Does Bullet auto-remove bodies once settled?

Tagged: bullet, delete, physics, remove, simulation

This topic contains 5 replies, has 2 voices, and was last updated by DruggedBunny 1 year, 3 months ago.

Viewing 6 posts - 1 through 6 (of 6 total)

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January 15, 2018 at 12:25 am #12864

DruggedBunny

Participant

This little demo builds a wall of blocks, and if you hold B it applies a vertical force to all blocks.

If you press it before all blocks have settled, they rise up as expected.

However, if you just run it and let the blocks settle (leave for 5 seconds or so), they don’t respond to B, even though the list count shows all the objects are present.

If you run it and boost them into the air, then wait until all are settled (again, leave for around 5 seconds), they no longer respond.

As I see it, either something’s wrong in my logic (no way!!), or Bullet is auto-removing/deactivating the rigid bodies from the simulation 5 seconds or so after they’ve settled.

It’s not down to UpdateBoxes (this can be commented out) or rebuilding the wall via Space bar, as if you do nothing my PhysBox removal logic isn’t even activated.

EDIT: Fixed

#Import "<std>"
#Import "<mojo>"
#Import "<mojo3d>"
#Import "<bullet>"

Using std..
Using mojo..
Using mojo3d..

Const WALL_WIDTH:Int	= 10
Const WALL_HEIGHT:Int	= 5

Class PhysBox

	Class PhysParams
		Field mass:Float
		Field group:Short
		Field mask:Short
	End
	
	Field box:Boxf
	Field model:Model
	Field collider:BoxCollider
	Field body:RigidBody

	Field init:PhysParams
	 
	Method New (width:Float = 1, height:Float = 1, depth:Float = 1, mass:Float = 1, material:Material = Null, group:Int = 1, mask:Int = 1)

		' Store setup params for PhysBox.Start ()
		
		init = New PhysParams
		
		init.mass	= mass
		init.group	= group
		init.mask	= mask
		
		If Not material
			material = New PbrMaterial (Color.Red)
		Endif
		
		box					= New Boxf (-width * 0.5, -height * 0.5, -depth * 0.5, width * 0.5, height * 0.5, depth * 0.5)
		model				= Model.CreateBox (box, 1, 1, 1, material)

	End

	Method Start ()

		collider			= New BoxCollider (model)
		body				= New RigidBody (model)
 
		collider.Box		= box
		
		body.Mass			= init.mass
		body.CollisionGroup	= init.group
		body.CollisionMask	= init.mask
		
		body.btBody.setActivationState (bullet.DISABLE_DEACTIVATION)
		
		box					= Null
		init				= Null
		
	End
	 
	Method Move (x:Float, y:Float, z:Float)
		model.Move (x, y, z)
	End

	Method Rotate (pitch:Float, roll:Float, yaw:Float, localspace:Bool = False)
		model.Rotate (pitch, roll, yaw, localspace)
	End
	
End

Class Game Extends Window

	Const CAMERA_MOVE:Float = 0.05
	Const CAMERA_BOOST:Float = 4.0
	
	Field cam_boost:Float = 1.0
	 
	Field scene:Scene
	Field cam:Camera
	Field light:Light
	
	Field ground:PhysBox

	Field boxes:List <PhysBox>
	Field bullets:List <PhysBox>
	
	Method New (title:String, width:Int, height:Int, flags:WindowFlags)
 
		Super.New (title, width, height, flags)

		SwapInterval = 1
		
		CreateArena (15)
		
	End
	
	Method CreateArena:Void (ground_size:Float = 100)

		SeedRnd (Millisecs ())
		
		scene					= Scene.GetCurrent ()
		ground					= New PhysBox (ground_size, 1, ground_size, 0, New PbrMaterial (Color.Green * 0.25))
		cam						= New Camera
		light					= New Light
 
		scene.AmbientLight	= Color.White * 0.75
		scene.ClearColor	= Color.Sky * 0.75

		cam.FOV = 100
		cam.Move (0, 5, -15)
		
		ground.Start ()
		
		cam.Near				= 0.01
		cam.Far					= 1000
	
		light.CastsShadow		= True
		light.Range				= 1000

		light.Move (0, 20, 10)
		
		cam.PointAt (ground.model)
		light.PointAt (ground.model)

		boxes	= New List <PhysBox>
		bullets	= New List <PhysBox>

		BuildWall (WALL_WIDTH, WALL_HEIGHT)
		
	End

	Method BuildWall (width:Int, height:Int)
	
		For Local y:Int = 0 Until height
			For Local x:Int = 0 Until width
				
				Local color:Color = New Color (Rnd (0.4, 1.0), Rnd (0.4, 1.0), Rnd (0.4, 1.0))
				
				' Create new PhysBox...
				
