Merge pull request #4041 from AndrewMeadows/inertia

Include damping in model of remote extrapolation

BUILD.md

@@ -6,6 +6,7 @@
 * [OpenSSL](https://www.openssl.org/related/binaries.html) ~> 1.0.1g
   * IMPORTANT: OpenSSL 1.0.1g is critical to avoid a security vulnerability.
 * [Intel Threading Building Blocks](https://www.threadingbuildingblocks.org/) ~> 4.3
+* [Bullet Physics Engine](http://bulletphysics.org) ~> 2.82
 
 ### OS Specific Build Guides
 * [BUILD_OSX.md](BUILD_OSX.md) - additional instructions for OS X.

examples/toyball.js

@@ -29,7 +29,7 @@ var RIGHT_BUTTON_FWD = 11;
 var RIGHT_BUTTON_3 = 9;
 
 var BALL_RADIUS = 0.08;
-var GRAVITY_STRENGTH = 0.5;
+var GRAVITY_STRENGTH = 1.0;
 
 var HELD_COLOR = { red: 240, green: 0, blue: 0 };
 var THROWN_COLOR = { red: 128, green: 0, blue: 0 };
@@ -136,7 +136,7 @@ function checkControllerSide(whichSide) {
                 velocity: { x: 0, y: 0, z: 0}, 
                 gravity: { x: 0, y: 0, z: 0}, 
                 inHand: true,
-                radius: { x: BALL_RADIUS * 2, y: BALL_RADIUS * 2, z: BALL_RADIUS * 2 },
+                dimensions: { x: BALL_RADIUS * 2, y: BALL_RADIUS * 2, z: BALL_RADIUS * 2 },
                 damping: 0.00001,
                 color: HELD_COLOR,
 
@@ -185,6 +185,7 @@ function checkControllerSide(whichSide) {
                     velocity: { x: tipVelocity.x * THROWN_VELOCITY_SCALING, 
                                 y: tipVelocity.y * THROWN_VELOCITY_SCALING, 
                                 z: tipVelocity.z * THROWN_VELOCITY_SCALING } ,
+                    collisionsWillMove: true,
                     inHand: false,
                     color: THROWN_COLOR,
                     lifetime: 10,

examples/twoFallingEntities.js

@@ -4,21 +4,21 @@
 //  Creates a red 0.2 meter diameter ball right in front of your avatar that lives for 60 seconds
 // 
 
-var radius = 0.1;
+var diameter = 0.2;
 var position = Vec3.sum(MyAvatar.position, Quat.getFront(MyAvatar.orientation));  
 var properties = {
                 type: "Sphere",
                 position: position, 
                 velocity: { x: 0, y: 0, z: 0}, 
                 gravity: { x: 0, y: -0.05, z: 0}, 
-                radius: radius,
+                dimensions: { x: diameter, y: diameter, z: diameter };
                 damping: 0.00001,
                 color: { red: 200, green: 0, blue: 0 },
                 lifetime: 60     
             };
 
 var newEntity = Entities.addEntity(properties);
-position.x -= radius * 1.0;
+position.x -= 0.5 * diameter;
 properties.position = position; 
 var newEntityTwo = Entities.addEntity(properties);
 

libraries/physics/src/ObjectMotionState.cpp

@@ -27,7 +27,7 @@ const float MAX_VOLUME = 1000000.0f;
 const float DEFAULT_FRICTION = 0.5f;
 const float MAX_FRICTION = 10.0f;
 
-const float DEFAULT_RESTITUTION = 0.0f;
+const float DEFAULT_RESTITUTION = 0.5f;
 
 // origin of physics simulation in world frame
 glm::vec3 _worldOffset(0.0f);
@@ -123,9 +123,10 @@ bool ObjectMotionState::doesNotNeedToSendUpdate() const {
 
 const float FIXED_SUBSTEP = 1.0f / 60.0f;
 
-bool ObjectMotionState::shouldSendUpdate(uint32_t simulationFrame, float subStepRemainder) const {
+bool ObjectMotionState::shouldSendUpdate(uint32_t simulationFrame, float subStepRemainder) {
     assert(_body);
     float dt = (float)(simulationFrame - _sentFrame) * FIXED_SUBSTEP + subStepRemainder;
+    _sentFrame = simulationFrame;
     bool isActive = _body->isActive();
 
     if (isActive) {
@@ -156,28 +157,35 @@ bool ObjectMotionState::shouldSendUpdate(uint32_t simulationFrame, float subStep
     // TODO: Andrew to reconcile Bullet and legacy damping coefficients.
 
