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ReactPhysics3D library User Manual

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1. g key to generate the makefiles in the build directory that you have created before and exit Now that you have generated the makefiles with the CMake software you can compile the code to build the static library in the lib folder with the following command in your build directory make 4 2 CMake using the graphical interface Linux Mac OS X and Windows You can also use the graphical user interface of CMake To do this run the cmake gui program The program will ask you for the source folder which is the reactphysics3d 0 5 0 folder of the library You will also have to select a folder where you want to build the library and the examples Select any empty folder that is on your system Then you can click on Configure CMake will ask you to choose an IDE that is on your system For instance you can select Visual Studio Qt Creator XCode Then you can change the compilation options See section 4 3 to see what are the possible options Once this is done you can click on Configure again and finally on Generate Now if you go into the folder you have chosen to build the library you should be able to open the project file that corresponds to your IDE and compile the library If your want to run the examples within the Microsoft Visual Studio IDE you need to make sure that in the Debugging section of the Configuration Properties of the example projects the Working Directory is set to OutDir Otherwise you might have pr
2. yum on Linux Then you will be able to compile the library to create the static library file In order to use ReactPhysics3D in your application you can link your program with this static library If you have never used cmake before you should read the page http www cmake org cmake help runningcmake html as it contains a lot of useful information Note that by default the library is built in debugging mode In this mode a lot of debugging information is compiled together with the code This might cause the application to run much slower that it should be in release mode Therefore you should not forget to build the library in release mode when releasing your final application 4 1 CMake using the command line Linux and Mac OS X Now we will see how to build the ReactPhysics3D library using the CMake tool with the command line First create a folder where you want to build the library Then go into that folder and run the ccmake command ccmake lt path_to_library_source gt where lt path_to_library_source gt must be replaced by the path to the reactphysics3d 0 5 0 folder It is the folder that contains the CMakeLists txt file Running this command will launch the CMake command line interface Hit the c key to configure the project There you can also change some predefined variables see section 4 3 for more details and then hit the c key again Once you have set all the values as you like you can hit the
3. ML li eee pm eye SI Se rl Ti me SR Dre des 9 2 6 Applying Force or Torque to a Rigid Body 9 3 Updating a Rigid Body nica Sa Gas sa Ged ek el 9 4 Destroying a Rigid Body 0 o oo ll dans eh dun res 10 Collision Shapes 10 1 Box Shape 10 2 Sphere Shape 10 3 Cone Shape 10 4 Cyhnder Shap cinne deee ar ge ee cig ae geet Ya ae Tara Bee o Capsule Shape al tn oot Se eh Bie ea ble Rae Si Bet 10 6 Convex Mesh Shape ter hed he dr du ie Mae 10 7 Adding a Collision Shape to a body The Proxy Shape concept TOPS COST INR A de ip a ata te OS aN ae ee ANS Mes ade igs 11 Joints 11 1 Ball and Socket Joint T2 il A tig Ah E IN de ol 1221 Limit sas LR SES fl ela ee ee ee 11 22 Motor oc ee Oo ee ee a a fut A SS lider Jont zatie i Bet ie i Sethe M e sa Aie Suds ESAR MIS aps par Be ce co A Dias ee ate eS eee EAS P3225 Motor y Dubra PEN cei ee A decir ey deer de anus E di aes A Ered 22 428 a aie eral 6 ie eis ee A een Gay Beg he 11 5 Collision between the bodies of a Joint 11 6 Destroy a lol seu dean AS cee ek dd iy oe eee Reh Te BS 12 Ray casting 12 1 Ray casting against multiple bodies 12 1 1 The RaycastCallback class sens aca BS eve Yee 4 12 1 2 Raycast query in the world ul boxe ae ea ee ais 12 2 Ray casting against a single body eG 24 4 ass aa 12 3 Ray casting against the proxy shape of a body 13 Examples IL OES e
4. a A E ee dn es LR G lli ion Shapes po ds ta a a ore a abs Io OMS ato fg do be tie ios a ei ea SE RMS scs o a SA aa as Na IA 2 14 Receiving Feedback JAN Contacts ee Sy Sh Ua gosh Ge ssa a aes der Ph At ae AEE Be ee Re 15 Profiler 16 API Documentation 17 Bugs 37 37 37 1 Introduction ReactPhysics3D is an open source C physics engine library that can be used in 3D simulations and games The library is released under the ZLib license 2 Features The ReactPhysics3D library has the following features Rigid body dynamics Discrete collision detection Collision shapes Sphere Box Cone Cylinder Capsule Convex Mesh Multiple collision shapes per body Broadphase collision detection Dynamic AABB tree Narrowphase collision detection GJK EPA Collision response and friction Sequential Impulses Solver Joints Ball and Socket Hinge Slider Fixed Collision filtering with categories Ray casting Sleeping technique for inactive bodies Integrated Profiler Multi platform Windows Linux Mac OS X Documentation User manual and Doxygen API Examples Unit tests 3 License The ReactPhysics3D library is released under the open source ZLib license For more information read the LICENSE file 4 Building the library You should use the CMake software to generate the makefiles or the project files for your IDE CMake can be downloaded at http www cmake org or using your package management program apt
5. be copied internally Therefore you can destroy the collision shape object right after it has been added to the body In order to add a collision shape to a body you need to use the CollisionBody addCollisionShape method for a Collision Body and 22 the RigidBody addCollisionShape method for a Rigid Body You will have to provide the collision shape transform in parameter This is the transformation mapping the local space of the collision shape to the local space of the body For a Rigid Body you will also have to provide the mass of the shape you want to add As explained before this is used to automatically compute the center of mass total mass and inertia tensor of the body The addCollisionShape method returns a pointer to a Proxy Shape A Proxy Shape is what links a given collision shape to the body it has been added You can use the returned Proxy Shape to get or set parameters of the given collision shape in that particular body This concept is also called fixture in some other physics engines In ReactPhysics3D a Proxy Shape is represented by the ProxyShape class When you create a collision shape you can add it to multiple bodies You do not need to create several times the same collision shape The following example shows how to add a sphere collision shape with a given mass to a rigid body and also how to remove it from the body using the Proxy Shape pointer Create the sphere collision shape rp3d decimal ra
6. is called information about the running time of the library will be displayed in the standard output This can be useful to know where time is spent in the different parts of the ReactPhysics3D library in case your application is too slow 16 API Documentation Some documentation about the API of the code has been generated using Doxygen You will be able to find this documentation in the library archive in the folder documentation API htm1 You just need to open the index html file with your favorite web browser 17 Bugs If you find some bugs do not hesitate to report them on our issue tracker here https github com DanielChappuis reactphysics3d issues Thanks a lot for reporting the issues that you find It will help us to correct and improve the library 37
