SetPhysicsBodyTag body,tag

Parameters

body - live explicit physics body handle

tag - signed 32-bit application value

Description

Stores a signed 32-bit application tag on this body.

The default is zero. Tags do not alter native user data, wake bodies or affect simulation. Tags expire with the object and are not part of a native physics recording.

Ordinary accessors and setters reject stale or wrong-kind handles. Physics objects are owned by their world; deleting a body, entity tree or world also invalidates its dependent handles.

Requires Extended mode.

See also: CreatePhysicsBody, PhysicsBodyImpulseAt, StepPhysics.

Example

; SetPhysicsBodyTag Example
; -------------------------
; Requires Extended mode.

Graphics3D 640,480,0,2
SetBuffer BackBuffer()

Const PHYSICS_STATIC=0
Const PHYSICS_DYNAMIC=2
Const MAX_CRATES=20

SeedRnd MilliSecs()

camera=CreateCamera()
PositionEntity camera,0,5,-12
RotateEntity camera,15,0,0

light=CreateLight()
RotateEntity light,45,-30,0
AmbientLight 60,60,60

; An independent Box3D world with standard gravity
world=CreatePhysicsWorld()

; Blue static floor
ground=CreateCube()
ScaleEntity ground,6,0.5,6
PositionEntity ground,0,-0.5,0
EntityColor ground,80,160,255
ground_body=CreatePhysicsBody(world,ground,PHYSICS_STATIC)
ground_shape=PhysicsBodyBox(ground_body,12,1,12)

; A static hook, and a lamp that swings from it on a ball joint
hook=CreateCube()
ScaleEntity hook,0.2,0.2,0.2
PositionEntity hook,0,6,0
hook_body=CreatePhysicsBody(world,hook,PHYSICS_STATIC)
hook_shape=PhysicsBodyBox(hook_body,0.4,0.4,0.4)
lamp=CreateSphere(12)
ScaleMesh lamp,0.4,0.4,0.4
PositionEntity lamp,1.5,4,0
EntityColor lamp,255,230,120
lamp_body=CreatePhysicsBody(world,lamp,PHYSICS_DYNAMIC)
bulb_shape=PhysicsBodySphere(lamp_body,0.8)
cord=CreatePhysicsBallJoint(hook_body,lamp_body,0,6,0)

; The shade is a second shape on the lamp's body
shade=CreateCone(12,True,lamp)
ScaleEntity shade,0.6,0.3,0.6
PositionEntity shade,0,0.5,0
shade_shape=PhysicsBodyBox(lamp_body,1.2,0.6,1.2,1,0,0.5,0)

Dim crates(MAX_CRATES)
Dim crate_bodies(MAX_CRATES)
Dim crate_shapes(MAX_CRATES)

While Not KeyDown(1)

    ; Space drops a crate
    If KeyHit(57) And count<MAX_CRATES
        count=count+1
        crates(count)=CreateCube()
        ScaleEntity crates(count),0.4,0.4,0.4
        EntityColor crates(count),255,120,70
        crate_bodies(count)=CreatePhysicsBody(world,crates(count),PHYSICS_DYNAMIC)
        crate_shapes(count)=PhysicsBodyBox(crate_bodies(count),0.8,0.8,0.8)
        ResetPhysicsBody crate_bodies(count),Rnd(-3,3),5,Rnd(-3,3),0,Rnd(Pi),0

        ; Number each crate with a body tag
        SetPhysicsBodyTag crate_bodies(count),count
    EndIf

    StepPhysics world,1.0/60.0,4

    ; Arrow keys move the camera
    If KeyDown(200) Then MoveEntity camera,0,0,0.1
    If KeyDown(208) Then MoveEntity camera,0,0,-0.1
    If KeyDown(203) Then TurnEntity camera,0,1,0
    If KeyDown(205) Then TurnEntity camera,0,-1,0

    RenderWorld

    ; Draw the lamp's cord from the hook
    CameraProject camera,0,6,0
    hook_x=ProjectedX()
    hook_y=ProjectedY()
    CameraProject camera,EntityX(lamp),EntityY(lamp),EntityZ(lamp)
    Line hook_x,hook_y,ProjectedX(),ProjectedY()

    Text 0,0,"Arrow keys: move camera   Space: drop a crate   Esc: exit"
    If count>0 Then Text 0,20,"The newest crate's tag is "+PhysicsBodyTag(crate_bodies(count))

    Flip

Wend

FreePhysicsWorld world
End

Index

Blitz3D+ Command Reference

SetPhysicsBodyTag body,tag

Parameters

Description

Example