     // compute position error
-    glm::vec3 extrapolatedPosition = _sentPosition + dt * (_sentVelocity + (0.5f * dt) * _sentAcceleration);
+    if (glm::length2(_sentVelocity) > 0.0f) {
+        _sentVelocity += _sentAcceleration * dt;
+        _sentVelocity *= powf(1.0f - _linearDamping, dt);
+        _sentPosition += dt * _sentVelocity;
+    }
 
     btTransform worldTrans = _body->getWorldTransform();
     glm::vec3 position = bulletToGLM(worldTrans.getOrigin());
     
-    float dx2 = glm::distance2(position, extrapolatedPosition);
+    float dx2 = glm::distance2(position, _sentPosition);
     const float MAX_POSITION_ERROR_SQUARED = 0.001f; // 0.001 m^2 ~~> 0.03 m
     if (dx2 > MAX_POSITION_ERROR_SQUARED) {
         return true;
     }
 
-    // compute rotation error
+    if (glm::length2(_sentAngularVelocity) > 0.0f) {
-    float spin = glm::length(_sentAngularVelocity);
+        // compute rotation error
-    glm::quat extrapolatedRotation = _sentRotation;
+        _sentAngularVelocity *= powf(1.0f - _angularDamping, dt);
-    const float MIN_SPIN = 1.0e-4f;
+    
-    if (spin > MIN_SPIN) {
+        float spin = glm::length(_sentAngularVelocity);
-        glm::vec3 axis = _sentAngularVelocity / spin;
+        const float MIN_SPIN = 1.0e-4f;
-        extrapolatedRotation = glm::angleAxis(dt * spin, axis) * _sentRotation;
+        if (spin > MIN_SPIN) {
+            glm::vec3 axis = _sentAngularVelocity / spin;
+            _sentRotation = glm::normalize(glm::angleAxis(dt * spin, axis) * _sentRotation);
+        }
     }
     const float MIN_ROTATION_DOT = 0.98f;
     glm::quat actualRotation = bulletToGLM(worldTrans.getRotation());
-    return (glm::dot(actualRotation, extrapolatedRotation) < MIN_ROTATION_DOT);
+    return (glm::dot(actualRotation, _sentRotation) < MIN_ROTATION_DOT);
 }
 
 #endif // USE_BULLET_PHYSICS

libraries/physics/src/ObjectMotionState.h

@@ -84,7 +84,7 @@ public:
     void clearOutgoingPacketFlags(uint32_t flags) { _outgoingPacketFlags &= ~flags; }
 
     bool doesNotNeedToSendUpdate() const;
-    virtual bool shouldSendUpdate(uint32_t simulationFrame, float subStepRemainder) const;
+    virtual bool shouldSendUpdate(uint32_t simulationFrame, float subStepRemainder);
     virtual void sendUpdate(OctreeEditPacketSender* packetSender, uint32_t frame) = 0;
 
     virtual MotionType computeMotionType() const = 0;

libraries/physics/src/PhysicsEngine.cpp

@@ -24,7 +24,6 @@ PhysicsEngine::PhysicsEngine(const glm::vec3& offset)
         _constraintSolver(NULL), 
         _dynamicsWorld(NULL),
         _originOffset(offset),
-        _voxels(),
         _entityPacketSender(NULL),
         _frameCount(0) {
 }
@@ -221,62 +220,6 @@ void PhysicsEngine::stepSimulation() {
     _frameCount += (uint32_t)numSubSteps;
 }
 
