initial work on smoothDamp

schteppe · schteppe · commit 6d88961b090d · 2016-06-22T15:12:18.000+02:00
diff --git a/src/goo/math/MathUtils.js b/src/goo/math/MathUtils.js
@@ -409,4 +409,44 @@ MathUtils.warnNaN = function (object, property) {
 	});
 };
 
+/**
+ * Gradually changes a value towards a desired goal over time. The value is smoothed by some spring-damper like function, which will never overshoot. The function can be used to smooth any kind of value, positions, colors, scalars.
+ * @param {number} current The current position.
+ * @param {number} target The position we are trying to reach.
+ * @param {Vector2} store An object to store the current position and velocity in.
+ * @param {number} deltaTime The time since the last call to this function.
+ * @param {number} [smoothTime=0.3] Approximately the time it will take to reach the target. A smaller value will reach the target faster.
+ * @param {number} [maxSpeed=1e7] Optionally allows you to clamp the maximum speed.
+ */
+MathUtils.smoothDamp = function (current, target, store, deltaTime, smoothTime, maxSpeed) {
+	if (smoothTime === undefined) {
+		smoothTime = 0.3;
+	}
+	if (maxSpeed === undefined) {
+		maxSpeed = 1e7;
+	}
+
+	smoothTime = Math.max(0.0001, smoothTime);
+	var num = 2 / smoothTime;
+	var num2 = num * deltaTime;
+	var num3 = 1 / (1 + num2 + 0.48 * num2 * num2 + 0.235 * num2 * num2 * num2);
+	var num4 = current - target;
+	var num5 = target;
+	var num6 = maxSpeed * smoothTime;
+	num4 = Math.max(-num6, Math.min(num6, num4));
+	target = current - num4;
+	var currentVelocity = store.y;
+	var num7 = (currentVelocity + num * num4) * deltaTime;
+	currentVelocity = (currentVelocity - num * num7) * num3;
+	var num8 = target + (num4 + num7) * num3;
+	if (num5 - current > 0 === num8 > num5){
+		num8 = num5;
+		currentVelocity = (num8 - num5) / deltaTime;
+	}
+	store.x = num8;
+	store.y = currentVelocity;
+
+	return num8;
+};
+
 module.exports = MathUtils;
diff --git a/src/goo/math/Vector2.js b/src/goo/math/Vector2.js
@@ -765,6 +765,27 @@ Vector2.prototype.subVector = ObjectUtils.warnOnce('Vector2.prototype.subVector
 	return this;
 });
 
+/**
+ * Gradually changes the vector value value towards a desired goal over time. See MathUtils.smoothDamp.
+ * @param {Vector2} target The position we are trying to reach.
+ * @param {Vector2} currentVelocity An object to store the current position and velocity in.
+ * @param {number} deltaTime The time since the last call to this function.
+ * @param {number} [smoothTime=0.3] Approximately the time it will take to reach the target. A smaller value will reach the target faster.
+ * @param {number} [maxSpeed=1e7] Optionally allows you to clamp the maximum speed.
+ */
+Vector2.prototype.smoothDamp = (function () {
+	var tempVec2 = new Vector2();
+	return function (target, currentVelocity, deltaTime, smoothTime, maxSpeed) {
+		tempVec2.y = currentVelocity.x;
+		this.x = MathUtils.smoothDamp(this.x, target.x, tempVec2, deltaTime, smoothTime, maxSpeed);
+		currentVelocity.x = tempVec2.y;
+
+		tempVec2.y = currentVelocity.y;
+		this.y = MathUtils.smoothDamp(this.y, target.y, tempVec2, deltaTime, smoothTime, maxSpeed);
+		currentVelocity.y = tempVec2.y;
+	};
+})();
+
 //!schteppe: not shimming Vector2.prototype.seta, it's been warned about forever
 //!schteppe: not shimming Vector2.prototype.setd, it's been warned about forever
 //!schteppe: not shimming Vector2.prototype.setv, it's been warned about forever
diff --git a/src/goo/math/Vector3.js b/src/goo/math/Vector3.js
@@ -1,6 +1,7 @@
 var ObjectUtils = require('../util/ObjectUtils');
 var MathUtils = require('./MathUtils');
 var Vector = require('./Vector');
+var Vector2 = require('./Vector2');
 var Vector4 = require('./Vector4');
 
 /**
@@ -732,6 +733,31 @@ Vector3.prototype.setArray = function (array) {
 	return this;
 };
 
+/**
+ * Gradually changes the vector value value towards a desired goal over time. See MathUtils.smoothDamp.
+ * @param {Vector3} target The position we are trying to reach.
+ * @param {Vector3} currentVelocity An object to store the current position and velocity in.
+ * @param {number} deltaTime The time since the last call to this function.
+ * @param {number} [smoothTime=0.3] Approximately the time it will take to reach the target. A smaller value will reach the target faster.
+ * @param {number} [maxSpeed=1e7] Optionally allows you to clamp the maximum speed.
+ */
+Vector3.prototype.smoothDamp = (function () {
+	var tempVec2 = new Vector2();
+	return function (target, currentVelocity, deltaTime, smoothTime, maxSpeed) {
+		tempVec2.y = currentVelocity.x;
+		this.x = MathUtils.smoothDamp(this.x, target.x, tempVec2, deltaTime, smoothTime, maxSpeed);
+		currentVelocity.x = tempVec2.y;
+
+		tempVec2.y = currentVelocity.y;
+		this.y = MathUtils.smoothDamp(this.y, target.y, tempVec2, deltaTime, smoothTime, maxSpeed);
+		currentVelocity.y = tempVec2.y;
+
+		tempVec2.y = currentVelocity.z;
+		this.z = MathUtils.smoothDamp(this.z, target.z, tempVec2, deltaTime, smoothTime, maxSpeed);
+		currentVelocity.z = tempVec2.y;
+	};
+})();
+
 // SHIM START
 Object.defineProperty(Vector3.prototype, 'data', {
 	get: ObjectUtils.warnOnce('The .data property of Vector3 was removed. Please use the .x, .y and .z properties instead.', function () {
diff --git a/test/unit/math/Vector3-test.js b/test/unit/math/Vector3-test.js
@@ -377,6 +377,14 @@ describe('Vector3', function () {
 		});
 	});
 
+	describe('smoothDamp', function () {
+		it('can smoothDamp', function () {
+			var target = new Vector3(1,1,1);
+			var currentVelocity = new Vector3();
+			expect(new Vector3().smoothDamp(target, currentVelocity, 0.1, 0.3, 1e7)).not.toEqual([0, 0, 0]);
+		});
+	});
+
 	describe('deprecated shim added 2015-10-07 (v1.0)', function () {
 		describe('.data', function () {
 			it('has working getters', function () {
