Physics Engine Interface - Revision history

MakoBot: Robot: Replacing 'OpenSim' to 'OpenSimulator', which is the precise name

2012-03-04T06:54:09Z

Robot: Replacing 'OpenSim' to 'OpenSimulator', which is the precise name

MakoBot: Robot: Cosmetic changes

2012-03-04T03:54:59Z

Robot: Cosmetic changes

Fritigern: Reverted edits by Xadmin (Talk) to last version by Teravus

2011-09-14T10:30:10Z

Reverted edits by Xadmin (Talk) to last version by Teravus

Xadmin: /* PhysicsScene */

2011-09-14T07:33:57Z

‎PhysicsScene

Teravus: /* Fleshed out the PhysicsActor section a bit more */

2009-09-18T21:12:33Z

‎Fleshed out the PhysicsActor section a bit more

Show changes

Teravus: /* PhysicsScene */ Filled in a few more spots

2009-09-18T20:47:26Z

‎PhysicsScene: Filled in a few more spots

Rknop: /* PhysicsActor */

2009-09-18T20:24:48Z

‎PhysicsActor

Rknop: /* PhysicsScene */

2009-09-18T20:24:03Z

‎PhysicsScene

Rknop at 20:21, 18 September 2009

2009-09-18T20:21:47Z

Rknop at 20:20, 18 September 2009

2009-09-18T20:20:02Z

@@ Line 397: / Line 397: @@
 ;'''void SubscribeEvents(int ms)'''
-:I do not know what sorts of events the PhysicsActor sends... hopefully I'll update this if/when I figure that out! It looks like you can ask for OnPositionUpdate, OnVelocityUpdate, OnOrientationUpdate, OnRequestTerseUpdate, OnCollisionUpdate, and OnOutOfBounds... but I have yet to fully understand the OpenSim event system, so I may be speaking out of the side of my mouth here.
+:I do not know what sorts of events the PhysicsActor sends... hopefully I'll update this if/when I figure that out! It looks like you can ask for OnPositionUpdate, OnVelocityUpdate, OnOrientationUpdate, OnRequestTerseUpdate, OnCollisionUpdate, and OnOutOfBounds... but I have yet to fully understand the OpenSimulator event system, so I may be speaking out of the side of my mouth here.
 :This actually gets called when the Script engine script handles collision, collision_start, and collision_end events. &nbsp;&nbsp; The scene is requesting that the Physics Plugin send collision updates back to the scene every n Milliseconds.&nbsp; If it's 0, then it's Physics Plugin default.&nbsp; This also gets called for Avatar.&nbsp; PhysicsActor has an method called SendCollisionUpdate that needs to be called to send collision data (pairs) back to the scene.<br />