7. the hit point in world space coordinates 32 hitFraction Fraction distance of the hit point between startPoint and endPoint of the ray The hit point p is such that p start Point hit Fraction endPoint start Point body Pointer to the Collision Body or Rigid Body that has been hit by the ray proxyShape Pointer to the Proxy Shape that has been hit by the ray Note that you can also use collision filtering with ray casting in order to only test ray intersection with specific proxy shapes Collision filtering is described in section 10 8 12 1 Ray casting against multiple bodies This ray casting query will return all the proxy shapes of all bodies in the world that are intersected by a given ray 12 1 1 The RaycastCallback class First you have to implement your own class that inherits from the RaycastCallback class Then you need to override the RaycastCallback notifyRaycastHit method in your own class An instance of your class have to be provided as a pa rameter of the raycast method and the notifyRaycastHit method will be called for each proxy shape that is hit by the ray You will receive as a parameter of this method a RaycastInfo object that will contain the information about the raycast hit hit point hit surface normal hit body hit proxy shape In your notifyRaycastHit method you need to return a fraction value that will specify the continuation of the ray cast after a hit The return value is the nex
8. used to save computation time because simulating many bodies is costly A sleeping body or group of sleeping bodies is awaken as soon as another body collides with it or a joint in which it is involed is enabled The sleeping technique is enabled by default You can disable it using the following method Disable the sleeping technique world enableSleeping false Note that it is not recommended to disable the sleeping technique because the simulation might become slower It is also possible to deactivate the sleeping tech nique on a per body basis See section 9 2 5 for more information A body is put to sleep when its linear and angular velocity stay under a given velocity threshold for a certain amount of time one second by de fault It is possible to change the two linear and angular velocity thresh olds using the two methods DynamicsWorld setSleepLinearVelocity and DynamicsWorld setSleepAngularVelocity Note that the velocities must be specified in meters per second You can also change the amount of time in seconds the velocity of a body needs to stay under the threshold to be considered sleeping To do this use the DynamicsWorld setTimeBeforeSleep method 8 3 Updating the Dynamics World The first thing you have to do to simulate the dynamics of your world is to start the simulation using the following method Start the simulation morir Sineucis O Then each time you have to compute the ne
9. In order to destroy a joint you simply need to call the DynamicsWorld destroyJoint method using the pointer to a previously created joint object as argument as shown in the following code rp3d BallAndSocketJoint joint is a previously created joint Destroy the joint world destroyJoint joint It is important that you destroy all the joints that you have created at the end of the simulation Also note that destroying a rigid body involved in a joint will automatically destroy that joint 12 Ray casting You can use ReactPhysics3D to test intersection between a ray and the bodies of the world you have created Ray casting can be performed against multiple bodies a single body or any proxy shape of a given body The first thing you need to do is to create a ray using the Ray class of React Physics3D As you can see in the following example this is very easy You simply need to specify the point where the ray starts and the point where the ray ends in world space coordinates Start and end points of the ray rpod Vectors startPoint OOOO IO rpd Vectors endPoint COMOL Sr Oro Create the ray rp3d Ray ray startPoint endPoint Any ray casting test that will be described in the following sections returns a RaycastInfo object in case of intersection with the ray This structure contains the following attributes worldPoint Hit point in world space coordinates worldNormal Surface normal of the proxy shape at
10. ReactPhysics3D library User Manual Version 0 5 0 Daniel Chappuis US http www reactphysics3d com March 4 2015 Contents 1 2 Introduction Features License Building the library 4 1 CMake using 4 2 CMake using the graphical interface Linux Mac OS X and Windows the command line Linux and MacOSX 4 3 CMake Variables 0 0 0 0 00000 2 ee ees Using ReactPhysics3D in your application The Collision World 6 1 Creating the Collision World sa a data as deh eo Bed te wo ce 6 2 Destroying the Collision World Collision Bodies 7 1 Creating a Collision Body 4 93 4 2 fae he Paha A ae 7 2 Moving a Collision Body 0 A in tek eee ake ee a ee 7 3 Destroying a Collision Body The Dynamics World 8 1 Creating the Dynamics World 8 2 Customizing the Dynamics World 8 2 1 Solver paTameters 4 3 4 ey 8 ut en eg a gra a AS Le 6 101 Om re PE p ee Se ee A 8 3 Updating the Dynamics World 8 4 Destroying the Dynamics World Rigid Bodies 9 1 Creating a Rigid Body 22024 243 44 24254 a 25 4 be Ss 9 2 Customizing a Rigid Body hacias Lal e Gey ee NE 2 9 2 1 Type of a Rigid Body static kinematic or dynamic 9 2 2 Gravity ob eee tage ddr ad he Ae ae ede a Be rs as beg 9 2 3 Material of a Rigid Body 2 4 44 4 4h 544425440244 9 2 4 Velocity Damping cee
11. al Studio XCode or to specify them when you run the example in command line You can find the command line arguments to use for each example bellow 35 13 1 Cubes Command line arguments shaders In this example you will see how to create a floor and some cubes using the Box Shape for collision detection Because of gravity the cubes will fall down on the floor After falling down the cubes will come to rest and start sleeping become inactive In this demo the cubes are green when they are active and become red as they get inactive sleeping 13 2 Collision Shapes Command line arguments shaders meshes In this example you will see how to create a floor using the Box Shape and some other bodies using the different collision shapes available in the ReactPhysics3D library like Cylinders Capsules Spheres Convex Meshes and Cones Those bodies will fall down to the floor 13 3 Joints Command line arguments shaders In this example you will learn how to create different joints Ball and Socket Hinge Slider Fixed into the dynamics world You can also see how to set the motor or limits of the joints 13 4 Raycast Command line arguments shaders meshes In this example you will see how to use the ray casting methods of the library Several rays are thrown against the different collision shapes It is possible to switch from a collision shape to another using the space key 14 Receiving Feedback Som
12. be set to OFF when you compile the final release of your application DOUBLE PRECISION ENABLED If this variable is ON the library will be compiled with double floating point precision Otherwise the library will be compiled with single precision 5 Using ReactPhysics3D in your application In order to use the library in your own application first build the static library of ReactPhysics3d as described above to get the static library file in the 1ib folder Then in your code you have to include the ReactPhysics3D header file with the line Include the ReactPhysics3D header file include reactphysics3d h Note that the reactphysics3d h header file can be found in the src folder of the library Do not forget to add the src folder in your include directories in order that the reactphysics3d h file is accessible in your code Do not forget to also link your application with the ReactPhysics3D static library Then you should be able to compile your application using the ReactPhysics3D library All the classes of the library are available in the reactphysics3d namespace or its shorter alias rp3d Therefore you need to include this namespace into your code with the following declaration Use the ReactPhysics3D namespace using namespace reactphysics3d You can also take a look at the examples and the API documentation to get a better idea of how to use the ReactPhysics3D library 6 The Collision World There are two main
