Merge pull request #8786 from CesiumGS/stepped-animation

Add glTF animation STEP interpolation
CesiumGS · Apr 23, 2020 · 3f6bd3e · 3f6bd3e
2 parents 4ca9e1b + 90ca49f
commit 3f6bd3e
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diff --git a/CHANGES.md b/CHANGES.md
@@ -26,6 +26,7 @@
 
 - Added basic underground rendering support. When the camera is underground the globe will be rendered as a solid surface and underground entities will not be culled. [#8572](https://github.com/AnalyticalGraphicsInc/cesium/pull/8572)
 - The `CesiumUnminified` build now includes sourcemaps. [#8572](https://github.com/CesiumGS/cesium/pull/8659)
+- Added glTF `STEP` animation interpolation. [#8786](https://github.com/CesiumGS/cesium/pull/8786)
 - Added the ability to edit CesiumJS shaders on-the-fly using the [SpectorJS](https://spector.babylonjs.com/) Shader Editor. [#8608](https://github.com/CesiumGS/cesium/pull/8608)
 
 ##### Fixes :wrench:

diff --git a/Source/Scene/ModelAnimationCache.js b/Source/Scene/ModelAnimationCache.js
@@ -6,6 +6,7 @@ import LinearSpline from "../Core/LinearSpline.js";
 import Matrix4 from "../Core/Matrix4.js";
 import Quaternion from "../Core/Quaternion.js";
 import QuaternionSpline from "../Core/QuaternionSpline.js";
+import Spline from "../Core/Spline.js";
 import WebGLConstants from "../Core/WebGLConstants.js";
 import WeightSpline from "../Core/WeightSpline.js";
 import getAccessorByteStride from "../ThirdParty/GltfPipeline/getAccessorByteStride.js";
@@ -107,6 +108,34 @@ ConstantSpline.prototype.clampTime = function (time) {
   return 0.0;
 };
 
+function SteppedSpline(backingSpline) {
+  this._spline = backingSpline;
+  this._lastTimeIndex = 0;
+}
+SteppedSpline.prototype.findTimeInterval = Spline.prototype.findTimeInterval;
+SteppedSpline.prototype.evaluate = function (time, result) {
+  var i = (this._lastTimeIndex = this.findTimeInterval(
+    time,
+    this._lastTimeIndex
+  ));
+  var times = this._spline.times;
+  var steppedTime = time >= times[i + 1] ? times[i + 1] : times[i];
+  return this._spline.evaluate(steppedTime, result);
+};
+Object.defineProperties(SteppedSpline.prototype, {
+  times: {
+    get: function () {
+      return this._spline.times;
+    },
+  },
+});
+SteppedSpline.prototype.wrapTime = function (time) {
+  return this._spline.wrapTime(time);
+};
+SteppedSpline.prototype.clampTime = function (time) {
+  return this._spline.clampTime(time);
+};
+
 ModelAnimationCache.getAnimationSpline = function (
   model,
   animationName,
@@ -126,7 +155,10 @@ ModelAnimationCache.getAnimationSpline = function (
 
     if (times.length === 1 && controlPoints.length === 1) {
       spline = new ConstantSpline(controlPoints[0]);
-    } else if (sampler.interpolation === "LINEAR") {
+    } else if (
+      sampler.interpolation === "LINEAR" ||
+      sampler.interpolation === "STEP"
+    ) {
       if (path === "translation" || path === "scale") {
         spline = new LinearSpline({
           times: times,
@@ -143,6 +175,10 @@ ModelAnimationCache.getAnimationSpline = function (
           weights: controlPoints,
         });
       }
+
+      if (defined(spline) && sampler.interpolation === "STEP") {
+        spline = new SteppedSpline(spline);
+      }
     }
 