@@ Line 1: / Line 1: @@
 == Base Classes ==
-''Note: I ([[User:Rknop]]) am trying to figure this out by looking at some of the code; my main interest is the NewtonPlugin.  AS such, there are whole swaths of the physics engine, such as joints, that I have no clue about at the moment''
+''Note: I ([[User:Rknop]]) am trying to figure this out by looking at some of the code; my main interest is the NewtonPlugin. AS such, there are whole swaths of the physics engine, such as joints, that I have no clue about at the moment''
-The base classes for a physics module can be found in OpenSim.Region.Physics.Manager.  The physics module itself should be a subclass of Physics, e.g. OpenSim.Region.Physics.OdePlugin.
+The base classes for a physics module can be found in OpenSim.Region.Physics.Manager. The physics module itself should be a subclass of Physics, e.g. OpenSim.Region.Physics.OdePlugin.
 * '''<tt>PhysicsActor</tt>''' is the base class for both prims and avatars.
@@ Line 9: / Line 9: @@
 * (others)
-The Physics Scene doesn't access the Region Scene.  The region scene will tell the physics engine about prims and avatars, and will send updates to the physics engine.  It will then pull positions and velocities of objects and avatars out of the physics engine.
+The Physics Scene doesn't access the Region Scene. The region scene will tell the physics engine about prims and avatars, and will send updates to the physics engine. It will then pull positions and velocities of objects and avatars out of the physics engine.
 For the most part, the things that will be interfacing with the physics engine are the classes <tt>OpenSim.Region.Framework.Scenes.Scene</tt>, <tt>OpenSim.Region.Framework.Scenes.SceneObjectGroup</tt>, and <tt>OpenSim.Region.Framework.Scenes.SceneObjectPart</tt>
@@ Line 17: / Line 17: @@
 If you're writing a Physics engine named Foo, you need to write a class OpenSim.Region.Physics.FooPlugin with the following methods:
-* '''FooPlugin()''' &mdash; constructor
+* '''FooPlugin()''' — constructor
-* '''bool Init()''' &mdash; (not sure exactly when this is called.  return true)
+* '''bool Init()''' — (not sure exactly when this is called. return true)
-* '''PhysicsScene GetScene(String sceneIdentifier)''' &mdash; return a FooScene, which is derived from PhysicsScene
+* '''PhysicsScene GetScene(String sceneIdentifier)''' — return a FooScene, which is derived from PhysicsScene
-* '''string GetName()''' &mdash; return the name that folks can use in OpenSim.ini to select this physics engine
+* '''string GetName()''' — return the name that folks can use in OpenSim.ini to select this physics engine
-* '''Dispose()''' &mdash; destructor
+* '''Dispose()''' — destructor
-== PhysicsScene  ==
+== PhysicsScene ==
 Your class OpenSim.Region.Physics.FooScene must derive from OpenSim.Region.Physics.PhysicsScene. Members include:
@@ Line 110: / Line 110: @@
 :This is the core function. This gets called by the main loop when it wants the Physics engine to do its magic and propagate forward the positions and velocities of all the stuff it knows about. The physics engine should update the Position and Velocity members of the PhysicsActor class it knows about (those things that have been added to it by the methods above). '''Important:''' when the physics engine thinks that things have changed enough for any given prims that the surrounding scene should updates it's own idea about the positions and velocities of those prims, it should call the RequestPhysicsterseUpdate() method of the changed PhysicsActors(). (The safest, but slowest, way to do this is for Simulate() to call this for every physical prim it knows about every time it is called.)
-== PhysicsActor  ==
+== PhysicsActor ==
-PhysicsActor represents both prims and characters. You may want to make separate classes for the two. You can get away with this because PhysicsActors are actually created by PhysicsScene. Your subclass of PhysicsScene has different methods called when an avatar or a prim is added to the scene, returning a PhysicsActor. You can return the appropriate subclass in each case.&nbsp; Be aware, that these properties are not thread safe by default and multiple threads *will* reach in here.<br>
+PhysicsActor represents both prims and characters. You may want to make separate classes for the two. You can get away with this because PhysicsActors are actually created by PhysicsScene. Your subclass of PhysicsScene has different methods called when an avatar or a prim is added to the scene, returning a PhysicsActor. You can return the appropriate subclass in each case.&nbsp; Be aware, that these properties are not thread safe by default and multiple threads *will* reach in here.<br />