13. body Every collision shapes use a collision margin which is a small distance around the shape that is used internally in the collision detection Some collision shapes have their collision margin integrated into the shape that you define and therefore you do not have to worry about it However for some collision shapes the collision margin is added around the shape that you define and therefore you might have to compensate for this small margin when you render the object 10 1 Box Shape The BoxShape class describes a box collision The box is aligned with the shape local X Y and Z axis In order to create a box shape you only need to specify the three half extents dimensions of the box in the three X Y and Z directions For instance if you want to create a box shape with dimensions of 4 meters 6 meters and 10 meters along the X Y and Z axis respectively you need to use the following code 17 Half extents of the box in the x y and z directions const rpsd Vectors halfExtents 2 NO PSS NO ME 0 Create the box shape const rp3d BoxShape boxShape halfExtents The BoxShape has a collision margin that is added to the box dimension you define Therefore the actual box shape will be a little bit larger that the one you define It is recommended that you use the default margin In case you really need to change the collision margin of your box shape if the dimension of your box is small compared to the default collisio
14. collide proxyShapeBodyi gt setCollideWithMaskBits CATEGORY3 proxyShapeBody2 gt setCollideWithMaskBits CATEGORY1 CATEGORY3 proxyShapeBody3 gt setCollideWithMaskBits CATEGORY2 proxyShapeBody4 gt setCollideWithMaskBits CATEGORY2 As you can see we specify that the body 1 will be allowed to collide with bodies from the categorie 3 We also indicate that the body 2 will be allowed to collide 24 with bodies from the category 1 and 3 using the bitwise OR operator Finally we specify that bodies 3 and 4 will be allowed to collide against bodies of the category 2 A collision shape is able to collide with another only if you have specify that the category mask of the first shape is part of the collide with mask of the second shape It is also important to understand that this condition must be satisfied in both directions For instance in the previous example the body 1 of category 1 says that it wants to collide against bodies of the category 3 for instance against body 3 However body 1 and body 3 will not be able to collide because the body 3 does not say that it wants to collide with bodies from category 1 Therefore in the previous example the body 2 is allowed to collide against bodies 3 and 4 but no other collision is allowed In the same way you can perform this filtering for ray casting described in section 12 For instance you can perform a ray cast test against a given subset of categories of collision sha
15. create Collision Bodies into the world A Collision Body represents an object in the Collision World It has a posi tion an orientation and one or more collision shapes It has to be moved manually in the Collision World You can then test collisions between the Collision Bodies of the world In ReactPhysics3D the CollisionBody class is used to describe a Collision Body If you do not want to simply test collision between your bodies but want them to move automatically according to the physics you should use Rigid Bodies in a Dynamics World instead See section 8 for more information about the Dynamics World and section 9 if you would like to know more about the Rigid Bodies 7 1 Creating a Collision Body In order to create a Collision Body you need to specify its transform The transform describes the initial position and orientation of the body in the world You need to create an instance of the Transform class with a vector describing the initial position and a quaternion for the initial orientation of the body In order to test collision between your body and other bodies in the world you need to add one or several collision shapes to your body Take a look at section 10 to learn about the different collision shapes and how to create them You need to call the CollisionWorld createCollisionBody method to cre ate a Collision Body in the world previously created This method will return a pointer to the instance of the CollisionBod
16. ctPhysics3D uses bits mask to represent categories The first thing to do is to assign a category to the collision shapes of your body To do this you need to call the ProxyShape setCollisionCategoryBits method on the corresponding Proxy Shape as in the following example Here we consider that we have four bodies where each one has a single collision shape Enumeration for categories enum Category CATEGORY1 0x0001 CATEGORY2 0x0002 CATEGORY3 0x0004 Set the collision category for each proxy shape of each of the four bodies proxyShapeBodyi gt setCollisionCategoryBits CATEGORY1 proxyShapeBody2 gt setCollisionCategoryBits CATEGORY2 proxyShapeBody3 gt setCollisionCategoryBits CATEGORY3 proxyShapeBody4 gt setCollisionCategoryBits CATEGORY3 As you can see the collision shape of body 1 will be part of the category 1 the collision shape of body 2 will be part of the category 2 and the collision shapes of bodies 3 and 4 will be part of the category 3 Now for each collision shape we need to specify with which categories the shape is allowed to collide with To do this you need to use the ProxyShape setCollideWithMaskBits method of the Proxy Shape Note that you can specify one or more categories using the bitwise OR operator The following example shows how to specify with which categories the shapes can collide For each shape we specify with which categories it is allowed to
17. d variable and also the maximum allowed force in Newtons with the maxMotorForce variable For instance here is how to enable the motor of the slider joint when the joint is created Create the joint info object rp3d SliderJointInfo jointInfo body1 body2 anchorPoint axis Enable the motor of the joint Jolmw lito ishtiororimealollesl US Motor linear speed Jonne lito Moro eco 2 07 Maximum allowed force jointInfo maxMotorForce 10 0 Create the slider joint in the dynamics world ells FSllaCloeYOauimiess Ould p joint dynamic_cast lt rp3d SliderJoint gt world createJoint jointInfo It is also possible to use the SliderJoint enableMotor SliderJoint setMotorSpeed and SliderJoint setMaxMotorForce meth ods to enable the motor of the joint after its creation See the APT documentation for more information 30 11 4 Fixed Joint The FixedJoint class describes a fixed joint between two bodies In a fixed joint there is no degree of freedom the bodies are not allowed to translate or rotate with respect to each other In order to create a fixed joint you simply need to specify an anchor point in world space to create the FixedJointInfo object For instance here is how to create the joint info object for a fixed joint Anchor point in world space rpod Vectors anchomPornti 2N0 MO A ODE Create the joint info object rp3d FixedJointInfo jointInfoi bodyi body2 anchorPoi
18. dius rp3d decimal 3 0 const rp3d BoxShape shape radius Transform of the collision shape Place the shape at the origin of the body local space rp3d Transform transform rp3 Transform identity Mass of the collision shape in kilograms rp3d decimal mass rp3d decimal 4 0 Add the collision shape to the rigid body rp3d ProxyShape proxyShape proxyShape body gt addCollisionShape shape transform mass If you want to remove the collision shape from the body at some point you need to use the proxy shape body gt removeCollisionShape proxyShape As you can see you can use the removeCollisionShape method to remove a collision shape from a body by using the Proxy Shape Note that after removing a collision shape the corresponding Proxy Shape pointer will not be valid anymore It is not necessary to manually remove all the collision shapes from a body at the end of your application They will automatically be removed when you destroy the body 23 10 8 Collision filtering By default all the collision shapes of all your bodies are able to collide with each other in the world However sometimes we want a body to collide only with a given group of bodies and not with other bodies This is called collision filtering The idea is to group the collision shapes of bodies into categories Then we can specify for each collision shape against which categories it will be able to collide Rea
