; FreePhysicsWorld Example
; ------------------------
; Requires Extended mode.

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

Const PHYSICS_STATIC=0
Const PHYSICS_DYNAMIC=2

camera=CreateCamera()
PositionEntity camera,0,3,-9

light=CreateLight()
RotateEntity light,45,-30,0
AmbientLight 50,50,50

; Independent Box3D world with Earth-like gravity
world=CreatePhysicsWorld()
PhysicsGravity world,0,-9.81,0

; Blue static ground slab
ground=CreateCube()
ScaleEntity ground,4,0.5,4
PositionEntity ground,0,-0.5,0,True
EntityColor ground,80,160,255
ground_body=CreatePhysicsBody(world,ground,PHYSICS_STATIC)
ground_shape=PhysicsBodyBox(ground_body,8,1,8,0)

; Orange crate bouncing under physics control
crate=CreateCube()
ScaleEntity crate,0.5,0.5,0.5
PositionEntity crate,0,3,0,True
EntityColor crate,255,120,70
crate_body=CreatePhysicsBody(world,crate,PHYSICS_DYNAMIC)
crate_shape=PhysicsBodyBox(crate_body,1,1,1,1)
PhysicsShapeRestitution crate_shape,0.5

While Not KeyDown(1)

    ; Space frees the whole world, or rebuilds it from scratch
    If KeyHit(57)
        If world<>0
            ; Free the world - every body and shape dies with it
            FreePhysicsWorld world
            world=0
            ground_body=0
            ground_shape=0
            crate_body=0
            crate_shape=0
            EntityColor crate,80,220,120
        Else
            ; Build a fresh world and new bodies for the surviving entities
            world=CreatePhysicsWorld()
            PhysicsGravity world,0,-9.81,0
            ground_body=CreatePhysicsBody(world,ground,PHYSICS_STATIC)
            ground_shape=PhysicsBodyBox(ground_body,8,1,8,0)
            PositionEntity crate,0,3,0,True
            RotateEntity crate,0,0,0
            crate_body=CreatePhysicsBody(world,crate,PHYSICS_DYNAMIC)
            crate_shape=PhysicsBodyBox(crate_body,1,1,1,1)
            PhysicsShapeRestitution crate_shape,0.5
            EntityColor crate,255,120,70
        EndIf
    EndIf

    ; Only step the simulation while the world exists
    If world<>0 Then StepPhysics world,1.0/60.0,4

    ; The entities survive the freed world - spin the crate to prove it
    If world=0 Then TurnEntity crate,0,2,0

    ; 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

    Text 0,0,"Arrow keys: move camera   Space: free / rebuild world   Esc: exit"
    If world<>0
        Text 0,20,"World handle: "+world+"   (simulating)"
    Else
        Text 0,20,"World freed - the green entity remains alive"
    EndIf

    Flip

Wend

If world<>0 Then FreePhysicsWorld world
FreeEntity crate
FreeEntity ground
End