-bool PhysicsEngine::addVoxel(const glm::vec3& position, float scale) {
-    glm::vec3 halfExtents = glm::vec3(0.5f * scale);
-    glm::vec3 trueCenter = position + halfExtents;
-    PositionHashKey key(trueCenter);
-    VoxelObject* proxy = _voxels.find(key);
-    if (!proxy) {
-        // create a shape
-        ShapeInfo info;
-        info.setBox(halfExtents);
-        btCollisionShape* shape = _shapeManager.getShape(info);
-
-        // NOTE: the shape creation will fail when the size of the voxel is out of range
-        if (shape) {
-            // create a collisionObject
-            btCollisionObject* object = new btCollisionObject();
-            object->setCollisionShape(shape);
-            btTransform transform;
-            transform.setIdentity();
-            // we shift the center into the simulation's frame
-            glm::vec3 shiftedCenter = (position - _originOffset) + halfExtents;
-            transform.setOrigin(btVector3(shiftedCenter.x, shiftedCenter.y, shiftedCenter.z));
-            object->setWorldTransform(transform);
-
-            // add to map and world
-            _voxels.insert(key, VoxelObject(trueCenter, object));
-            _dynamicsWorld->addCollisionObject(object);
-            return true;
-        }
-    }
-    return false;
-}
-
-bool PhysicsEngine::removeVoxel(const glm::vec3& position, float scale) {
-    glm::vec3 halfExtents = glm::vec3(0.5f * scale);
-    glm::vec3 trueCenter = position + halfExtents;
-    PositionHashKey key(trueCenter);
-    VoxelObject* proxy = _voxels.find(key);
-    if (proxy) {
-        // remove from world
-        assert(proxy->_object);
-        _dynamicsWorld->removeCollisionObject(proxy->_object);
-
-        // release shape
-        ShapeInfo info;
-        info.setBox(halfExtents);
-        bool released = _shapeManager.releaseShape(info);
-        assert(released);
-
-        // delete object and remove from voxel map
-        delete proxy->_object;
-        _voxels.remove(key);
-        return true;
-    }
-    return false;
-}
-
 // Bullet collision flags are as follows:
 // CF_STATIC_OBJECT= 1,
 // CF_KINEMATIC_OBJECT= 2,

libraries/physics/src/PhysicsEngine.h

@@ -24,10 +24,8 @@ typedef unsigned int uint32_t;
 
 #include "BulletUtil.h"
 #include "EntityMotionState.h"
-#include "PositionHashKey.h"
 #include "ShapeManager.h"
 #include "ThreadSafeDynamicsWorld.h"
-#include "VoxelObject.h"
 
 const float HALF_SIMULATION_EXTENT = 512.0f; // meters
 
@@ -56,16 +54,6 @@ public:
     /// \return position of simulation origin in domain-frame
     const glm::vec3& getOriginOffset() const { return _originOffset; }
 
-    /// \param position the minimum corner of the voxel
-    /// \param scale the length of the voxel side
-    /// \return true if Voxel added
-    bool addVoxel(const glm::vec3& position, float scale);
-
-    /// \param position the minimum corner of the voxel
-    /// \param scale the length of the voxel side
-    /// \return true if Voxel removed
-    bool removeVoxel(const glm::vec3& position, float scale);
-
     /// \param motionState pointer to Object's MotionState
     /// \return true if Object added
     bool addObject(ObjectMotionState* motionState);
@@ -103,7 +91,6 @@ protected:
 
 private:
     glm::vec3 _originOffset;
-    btHashMap<PositionHashKey, VoxelObject> _voxels;
 
