Game Object Movement and Animation States

[Jackdaw]

Not often that I will post something, but here's a little something based from a chapter from the book 'Game Programming Patterns'. It's very primitive, and there are no comments, as the code is quite large.

There's also a BlitzMax version.

Demo video


You will need to download the warpsara-nohelmet-anim-sheet-alpha_1.png file from https://opengameart.org/content/space-sara and remain it heroine.png, and place it in a directory called heroine.data the has to be created at the same level as the code below.

Save the code below as heroine.cxs.

Code  cerberus Select Expand

Strict
Import mojo

Enumerate
	MOVE_NONE = 0,
	MOVE_LEFT = 1,
	MOVE_RIGHT,
	MOVE_JUMP,
	MOVE_JUMP_LEFT,
	MOVE_JUMP_RIGHT,
	MOVE_DUCK

Const FLAG_FACE:Int = $01
Const FLAG_RUNNING:Int = $02

Class CControllerInput
	Method Update:Void()
		Self._inputState = PRESS_NONE
		If KeyDown(KEY_S) _inputState |= PRESS_DUCK
		If KeyDown(KEY_W) _inputState |= PRESS_JUMP
		If KeyDown(KEY_A) _inputState |= PRESS_LEFT
		If KeyDown(KEY_D) _inputState |= PRESS_RIGHT
		If KeyDown(KEY_SPACE) _inputState |= PRESS_FIRE
	End

	Method GetAction:Int()
		If _inputState & PRESS_JUMP
			If _inputState & PRESS_LEFT
				Return MOVE_JUMP_LEFT
			Elseif _inputState & PRESS_RIGHT
				Return MOVE_JUMP_RIGHT
			Else
				Return MOVE_JUMP
			Endif
		ElseIf _inputState & PRESS_DUCK
			Return MOVE_DUCK
		ElseIf _inputState & PRESS_LEFT
			Return MOVE_LEFT
		ElseIf _inputState & PRESS_RIGHT
			Return MOVE_RIGHT
		EndIf
		Return MOVE_NONE	
	End
	
	Private
		Const PRESS_NONE:Int = $00
		Const PRESS_LEFT:Int = $01
		Const PRESS_RIGHT:Int = $02
		Const PRESS_JUMP:Int = $04
		Const PRESS_DUCK:Int = $08
		Const PRESS_FIRE:Int = $10
		Field _inputState:Int
End

Class CFrame
	Field _srcX:Int
	Field _srcY:Int
	Field _srcW:Int
	Field _srcH:Int
End

Class CAnimation
	Field _frames:CFrame[]
	Field _totalFrames:Int
	Field _frameRate:Float
	
	Method GetFrameRate:Float()
		Return _frameRate
	End
	
	Method GetFrameData:CFrame(currentFrame:Int)
		Return _frames[currentFrame]
	End
	
	Method AddFrames:Void(totalFrames:Int, frameRate:Float, column:Int, row:Int, frameWidth:Int = 48, frameHeight:Int = 48)
		Local cfl:Int = 0
		If _frames.Length() = 0
			_frames = _frames.Resize(totalFrames)
		Else
			cfl = _frames.Length()
			_frames = _frames.Resize(_frames.Length() + totalFrames)
		EndIf
		_frameRate = 1000 / frameRate
		_totalFrames = _frames.Length()
		Local i:Int = cfl, p:Int = column * frameWidth
		While i < totalFrames
			_frames[i] = New CFrame
			_frames[i]._srcX = p
			_frames[i]._srcY = row * frameHeight
			_frames[i]._srcW = frameWidth
			_frames[i]._srcH = frameHeight
			i += 1
			p += frameWidth
		Wend
	End
End

Class CHeroineState
	Field _strID:String
	Field _animationSequence:CAnimation
	Field _idle1:CHeroineIdleState