 Members:
@@ Line 143: / Line 143: @@
 ;'''PhysicsVector RotationalVelocity'''
-:Needs get and set Angular Velocity of the object being simulated<br>
+:Needs get and set Angular Velocity of the object being simulated<br />
@@ Line 149: / Line 149: @@
 ;'''PhysicsVector Acceleration'''
-:Needs get; there's no set method. The Linear Acceleration of the object<br>
+:Needs get; there's no set method. The Linear Acceleration of the object<br />
@@ Line 167: / Line 167: @@
 ;'''float Mass'''
-:Needs get; there is no set method at the moment.&nbsp;&nbsp; The scene reaches requests the mass from the physics engine here<br>
+:Needs get; there is no set method at the moment.&nbsp;&nbsp; The scene reaches requests the mass from the physics engine here<br />
@@ Line 191: / Line 191: @@
 ;'''bool ThrottleUpdates'''
-:Needs get and set. I'm not sure what this means, exactly.&nbsp; This informs the scene and physics engine to reduce the number of updates to save Resources.<br>
+:Needs get and set. I'm not sure what this means, exactly.&nbsp; This informs the scene and physics engine to reduce the number of updates to save Resources.<br />
@@ Line 197: / Line 197: @@
 ;'''bool IsColliding'''
-:Needs get and set. True if object is colliding with another object<br>
+:Needs get and set. True if object is colliding with another object<br />
@@ Line 203: / Line 203: @@
 ;'''bool CollidingGround'''
-:Needs get and set. True if object is colliding with the ground<br>
+:Needs get and set. True if object is colliding with the ground<br />
@@ Line 209: / Line 209: @@
 ;'''bool CollidingObj'''
-:Needs get and set True if object is colliding with another object (but not the ground)<br>
+:Needs get and set True if object is colliding with another object (but not the ground)<br />
@@ Line 221: / Line 221: @@
 ;'''PhysicsVector CenterOfMass&nbsp;'''
-:Just needs get. Returns the Center of Mass of the object.&nbsp;&nbsp; In most cases that will be &lt;0,0,0&gt;<br>
+:Just needs get. Returns the Center of Mass of the object.&nbsp;&nbsp; In most cases that will be &lt;0,0,0&gt;<br />
@@ Line 233: / Line 233: @@
 ;'''PrimitiveBaseShape Shape'''
-:Just needs set.&nbsp; When a user changes the type of object to simulate, Shape gets set by the scene. &nbsp; Going from a Cube, to a Sphere or Torus, for example.<br>
+:Just needs set.&nbsp; When a user changes the type of object to simulate, Shape gets set by the scene. &nbsp; Going from a Cube, to a Sphere or Torus, for example.<br />
@@ Line 314: / Line 314: @@
 ;'''bool SetAlwaysRun'''
-:Needs get and set. Avatar running -&gt; True, Else false<br>
+:Needs get and set. Avatar running -&gt; True, Else false<br />
@@ Line 359: / Line 359: @@
 ;'''PhysicsVector PIDTarget'''
-:Just needs set. A position to which an object is supposed to move. Correct!<br>
+:Just needs set. A position to which an object is supposed to move. Correct!<br />
@@ Line 399: / Line 399: @@
 :I do not know what sorts of events the PhysicsActor sends... hopefully I'll update this if/when I figure that out! It looks like you can ask for OnPositionUpdate, OnVelocityUpdate, OnOrientationUpdate, OnRequestTerseUpdate, OnCollisionUpdate, and OnOutOfBounds... but I have yet to fully understand the OpenSim event system, so I may be speaking out of the side of my mouth here.
-:This actually gets called when the Script engine script handles collision, collision_start, and collision_end events. &nbsp;&nbsp; The scene is requesting that the Physics Plugin send collision updates back to the scene every n Milliseconds.&nbsp; If it's 0, then it's Physics Plugin default.&nbsp; This also gets called for Avatar.&nbsp; PhysicsActor has an method called SendCollisionUpdate that needs to be called to send collision data (pairs) back to the scene.<br>
+:This actually gets called when the Script engine script handles collision, collision_start, and collision_end events. &nbsp;&nbsp; The scene is requesting that the Physics Plugin send collision updates back to the scene every n Milliseconds.&nbsp; If it's 0, then it's Physics Plugin default.&nbsp; This also gets called for Avatar.&nbsp; PhysicsActor has an method called SendCollisionUpdate that needs to be called to send collision data (pairs) back to the scene.<br />

