Removing quadrilateral interpolation

CHANGES.md

@@ -25,6 +25,7 @@ Change Log
    * Only one node is supported.
    * Only one mesh per node is supported.
    * Only one primitive per mesh is supported.
+* Fixed a glTF animation bug that caused certain animations to jitter. [#5740](https://github.com/AnalyticalGraphicsInc/cesium/pull/5740)
 * Updated documentation links to reflect new locations on cesiumjs.org and cesium.com. 
 
 ### 1.41 - 2018-01-02

Source/Core/QuaternionSpline.js

@@ -14,43 +14,11 @@ define([
         Spline) {
     'use strict';
 
-    function computeInnerQuadrangles(points, firstInnerQuadrangle, lastInnerQuadrangle) {
-        var length = points.length;
-        var quads = new Array(length);
-
-        quads[0] = defined(firstInnerQuadrangle) ? firstInnerQuadrangle : points[0];
-        quads[length - 1] = defined(lastInnerQuadrangle) ? lastInnerQuadrangle : points[length - 1];
-
-        for (var i = 1; i < length - 1; ++i) {
-            quads[i] = Quaternion.computeInnerQuadrangle(points[i - 1], points[i], points[i + 1], new Quaternion());
-        }
-
-        return quads;
-    }
-
     function createEvaluateFunction(spline) {
         var points = spline.points;
-        var quads = spline.innerQuadrangles;
         var times = spline.times;
 
-        // use slerp interpolation for 2 points
-        if (points.length < 3) {
-            var t0 = times[0];
-            var invSpan = 1.0 / (times[1] - t0);
-
-            var q0 = points[0];
-            var q1 = points[1];
-
-            return function(time, result) {
-                if (!defined(result)){
-                    result = new Quaternion();
-                }
-                var u = (time - t0) * invSpan;
-                return Quaternion.fastSlerp(q0, q1, u, result);
-            };
-        }
-
-        // use quad interpolation for more than 3 points
+        // use slerp interpolation
         return function(time, result) {
             if (!defined(result)){
                 result = new Quaternion();
@@ -60,15 +28,13 @@ define([
 
             var q0 = points[i];
             var q1 = points[i + 1];
-            var s0 = quads[i];
-            var s1 = quads[i + 1];
 
-            return Quaternion.fastSquad(q0, q1, s0, s1, u, result);
+            return Quaternion.fastSlerp(q0, q1, u, result);
         };
     }
 
     /**
-     * A spline that uses spherical quadrangle (squad) interpolation to create a quaternion curve.
+     * A spline that uses spherical linear (slerp) interpolation to create a quaternion curve.
      * The generated curve is in the class C<sup>1</sup>.
      *
      * @alias QuaternionSpline
@@ -78,10 +44,6 @@ define([
      * @param {Number[]} options.times An array of strictly increasing, unit-less, floating-point times at each point.
      *                The values are in no way connected to the clock time. They are the parameterization for the curve.
      * @param {Quaternion[]} options.points The array of {@link Quaternion} control points.
-     * @param {Quaternion} [options.firstInnerQuadrangle] The inner quadrangle of the curve at the first control point.
-     *                     If the inner quadrangle is not given, it will be estimated.
-     * @param {Quaternion} [options.lastInnerQuadrangle] The inner quadrangle of the curve at the last control point.
-     *                     If the inner quadrangle is not given, it will be estimated.
      *
      * @exception {DeveloperError} points.length must be greater than or equal to 2.
      * @exception {DeveloperError} times.length must be equal to points.length.
@@ -96,8 +58,6 @@ define([
 
         var points = options.points;
         var times = options.times;
-        var firstInnerQuadrangle = options.firstInnerQuadrangle;
-        var lastInnerQuadrangle = options.lastInnerQuadrangle;
 
         //>>includeStart('debug', pragmas.debug);
         if (!defined(points) || !defined(times)) {
@@ -111,11 +71,8 @@ define([
         }
         //>>includeEnd('debug');
 
-        var innerQuadrangles = computeInnerQuadrangles(points, firstInnerQuadrangle, lastInnerQuadrangle);
-
         this._times = times;
         this._points = points;
-        this._innerQuadrangles = innerQuadrangles;
 
         this._evaluateFunction = createEvaluateFunction(this);
         this._lastTimeIndex = 0;
@@ -148,20 +105,6 @@ define([
             get : function() {
                 return this._points;
             }
-        },
-
-        /**
-         * An array of {@link Quaternion} inner quadrangles for the control points.
-         *
-         * @memberof QuaternionSpline.prototype
-         *
-         * @type {Quaternion[]}
-         * @readonly
-         */
-        innerQuadrangles : {
-            get : function() {
-                return this._innerQuadrangles;
-            }
         }
     });
 

Specs/Core/QuaternionSplineSpec.js

@@ -79,9 +79,8 @@ defineSuite([
         var time = (times[2] + times[1]) * 0.5;
         var t = (time - times[1]) / (times[2] - times[1]);
 
-        var quads = qs.innerQuadrangles;
         var actual = qs.evaluate(time);
-        var expected = Quaternion.squad(points[1], points[2], quads[1], quads[2], t, new Quaternion());
+        var expected = Quaternion.slerp(points[1], points[2], t, new Quaternion());
         expect(actual).toEqualEpsilon(expected, CesiumMath.EPSILON6);
     });