	Field _startRun:CHeroineStartRunState
	Field _startRunJump:CHeroineStartRunJumpState
	Field _runLoop:CHeroineRunLoopState
	Field _stopRun:CHeroineStopRunState

	Field _crouch:CHeroineCrouchState
	Field _stand:CHeroineStandUpState
	
	Field _startJump:CHeroineStandJumpState
	Field _jumpLoop:CHeroineJumpLoopState
	Field _stopJump:CHeroineStopJumpState

	Method HandleInput:Void(heroine:CHeroine, action:Int)
	End Method

	Method Update:Void(heroine:CHeroine)
		Local tick:Float = Millisecs()
		Local elapsed_time:Float = tick - heroine.GetLastFrameTime()
		
		If elapsed_time >= _animationSequence.GetFrameRate()
			heroine.SetLastFrameTime(tick)
			If heroine._currentFrame < heroine.FrameCountEnd()
				 heroine._currentFrame = heroine._currentFrame + 1
			Else
				heroine._currentFrame = 0
			EndIf
			Motion(heroine)
		Endif
	End Method
	
	Method Motion:Void(heroine:CHeroine)
		If heroine._xPos < 24 heroine._xPos = 24
		If heroine._xPos > DeviceWidth() - 25 heroine._xPos = DeviceWidth() - 25
	End Method

	Method GetCurrentFrameData:CFrame(heroine:CHeroine)
		Return heroine._state._animationSequence.GetFrameData(heroine._currentFrame)
	End Method
	
	Method GetTotalFrameCount:Int()
		Return _animationSequence._totalFrames
	End Method
	
	Method AddFrames:Void(totalFrames:Int, frameRate:Float, column:Int, row:Int, frameWidth:Int = 48, frameHeight:Int = 48)
		If _animationSequence = Null _animationSequence = New CAnimation()
		_animationSequence.AddFrames(totalFrames, frameRate, column, row, frameWidth, frameHeight)
	End Method

	Function CreateStates:CHeroineState()
		Local state:CHeroineState = New CHeroineState()
		state._idle1 = New CHeroineIdleState()
		state._crouch = New CHeroineCrouchState()
		state._stand = New CHeroineStandUpState()
		state._startRun = New CHeroineStartRunState()
		state._runLoop = New CHeroineRunLoopState()
		state._stopRun = New CHeroineStopRunState()
		state._startJump = New CHeroineStandJumpState()
		state._jumpLoop = New CHeroineJumpLoopState()
		state._stopJump = New CHeroineStopJumpState()
		state._startRunJump = New CHeroineStartRunJumpState()
		Return state
	End Function
End

Class CHeroine
	Method New()
#If CONFIG="debug"
			_atlas = LoadImage("heroine_debug.png")
#Else
			_atlas = LoadImage("heroine.png")
#Endif
		_states = CHeroineState.CreateStates()
		SetState(_states._idle1)
		_xSpeed = 0
		_ySpeed = 0
		_flags|=FLAG_FACE
	End
	
	Method HandleInput:Void(action:Int)
		_state.HandleInput(Self, action)
	End

	Method Update:Void()
		_state.Update(Self)
	End

	Method Render:Void()
		Local frame:CFrame = _state.GetCurrentFrameData(Self)
		PushMatrix()
		If _flags & FLAG_FACE
			Translate(-24,-24)
			DrawImageRect(_atlas, _xPos, _yPos, frame._srcX, frame._srcY, frame._srcW, frame._srcH)
		ElseIf _flags & FLAG_FACE = 0
			Translate(24,-24)
			DrawImageRect(_atlas, _xPos, _yPos, frame._srcX, frame._srcY, frame._srcW, frame._srcH, 0, -1,1)
		EndIf
		PopMatrix
	End
	
	Method SetState:Void(state:CHeroineState)
		_state = state
		_totalFrameCount = state.GetTotalFrameCount()
		_currentFrame = 0
	End
	