@@ Line 109: / Line 109: @@
 ;'''public override float Simulate(float timestep)'''
 :This is the core function. This gets called by the main loop when it wants the Physics engine to do its magic and propagate forward the positions and velocities of all the stuff it knows about. The physics engine should update the Position and Velocity members of the PhysicsActor class it knows about (those things that have been added to it by the methods above). '''Important:''' when the physics engine thinks that things have changed enough for any given prims that the surrounding scene should updates it's own idea about the positions and velocities of those prims, it should call the RequestPhysicsterseUpdate() method of the changed PhysicsActors(). (The safest, but slowest, way to do this is for Simulate() to call this for every physical prim it knows about every time it is called.)
 == PhysicsActor  ==

@@ Line 109: / Line 109: @@
 ;'''public override float Simulate(float timestep)'''
 :This is the core function. This gets called by the main loop when it wants the Physics engine to do its magic and propagate forward the positions and velocities of all the stuff it knows about. The physics engine should update the Position and Velocity members of the PhysicsActor class it knows about (those things that have been added to it by the methods above). '''Important:''' when the physics engine thinks that things have changed enough for any given prims that the surrounding scene should updates it's own idea about the positions and velocities of those prims, it should call the RequestPhysicsterseUpdate() method of the changed PhysicsActors(). (The safest, but slowest, way to do this is for Simulate() to call this for every physical prim it knows about every time it is called.)
 == PhysicsActor  ==

@@ Line 23: / Line 23: @@
 * '''Dispose()''' &mdash; destructor
-== PhysicsScene ==
+== PhysicsScene  ==
-Your class OpenSim.Region.Physics.FooScene must derive from OpenSim.Region.Physics.PhysicsScene.  Members include:
+Your class OpenSim.Region.Physics.FooScene must derive from OpenSim.Region.Physics.PhysicsScene. Members include:
-<dt>'''public override void SetWaterLevel(float baseheight)'''
+;'''public override void Initialize(IMesher meshmerizer, IConfigSource config)'''
-<dt>'''public override PhysicsActor AddPrimShape(string primName, PrimitiveBaseShape pbs, PhysicsVector position, PhysicsVector size, Quarternion rotation, bool isPhysical)'''
+;'''public override PhysicsActor AddAvatar(string avName, PhysicsVector position, PhysicsVector size, bool isFlying)'''
-<dd>Like the previous one, but you've got the flag that tells you if it's physical or not.
+:Scene calls this method when adding an avatar to the physics scene or changing appearance
-<dt>'''public override void SetTerrain(float[] heightMap)'''
+;'''public override void SetWaterLevel(float baseheight)'''
-</dl>
+;'''public override void RemovePrim(PhysicsActor prim)'''
 == PhysicsActor ==

@@ Line 40: / Line 40: @@
 <dd> Like RemovePrim, but for avatars.
-<dt>'''public override void AddPrimShape(string primName, PrimitiveBaseShape pbs, PhysicsVector position, PhysicsVector size, Quarternion rotation)'''
+<dt>'''public override PhysicsActor AddPrimShape(string primName, PrimitiveBaseShape pbs, PhysicsVector position, PhysicsVector size, Quarternion rotation)'''
-<dd> Tells the physics engine to add a new prim it needs to keep track of.  This prim is ''not'' a physical prim, but as long as it's not phantom, physical objects may collide with it, and thus the physics engine (may) need to know about it.  (Unless the physics engine punts on collisions, as, for instance, NewtonPlugin does.)
+<dd> Tells the physics engine to add a new prim it needs to keep track of.  This prim is ''not'' a physical prim, but as long as it's not phantom, physical objects may collide with it, and thus the physics engine (may) need to know about it.  (Unless the physics engine punts on collisions, as, for instance, NewtonPlugin does.)  Comments in the code indicate that this method is slated to be removed....
-<dt>'''public override void AddPrimShape(string primName, PrimitiveBaseShape pbs, PhysicsVector position, PhysicsVector size, Quarternion rotation, bool isPhysical)'''
+<dt>'''public override PhysicsActor AddPrimShape(string primName, PrimitiveBaseShape pbs, PhysicsVector position, PhysicsVector size, Quarternion rotation, bool isPhysical)'''
 <dd>Like the previous one, but you've got the flag that tells you if it's physical or not.

← Older revision		Revision as of 20:21, 18 September 2009
Line 10:		Line 10:

	The Physics Scene doesn't access the Region Scene. The region scene will tell the physics engine about prims and avatars, and will send updates to the physics engine. It will then pull positions and velocities of objects and avatars out of the physics engine.		The Physics Scene doesn't access the Region Scene. The region scene will tell the physics engine about prims and avatars, and will send updates to the physics engine. It will then pull positions and velocities of objects and avatars out of the physics engine.
		+
		+	For the most part, the things that will be interfacing with the physics engine are the classes <tt>OpenSim.Region.Framework.Scenes.Scene</tt>, <tt>OpenSim.Region.Framework.Scenes.SceneObjectGroup</tt>, and <tt>OpenSim.Region.Framework.Scenes.SceneObjectPart</tt>