				Local pb:PhysBox = New PhysBox (1, 1, 1, 1, New PbrMaterial (color))
				
				' Position PhysBox...
				
	 			pb.Move (x - (width / 2.0), y + 1, 0)
	
				boxes.Add (pb)
				
				' Start its physics...
				
				pb.Start ()
				
			Next
		Next

	End

	Method DropBox ()

		Local pb:PhysBox = New PhysBox (1, 1, 1, 1, New PbrMaterial (Color.Red))
		
		pb.Move (0, 50, 0)

		boxes.Add (pb)
		
		pb.Start ()

	End
	
	Method BumpWall ()

		Local vec:Vec3f = New Vec3f (0.0, 0.5, 0.0)
	
		'Local count:Int
		
		For Local pb:PhysBox = Eachin boxes
			'If Not pb.collider Then Print "No collider"
			'If Not pb.body Then Print "No body"
			pb.body.ApplyImpulse (vec)
			'Print "Body count: " + count
			'count = count + 1
		Next
		
		'Print Millisecs ()
		
	End
	
	Method UpdateBoxes ()

		For Local pb:PhysBox = Eachin boxes

			If pb.model.Y < -20

				pb.model.Scale = pb.model.Scale * 0.75

				If pb.model.Scale.x < 0.01
					pb.model.Destroy ()
					boxes.Remove (pb)
				Endif

			Endif

		Next

	End

	Method UpdateGame ()
		
		UpdateBoxes ()
		
		If Keyboard.KeyDown (Key.D)
			DropBox ()
		Endif
 	
		If Keyboard.KeyDown (Key.B)
			BumpWall ()
		Endif
 	
		If Keyboard.KeyHit (Key.Escape)
			App.Terminate ()
		Endif
 	
 		If Keyboard.KeyHit (Key.S)
			light.CastsShadow = Not light.CastsShadow
		Endif
	 
 		If Keyboard.KeyHit (Key.Space)
 			
 			For Local pb:PhysBox = Eachin boxes
				pb.model.Destroy ()
				boxes.Remove (pb)
			Next
			
			BuildWall (WALL_WIDTH, WALL_HEIGHT)
			
		Endif
	 
		If Keyboard.KeyDown (Key.LeftShift)
			cam_boost = CAMERA_BOOST
		Else
			cam_boost = 1.0
		Endif
		
		If Keyboard.KeyDown (Key.A)
			cam.Move (0.0, 0.0, CAMERA_MOVE * cam_boost)
		Endif
 
		If Keyboard.KeyDown (Key.Z)
			cam.Move (0.0, 0.0, -CAMERA_MOVE * cam_boost)
		Endif
 
		If Keyboard.KeyDown (Key.Left)
			cam.Rotate (0.0, 1.0, 0.0)
		Endif
 
		If Keyboard.KeyDown (Key.Right)
			cam.Rotate (0.0, -1.0, 0.0)
		Endif
 
		If Keyboard.KeyDown (Key.Up)
			cam.Rotate (1.0, 0.0, 0.0, True)
		Endif
 
		If Keyboard.KeyDown (Key.Down)
			cam.Rotate (-1.0, 0.0, 0.0, True)
		Endif
		
	End
 
	Method ShadowText:Void (canvas:Canvas, s:String, x:Float, y:Float)
		canvas.Color = Color.Black
		canvas.DrawText	(s, x + 1, y + 1)
		canvas.Color = Color.White
		canvas.DrawText	(s, x, y)
	End
 
	Method RenderText (canvas:Canvas)
		
		ShadowText (canvas, "FPS: " + App.FPS, 20.0, 20.0)
		ShadowText (canvas, "A/Z + Cursors to move camera", 20.0, 40.0)
		ShadowText (canvas, "SHIFT to boost", 20.0, 60.0)
		ShadowText (canvas, "SPACE to rebuild wall", 20.0, 80.0)
		ShadowText (canvas, "S to toggle shadows", 20.0, 100.0)
		ShadowText (canvas, "B to boost boxes", 20.0, 120.0)
 		ShadowText (canvas, "Boxes: " + boxes.Count (), 20.0, 160.0)
		
	End
	
	Method OnRender (canvas:Canvas) Override
 
		UpdateGame ()
		
		RequestRender ()
		
		scene.Update ()
		scene.Render (canvas, cam)
 
		RenderText (canvas)
		
	End
	
End
 
Function Run3D (title:String, width:Int, height:Int, flags:WindowFlags = WindowFlags.Center)
 
	New AppInstance
	New Game (title, width, height, flags)
 
	App.Run ()
 
End

Function Main ()
	Run3D ("3D Scene", 960, 540, WindowFlags.Center)		' 1/4 HD!
'	Run3D ("3D Scene", 1920, 1080, WindowFlags.Fullscreen) 
End

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#Import "<std>"

#Import "<mojo>"

#Import "<mojo3d>"

#Import "<bullet>"

Using std..

