[Math] Lerp Interpolations (Lerp, LerpDuration, LerpSpeed)

[coconParticipant]

One very important function is Lerp, this will allow you to transition from the source value to the target value using a more clean and predicable way, instead of changing it directly. For more advanced uses you might use a Tweening system instead, but in more simpler uses this will be it.

Monkey

#Import "<mojo>" Using mojo.. Using std.collections ' List Using std.random ' Rnd Using std.graphics ' Color Using std.time ' Millisecs Using std.geom ' Vec2f '________________________________________________________________ #rem monkeydoc Performs a linear interpolation between two values based on blending value. @param a The original value. @param b The target value. @param blend The blending percentage factor (normalized between 0.0 and 1.0). #end Function Lerp:Float(a:Float, b:Float, blend:Float) Return blend * (b - a) + a End #rem monkeydoc Performs a linear interpolation between two values based on a time duration. @param a The original value. @param b The target value. @param startTime The time at when the interpolation started in milliseconds. @param duration The time at when the interpolation will end in milliseconds. #end Function LerpDuration:Float(a:Float, b:Float, startTime:Int, duration:Int) Local elapsed := Cast<Float>(Millisecs()) - startTime Local progress := Cast<Float>(elapsed) / duration If elapsed >= duration Return b Return Lerp(a, b, progress) End #rem monkeydoc Performs a linear interpolation between two values based on a speed value. @param a The original value. @param b The target value. @param speed The speed factor at which the interpolation occurs. #end Function LerpSpeed:Float(a:Float, b:Float, speed:Float) Local diff := b - a speed = Abs(speed) If Abs(diff) < speed Then Return b Return a + speed * Sgn(diff) End '________________________________________________________________ Class MovableObject ' The position of the movable object. Field Position := New Vec2f ' The new position of the movable object. Field PositionNew := New Vec2f ' The starting position of the movable object, at the time new position is updated. Field PositionStart := New Vec2f Field TimeStart :Int ' Decoration Field DecorColor:Color Field DecorText:String Field DecorSize:Float ' Decoration Method New(text:String, x:Int, y:Int, s:Int, c:Color) Position = New Vec2f(x, y) PositionNew = New Vec2f(x, y) DecorText = text DecorSize = s DecorColor = c End Method SetNewPosition(x:Float, y:Float) PositionStart.X = Position.X PositionStart.Y = Position.Y PositionNew.X = x PositionNew.Y = y TimeStart = Millisecs() End Method UpdateSmooth() Position.X = Lerp(Position.X, PositionNew.X, 0.05) Position.Y = Lerp(Position.Y, PositionNew.Y, 0.05) End Method UpdateDuration(duration:Int = 2000) Position.X = LerpDuration(PositionStart.X, PositionNew.X, TimeStart, duration) Position.Y = LerpDuration(PositionStart.Y, PositionNew.Y, TimeStart, duration) End Method UpdateSpeed(speed:Float = 1.0) Position.X = LerpSpeed(Position.X, PositionNew.X, speed) Position.Y = LerpSpeed(Position.Y, PositionNew.Y, speed) End Method Draw(canvas:Canvas) canvas.Color = Color.White canvas.DrawText(DecorText, Position.X, Position.Y, -1, 0.5) canvas.Color = DecorColor canvas.DrawRect(Position.X - (DecorSize/2), Position.Y - (DecorSize/2), DecorSize, DecorSize) End Property GetStringPosition:String() Return Position.X + " " + Position.Y End Property GetStringPositionNew:String() Return PositionNew.X + " " + PositionNew.Y End End Class MyWindow Extends Window Field objects:List<MovableObject> Field obSmooth:MovableObject Field obDuration:MovableObject Field obSpeed:MovableObject Method New() ' Create the objects obSmooth = New MovableObject("Smooth", Width/2, Height/2, 50, New Color(0.9, 0.9, 0.0, 0.8)) obDuration = New MovableObject("Duration", Width/2, Height/2, 40, New Color(0.9, 0.0, 0.0, 0.8)) obSpeed = New MovableObject("Speed", Width/2, Height/2, 30, New Color(0.0, 0.0, 0.9, 0.8)) ' Add them to a list objects = New List<MovableObject> objects.AddLast(obSmooth) objects.AddLast(obDuration) objects.AddLast(obSpeed) End Method OnRender(canvas:Canvas) Override ' Update each of the movable objects in it's specific way. obSmooth.UpdateSmooth() obDuration.UpdateDuration() obSpeed.UpdateSpeed() App.RequestRender() ' Draw the objects canvas.Clear(Color.Black) For Local o := Eachin objects o.Draw(canvas) End ' Draw messages canvas.Color = Color.White canvas.DrawText("Press Left Mouse To Set Positions", 15, 15*1, 0, 0.5) canvas.DrawText("Press Left Mouse To Set Random Positions", 15, 15*2, 0, 0.5) End Method OnMouseEvent( event:MouseEvent ) Override If event.Type = EventType.MouseDown ' When there's a left mouse click set the new position of the objects. If event.Button = MouseButton.Left For Local o := Eachin objects o.SetNewPosition(event.Location.X, event.Location.Y) End ' When there's a right click set random positions. Elseif event.Button = MouseButton.Right For Local o := Eachin objects o.SetNewPosition(Rnd(Width), Rnd(Height)) End End End End End Function Main() New AppInstance New MyWindow App.Run() End