	== The Plugin Class ==		== The Plugin Class ==

← Older revision		Revision as of 20:20, 18 September 2009
Line 60:		Line 60:
	<dt>'''public override float Simulate(float timestep)'''		<dt>'''public override float Simulate(float timestep)'''
	<dd>This is the core function. This gets called by the main loop when it wants the Physics engine to do its magic and propagate forward the positions and velocities of all the stuff it knows about. The physics engine should update the Position and Velocity members of the PhysicsActor class it knows about (those things that have been added to it by the methods above). '''Important:''' when the physics engine thinks that things have changed enough for any given prims that the surrounding scene should updates it's own idea about the positions and velocities of those prims, it should call the RequestPhysicsterseUpdate() method of the changed PhysicsActors(). (The safest, but slowest, way to do this is for Simulate() to call this for every physical prim it knows about every time it is called.)		<dd>This is the core function. This gets called by the main loop when it wants the Physics engine to do its magic and propagate forward the positions and velocities of all the stuff it knows about. The physics engine should update the Position and Velocity members of the PhysicsActor class it knows about (those things that have been added to it by the methods above). '''Important:''' when the physics engine thinks that things have changed enough for any given prims that the surrounding scene should updates it's own idea about the positions and velocities of those prims, it should call the RequestPhysicsterseUpdate() method of the changed PhysicsActors(). (The safest, but slowest, way to do this is for Simulate() to call this for every physical prim it knows about every time it is called.)
		+
		+	</dl>
		+
		+	== PhysicsActor ==
		+
		+	PhysicsActor represents both prims and characters. You may want to make separate classes for the two.
		+
		+	Members:
		+
		+	<dl>
		+	<dt>'''int PhysicsActorType'''
		+	<dd>Needs get and set methods. Return ActorTypes.Prim or ActorTypes.Agent if it's a prim or an avatar.
		+
		+	<dt>'''bool IsPhysical'''
		+	<dd>Needs get and set
		+
		+	<dt>'''PhysicsVector Position'''
		+	<dd>Needs get and set. If an object is physical, the physics engine keeps the "real" position for that object. However, it's the surrounding scene's impression of the position that gets rendered and sent to the client. It will pull the position out of the physics engine by looking at this member, and tell the physics engine about any external changes in its position through this member. Note that the scene doesn't automatically pull out the position, but only when it thinks it needs to. You can call the RequestPhysicsterseUpdate() method of PhysicsActor to ask the Scene to update its position for any given PhysicsActor. (See PhysicsScene.Simulate() above.)
		+
		+	<dt>'''PhysicsVector Velocity'''
		+	<dd>Need get and set. Similar considerations to Position
		+
		+	<dt>'''PhysicsVector RotationalVelocity'''
		+	<dd>Needs get and set
		+
		+	<dt>'''PhysicsVector Acceleration'''
		+	<dd>Needs get; there's no set method.
		+
		+	<dt>'''void SetAcceleration(PhysicsVector accel)'''
		+	<dd>Do what you'd think Acceleration.set would do
		+
		+	<dt>'''PhysicsVector Size'''
		+	<dd>Needs get and set
		+
		+	<dt>'''float Mass'''
		+	<dd>Needs get; there is no set method at the moment
		+
		+	<dt>'''void SetMass(float mass)'''
		+	<dd>Instead of Mass.set
		+
		+	<dt>'''void SetMomentum(PhysicsVector momentum)'''
		+	<dd>I am disturbed that this exists in addition to Velocity.set and SetMass....
		+