Using mojo..

Using mojo3d..

Const WALL_WIDTH:Int = 10

Const WALL_HEIGHT:Int = 5

Class PhysBox

Class PhysParams

Field mass:Float

Field group:Short

Field mask:Short

End

Field box:Boxf

Field model:Model

Field collider:BoxCollider

Field body:RigidBody

Field init:PhysParams

Method New (width:Float = 1, height:Float = 1, depth:Float = 1, mass:Float = 1, material:Material = Null, group:Int = 1, mask:Int = 1)

' Store setup params for PhysBox.Start ()

init = New PhysParams

init.mass = mass

init.group = group

init.mask = mask

If Not material

material = New PbrMaterial (Color.Red)

Endif

box = New Boxf (-width * 0.5, -height * 0.5, -depth * 0.5, width * 0.5, height * 0.5, depth * 0.5)

model = Model.CreateBox (box, 1, 1, 1, material)

End

Method Start ()

collider = New BoxCollider (model)

body = New RigidBody (model)

collider.Box = box

body.Mass = init.mass

body.CollisionGroup = init.group

body.CollisionMask = init.mask

body.btBody.setActivationState (bullet.DISABLE_DEACTIVATION)

box = Null

init = Null

End

Method Move (x:Float, y:Float, z:Float)

model.Move (x, y, z)

End

Method Rotate (pitch:Float, roll:Float, yaw:Float, localspace:Bool = False)

model.Rotate (pitch, roll, yaw, localspace)

End

Class Game Extends Window

Const CAMERA_MOVE:Float = 0.05

Const CAMERA_BOOST:Float = 4.0

Field cam_boost:Float = 1.0

Field scene:Scene

Field cam:Camera

Field light:Light

Field ground:PhysBox

Field boxes:List <PhysBox>

Field bullets:List <PhysBox>

Method New (title:String, width:Int, height:Int, flags:WindowFlags)

Super.New (title, width, height, flags)

SwapInterval = 1

CreateArena (15)

End

Method CreateArena:Void (ground_size:Float = 100)

SeedRnd (Millisecs ())

scene = Scene.GetCurrent ()

ground = New PhysBox (ground_size, 1, ground_size, 0, New PbrMaterial (Color.Green * 0.25))

cam = New Camera

light = New Light

scene.AmbientLight = Color.White * 0.75

scene.ClearColor = Color.Sky * 0.75

cam.FOV = 100

cam.Move (0, 5, -15)

ground.Start ()

cam.Near = 0.01

cam.Far = 1000

light.CastsShadow = True

light.Range = 1000

light.Move (0, 20, 10)

cam.PointAt (ground.model)

light.PointAt (ground.model)

boxes = New List <PhysBox>

bullets = New List <PhysBox>

BuildWall (WALL_WIDTH, WALL_HEIGHT)

End

Method BuildWall (width:Int, height:Int)

For Local y:Int = 0 Until height

For Local x:Int = 0 Until width

Local color:Color = New Color (Rnd (0.4, 1.0), Rnd (0.4, 1.0), Rnd (0.4, 1.0))

' Create new PhysBox...

Local pb:PhysBox = New PhysBox (1, 1, 1, 1, New PbrMaterial (color))

' Position PhysBox...

pb.Move (x - (width / 2.0), y + 1, 0)

boxes.Add (pb)

' Start its physics...

pb.Start ()

End

Method DropBox ()

Local pb:PhysBox = New PhysBox (1, 1, 1, 1, New PbrMaterial (Color.Red))

pb.Move (0, 50, 0)

boxes.Add (pb)

pb.Start ()

End

Method BumpWall ()

Local vec:Vec3f = New Vec3f (0.0, 0.5, 0.0)

'Local count:Int

For Local pb:PhysBox = Eachin boxes

'If Not pb.collider Then Print "No collider"

'If Not pb.body Then Print "No body"

pb.body.ApplyImpulse (vec)

'Print "Body count: " + count

'count = count + 1

'Print Millisecs ()

End

Method UpdateBoxes ()

For Local pb:PhysBox = Eachin boxes

If pb.model.Y < -20

pb.model.Scale = pb.model.Scale * 0.75

If pb.model.Scale.x < 0.01

pb.model.Destroy ()

boxes.Remove (pb)

Endif

End

Method UpdateGame ()

UpdateBoxes ()

If Keyboard.KeyDown (Key.D)

DropBox ()

Endif

If Keyboard.KeyDown (Key.B)

