium/issues/8927)
 
 ##### Fixes :wrench:
 

CONTRIBUTORS.md

@@ -262,3 +262,4 @@ See [CONTRIBUTING.md](CONTRIBUTING.md) for details on how to contribute to Cesiu
 - [Edvinas Pranka](https://github.com/epranka)
 - [James Bromwell](https://github.com/thw0rted)
 - [Brandon Nguyen](https://github.com/bn-dignitas)
+- [John Remsberg](https://github.com/easternmotors)

Source/Core/Transforms.js

@@ -949,7 +949,13 @@ var rightScratch = new Cartesian3();
 var upScratch = new Cartesian3();
 
 /**
- * @private
+ * Transform a position and velocity to a rotation matrix.
+ *
+ * @param {Cartesian3} position The position to transform.
+ * @param {Cartesian3} velocity The velocity vector to transform.
+ * @param {Ellipsoid} [ellipsoid=Ellipsoid.WGS84] The ellipsoid whose fixed frame is used in the transformation.
+ * @param {Matrix3} [result] The object onto which to store the result.
+ * @returns {Matrix3} The modified result parameter or a new Matrix3 instance if none was provided.
  */
 Transforms.rotationMatrixFromPositionVelocity = function (
   position,

Specs/Core/TransformsSpec.js

@@ -1716,6 +1716,59 @@ describe("Core/Transforms", function () {
     expect(returnedResult).toEqualEpsilon(expected, CesiumMath.EPSILON12);
   });
 
+  it("rotationMatrixFromPositionVelocity works without a result parameter", function () {
+    var matrix = Transforms.rotationMatrixFromPositionVelocity(
+      Cartesian3.UNIT_X,
+      Cartesian3.UNIT_Y
+    );
+    var expected = new Matrix3(0, 0, 1, 1, 0, 0, 0, 1, 0);
+    expect(matrix).toEqualEpsilon(expected, CesiumMath.EPSILON14);
+
+    matrix = Transforms.rotationMatrixFromPositionVelocity(
+      Cartesian3.UNIT_X,
+      Cartesian3.UNIT_Z
+    );
+    expected = new Matrix3(0, 0, 1, 0, -1, 0, 1, 0, 0);
+    expect(matrix).toEqualEpsilon(expected, CesiumMath.EPSILON14);
+
+    matrix = Transforms.rotationMatrixFromPositionVelocity(
+      Cartesian3.UNIT_Y,
+      Cartesian3.UNIT_Z
+    );
+    expected = new Matrix3(0, 1, 0, 0, 0, 1, 1, 0, 0);
+    expect(matrix).toEqualEpsilon(expected, CesiumMath.EPSILON14);
+  });
+
+  it("rotationMatrixFromPositionVelocity works with a result parameter", function () {
+    var result = new Matrix3();
+    Transforms.rotationMatrixFromPositionVelocity(
+      Cartesian3.UNIT_X,
+      Cartesian3.UNIT_Y,
+      Ellipsoid.WGS84,
+      result
+    );
+    var expected = new Matrix3(0, 0, 1, 1, 0, 0, 0, 1, 0);
+    expect(result).toEqualEpsilon(expected, CesiumMath.EPSILON14);
+
+    Transforms.rotationMatrixFromPositionVelocity(
+      Cartesian3.UNIT_X,
+      Cartesian3.UNIT_Z,
+      Ellipsoid.WGS84,
+      result
+    );
+    expected = new Matrix3(0, 0, 1, 0, -1, 0, 1, 0, 0);
+    expect(result).toEqualEpsilon(expected, CesiumMath.EPSILON14);
+
+    Transforms.rotationMatrixFromPositionVelocity(
+      Cartesian3.UNIT_Y,
+      Cartesian3.UNIT_Z,
+      Ellipsoid.WGS84,
+      result
+    );
+    expected = new Matrix3(0, 1, 0, 0, 0, 1, 1, 0, 0);
+    expect(result).toEqualEpsilon(expected, CesiumMath.EPSILON14);
+  });
+
   it("basisTo2D projects translation", function () {
     var ellipsoid = Ellipsoid.WGS84;
     var projection = new GeographicProjection(ellipsoid);