		+	<dt>'''Quarternion Orientation'''
		+	<dd>Needs get and set
		+
		+	<dt>'''bool ThrottleUpdates'''
		+	<dd>Needs get and set. I'm not sure what this means, exactly.
		+
		+	<dt>'''bool IsColliding'''
		+	<dd>Needs get and set.
		+
		+	<dt>'''bool CollidingGround'''
		+	<dd>Needs get and set
		+
		+	<dt>'''bool CollidingObj'''
		+	<dd>Needs get and set
		+
		+	<dt>'''bool Stopped'''
		+	<dd>Just needs get
		+
		+	<dt>'''PhysicsVector CenterOfMass'''
		+	<dd>Just needs get
		+
		+	<dt>'''PhysicsVector GeometricCenter'''
		+	<dd>Just needs get
		+
		+	<dt>'''PrimitiveBaseShape Shape'''
		+	<dd>Just needs set
		+
		+	<dt>'''PhysicsVector Force'''
		+	<dd>Needs get and set. I ''think'' this is a steady force (in N) always acting on the object.
		+
		+	<dt>'''PhysicsVector Torque'''
		+	<dd>Needs get and set. Like Force, I think this is a steady torque operating on the object.
		+
		+	<dt>'''void AddForce(PhysicsVector force, bool pushforce)'''
		+	<dd>This should apply a one-time impulse to the object of magnitude "force" Newton-seconds. I am not sure what "pushforce" means....
		+
		+	<dt>'''void AddAngularForce(PhsyicsVector force, bool pushforce)'''
		+	<dd>A one-time angular impulse. I'm not sure the units, nor what pushforce means.
		+
		+	<dt>'''int VehicleType'''
		+	<dd>(I don't know anything about the vehicle code requirements)
		+
		+	<dt>'''void VehicleFloatParam(int param, float value)'''
		+
		+	<dt>'''void VehicleVectorParam(int param, PhysicsVector value)'''
		+
		+	<dt>'''void VehicleRotationParam(int param, Quarternion rotation)'''
		+
		+	<dt>'''void SetVoulumeDetect(int param)'''
		+	<dd>This is some weird mode that can be set via a LSL function
		+
		+	<dt>'''float Buoyancy'''
		+	<dd>Needs get and set
		+
		+	<dt>'''bool FloatOnWater'''
		+	<dd>Just needs set
		+
		+	<dt>'''float CollisionScore'''
		+	<dd>Needs get and set. I don't know what this is.
		+
		+	<dt>'''bool Flying'''
		+	<dd>Needs get and set
		+
		+	<dt>'''bool SetAlwaysRun'''
		+	<dd>Needs get and set
		+
		+	<dt>'''unit LocalID'''
		+	<dd>Needs set. I don't know what this is
		+
		+	<dt>'''bool Grabbed'''
		+	<dd>Needs set. I'm not sure what this is, but I'm guessing it's when you control-click on an object?
		+
		+	<dt>'''void link(PhysicsActor obj)'''
		+	<dd>I haven't delved into how linking works in the physics engine. I'm ''guessing'' that this says "link yourself to obj with obj as the root", but I could be wrong.
		+
		+	<dt>'''void delink()'''
		+
		+	<dt>'''void LockAngularMomentum(PhysicsVector axis)'''
		+
		+	<dt>'''bool Selected'''
		+	<dd>Just needs set
		+
		+	<dt>'''void CrossingFailure()'''
		+
		+	<dt>'''PhysicsVector PIDTarget'''
		+	<dd>Just needs set. I don't know what this is, but I'm guessing it's a place to which an object is supposed to move.
		+
		+	<dt>'''bool PIDActive'''
		+	<dd>Just needs set.
		+
		+	<dt>'''float PIDTau'''
		+	<dd>Just needs set. I'm guessing that this is the timescale (in seconds) in which the object should move to PIDTarget when it is set to be PID Active.
		+
		+	<dt>'''float PIDHoverHeight'''
		+
		+	<dt>'''float PIDHoverActive'''
		+
		+	<dt>'''PIDHoverType PIDHoverType'''
		+
		+	<dt>'''float PIDHoverTau'''
		+
		+	<dt>'''void SubscribeEvents(int ms)'''
		+	<dd>I do not know what sorts of events the PhysicsActor sends... hopefully I'll update this if/when I figure that out! It looks like you can ask for OnPositionUpdate, OnVelocityUpdate, OnOrientationUpdate, OnRequestTerseUpdate, OnCollisionUpdate, and OnOutOfBounds... but I have yet to fully understand the OpenSim event system, so I may be speaking out of the side of my mouth here.
		+
		+	<dt>'''bool SubscribedEvents()'''