BumpWall ()

Endif

If Keyboard.KeyHit (Key.Escape)

App.Terminate ()

Endif

If Keyboard.KeyHit (Key.S)

light.CastsShadow = Not light.CastsShadow

Endif

If Keyboard.KeyHit (Key.Space)

For Local pb:PhysBox = Eachin boxes

pb.model.Destroy ()

boxes.Remove (pb)

BuildWall (WALL_WIDTH, WALL_HEIGHT)

Endif

If Keyboard.KeyDown (Key.LeftShift)

cam_boost = CAMERA_BOOST

Else

cam_boost = 1.0

Endif

If Keyboard.KeyDown (Key.A)

cam.Move (0.0, 0.0, CAMERA_MOVE * cam_boost)

Endif

If Keyboard.KeyDown (Key.Z)

cam.Move (0.0, 0.0, -CAMERA_MOVE * cam_boost)

Endif

If Keyboard.KeyDown (Key.Left)

cam.Rotate (0.0, 1.0, 0.0)

Endif

If Keyboard.KeyDown (Key.Right)

cam.Rotate (0.0, -1.0, 0.0)

Endif

If Keyboard.KeyDown (Key.Up)

cam.Rotate (1.0, 0.0, 0.0, True)

Endif

If Keyboard.KeyDown (Key.Down)

cam.Rotate (-1.0, 0.0, 0.0, True)

Endif

End

Method ShadowText:Void (canvas:Canvas, s:String, x:Float, y:Float)

canvas.Color = Color.Black

canvas.DrawText (s, x + 1, y + 1)

canvas.Color = Color.White

canvas.DrawText (s, x, y)

End

Method RenderText (canvas:Canvas)

ShadowText (canvas, "FPS: " + App.FPS, 20.0, 20.0)

ShadowText (canvas, "A/Z + Cursors to move camera", 20.0, 40.0)

ShadowText (canvas, "SHIFT to boost", 20.0, 60.0)

ShadowText (canvas, "SPACE to rebuild wall", 20.0, 80.0)

ShadowText (canvas, "S to toggle shadows", 20.0, 100.0)

ShadowText (canvas, "B to boost boxes", 20.0, 120.0)

ShadowText (canvas, "Boxes: " + boxes.Count (), 20.0, 160.0)

End

Method OnRender (canvas:Canvas) Override

UpdateGame ()

RequestRender ()

scene.Update ()

scene.Render (canvas, cam)

RenderText (canvas)

End

Function Run3D (title:String, width:Int, height:Int, flags:WindowFlags = WindowFlags.Center)

New AppInstance

New Game (title, width, height, flags)

App.Run ()

End

Function Main ()

Run3D ("3D Scene", 960, 540, WindowFlags.Center) ' 1/4 HD!

' Run3D ("3D Scene", 1920, 1080, WindowFlags.Fullscreen)

End

January 15, 2018 at 12:30 am #12865

DruggedBunny

Participant

Actually, they’re (apparently) being deactivated, not removed from the simulation — if some stop responding but others are still active (you need some settled on the ground for 5 seconds, while some are still in the air, to create this situation), they can be brought back into play when hit by others.

I assume this is some default Bullet setup…

It can also be way less than 5 seconds…

(If all are settled and non-responsive, BTW, hit Space to rebuild the wall and thereby bring all boxes into play.)

January 15, 2018 at 12:39 am #12866

DruggedBunny

Participant

Updated code to drop new boxes on hitting D — run the program, let boxes settle for 5 seconds, confirm no longer responding to B, then drop a box so it collides. They will now respond to B.

January 15, 2018 at 7:07 am #12868

Simon Armstrong

Participant

according to this a call to btCollisionObject::activate() might be needed to get the behavior you are after

January 15, 2018 at 8:02 am #12869

DruggedBunny

Participant

Looks good, thanks, Simon… will see if we have access to it later!

January 15, 2018 at 11:36 pm #12873

DruggedBunny

Participant

OK, fixed this (thanks, skidracer!)…

1) Added #Import “<bullet>”

2) Added body.btBody.setActivationState (bullet.DISABLE_DEACTIVATION) in PhysBox.Start ()

I suppose it’s just because it’s early days, but guess RigidBody would eventually expand to give more direct access to the rest of this stuff — it took a little bit of digging around in the source, and I don’t know what might get made private over time.

(I get that making most bodies sleep is expected, BTW!)

Reading Bullet resources online today, hope to see constraints come in next, and I notice there’s a built-in vehicle class — would be awesome to see that in mojo3d as standard (with demo, cough)!

Stiil, early days and plenty to learn with what’s there…

Code at top updated.

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Does Bullet auto-remove bodies once settled?

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