	Method TotalFrameCount:Int()
		Return _totalFrameCount
	End
	
	Method FrameCountEnd:Int()
		Return _totalFrameCount - 1
	End
	
	Method GetStateName:String()
		Return _state._strID
	End
	
	Method GetLastFrameTime:Float()
		Return _lastFrameTime
	End
	
	Method SetLastFrameTime:Void(value:Float)
		_lastFrameTime = value
	End
	
	Method FaceLeft:Void()
		_flags&=~FLAG_FACE
		_currentFrame = 0
		_xSpeed = -8.0
	End
	
	Method FaceRight:Void()
		_flags|=FLAG_FACE
		_currentFrame = 0
		_xSpeed = 8.0
	End
	
	Method EnableRunning:Void()
		_flags|=FLAG_RUNNING
	End
	
	Method DisableRunning:Void()
		_flags&=~FLAG_RUNNING
	End
	
	Global _xPos:Float
	Global _yPos:Float
	Global _xSpeed:Float
	Global _ySpeed:Float
	Global _flags:Int
	Global _currentFrame:Int
	Field _atlas:Image
	Field _states:CHeroineState
	Field _state:CHeroineState
	Field _totalFrameCount:Int
	Field _lastFrameTime:Float
End

Class CHeroineCrouchState Extends CHeroineState
	Method New()
		_strID = "CROUCH DOWN STATE"
		AddFrames(5, 16.5, 0, 13)
	End

	' Override the HandleInput to capture only the crouch action.
	Method HandleInput:Void(heroine:CHeroine, action:Int)
		' If the action input for ducking is no longer being pressed, set the action state to idle.
		If Not (action = MOVE_DUCK)
			If heroine._state = heroine._states._crouch heroine.SetState(heroine._states._stand)
		EndIf
	End

	' Update any action for the crouch state.
	' As this action state is not looped. It has to stop at the crouched position.
	Method Update:Void(heroine:CHeroine)
		Local tick:Int = Millisecs()
		Local elapsed_time:Int = tick - heroine.GetLastFrameTime()
		If elapsed_time >= _animationSequence.GetFrameRate()
			heroine.SetLastFrameTime(tick)		
			If heroine._currentFrame < heroine.FrameCountEnd() heroine._currentFrame = heroine._currentFrame + 1
		Endif
	End
End Class

' This is that animation for leaving the crouched state. 
Class CHeroineStandUpState Extends CHeroineState
	Method New()
		_strID = "STANB UP STATE"
		AddFrames(4, 16.5, 0, 14)
	End

	Method HandleInput:Void(heroine:CHeroine, action:Int)
	End

	Method Update:Void(heroine:CHeroine)
		Local tick:Int = Millisecs()
		Local elapsed_time:Int = tick - heroine.GetLastFrameTime()
		If elapsed_time >= _animationSequence.GetFrameRate()
			heroine.SetLastFrameTime(tick)	
			If heroine._currentFrame < heroine.FrameCountEnd()
				heroine._currentFrame = heroine._currentFrame + 1
			Else
				heroine.SetState(heroine._states._idle1)
			EndIf
		EndIf
	End
End

Class CHeroineIdleState Extends CHeroineState
	Method New()
		_strID = "IDLE STATE ONE"
		AddFrames(4, 4.5, 0, 1)
	End

	' Override the HandleInput to capture all actions.
	Method HandleInput:Void(heroine:CHeroine, action:Int)
		' The player is idling, so all inputs need to be checked.
		Select action
			Case MOVE_DUCK
				heroine.SetState(heroine._states._crouch)	
			Case MOVE_LEFT
				heroine.SetState(heroine._states._startRun)
				heroine.FaceLeft()
			Case MOVE_RIGHT
				heroine.SetState(heroine._states._startRun)
				heroine.FaceRight()
			Case MOVE_JUMP_LEFT
				heroine.SetState(heroine._states._startRunJump)
				heroine.FaceLeft()
				heroine.EnableRunning()
			Case MOVE_JUMP_RIGHT
				heroine.SetState(heroine._states._startRunJump)
				heroine.FaceRight()
				heroine.EnableRunning()
			Case MOVE_JUMP
				heroine.SetState(heroine._states._startJump)
		End Select
	End

