feat!: add translation limit to wheel and prismatic joint

example/Car.js

@@ -149,35 +149,33 @@ wheelBack.createFixture(new Circle(0.4), wheelFD);
 var wheelFront = world.createDynamicBody(new Vec2(1.0, 0.4));
 wheelFront.createFixture(new Circle(0.4), wheelFD);
 
+const massWheelBack = wheelBack.getMass();
+const massWheelFront = wheelFront.getMass();
+
+const omega = 2.0 * Math.PI * HZ;
+
 var springBack = world.createJoint(new WheelJoint({
  motorSpeed : 0.0,
  maxMotorTorque : 20.0,
  enableMotor : true,
- frequencyHz : HZ,
- dampingRatio : ZETA
+ stiffness : massWheelBack * omega * omega,
+ damping : 2.0 * massWheelBack * ZETA * omega,
+ lowerTranslation : -0.25,
+ upperTranslation : 0.25,
+ enableLimit : true
 }, car, wheelBack, wheelBack.getPosition(), new Vec2(0.0, 1.0)));
 
 var springFront = world.createJoint(new WheelJoint({
  motorSpeed : 0.0,
  maxMotorTorque : 10.0,
  enableMotor : false,
- frequencyHz : HZ,
- dampingRatio : ZETA
+ stiffness : massWheelFront * omega * omega,
+ damping : 2.0 * massWheelFront * ZETA * omega,
+ lowerTranslation : -0.25,
+ upperTranslation : 0.25,
+ enableLimit : true
 }, car, wheelFront, wheelFront.getPosition(), new Vec2(0.0, 1.0)));
 
-testbed.keydown = function() {
- if (testbed.activeKeys.down) {
- HZ = Math.max(0.0, HZ - 1.0);
- springBack.setSpringFrequencyHz(HZ);
- springFront.setSpringFrequencyHz(HZ);
-
- } else if (testbed.activeKeys.up) {
- HZ += 1.0;
- springBack.setSpringFrequencyHz(HZ);
- springFront.setSpringFrequencyHz(HZ);
- }
-};
-
 testbed.step = function() {
  if (testbed.activeKeys.right && testbed.activeKeys.left) {
  springBack.setMotorSpeed(0);

example/Prismatic.js

@@ -21,7 +21,7 @@
  * SOFTWARE.
  */
 
-// The motor in this test gets smoother with higher velocity iterations.
+// Test the prismatic joint with limits and motor options.
 
 const { World, Vec2, PrismaticJoint, Edge, Box, Circle } = planck;
 
@@ -30,6 +30,8 @@ var world = new World(new Vec2(0, -10));
 const testbed = planck.testbed();
 testbed.start(world);
 
+var ENABLE_LIMIT = true;
+var ENABLE_MOTOR = false;
 var MOTOR_SPEED = 10;
 
 var ground = world.createBody();
@@ -41,22 +43,17 @@ var body = world.createBody({
  angle : 0.5 * Math.PI,
  allowSleep : false
 });
-body.createFixture(new Box(2.0, 0.5), 5.0);
+body.createFixture(new Box(1.0, 1.5), 5.0);
 
 // Bouncy limit
-var axis = new Vec2(2.0, 1.0);
-axis.normalize();
 var joint = new PrismaticJoint({
  motorSpeed : MOTOR_SPEED,
  maxMotorForce : 10000.0,
- enableMotor : true,
- lowerTranslation : 0.0,
- upperTranslation : 20.0,
- enableLimit : true
-}, ground, body, new Vec2(0.0, 0.0), axis);
-
-// Non-bouncy limit
-// (ground, body, new Vec2(-10.0, 10.0), new Vec2(1.0, 0.0));
+ enableMotor : ENABLE_MOTOR,
+ lowerTranslation : -10.0,
+ upperTranslation : 10.0,
+ enableLimit : ENABLE_LIMIT
+}, ground, body, new Vec2(0.0, 0.0), new Vec2(1.0, 0.0));
 
 world.createJoint(joint);
 