     // EntitySimulation stuff
     QSet<EntityMotionState*> _entityMotionStates; // all entities that we track

libraries/physics/src/PositionHashKey.cpp

@@ -1,37 +0,0 @@
-//
-//  PositionHashKey.cpp
-//  libraries/physcis/src
-//
-//  Created by Andrew Meadows 2014.11.05
-//  Copyright 2014 High Fidelity, Inc.
-//
-//  Distributed under the Apache License, Version 2.0.
-//  See the accompanying file LICENSE or http://www.apache.org/licenses/LICENSE-2.0.html
-//
-
-#include <math.h>
-
-#include "PositionHashKey.h"
-
-// static 
-int computeHash(const glm::vec3& center) {
-    // NOTE: 0.49f is used to bump the float up almost half a millimeter
-    // so the cast to int produces a round() effect rather than a floor()
-    int hash = DoubleHashKey::hashFunction((int)(center.x * MILLIMETERS_PER_METER + copysignf(1.0f, center.x) * 0.49f), 0);
-    hash ^= DoubleHashKey::hashFunction((int)(center.y * MILLIMETERS_PER_METER + copysignf(1.0f, center.y) * 0.49f), 1);
-    return hash ^ DoubleHashKey::hashFunction((int)(center.z * MILLIMETERS_PER_METER + copysignf(1.0f, center.z) * 0.49f), 2);
-}
-
-// static 
-int computeHash2(const glm::vec3& center) {
-    // NOTE: 0.49f is used to bump the float up almost half a millimeter
-    // so the cast to int produces a round() effect rather than a floor()
-    int hash = DoubleHashKey::hashFunction2((int)(center.x * MILLIMETERS_PER_METER + copysignf(1.0f, center.x) * 0.49f));
-    hash ^= DoubleHashKey::hashFunction2((int)(center.y * MILLIMETERS_PER_METER + copysignf(1.0f, center.y) * 0.49f));
-    return hash ^ DoubleHashKey::hashFunction2((int)(center.z * MILLIMETERS_PER_METER + copysignf(1.0f, center.z) * 0.49f));
-}
-
-PositionHashKey::PositionHashKey(glm::vec3 center) : DoubleHashKey() {
-    _hash = computeHash(center);
-    _hash2 = computeHash2(center);
-}

libraries/physics/src/PositionHashKey.h

@@ -1,26 +0,0 @@
-//
-//  PositionHashKey.h
-//  libraries/physcis/src
-//
-//  Created by Andrew Meadows 2014.11.05
-//  Copyright 2014 High Fidelity, Inc.
-//
-//  Distributed under the Apache License, Version 2.0.
-//  See the accompanying file LICENSE or http://www.apache.org/licenses/LICENSE-2.0.html
-//
-
-#ifndef hifi_PositionHashKey_h
-#define hifi_PositionHashKey_h
-
-#include <glm/glm.hpp>
-
-#include <SharedUtil.h>
-
-#include "DoubleHashKey.h"
-
-class PositionHashKey : public DoubleHashKey {
-public:
-    PositionHashKey(glm::vec3 center);
-};
-
-#endif // hifi_PositionHashKey_h

libraries/physics/src/VoxelObject.h

@@ -1,31 +0,0 @@
-//
-//  VoxelObject.h
-//  libraries/physcis/src
-//
-//  Created by Andrew Meadows 2014.11.05
-//  Copyright 2014 High Fidelity, Inc.
-//
-//  Distributed under the Apache License, Version 2.0.
-//  See the accompanying file LICENSE or http://www.apache.org/licenses/LICENSE-2.0.html
-//
-
-#ifndef hifi_VoxelObject_h
-#define hifi_VoxelObject_h
-
-#ifdef USE_BULLET_PHYSICS
-
-#include <btBulletDynamicsCommon.h>
-#include <glm/glm.hpp>
-
-// VoxelObject is a simple wrapper for tracking a Voxel in a PhysicsEngine
-class VoxelObject {
-public:
-    VoxelObject(const glm::vec3& center, btCollisionObject* object) : _object(object), _center(center) {
-        assert(object != NULL);
-    }
-    btCollisionObject* _object;
-    glm::vec3 _center;
-};
-
-#endif // USE_BULLET_PHYSICS
-#endif // hifi_VoxelObject_h