	' Update any action for the idle state.
	Method Update:Void(heroine:CHeroine)
		Super.Update(heroine)
	End
End

Class CHeroineJumpLoopState Extends CHeroineState
	Method New()
		_strID = "JUMP LOOP STATE"
		AddFrames(4, 12.5, 0, 8)
	End

	Method HandleInput:Void(heroine:CHeroine, action:Int)
	End
	
	Method Update:Void(heroine:CHeroine)
		Local tick:Int = Millisecs()
		Local elapsed_time:Int = tick - heroine.GetLastFrameTime()
		If elapsed_time >= _animationSequence.GetFrameRate()	
			heroine.SetLastFrameTime(tick)			
			Motion(heroine)	
			If heroine._currentFrame < heroine.FrameCountEnd()
				heroine._currentFrame = heroine._currentFrame + 1
				If heroine._currentFrame > 2
				 	heroine._ySpeed = 8.0
				EndIf
			Else
				heroine.SetState(heroine._states._stopJump)
			EndIf
		EndIf
	End
	
	Method Motion:Void(heroine:CHeroine)
		heroine._yPos += heroine._ySpeed
		If heroine._flags & FLAG_RUNNING
			heroine._xPos += heroine._xSpeed
			Super.Motion(heroine)
		Endif
	End
End

Class CHeroineStartRunJumpState Extends CHeroineState
	Method New()
		_strID = "START RUN JUMP STATE"
		AddFrames(4, 12.5, 0, 6)
	End
	
	Method HandleInput:Void(heroine:CHeroine, action:Int)
	End
	
	Method Update:Void(heroine:CHeroine)
		Local tick:Float = Millisecs()
		Local elapsed_time:Float = tick - heroine.GetLastFrameTime()
		If elapsed_time >= _animationSequence.GetFrameRate()
			heroine.SetLastFrameTime(tick)
			If heroine._currentFrame < heroine.FrameCountEnd()
				heroine._currentFrame = heroine._currentFrame + 1
				If heroine._currentFrame > 0 heroine._ySpeed = -8.0
			Else
				heroine.SetState(heroine._states._jumpLoop)
				heroine._ySpeed = 0.0
			EndIf
			Motion(heroine)
		EndIf
	End
	
	Method Motion:Void(heroine:CHeroine)
		heroine._yPos += heroine._ySpeed
		If heroine._flags & FLAG_RUNNING
			heroine._xPos += heroine._xSpeed
			Super.Motion(heroine)
		Endif
	End
End

Class CHeroineStartRunState Extends CHeroineState
	Method New()
		_strID = "START RUN STATE"
		AddFrames(1, 12.5, 0, 3)
	End

	Method HandleInput:Void(heroine:CHeroine, action:Int)
		Select action
			Case MOVE_LEFT
				If (heroine._flags & FLAG_FACE)
					heroine.FaceLeft()
				Else
					heroine.EnableRunning()
				EndIf			
			Case MOVE_RIGHT
				If (heroine._flags & FLAG_FACE) = 0
					heroine.FaceRight()
				Else
					heroine.EnableRunning()
				EndIf	
			Case MOVE_JUMP_LEFT
				heroine.SetState(heroine._states._startRunJump)
				heroine.EnableRunning()
			Case MOVE_JUMP_RIGHT
				heroine.SetState(heroine._states._startRunJump)
				heroine.EnableRunning()
			Default
				heroine.SetState(heroine._states._stopRun)
				heroine.DisableRunning()
		End Select
	End
	
