FlatRedBall
  • 🖥️Downloading FlatRedBall
  • 🏗️Building FlatRedBall From Source
    • Linking Games to FlatRedBall Engine Source
    • Linking FNA
  • ❓Need Help?
  • ✨FlatRedBall Features
  • 🎓Tutorials
    • Introduction To FlatRedBall
    • Quick Start Guide
    • Beefball - A Full FlatRedBall Tutorial Project
      • Creating a FlatRedBall Project
      • Creating an Entity
      • Creating a Screen
      • Controlling an Entity
      • Creating the Screen Collision
      • Advanced PlayerBall Controls
      • Creating the Puck Entity
      • Adding Multiple Players
      • Scoring and Restarting Rounds
      • Scoring Hud
      • Scoring Hud Logic
      • Adding Dashing
    • Platformer Tutorials
      • Platformer Basics
        • Creating an Entity
        • Controlling a Platformer Entity
        • Movement Values
        • Double Jump
      • Checkpoint and Level End
      • Climbing Ladders
      • Doors
      • GroundCollidedAgainst and Movement Values
      • Moving Platforms
      • Multiple Players
      • NPC Dialog
      • Breaking Blocks
        • New Project Setup
        • Creating Level1 Map
        • Creating the Block Entity
        • Block Removal
      • Dealing Damage
        • New Project Setup
        • Enemy Entity
        • Shooting Bullets
        • Damaging the Enemy
      • Enemy Movement
        • New Project Setup
        • Enemy Entity
        • Enemy Input Logic
        • Detecting Platform Edges
      • Ground Type and Water Movement
        • New Project Setup
        • Creating Level1 Map
        • Adding Ice and Water
        • Platformer Movement Values
      • Animation and Platformer Values
        • New Project Setup
        • Creating AnimationLayers
        • Modifying Platformer Values
      • Wall Sliding and Jumping
    • Damage Dealing
      • Setup
      • Team Index
      • Damage Events
      • IDamageArea Removal
      • Melee Damage
    • Entity Variants Using Inheritance
    • FlatRedBall.Forms
      • Getting Started with FlatRedBall.Forms
        • Setup
        • Working with Common Controls
        • Forms vs Gum in Code
      • Forms and Xbox360GamePad
      • Data Binding (BindingContext)
        • BindingContext Property
        • Binding FlatRedBall.Forms
        • Parent and Children Binding using BindingContext
        • ListBox Templates
      • Styling Forms
      • Defining New Forms Types
        • Adding New Types to FlatRedBall.Forms Library
      • Accessing Forms Events in Gum Runtimes
    • Top Down Games
      • Top Down Basics
        • Setup
        • Input Device
        • CurrentMovement
      • Enemy Movement
        • Enemy Pathfinding
        • Direct Enemy Control
      • GroundVelocity
      • Animation
      • Sorting
    • Post Processing
    • Rock Blaster - A Full FlatRedBall Tutorial Project
      • Introduction
      • Setup
      • Game Skeleton
      • Player Entity
      • Player Behavior
      • Rock Entity
      • Collision
      • Rock States
      • HUD
      • Multiple Players
      • Health
      • Health Part 2
      • Destroying Entities
      • Cleaning Up
    • Code-Only Projects (No Editor)
      • Creating a FlatRedBall Project
      • Adding a Circle
      • Loading Textures and Using Sprites
    • Code Tutorials
      • 3D Camera Setup
      • Adding FlatRedBall to a MonoGame/FNA Project
      • Adding WPF to an Existing Game
      • async and await
      • CLR Profiler
      • Collision Jitter
      • Culling
      • Customizing Cursor Visuals
        • Windows Desktop
        • windows-rt
      • Depth Buffer Z Fighting
      • Dictionaries and Enum Keys
      • FlatRedBall XNA in Windows Form
      • Improving Performance
        • CustomActivity Performance
        • Identifying Screen Creation Performance Issues
        • Rendering Performance
        • Manually Updated Objects
          • Introduction
          • Measuring Automatic Updates
          • Measuring Sprite Automatic Updates
          • Manual Particle Systems
      • Object Sorting
      • Pix
      • Rendering Sprites with Shaders
      • Tile-Based Movement
      • Velocity
    • Distribution
      • App Icon
      • Emptying bin Folder Using Probing Path
      • itch.io
      • Release Build
      • Steam
    • FlatRedBall and Velcro Physics
      • Using Velcro Physics with the FlatRedBall Editor
      • Code-Only Velcro Projects
    • FlatRedBall Editor Plugins
      • Introduction to FlatRedBall Plugins
      • Creating a Plugin Project
      • Creating a Plugin Class
      • Adding UI to FlatRedBall
      • Using MVVM
      • Creating a NamedObjectSave-Editing Plugin
      • Adding File Format Support
      • Adding Code Files to a Game Project
      • Errors
      • Exporting a Plugin
    • Additional FlatRedBall Editor Tutorials
      • How to Create a First Person Camera
      • How to Play Sounds
      • How to Share Reference Data Between Screens and Entities
    • Math Tutorials
      • Circle Collision
      • Determining required magnitude for trajectory
      • Introduction to Collision
      • Power of Two
      • Rectangle Collision
      • rotation
      • statistics
      • trigonometry
      • vector
      • matrix
      • interpolation
    • Overworld Tutorials
      • Spinning Mode 7
        • New Project Setup
        • Adding Camera Code
        • Fading In and Out
  • 🎞️Videos
  • 📐FlatRedBall Editor