example/WheelJoint.js

@@ -0,0 +1,89 @@
+/*
+ * MIT License
+ * Copyright (c) 2019 Erin Catto
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+// Test the wheel joint with motor, spring, and limit options.
+
+var { World, Vec2, Edge, Box, Circle, Polygon, RevoluteJoint, WheelJoint } = planck;
+
+var testbed = planck.testbed();
+
+var world = new World({
+ gravity : new Vec2(0, -10)
+});
+
+testbed.start(world); 
+
+var ground = world.createBody();
+ground.createFixture(new Edge(new Vec2(-40.0, 0.0), new Vec2(40.0, 0.0)), 0.0);
+
+
+var enableLimit = true;
+var enableMotor = false;
+var motorSpeed = 0.0;
+
+var body = world.createBody({
+ type : 'dynamic',
+ position : new Vec2(0.0, 10.0),
+ allowSleep : false
+});
+body.createFixture(new Circle(2.0), 5.0);
+
+var mass = body.getMass();
+var hertz = 1.0;
+var dampingRatio = 0.7;
+var omega = 2.0 * Math.PI * hertz;
+
+var joint = new WheelJoint({
+ motorSpeed : motorSpeed,
+ maxMotorTorque : 10000.0,
+ enableMotor : enableMotor,
+ stiffness : mass * omega * omega,
+ damping : 2.0 * mass * dampingRatio * omega,
+ lowerTranslation : -3.0,
+ upperTranslation : 3.0,
+ enableLimit : enableLimit
+}, ground, body, new Vec2(0.0, 10.0), new Vec2(0.0, 1.0));
+
+world.createJoint(joint);
+
+testbed.step = function() {
+ var torque = joint.getMotorTorque(testbed.hz);
+ testbed.status({
+ "Motor Torque" : torque,
+ "Motor Speed" : joint.getMotorSpeed(),
+ });
+
+ if (testbed.activeKeys.right && testbed.activeKeys.left) {
+ joint.setMotorSpeed(0);
+ joint.enableMotor(true);
+ } else if (testbed.activeKeys.right) {
+ joint.setMotorSpeed(-10);
+ joint.enableMotor(true);
+ } else if (testbed.activeKeys.left) {
+ joint.setMotorSpeed(10);
+ joint.enableMotor(true);
+ } else {
+ joint.setMotorSpeed(0);
+ joint.enableMotor(false);
+ }
+};

example/list.json

@@ -57,5 +57,6 @@
  "VaryingFriction",
  "VaryingRestitution",
  "VerticalStack",
- "Web"
+ "Web",
+ "WheelJoint"
 ]

src/collision/shape/CircleShape.ts

@@ -38,6 +38,9 @@ const _CONSTRUCTOR_FACTORY = typeof CONSTRUCTOR_FACTORY === 'undefined' ? false
 
 const temp = matrix.vec2(0, 0);
 
+/**
+ * A solid circle shape
+ */
 export class CircleShape extends Shape {
  static TYPE = 'circle' as const;
  m_type: 'circle';
@@ -139,6 +142,8 @@ export class CircleShape extends Shape {
 
  /**
  * Cast a ray against a child shape.
+ * @note because the circle is solid, rays that start inside do not hit
+ * because the normal is not defined.
  *
  * @param output The ray-cast results.
  * @param input The ray-cast input parameters.

src/collision/shape/PolygonShape.ts

@@ -45,8 +45,8 @@ const center = matrix.vec2(0, 0);
 const s = matrix.vec2(0, 0);
 
 /**
- * A convex polygon. It is assumed that the interior of the polygon is to the
- * left of each edge. Polygons have a maximum number of vertices equal to
+ * A solid convex polygon. It is assumed that the interior of the polygon is to
+ * the left of each edge. Polygons have a maximum number of vertices equal to
  * Settings.maxPolygonVertices. In most cases you should not need many vertices
  * for a convex polygon. extends Shape
  */
@@ -323,6 +323,8 @@ export class PolygonShape extends Shape {
 
  /**
  * Cast a ray against a child shape.
+ * @note because the polygon is solid, rays that start inside do not hit
+ * because the normal is not defined.
  *
  * @param output The ray-cast results.
  * @param input The ray-cast input parameters.