19. dynamicsWorld createRigidBody transform Once your Rigid Body has been created in the world you need to add one or several collision shapes to it Take a look at section 10 to learn about the different collision shapes and how to create them 9 2 Customizing a Rigid Body Once a Rigid Body has been created you can change some of its properties 9 2 1 Type of a Rigid Body static kinematic or dynamic There are three types of bodies static kinematic and dynamic A static body has infinite mass zero velocity but its position can be changed manually Moreover a static body does not collide with other static or kinematic bodies On the other side a kinematic body has infinite mass its velocity can be changed manually and its position is computed by the physics engine A kinematic body does not collide with other static or kinematic bodies Finally A dynamic body has non zero mass non zero velocity determined by forces and its position is determined by the physics engine Moreover a dynamic body can collide with other dynamic static or kinematic bodies When you create a new body in the world it is of dynamic type by default You can change the type of the body using the CollisionBody setType method as follows Change the type of the body to Kinematic body gt setType KINEMATIC 9 2 2 Gravity By default all the rigid bodies with react to the gravity force of the world If you do not want the gravity to be appl
20. en the joint is created Here is the code to create the HingeJointInfo object Anchor point in world space const rp3d Vector3 anchorpoint 210 Aror om0 Hinge rotation aris in world space consta dise cio axis OTOL Onon mO Create the Joint wro object rp3d HingeJointInfo jointInfo body1 body2 anchorPoint axis 26 Now it is time to create the actual joint in the dynamics world using the DynamicsWorld createJoint method Note that this method will also return a pointer to the HingeJoint object that has been created internally You will then be able to use that pointer to change properties of the joint and also to destroy it at the end Here is how to create the joint in the world Create the hinge joint in the dynamics world rp3d HingeJoint joint joint dynamic_cast lt rp3d HingeJoint gt world createJoint jointInfo 11 2 1 Limits With the hinge joint you can constrain the motion range using limits The limits of the hinge joint are the minimum and maximum angle of rotation allowed with respect to the initial angle between the bodies when the joint is created The limits are disabled by default If you want to use the limits you first need to enable them by setting the isLimitEnabled variable of the HingeJointInfo object to true be fore you create the joint You also have to specify the minimum and maximum limit angles in radians using the minAngleLimit and maxAngleLimit variables of the
21. estroy the world Here is how to destroy a Collision Body Here world is an instance of the CollisionWorld class and body is a CollisionBody pointer Destroy the collision body and remove it from the world world destroyCollisionBody body 8 The Dynamics World The Collision World of the previous section is used to manually move the bodies and check for collision between them On the other side the Dynamics World is used to automatically simulate the motion of your bodies using the physics You do not have to move the bodies manually but you still can if needed The Dynamics World will contain the bodies and joints that you create You will then be able to run your simulation across time by updating the world at each frame The DynamicsWorld class which inherits from the CollisionWorld class represents a Dynamics World in the ReactPhysics3D library 8 1 Creating the Dynamics World The first thing you have to do when you want to simulate the dynamics of rigid bodies in time is to create an instance of the DynamicsWorld You need to specify two parameters when constructing the world The first one is the gravity accelera tion vector in m s in the world and the second one is the simulation time step in seconds Note that gravity is activated by default when you create the world The time step is the fixed amount of time used at each internal physics tick Note that multiple internal physics ticks can be taken at each fra
22. et to zero Therefore you need to call the previous methods during 15 several frames if you want the force torque to be applied during a certain amount of time 9 3 Updating a Rigid Body When you call the DynamicsWorld update method the collisions between the bodies are computed and the joints are evaluated Then the bodies position and orientation are updated accordingly After calling this method you can get the updated position and orientation of each body to render it To do that you sim ply need to use the RigidBody getInterpolatedTransform method to get the interpolated transform This transform represents the current local to world space transformation of the body Here is how to get the interpolated transform of a rigid body Here body is a RigidBody pointer previously created Get the interpolated transform of the rigid body rp3d Transform transform body gt getInterpolatedTransform If you need the array with the corresponding 4 x 4 OpenGL transformation ma trix you can use the Transform getOpenGLMatrix method as in the following code Get the OpenGL matriz array of the transform Montana 116 2 transform getOpenGLMatrix matrix 9 4 Destroying a Rigid Body It is really simple to destroy a rigid body You simply need to use the DynamicsWorld destroyRigidBody method You need to use the pointer to the body you want to destroy as a parameter Note that after calling that me
23. etimes you want to receive notifications from the physics engine when a given event happens The EventListener class can be used for that purpose In order to use it you need to create a new class that inherits from the EventListener class and overrides some methods that will be called by the ReactPhysics3D library when some events occur You also need to register your class in the physics world using the DynamicsWorld setEventListener as in the following code Here YourEventListener is a class that inherits from the EventListener class of reactphysics3d 36 YourEventListener listener Register your event listener class world setEventListener amp listener 14 1 Contacts If you want to be notified when two bodies that were separated before become in contact you need to override the EventListener beginContact method in your event listener class Then this method will be called when the two separated bodies becomes in contact If you receive a notification when a new contact between two bodies is found you need to override the EventListener newContact method in your event listener class Then this method will be called when a new contact is found 15 Profiler If you build the library with the PROFILING_ENABLED variable enabled see section 4 3 a real time profiler will collect information while the application is running Then at the end of your application when the destructor of the DynamicsWorld class
24. ex mesh shape you need to supply the array with the co ordinates of the vertices of the mesh The array is supposed to start with the three X Y and Z coordinates of the first vertex then the X Y and Z coordinates of the second vertex and so on The first parameter of the ConvexMeshShape constructor is a pointer to the array of the vertices coordinates the second parameter is the number of vertices in the array and the third parameter is the size in bytes of the data needed for a single vertex in the array data used by all the three coordinates of a single vertex The following example shows how to create a convex mesh shape Construct a conver mesh shape rp3d ConvexMeshShape shape verticesArray nbVertices 3 sizeof float You need to make sure that the mesh you provide is indeed convex and also that the origin of its local space is inside the mesh The collision detection test with a convex mesh shape runs in O n where n is the number of vertices in the mesh Collision detection can become expensive if there 21 are too many vertices in the mesh It is possible to speed up the collision detection by providing information about the edges of the convex mesh If you provide edges information the collision detection will run in almost constant time at the cost of a little extra memory to store the edges information In order to provide the edges information you need to call the ConvexMeshShape addEdge method for eac