	Method Update:Void(heroine:CHeroine)
		Local tick:Int = Millisecs()
		Local elapsed_time:Int = tick - heroine.GetLastFrameTime()
		If elapsed_time >= _animationSequence.GetFrameRate()
			heroine.SetLastFrameTime(tick)	
			If heroine._currentFrame > heroine.FrameCountEnd()
				heroine._currentFrame = heroine._currentFrame + 1
			Else
				heroine.SetState(heroine._states._runLoop)
			EndIf
			Motion(heroine)	
		Endif
	End
	
	Method Motion:Void(heroine:CHeroine)
		If heroine._xPos > 23 And heroine._xPos < DeviceWidth() - 24 heroine._xPos += heroine._xSpeed
		Super.Motion(heroine)
	End
End

Class CHeroineRunLoopState Extends CHeroineState
	Method New()
		_strID = "RUN STATE"
		AddFrames(10, 12.5, 0, 4)
	End

	' the HandleInput to capture all actions.
	Method HandleInput:Void(heroine:CHeroine, action:Int)
		Select action
			Case MOVE_LEFT
				If (heroine._flags & FLAG_FACE)
					heroine.FaceLeft()
				Else
					heroine._flags |= FLAG_RUNNING
				EndIf
			Case MOVE_RIGHT
				If (heroine._flags & FLAG_FACE) = 0
					heroine.FaceRight()
				Else
					heroine._flags |= FLAG_RUNNING
				EndIf
			Case MOVE_JUMP_LEFT
				heroine.SetState(heroine._states._startRunJump)
				heroine.FaceLeft()				
			Case MOVE_JUMP_RIGHT
				heroine.SetState(heroine._states._startRunJump)
				heroine.FaceRight()
			Default
				heroine.SetState(heroine._states._stopRun)
				heroine.DisableRunning()
		End Select
		
	End

	Method Update:Void(heroine:CHeroine)
		If heroine._flags & FLAG_RUNNING
			Local tick:Int = Millisecs()
			Local elapsed_time:Int = tick - heroine.GetLastFrameTime()
			If elapsed_time >= _animationSequence.GetFrameRate()
				heroine.SetLastFrameTime(tick)
				If heroine._currentFrame < heroine.FrameCountEnd()
					heroine._currentFrame = heroine._currentFrame + 1
				Else
					heroine._currentFrame = 0
				EndIf
				Motion(heroine)
			EndIf
		EndIf
	End
	
	Method Motion:Void(heroine:CHeroine)
		If heroine._xPos > 23 And heroine._xPos < DeviceWidth() - 24 heroine._xPos += heroine._xSpeed
		Super.Motion(heroine)
	End
End

Class CHeroineStopRunState Extends CHeroineState
	 Method New()
		_strID = "STOP RUN STATE"
		AddFrames(3, 12.5, 0, 5)
	 End
	 
	 Method HandleInput:Void(heroine:CHeroine, action:Int)	
	 End
	 
	 Method Update:Void(heroine:CHeroine)
		Local tick:Int = Millisecs()
		Local elapsed_time:Int = tick - heroine.GetLastFrameTime()
		If elapsed_time >= _animationSequence.GetFrameRate()
			heroine.SetLastFrameTime(tick)
			If heroine._currentFrame > heroine.FrameCountEnd()
				heroine._currentFrame = heroine._currentFrame + 1
			Else
				heroine.SetState(heroine._states._idle1)
				heroine.DisableRunning()
			EndIf
			Motion(heroine)
		Endif
	 End
	 
	 Method Motion:Void(heroine:CHeroine)
		If heroine._xPos > 23 And heroine._xPos < DeviceWidth() - 24 heroine._xPos += heroine._xSpeed
		Super.Motion(heroine)
	End
End


Class CHeroineStandJumpState Extends CHeroineState
	Method New()
		_strID = "START STAND JUMP STATE"
		AddFrames(6, 12.5, 0, 7)
	End
	