     if (defined(model.cacheKey)) {

diff --git a/Specs/Data/Models/InterpolationTest/InterpolationTest.glb b/Specs/Data/Models/InterpolationTest/InterpolationTest.glb
diff --git a/Specs/Scene/ModelSpec.js b/Specs/Scene/ModelSpec.js
@@ -111,6 +111,8 @@ describe(
     var riggedSimpleQuantizedUrl =
       "./Data/Models/WEB3DQuantizedAttributes/RiggedSimple-Quantized.gltf";
     var CesiumManUrl = "./Data/Models/MaterialsCommon/Cesium_Man.gltf";
+    var interpolationTestUrl =
+      "./Data/Models/InterpolationTest/InterpolationTest.glb";
 
     var boomBoxUrl = "./Data/Models/PBR/BoomBox/BoomBox.gltf";
     var boomBoxPbrSpecularGlossinessUrl =
@@ -2232,6 +2234,106 @@ describe(
       });
     });
 
+    it("animates with STEP interpolation", function () {
+      return loadModel(interpolationTestUrl).then(function (model) {
+        var time = JulianDate.fromDate(
+          new Date("January 1, 2014 12:00:00 UTC")
+        );
+
+        model.show = true;
+        var animations = model.activeAnimations;
+        var a = animations.add({
+          name: "Step Translation",
+          startTime: time,
+        });
+
+        var animatedNode = model.getNode("Cube.006");
+
+        scene.renderForSpecs(time);
+        expect(animatedNode.matrix[13]).toEqualEpsilon(
+          6.665,
+          CesiumMath.EPSILON3
+        );
+
+        scene.renderForSpecs(
+          JulianDate.addSeconds(time, 0.5, new JulianDate())
+        );
+        expect(animatedNode.matrix[13]).toEqualEpsilon(
+          10.0,
+          CesiumMath.EPSILON14
+        );
+
+        scene.renderForSpecs(
+          JulianDate.addSeconds(time, 1.0, new JulianDate())
+        );
+        expect(animatedNode.matrix[13]).toEqualEpsilon(
+          6.0,
+          CesiumMath.EPSILON14
+        );
+
+        scene.renderForSpecs(
+          JulianDate.addSeconds(time, 2.0, new JulianDate())
+        );
+        expect(animatedNode.matrix[13]).toEqualEpsilon(
+          6.0,
+          CesiumMath.EPSILON14
+        );
+
+        expect(animations.remove(a)).toEqual(true);
+        primitives.remove(model);
+      });
+    });
+
+    it("animates with LINEAR interpolation", function () {
+      return loadModel(interpolationTestUrl).then(function (model) {
+        var time = JulianDate.fromDate(
+          new Date("January 1, 2014 12:00:00 UTC")
+        );
+
+        model.show = true;
+        var animations = model.activeAnimations;
+        var a = animations.add({
+          name: "Linear Translation",
+          startTime: time,
+        });
+
+        var animatedNode = model.getNode("Cube.009");
+
+        scene.renderForSpecs(time);
+        expect(animatedNode.matrix[13]).toEqualEpsilon(
+          6.621,
+          CesiumMath.EPSILON3
+        );
+
+        scene.renderForSpecs(
+          JulianDate.addSeconds(time, 0.5, new JulianDate())
+        );
+        expect(animatedNode.matrix[13]).toEqualEpsilon(
+          9.2,
+          CesiumMath.EPSILON3
+        );
+
+        scene.renderForSpecs(
+          JulianDate.addSeconds(time, 1.0, new JulianDate())
+        );
+        expect(animatedNode.matrix[13]).toEqualEpsilon(
+          7.6,
+          CesiumMath.EPSILON3
+        );
+
+        scene.renderForSpecs(
+          JulianDate.addSeconds(time, 2.0, new JulianDate())
+        );
+        expect(animatedNode.matrix[13]).toEqualEpsilon(
+          6.0,
+          CesiumMath.EPSILON14
+        );
+
+        expect(animations.remove(a)).toEqual(true);
+        primitives.remove(model);
+      });
+    });
+
     ///////////////////////////////////////////////////////////////////////////
 
     it("renders riggedFigure without animation", function () {