25. f the force is applied to the center of mass no torque will be created and only the linear motion of the body will be affected Force vector in Newton rpd Vectors force 2 0 0 0 0 0 Apply a force to the center of the body rigidBody gt applyForceToCenter force You can also apply a force to any given point in world space using the RigidBody applyForce method You need to specify the force vector in Newton and the point in world space where to apply the given force Note that if the point is not the center of mass of the body applying a force will generate some torque and therefore the angular motion of the body will be affected as well Force vector in Newton pee e Vectors forces 2 0 0 0 0 0 Point where the force is applied rpod Vectors pour AOS OPMENO E Apply a force to the body rigidBody gt applyForce force point It is also possible to apply a torque to a given body using the RigidBody applyTorque method You simply need to specify the torque vector in Newton meter as in the following example Torque vector eped Vector Longue OMOR OOOO Apply a torque to the body rigidBody gt applyTorque torque Note that when you call the previous methods the specified force torque will be added to the total force torque applied to the rigid body and that at the end of each call to the DynamicsWorld update the total force torque of all the rigid bodies will be res
26. h edge of the mesh The first parameter is the index of the first vertex of the edge and the second parameter is the index of the second vertex Do not worry about calling this method multiple times for the same edge the edge information will be added only once For instance the following code adds the edges information into a convex mesh shape Add the edges information of the mesh into the shape for unsigned int i 0 i lt mesh getNbFaces i Get the three verter IDs of the vertices of the face unsigned int vi getVertexIndexInFace i 0 unsigned int v2 getVertexIndexInFace i 1 unsigned int v3 getVertexIndexInFace i 2 Add the three edges into the collision shape convexShape addEdge vi v2 convexShape addEdge vi v3 convexShape addEdge v2 v3 Do not forget to enable the fast collision detection by asking the collision shape to use the edges information you have just provided To do this you need to call the ConvexMeshShape setIsEdgesInformationUsed method as in the following example Enable the fast collision detection using the edges information collisionShape setIsEdgesInformationUsed true 10 7 Adding a Collision Shape to a body The Proxy Shape concept Now that you know how to create a collision shape we will see how to add it to a given body First note that when you add a collision shape to a body the collision shape object that you gave as a parameter will
27. ied to a given body you can disable it using the RigidBody enableGravity method as in the following example Disable gravity for this body rigidBody gt enableGravity false 13 9 2 3 Material of a Rigid Body The material of a rigid body is used to describe the physical properties it is made of The Material class represents the material of a body Each body that you create will have a default material You can get the material of the rigid body using the RigidBody getMaterial method Then you will be able to change some properties For instance you can change the bounciness of the rigid body The bounciness is a value between 0 and 1 The value 1 is used for a very bouncy object and the value 0 means that the body will not be bouncy at all To change the bounciness of the material you can use the Material setBounciness method You are also able to change the friction coefficient of the body This value needs to be between 0 and 1 If the value is 0 no friction will be applied when the body is in contact with another body However if the value is 1 the friction force will be high You can change the friction coefficient of the material with the Material setFrictionCoefficient method Here is how to get the material of a rigid body and how to modify some of its properties Get the current material of the body rp3d Material amp material rigidBody gt getMaterial Change the bounciness of
28. joint info object Note that the minimum limit angle must be in the range 27 0 and the maximum limit angle must be in the range 0 27 For instance here is the way to use the limits for a hinge joint when the joint is created Create the joint info object rp3d HingeJointInfo jointInfo body1 body2 anchorPoint axis Enable the limits of the joint Jo nii nfor is mat Ema ble die Minimum limit angle jointInfo minAngleLimit PI 2 0 Maximum limit angle jointInfo maxAngleLimit PI 2 0 Create the hinge joint in the dynamics world rp3d HingeJoint joint joint dynamic_cast lt rp3d HingeJoint gt world createJoint jointInfo It is also possible to use the HingeJoint enableLimit HingeJoint setMinAngleLimit and HingeJoint setMaxAngleLimit methods to specify the limits of the joint after its creation See the API documentation for more information 27 11 2 2 Motor A motor is also available for the hinge joint It can be used to rotate the bodies around the hinge axis at a given angular speed and such that the torque applied to rotate the bodies does not exceed a maximum allowed torque The motor is disabled by default If you want to use it you first have to activate it using the isMotorEnabled boolean variable of the HingeJointInfo object before you create the joint Then you need to specify the angular motor speed in radians seconds using the motorSpeed variable and al
29. ly need to change the collision margin of your cylinder shape if the dimen sion of your cylinder is small compared to the default collision margin for instance you can pass the length of the new collision margin in meters as a third parameter of the CylinderShape constructor For instance if you want to use a collision margin of 1 centimeter for your cylin der shape you can do it like this Create the cylinder shape with a custom collision margin const rp3d CylinderShape cylinderShape 1 0 3 0 0 01 10 5 Capsule Shape The CapsuleShape class describes a capsule collision shape around the Y axis and centered at the origin of the shape local space It is the convex hull of two spheres It can also be seen as an elongated sphere In order to create it you only need to specify the radius of the two spheres and the height of the capsule distance 20 between the centers of the two spheres For instance if you want to create a capsule shape with a radius of 1 meter and the height of 2 meters you need to use the following code Create the capsule shape const rp3d CapsuleShape capsuleShape 1 0 2 0 As for the SphereShape the collision margin of the CapsuleShape is integrated into the capsule you define Therefore you do not need to worry about it and you cannot change it 10 6 Convex Mesh Shape The ConvexMeshShape class can be used to describe the shape of a convex mesh In order to create a conv
30. me For real time appli cations a time step of 5 seconds 60 Hz is usually used Using a smaller time step makes the simulation more precise but also more expensive to compute Here is how to create the Dynamics World Gravity vector rp3d Vector3 gravity 0 0 9 81 0 0 Time step in seconds rp3d decimal timeStep 1 0 60 0 Create the dynamics world rp3d DynamicsWorld world gravity timeStep 8 2 Customizing the Dynamics World 8 2 1 Solver parameters ReactPhysics3D uses an iterative solver to compute the contacts and joints For contacts there is a unique velocity solver and for joints there are a velocity and a position solver By default the number of iterations of the velocity solver is 10 and the number of iterations for the position solver is 5 It is possible to change the number of iterations for both solvers To do this you need to use the following two methods Change the number of iterations of the velocity solver world setNbIterationsVelocitySolver 15 10 Change the number of iterations of the position solver world setNblterationsPositionSolver 8 Increasing the number of iterations of the solvers will make the simulation more precise but also more expensive to compute Therefore you need to change those values only if needed 8 2 2 Sleeping The purpose of the sleeping technique is to deactivate resting bodies so that they are not simulated anymore This is
