Michael Fabian Dirks
158 lines
4.2 KiB
BlitzBasic
158 lines
4.2 KiB
BlitzBasic
; ---------------------------------------------------------------------------- ;
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; Example 4 - Callbacks
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; ---------------------------------------------------------------------------- ;
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; License: Creative Commons Attribution 2.0
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; Author: Michael Fabian Dirks<michael.dirks@realitybends.de>
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; Prerequisite: Example 4
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; Now that we have learned how to use functions, let's go for something really
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; advanced - Callbacks! We can use these to practically fake a OOP language.
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Include "Example_Shared.bb"
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ExampleInit()
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; Let's create a Type to hold our generic object that only contains callback and
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; a pointer to the type object. This allows us to have a generic interface that
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; takes BObject and whatever type-object the user wants and returns weether or
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; not the BObject should be destroyed.
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Type BObject
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Field DataCallback
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Field DataValue%
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End Type
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; Our Update loop looks like this, there's not much to do - after all we have
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; the callbacks to do the dirty work for us.
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Function BObjectUpdate()
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Local Obj.BObject
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For Obj.BObject = Each BObject
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; Check if the Callback and Value is set.
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If Obj\DataCallback <> 0 And Obj\DataValue <> 0 Then
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; Our Callback tells us when we need to dispose of an object.
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If BlitzPointer_CallFunctionIII(Obj\DataCallback, Int(Obj), Obj\DataValue)
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Delete Obj
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EndIf
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Else
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Delete Obj
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EndIf
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Next
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End Function
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; We'll have two different sub-objects:
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; * BCube - Cubes with movement
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; * BSphere - Randomly colored spheres
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; BCube - Spawned when we press '1'
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Type BCube
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Field Entity
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Field PosX#, PosY#, PosZ#
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Field Time
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End Type
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; Our Callback for BCube - relatively simple.
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Global fpBCubeCallback = 0
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Function BCubeCallback%(Obj.BObject, Cube.BCube)
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If fpBCubeCallback = 0 Then
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fpBCubeCallback = BlitzPointer_GetFunctionPointer()
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Return
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EndIf
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Local Prc# = 1.0 - ((MilliSecs() - Cube\Time) / 5000.0)
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PositionEntity Cube\Entity, Cube\PosX, Cos(Cube\PosX + Prc * 360) * Sin(Cos(Cube\PosZ) * 180 + Prc * 360) * 50, Cube\PosZ
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EntityAlpha Cube\Entity, Prc
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If Prc < 0.0 Then
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FreeEntity Cube\Entity
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Delete Cube
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Return True
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EndIf
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Return False
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End Function
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BCubeCallback(Null, Null)
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Function BCubeCreate.BObject(X#, Y#, Z#)
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Local Obj.BObject = New BObject
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Obj\DataCallback = fpBCubeCallback
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Local Cube.BCube = New BCube
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Cube\Entity = CreateCube()
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Cube\PosX = X
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Cube\PosY = Y
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Cube\PosZ = Z
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Cube\Time = MilliSecs()
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Obj\DataValue = Int(Cube)
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Return Obj
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End Function
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; Our BSphere implementation, spawned when pressing 2
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Type BSphere
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Field Entity
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Field StartColor[2]
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Field EndColor[2]
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Field Time
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End Type
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Global fpBSphereCallback = 0
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Function BSphereCallback%(Obj.BObject, Sphere.BSphere)
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If fpBSphereCallback = 0 Then
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fpBSphereCallback = BlitzPointer_GetFunctionPointer()
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Return
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EndIf
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Local Prc# = (MilliSecs() - Sphere\Time) / 5000.0
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EntityColor Sphere\Entity, Sphere\StartColor[0] * (1.0 - Prc) + Sphere\EndColor[0] * Prc, Sphere\StartColor[1] * (1.0 - Prc) + Sphere\EndColor[1] * Prc, Sphere\StartColor[2] * (1.0 - Prc) + Sphere\EndColor[2] * Prc
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EntityAlpha Sphere\Entity, 1.0 - Prc
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If Prc >= 1.0 Then
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FreeEntity Sphere\Entity
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Delete Sphere
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Return True
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EndIf
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Return False
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End Function
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BSphereCallback(Null, Null)
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Function BSphereCreate.BObject(X#, Y#, Z#)
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Local Obj.BObject = New BObject
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Obj\DataCallback = fpBSphereCallback
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Local Sphere.BSphere = New BSphere
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Sphere\Entity = CreateSphere(2)
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PositionEntity Sphere\Entity, X, Y, Z
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Sphere\StartColor[0] = Rand(0, 255)
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Sphere\StartColor[1] = Rand(0, 255)
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Sphere\StartColor[2] = Rand(0, 255)
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Sphere\EndColor[0] = Rand(0, 255)
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Sphere\EndColor[1] = Rand(0, 255)
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Sphere\EndColor[2] = Rand(0, 255)
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Sphere\Time = MilliSecs()
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Obj\DataValue = Int(Sphere)
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Return Obj
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End Function
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SeedRnd MilliSecs()
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While Not KeyHit(1)
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;'1' spawns a few instances of BCube
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If KeyHit(2) Then
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For X = -100 To 100 Step 10
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For Z = -100 To 100 Step 10
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BCubeCreate(X, 0, Z)
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Next
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Next
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EndIf
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;'2' spawns a few instances of BSphere
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If KeyHit(3) Then
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Local O# = Rnd(-360, 360)
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For R# = -180 To 180 Step 2.25
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BSphereCreate(Cos(R+O)*100, Sin(R * 90) * 10 + 10, Sin(R+O)*100)
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Next
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EndIf
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; We only need one function here, all other updates are done using callbacks.
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BObjectUpdate()
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ExampleUpdate()
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ExampleLoop()
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Wend
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;~IDEal Editor Parameters:
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;~C#Blitz3D |