	Method HandleInput:Void(heroine:CHeroine, action:Int)
	End
	
	Method Update:Void(heroine:CHeroine)
		Local tick:Float = Millisecs()
		Local elapsed_time:Float = tick - heroine.GetLastFrameTime()
		If elapsed_time >= _animationSequence.GetFrameRate()
			heroine.SetLastFrameTime(tick)
			If heroine._currentFrame < heroine.FrameCountEnd()
				heroine._currentFrame = heroine._currentFrame + 1
				If heroine._currentFrame > 2 heroine._ySpeed = -8.0
			Else
				heroine.SetState(heroine._states._jumpLoop)
				heroine._ySpeed = 0.0
			EndIf
			Motion(heroine)		
		EndIf
	End
	
	Method Motion:Void(heroine:CHeroine)
		heroine._yPos += heroine._ySpeed
	End
	
End

Class CHeroineStopJumpState Extends CHeroineState
	Method New()
		_strID = "STOP JUMP STATE"
		AddFrames(2, 12.5, 0, 9)
	End
	
	Method HandleInput:Void(heroine:CHeroine, action:Int)
	End
	
	Method Update:Void(heroine:CHeroine)
		Local tick:Float = Millisecs()
		Local elapsed_time:Float = tick - heroine.GetLastFrameTime()
		If elapsed_time >= _animationSequence.GetFrameRate()
			heroine.SetLastFrameTime(tick)
			Motion(heroine)
			If heroine._currentFrame < heroine.FrameCountEnd()
				heroine._currentFrame = heroine._currentFrame + 1
			Else
				heroine.SetState(heroine._states._idle1)
				heroine._ySpeed = 0.0
				heroine.DisableRunning()
			EndIf
		EndIf
	End
	
	Method Motion:Void(heroine:CHeroine)
		heroine._yPos += heroine._ySpeed
		If heroine._flags & FLAG_RUNNING
			heroine._xPos += heroine._xSpeed
			Super.Motion(heroine)
		Endif
	End
End

#If TARGET="html"
#HTML5_CANVAS_WIDTH=800
#HTML5_CANVAS_HEIGHT=600
#Endif

Function Main:Int()
	New CGame()
	Return 0
End

Class CGame Extends App
	Method OnCreate:Int()
#If TARGET<>"html"
		SetDeviceWindow(800, 600, 4)
#Endif
		SetUpdateRate(60)
		player = New CHeroine()
		player._xPos = DeviceWidth() / 2
		player._yPos = DeviceHeight() / 2
		
		controls = New CControllerInput()
		Return 0
	End
	
	Method OnUpdate:Int()
#If TARGET="glfw"
		If KeyDown(KEY_ESCAPE) EndApp()
#Endif
		controls.Update()
		player.HandleInput(controls.GetAction())
		player.Update()
		Return 0
	End
	
	Method OnRender:Int()
		Cls
		DrawRect(0, (DeviceHeight() / 2) + 24, DeviceWidth(), 8)
		DrawText("EXAMPLE 001: ANIMATION STATES", 0, 0)
		DrawText("BASED ON STATES CHAPTER FROM: https://gameprogrammingpatterns.com/",0, 12)
		DrawText("MEDIA FROM: https://opengameart.org/content/space-sara", 0, 25)
		DrawText("HEROINE STATE: " + player.GetStateName(), 0, 38)
		DrawText("XPOS: " + player._xPos + " - YPOS: " + player._yPos, 0, 51)
		DrawText("KEYS: W,A,D,S AND ESCAPE TO QUIT", 0, 64)
		player.Render()
		Return 0
	End

	Field player:CHeroine
	Field controls:CControllerInput
End

[Jackdaw]

Okay. If you want to see a better example of a Cerberus-X project.
Then you can download the sources from here.

You will still need to download the image file linked above.

It's a shame that BlitzMax doesn't support method properties. It would make it a lot easier to work with.