31. n margin for instance you can pass the length of the new collision margin in meters as a second parameter of the BoxShape constructor For instance if you want to use a collision margin of 1 centimeter for your box shape you can do it like this Create the box shape with a custom collision margin const rp3d BoxShape boxShape halfExtents 0 01 10 2 Sphere Shape The SphereShape class describes a sphere collision shape centered at the origin of the shape local space You only need to specify the radius of the sphere to create it For instance if you want to create a sphere shape with a radius of 2 meters you need to use the following code Create the sphere shape with a radius of 2m const rp3d SphereShape sphereShape 2 0 The collision margin of the SphereShape is integrated into the sphere you define Therefore you do not need to worry about it and you cannot change it 18 10 3 Cone Shape The ConeShape class describes a cone collision shape centered at the origin of the shape local space The cone is aligned along the Y axis In order to create a cone shape you need to give the radius of its base and its height along the Y axis For instance if you want to create a cone shape with a radius of 1 meter and the height of 3 meters you need to use the following code Create the cone shape const rp3d ConeShape coneShape 1 0 3 0 The ConeShape has a collision margin that is added
32. n the following code how to specify the information to create a slider joint 28 Anchor point in world space const rp3d Vector3 anchorPoint rp3d decimal 0 5 body2Position body1Position Slider atis in world space const rp3d Vector3 axis body2Position bodyiPosition Create the joint info object rp3d SliderJointInfo jointIinfo bodyi body2 anchorPoint axis Now it is possible to create the actual joint in the dynamics world using the DynamicsWorld createJoint method Note that this method will also return a pointer to the SliderJoint object that has been created internally You will then be able to use that pointer to change properties of the joint and also to destroy it at the end Here is how to create the joint in the world Create the slider joint in the dynamics world ells 8 Silicona Olla joint dynamic_cast lt rp3d SliderJoint gt world createJoint jointInfo 11 3 1 Limits It is also possible to control the range of the slider joint motion using limits The limits are disabled by default In order to use the limits when the joint is cre ated you first need to activate them using the isLimitEnabled variable of the SliderJointInfo class Then you need to specify the minimum and maximum translation limits in meters using the minTranslationLimit and maxTranslation Limit variables Note that the initial position of the two bodies when the joint is created corresponds to a
33. need to be in a correct position at the joint creation 25 Here is the code to create the BallAndSocket JointInfo object Anchor point in world space const rpd Vectors anchorPoint 250R OOO Create the joint info object rp3d BallAndSocketJointInfo jointInfo body1 body2 anchorPoint Now it is time to create the actual joint in the dynamics world using the DynamicsWorld createJoint method Note that this method will also return a pointer to the BallAndSocketJoint object that has been created internally You will then be able to use that pointer to change properties of the joint and also to destroy it at the end Here is how to create the joint in the world Create the joint in the dynamics world rp3d BallAndSocketJoint joint joint dynamic_cast lt rp3d BallAndSocketJoint gt world createJoint jointInfo 11 2 Hinge Joint The HingeJoint class describes a hinge joint or revolute joint between two rigid bodies The hinge joint only allows rotation around an anchor point and around a single axis the hinge axis This joint can be used to simulate doors or pendulums for instance In order to create a hinge joint you first need to create a HingeJointInfo ob ject with the necessary information You need to provide the pointers to the two rigid bodies the coordinates of the anchor point in world space and also the hinge rotation axis in world space The two bodies need to be in a correct position wh
34. nt Now it is possible to create the actual joint in the dynamics world using the DynamicsWorld createJoint method Note that this method will also return a pointer to the FixedJoint object that has been created internally You will then be able to use that pointer to change properties of the joint and also to destroy it at the end Here is how to create the joint in the world Create the fixed joint in the dynamics world DSC gS WaeSclI aimiges Joe joint dynamic_cast lt rp3d FixedJoint gt world createJoint oli E 11 5 Collision between the bodies of a Joint By default the two bodies involved in a joint are able to collide with each other However it is possible to disable the collision between the two bodies that are part of the joint To do it you simply need to set the variable isCollisionEnabled of the joint info object to false when you create the joint For instance when you create a HingeJointInfo object in order to construct a hinge joint you can disable the collision between the two bodies of the joint as in the following example Create the joint info object rp3d HingeJointInfo jointInfo body1 body2 anchorPoint axis Disable the collision between the bodies Joi nti nfor is Collis tomen able deals Create the joint in the dynamics world rp3d HingeJoint joint 31 joint dynamic_cast lt rp3d HingeJoint gt world createJoint jJjoimsinrto s 11 6 Destroying a Joint
35. oblems to run the examples 4 3 CMake Variables You can find bellow the different CMake variables that you can set before generating the makefiles CMAKE BUILD TYPE If this variable is set to Debug the library will be compiled in debugging mode This mode should be used during development stage to know where things might crash In debugging mode the library might run a bit slow due to all the debugging information However if this variable is set to Release no debugging information is stored and therefore it will run much faster This mode must be used when you compile the final release of you application COMPILE EXAMPLES If this variable is ON the examples of the library will be compiled The examples use OpenGL for rendering You will also need to have the GLEW library http glew sourceforge net to run them Take a look at the section 13 for more information about the examples COMPILE TESTS If this variable is ON the unit tests of the library will be compiled You will then be able to launch the tests to make sure that they are running fine on your system PROFILING ENABLED If this variable is ON the integrated profiler will col lect data while the application is running and the profiling report will be displayed in the console at the end of the application in the destructor of the DynamicsWorld class This might be useful to see what part of the react physics3d library takes time during its execution This variable must
36. pes only 11 Joints Joints are used to constraint the motion of the rigid bodies between each other A single joint represents a constraint between two rigid bodies When the motion of the first body of the joint is known the relative motion of the second body has at most six degrees of freedom three for the translation and three for the rotation The different joints can reduce the number of degrees of freedom between two rigid bodies Some joints have limits to control the range of motion and some joints have mo tors to automatically move the bodies of the joint at a given speed 11 1 Ball and Socket Joint The BallAndSocketJoint class describes a ball and socket joint between two bod ies In a ball and socket joint the two bodies cannot translate with respect to each other However they can rotate freely around a common anchor point This joint has three degrees of freedom and can be used to simulate a chain of bodies for in stance In order to create a ball and socket joint you first need to create an instance of the BallAndSocket JointInfo class with the necessary information You need to provide the pointers to the two rigid bodies and also the coordinates of the anchor point in world space At the joint creation the world space anchor point will be converted into the local space of the two rigid bodies and then the joint will make sure that the two local space anchor points match in world space Therefore the two bodies
