Float and Double image rotation problem

[PakzParticipant]

When I use doubles for the rotation variable and the rotation modification variable the behaviour is like I want it to be, but when I change them to float the behaviour seems to be different. In one direction it does not rotate at all.

What can be the problem?

 

Monkey

#Import "<std>" #Import "<mojo>" Using std.. Using mojo.. Class item Field can:Canvas Field image:Image Field rot:Float 'change to double and it works Field rotspd:Float ',, ,, Method New() rot=Rnd(TwoPi) rotspd=Rnd(-0.2,0.2) image = New Image(64,64) can = New Canvas(image) image.Handle=New Vec2f( .5,.5 ) makeimage() End Method Method makeimage() can.Color = Color.None can.BlendMode=BlendMode.Opaque can.DrawRect(0,0,64,64) Local w:Int=Rnd(4,30) Local h:Int=Rnd(4,30) For Local i:=0 Until 10 Local a:Float=Rnd() can.Color = New Color(a,a,a) If Rnd() <0.1 Then Local a:Int=Rnd()*4 Select a Case 0 can.Color = New Color(Rnd(.2,1),0,0) Case 1 can.Color = New Color(0,Rnd(.2,1),0) Case 2 can.Color = New Color(0,0,Rnd(.2,1)) Case 3 can.Color = New Color(Rnd(.2,1),Rnd(.2,1),0) End Select End If can.DrawTriangle( New Vec2f(32+Rnd(-w,w),32+Rnd(-h,h)), New Vec2f(32+Rnd(-w,w),32+Rnd(-h,h)), New Vec2f(32+Rnd(-w,w),32+Rnd(-h,h))) Next can.Flush() End Method End Class Global myitem:List<item> = New List<item> Class MyWindow Extends Window Method New() For Local y:=0 To 3 For Local x:=0 To 3 myitem.AddLast(New item()) Next Next ClearColor = Color.Black End Method Method OnRender( canvas:Canvas ) Override App.RequestRender() ' Activate this method Local x:Int=0 Local y:Int=0 canvas.Color = Color.White For Local i:=Eachin myitem canvas.DrawImage(i.image,x*120+96,y*96+32+32,i.rot) i.rot+=i.rotspd If i.rot<0 Then i.rot=TwoPi If i.rot>TwoPi Then i.rot=0 x+=1 If x>3 Then y+=1;x=0 Next 'if press escape then end If Keyboard.KeyReleased(Key.Escape) Then App.Terminate() End Method End Class Function Main() New AppInstance New MyWindow App.Run() End Function

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#Import "<std>" #Import "<mojo>"   Using std.. Using mojo..   Class item Field can:Canvas Field image:Image Field rot:Float 'change to double and it works Field rotspd:Float ',, ,, Method New() rot=Rnd(TwoPi) rotspd=Rnd(-0.2,0.2) image = New Image(64,64) can = New Canvas(image) image.Handle=New Vec2f( .5,.5 ) makeimage()   End Method Method makeimage() can.Color = Color.None can.BlendMode=BlendMode.Opaque can.DrawRect(0,0,64,64) Local w:Int=Rnd(4,30) Local h:Int=Rnd(4,30) For Local i:=0 Until 10 Local a:Float=Rnd() can.Color = New Color(a,a,a) If Rnd() <0.1 Then Local a:Int=Rnd()*4 Select a Case 0 can.Color = New Color(Rnd(.2,1),0,0) Case 1 can.Color = New Color(0,Rnd(.2,1),0) Case 2 can.Color = New Color(0,0,Rnd(.2,1)) Case 3 can.Color = New Color(Rnd(.2,1),Rnd(.2,1),0) End Select End If can.DrawTriangle(   New Vec2f(32+Rnd(-w,w),32+Rnd(-h,h)), New Vec2f(32+Rnd(-w,w),32+Rnd(-h,h)), New Vec2f(32+Rnd(-w,w),32+Rnd(-h,h))) Next can.Flush() End Method End Class   Global myitem:List<item> = New List<item>   Class MyWindow Extends Window Method New() For Local y:=0 To 3 For Local x:=0 To 3 myitem.AddLast(New item()) Next Next ClearColor = Color.Black End Method Method OnRender( canvas:Canvas ) Override App.RequestRender() ' Activate this method Local x:Int=0 Local y:Int=0 canvas.Color = Color.White For Local i:=Eachin myitem canvas.DrawImage(i.image,x*120+96,y*96+32+32,i.rot) i.rot+=i.rotspd If i.rot<0 Then i.rot=TwoPi If i.rot>TwoPi Then i.rot=0 x+=1 If x>3 Then y+=1;x=0 Next 'if press escape then end If Keyboard.KeyReleased(Key.Escape) Then App.Terminate() End Method End Class   Function Main() New AppInstance New MyWindow App.Run() End Function

[arpieParticipant]

This is because TwoPi is a Double.

On line 71, if rot < 0, rot is set to TwoPi (implicit cast from Double to Float) but on line 72 you then compare a Float with a Double.  It looks like they are being implicitly cast to Doubles before being compared and so rot is rounded to be slightly larger than TwoPi… and gets set back to zero.

Try changing line 72 to :

If i.rot > Cast<Float>(TwoPi) Then i.rot=0

Or define your own variable TwoPiF (or whatever) as a Float if you don’t like using an explicit cast.

[PakzParticipant]

Thank you ! That solved it.

[Author]

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