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#Import "<mojo>"   Using mojo.. Using std.collections ' List Using std.random ' Rnd Using std.graphics   ' Color Using std.time ' Millisecs Using std.geom ' Vec2f   '________________________________________________________________     #rem monkeydoc Performs a linear interpolation between two values based on blending value. @param a The original value. @param b The target value. @param blend The blending percentage factor (normalized between 0.0 and 1.0). #end Function Lerp:Float(a:Float, b:Float, blend:Float) Return blend * (b - a) + a End   #rem monkeydoc Performs a linear interpolation between two values based on a time duration. @param a The original value. @param b The target value. @param startTime The time at when the interpolation started in milliseconds. @param duration The time at when the interpolation will end in milliseconds. #end Function LerpDuration:Float(a:Float, b:Float, startTime:Int, duration:Int) Local elapsed := Cast<Float>(Millisecs()) - startTime Local progress := Cast<Float>(elapsed) / duration If elapsed >= duration Return b Return Lerp(a, b, progress) End   #rem monkeydoc Performs a linear interpolation between two values based on a speed value. @param a The original value. @param b The target value. @param speed The speed factor at which the interpolation occurs. #end Function LerpSpeed:Float(a:Float, b:Float, speed:Float) Local diff := b - a speed = Abs(speed) If Abs(diff) < speed Then Return b Return a + speed * Sgn(diff) End     '________________________________________________________________     Class MovableObject ' The position of the movable object. Field Position := New Vec2f ' The new position of the movable object. Field PositionNew := New Vec2f ' The starting position of the movable object, at the time new position is updated. Field PositionStart := New Vec2f Field TimeStart :Int   ' Decoration Field DecorColor:Color Field DecorText:String Field DecorSize:Float ' Decoration Method New(text:String, x:Int, y:Int, s:Int, c:Color) Position = New Vec2f(x, y) PositionNew = New Vec2f(x, y) DecorText = text DecorSize = s DecorColor = c End   Method SetNewPosition(x:Float, y:Float) PositionStart.X = Position.X PositionStart.Y = Position.Y PositionNew.X = x PositionNew.Y = y TimeStart = Millisecs() End Method UpdateSmooth() Position.X = Lerp(Position.X, PositionNew.X, 0.05) Position.Y = Lerp(Position.Y, PositionNew.Y, 0.05) End Method UpdateDuration(duration:Int = 2000) Position.X = LerpDuration(PositionStart.X, PositionNew.X, TimeStart, duration) Position.Y = LerpDuration(PositionStart.Y, PositionNew.Y, TimeStart, duration) End Method UpdateSpeed(speed:Float = 1.0) Position.X = LerpSpeed(Position.X, PositionNew.X, speed) Position.Y = LerpSpeed(Position.Y, PositionNew.Y, speed) End Method Draw(canvas:Canvas) canvas.Color = Color.White canvas.DrawText(DecorText, Position.X, Position.Y, -1, 0.5) canvas.Color = DecorColor canvas.DrawRect(Position.X - (DecorSize/2), Position.Y - (DecorSize/2), DecorSize, DecorSize) End Property GetStringPosition:String() Return Position.X + " " + Position.Y End Property GetStringPositionNew:String() Return PositionNew.X + " " + PositionNew.Y End End   Class MyWindow Extends Window Field objects:List<MovableObject> Field obSmooth:MovableObject Field obDuration:MovableObject Field obSpeed:MovableObject   Method New() ' Create the objects obSmooth = New MovableObject("Smooth", Width/2, Height/2, 50, New Color(0.9, 0.9, 0.0, 0.8)) obDuration = New MovableObject("Duration", Width/2, Height/2, 40, New Color(0.9, 0.0, 0.0, 0.8)) obSpeed = New MovableObject("Speed", Width/2, Height/2, 30, New Color(0.0, 0.0, 0.9, 0.8)) ' Add them to a list objects = New List<MovableObject> objects.AddLast(obSmooth) objects.AddLast(obDuration) objects.AddLast(obSpeed) End   Method OnRender(canvas:Canvas) Override ' Update each of the movable objects in it's specific way. obSmooth.UpdateSmooth() obDuration.UpdateDuration() obSpeed.UpdateSpeed() App.RequestRender() ' Draw the objects canvas.Clear(Color.Black) For Local o := Eachin objects o.Draw(canvas) End ' Draw messages canvas.Color = Color.White canvas.DrawText("Press Left Mouse To Set Positions", 15, 15*1, 0, 0.5) canvas.DrawText("Press Left Mouse To Set Random Positions", 15, 15*2, 0, 0.5) End Method OnMouseEvent( event:MouseEvent ) Override If event.Type = EventType.MouseDown ' When there's a left mouse click set the new position of the objects. If event.Button = MouseButton.Left For Local o := Eachin objects o.SetNewPosition(event.Location.X, event.Location.Y) End ' When there's a right click set random positions. Elseif event.Button = MouseButton.Right For Local o := Eachin objects o.SetNewPosition(Rnd(Width), Rnd(Height)) End End End End End   Function Main() New AppInstance New MyWindow App.Run() End

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