37. sents an object that you want to simulate in the world It has a mass a position an orientation and one or several collision shapes The Dynamics World will compute collisions between the bodies and will update their position and orientation accordingly at each time step You can also create joints between the bodies in the world In ReactPhysics3D the RigidBody class which inherits from the CollisionBody class is used to describe a Rigid Body 9 1 Creating a Rigid Body In order to create a Rigid Body you need to specify its transform The transform describes the initial position and orientation of the body in the world You need to create an instance of the Transform class with a vector describing the initial position and a quaternion for the initial orientation of the body You need to call the DynamicsWorld createRigidBody method to create a Rigid Body in the world previously created This method will return a pointer to the instance of the RigidBody object that has been created internally You will then be able to use that pointer to get or set values of the body 12 You can see in the following code how to create a Rigid Body in your world Initial position and orientation of the rigid body pode ectors AmaisPOesipiem O 0 SO O O rp3d Quaternion initOrientation rp3d Quaternion identity rp3d Transform transform initPosition initOrientation Create a rigid body in the world rp3d RigidBody body body
38. so the maximum allowed torque in Newton meters with the maxMotorTorque variable For instance here is how to enable the motor of the hinge joint when the joint is created Create the joint info object rp3d HingeJointInfo jointInfo body1 body2 anchorPoint axis Enable the motor of the joint J O1ntintorasMotorEnabled true Motor angular speed jointInfo motorSpeed PI 4 0 Maximum allowed torque jointInfo maxMotorTorque 10 0 Create the hinge joint in the dynamics world rp3d HingeJoint joint joint dynamic_cast lt rp3d HingeJoint gt world createJoint jointInfo It is also possible to use the HingeJoint enableMotor HingeJoint setMotorSpeed and HingeJoint setMaxMotorTorque meth ods to enable the motor of the joint after its creation See the APT documentation for more information 11 3 Slider Joint The SliderJoint class describes a slider joint or prismatic joint that only allows relative translation along a single direction It has a single degree of freedom and allows no relative rotation In order to create a slider joint you first need to specify the anchor point in world space and the slider axis direction in world space The constructor of the SliderJointInfo object needs two pointers to the bodies of the joint the anchor point and the axis direction Note that the two bodies have to be in a correct initial position when the joint is created You can see i
39. t maxFraction value to use If you return a fraction of 0 0 it means that the raycast should terminate If you return a fraction of 1 0 it indicates that the ray is not clipped and the ray cast should continue as if no hit occurred If you return the fraction in the parameter hitFraction value in the RaycastInfo object the current ray will be clipped to this fraction in the next queries If you return 1 0 it will ignore this ProxyShape and continue the ray cast Note that no assumption can be done about the order of the calls of the notifyRaycastHit method Here is an example about creating your own raycast callback class that inher its from the RaycastCallback class and how to override the notifyRaycastHit method Class WorldRaycastCallback class MyCallbackClass public rp3d RaycastCallback public virtual decimal notifyRaycastHit const RaycastInfo amp info Display the world hit point coordinates 33 SACO ES N E O O e Y eK IEG 5 Vere ILellP wali 528 lt lt lt info worldPoint y lt lt OO MIO 474 lt lt Sidcevenmdadee Vi keron o ROCCO OF 1 0 EO TOI Gh PETA return decimal 1 0 Bas 12 1 2 Raycast query in the world Now that you have your own raycast callback class you can use the raycast method to perform a ray casting test on a Collision World or a Dynamics World The first parameter of this method is a reference to the Ray object representing the ray you need to test in
40. tInfo 12 3 Ray casting against the proxy shape of a body You can also perform ray casting against a single specific Proxy Shape of a Collision Body or Rigid Body of the world To do this you need to use the ProxyShape raycast method of the given Proxy Shape This method takes two parameters The first one is a reference to the Ray object and the second one is a reference to the RaycastInfo object that will contain hit information if the ray hits the body This method re turns true if the ray hits the body The RaycastInfo object will only be valid if the returned value is true a hit occured The following example shows how to test ray intersection with a given Proxy Shape Create the ray rp3d Vector3 startPoint 1 2 10 rp3d Vector3 endPoint 1 2 20 Ray ray startPoint endPoint Create the raycast info object for the raycast result RaycastInfo raycastInfo Test raycasting against a proxy shape bool isHit proxyShape gt raycast ray raycastInfo 13 Examples You can find some demos in the examples folder of the ReactPhysics3D library Follow the instructions described in section 4 to compile the examples Note that OpenGL and the GLEW library are required to run those examples Studying the examples is a good way to understand how to use the ReactPhysics3D library All the examples require some command line arguments to be able to run them Do not forget to set them in your IDE Visu
41. tersection with The second parameter is a pointer to the object of your raycast callback object You can specify an optional third parameter which is the bit mask for collision filtering It can be used to raycast only against selected categories of proxy shapes as described in section 10 8 Create the ray podik e Vectora gtarthoine Gl y 2 10 rp3d Vector3 endPoint 1 2 20 Ray ray startPoint endPoint Create an instance of your callback class MyCallbackClass callbackObject Raycast test world gt raycast ray amp callbackObject 12 2 Ray casting against a single body You can also perform ray casting against a single specific Collision Body or Rigid Body of the world To do this you need to use the CollisionBody raycast method This method takes two parameters The first one is a reference to the Ray object and the second one is a reference to the RaycastInfo object that will contain hit information if the ray hits the body This method returns true if the ray hits the body The RaycastInfo object will only be valid if the returned value is true a hit occured The following example shows how test ray intersection with a body Create the ray Ep odes Vectors preto lL 2 10 rpod Vectors endPoint CTi ea ONE 34 Ray ray startPoint endPoint Create the raycast info object for the M TONGOL TEONE RaycastIinfo raycastInfo Raycast test bool isHit body gt raycast ray raycas
42. the body material setBounciness rp3d decimal 0 4 Change the friction coefficient of the body material setFrictionCoefficient rp3d decimal 0 2 9 2 4 Velocity Damping Damping is the effect of reducing the velocity of the rigid body during the sim ulation to simulate effects like air friction for instance By default no damping is applied However you can choose to damp the linear or and the angular ve locity of a rigid body For instance without angular damping a pendulum will never come to rest You need to use the RigidBody setLinearDamping and RigidBody setAngularDamping methods to change the damping values The damping value has to be positive and a value of zero means no damping at all 9 2 5 Sleeping As described in section 8 2 2 the sleeping technique is used to disable the simulation of resting bodies By default the bodies are allowed to sleep when they come to rest However if you do not want a given body to be put to sleep you can use the Body setIsAllowedToSleep method as in the next example 14 This rigid body cannot sleep rigidBody gt setIsAllowedToSleep false 9 2 6 Applying Force or Torque to a Rigid Body During the simulation you can apply a force or a torque to a given rigid body First you can apply a force to the center of mass of the rigid body using the RigidBody applyForceToCenter method You need to specify the force vector in Newton as a parameter I
43. thod the pointer will not be valid anymore and therefore you should not use it Note that you must destroy all the rigid bodies at the end of the simulation before you destroy the world When you destroy a rigid body that was part of a joint that joint will be automatically destroyed as well Here is how to destroy a rigid body Here world is an instance of the DynamicsWorld class and body is a RigidBody pointer Destroy the rigid body world destroyRigidBody body 16 10 Collision Shapes Once you have created a Collision Body or a Rigid Body in the world you need to add one or more collision shapes into it so that it is able to collide with other bod ies This section describes all the collision shapes available in the ReactPhysics3D library and how to use them The Collision Shapes are also the way to represent the mass of a Rigid Body Whenever you add a collision shape to a Rigid Body you need to specify the mass of the shape Then the Rigid Body will recompute its total mass its center of mass and its inertia tensor taking into account all its collision shapes Therefore you do not have to compute those things by yourself However if needed you can also specify your own center of mass or inertia tensor Note that the inertia tensor is a 3 x 3 matrix describing how the mass is distributed inside the rigid body which will be used to calculate its rotation The inertia tensor depends on the mass and the shape of the
44. to the cone dimension that you define Therefore the actual cone shape will be a little bit larger that the size you define It is recommended that you use the default margin In case you really need to change the collision margin of your cone shape if the dimension of your cone is small compared to the default collision margin for instance you can pass the length of the new collision margin in meters as a third parameter of the ConeShape constructor For instance if you want to use a collision margin of 1 centimeter for your cone shape you can do it like this Create the cone shape with a custom collision margin const rp3d ConeShape coneShape 1 0 3 0 0 01 10 4 Cylinder Shape The CylinderShape class describes a cylinder collision shape centered at the origin of the shape local space The cylinder is aligned along the Y axis In order to create a cylinder shape you need to specify the radius of its base and its height along the Y axis For instance if you want to create a cylinder shape with a radius of 1 meter and the height of 3 meters you need to use the following code 19 Create the cylinder shape const rp3d Cylinder cylinderShape 1 0 3 0 The CylinderShape has a collision margin that is added to the cylinder dimen sion that you define Therefore the actual cylinder shape will be a little bit larger that the one you define It is recommended that you use the default margin In case you real
45. translation of zero Therefore the minimum limit must be smaller or equal to zero and the maximum limit must be larger or equal to zero You can see in the following example how to set the limits when the slider joint is created Create the joint info object rp3d SliderJointInfo jointInfo bodyi body2 anchorPoint axis Enable the limits of the joint Joel eo y alada kedi mano E Minimum translation limit Om lilt Cy ma ra lao baaa oil iP Maximum translation limit 29 Joa lato merca ano bam ES ET Create the hinge joint in the dynamics world rT podio lider Jon ntk OS joint dynamic_cast lt rp3d SliderJoint gt world createJoint jointInfo You can also use the SliderJoint enableLimit SliderJoint setMinTranslationLimit and SliderJoint setMaxTranslationLimit methods to enable the limits of the joint after its creation See the API documentation for more information 11 3 2 Motor The slider joint also has a motor You can use it to translate the bodies along the slider axis at a given linear speed and such that the force applied to move the bodies does not exceed a maximum allowed force The motor is disabled by default If you want to use it when the joint is created you first have to activate it using the isMotorEnabled boolean variable of the SliderJointInfo object before you create the joint Then you need to specify the linear motor speed in meters seconds using the motorSpee
46. ways to use ReactPhysics3D The first one is to create bodies that you have to manually move so that you can test collision between them To do this you need to create a Collision World with several Collision Bodies in it The second way is to create bodies and let ReactPhysics3D simulate their motions automatically using the physics This is done by creating Rigid Bodies in a Dynam ics World instead In summary a Collision World is used to simply test collision between bodies that you have to manually move and a Dynamics World is used to create bodies that will be automatically moved using collisions joints and forces The CollisionWorld class represents a Collision World in the ReactPhysics3D library 6 1 Creating the Collision World If you only have to test collision between bodies the first thing to do is to create an instance of the CollisionWorld class Here is how to create a Collision World Create the collision world rp3d CollisionWorld world 6 2 Destroying the Collision World Do not forget to destroy the CollisionWorld instance at the end of your program in order to release the allocated memory If the object has been created statically it will be destroyed automatically at the end of the scope in which it has been created If the object has been created dynamically using the new operator you need to destroy it with the delete operator 7 Collision Bodies Once the Collision World has been created you can
47. xt frame to render in your applica tion you need to update the state of the world To do that you simply need to call this method 11 Update the world by taking a simulation step world update When the DynamicsWorld update method is called collision detection is per formed and the position and orientation of the bodies are updated accordingly After updating the world you will be able to get the updated position and orientation of the bodies for the next frame Make sure that you call the DynamicsWorld start method before calling the DynamicsWorld update method You can also use the DynamicsWorld stop method to stop the simulation You will then be able to start it again and continue updating it Note that you can get the elapsed time in seconds from the beginning of the physics simulation using the DynamicsWorld getPhysicsTime method This can be useful to create some animations 8 4 Destroying the Dynamics World Do not forget to destroy the DynamicsWorld instance at the end of your program in order to release the allocated memory If the object has been created statically it will automatically be destroyed at the end of the scope in which it has been created If the object has been created dynamically using the new operator you need to destroy it with the delete operator 9 Rigid Bodies Once the Dynamics World has been created you can create rigid bodies into the world A Rigid Body repre
48. y class that has been created internally You will then be able to use that pointer to get or set values of the body You can see in the following code how to create a Collision Body in the world Initial position and orientation of the collision body epode e Vectores lmitiresicion 0 0 8 00 0 0 rp3d Quaternion initOrientation rp3d Quaternion identity rp3d Transform transform initPosition initOrientation Create a collision body in the world rp3d CollisionBody body body world createCollisionBody transform 7 2 Moving a Collision Body Collision Body has to be moved manually in the world To do that you need to use the CollisionBody setTransform method to set a new position and new orientation to the body New position and orientation of the collision body rpod Vectors posa tion OUPS OO ODE rp3d Quaternion orientation rp3d Quaternion identity rp3d Transform newTransform position orientation Move the collision body body gt setTransform newTransform 7 3 Destroying a Collision Body In order to destroy a Collision Body from the world you need to use the CollisionWorld destroyCollisionBody method You need to use the pointer to the body you want to destroy in argument Note that after calling that method the pointer will not be valid anymore and therefore you should not use it Note that you must destroy all the bodies at the end of the simulation before you d

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