    • Display Settings
    • Entities
      • BaseEntity
      • Constructor
      • ConvertToManuallyUpdated
      • CreatedByOtherEntities
      • CustomActivity
      • CustomDestroy
      • CustomInitialize
      • Destroying Entities
      • Entity Performance
      • Export Entity
      • Implements IClickable
      • Implements ICollidable
      • Implements IDamageArea
      • Implements IDrawableBatch
      • Implements IGumCollidable
      • Implements IVisible
      • Implements IWindow
        • SlideOnClick
      • Import Entity
      • Inheriting from FlatRedBall Types
      • LayerProvidedByContainer
      • MoveToLayer
      • PooledByFactory
      • Top Down Movement
        • TopDownSpeedMultiplier
      • Use Global Content
    • Events
      • ResolutionRrOrientationChanged
    • Factories
      • CreateNew
      • EntitySpawned
      • Initialize
      • SortAxis
    • Files
      • File Types
        • Animation Chain List (.achx)
        • Comma Separated Values (.csv)
          • Combining .csvs With Entities
          • CreatesDictionary
          • Cross Referencing CSVs
          • Instantiating Custom Types
          • OrderedList
          • SetCreatedClass
            • generate-data-class
          • uniformrowtype
        • Effect (.fx, .fxb)
        • Font (.fnt)
        • JSON (.json)
        • Model (.fbx)
        • MP3
        • Node Network (.nntx)
        • OpenDocument Spreadsheet (.ods)
        • ShapeCollections (.shcx)
        • SplineList (.splx)
        • Texture2D (.png)
        • Wave (.wav)
      • Accessing Files in Code
      • Adding File Objects to Managers
      • Destroy on Unload
      • File Build Tool
      • Folders
      • Global Content Files
      • IsDatabaseForLocalizing
      • IsManuallyUpdated
      • IncludeDirectoryRelativeToContainer
      • LoadedAtRuntime
      • LoadedOnlyWhenReferenced
      • Name
      • Platform Inclusions
      • Project Specific Files
      • RuntimeType
      • SourceFile
      • UseContentPipeline
      • Wildcard Files
    • FileVersion (.gluj)
    • Generated Code
    • Global Content Files
      • LoadAsynchronously
      • Reload
      • Setting Files At Runtime
    • Live Edit
      • Render Targets
    • Menu
      • Content
        • Additional Content
          • Using Runtime Types as Objects
          • creating-runtime-objects
          • runtime-object-charateristics
          • simple-line-of-text-tutorial
        • Introduction
        • pipeline-settings
      • File
        • New Project
      • Edit
        • Find File References
      • Plugins
        • Install Plugin
        • Manage Plugins
      • Project
        • View Projects
      • Settings
        • Camera Settings
        • File Associations
        • File Build Tools
        • Performance Settings
      • Update
        • Introduction
        • glue-reference-menu-frbdk
        • glue-reference-menu-libraries
    • Multi-Platform
      • Synced Projects
      • Changing Main Project Type
      • Android
        • Distribution
        • Setup
      • iOS
        • Certificates and Profiles
        • Copying Projects to Mac
        • Using Xamarin Build Host
      • Switch (Nintendo)
      • Web
    • Objects
      • Object Types
        • AxisAlignedRectangle
        • Camera
        • CameraControllingEntity
        • Circle
        • CollisionRelationship
        • Layer
          • DestinationRectangle
          • Is2D
        • Polygon
        • PositionedObjectList
        • RenderTarget2D
        • ShapeCollection
        • SoundEffectInstance
        • Sprite
        • Text
        • TileNodeNetwork
      • AddToManagers
      • AttachToCamera
      • AttachToContainer
      • CallActivity
      • Collidable Objects
      • EntireFile
      • ExposedInDerived
      • HasPublicProperty
      • IgnoresPausing
      • IncludeInIClickable
      • IncludeInICollidable
      • IsContainer
      • LayerOn
      • Map
      • SetByDerived
      • SourceFile
      • SourceType
    • Plugins
      • glue-gluevault-component-pages-rendertargetrenderer
      • glue-gluevault-component-pages-simple-command-console
      • glue-gluevault-component-pages-squid-gui-integration
      • kalldrexx-interactive-debugging-console
    • Profiling
    • Screens
      • AsyncLoadingState
      • BaseScreen
      • Constructor
      • Creating a New Screen
      • CustomDestroy
      • CustomInitialize
      • DefaultLayer
      • GameScreen
      • IsActivityFinished
      • IsLoadingScreen
      • LoadStaticContent
      • MoveToScreen
      • PauseAdjustedCurrentTime
      • Set as StartUp Screen
      • UnloadsContentManagerWhenDestroyed
    • States
      • InterpolateToState
      • InterpolateToState vs InterpolateBetween
      • State Categories
      • State Classes
      • States and Inheritance
      • Tunneling Category Variables
    • Variables
      • CreatesEvent
      • HasAccompanyingVelocityProperty
      • IsShared
      • Proper Variable Naming
      • SetByDerived
      • Type
      • Variable Order
    • Visual Studio Project (.csproj)
  • 🏃Animation Editor
    • Frame Time
    • Animation Shapes and Collision
  • Tiled
    • Tiled Basics
      • Introduction
      • Creating a GameScreen
      • Adding Collision
      • Colliding Entities Against TileShapeCollections
      • Working with Multiple Levels
      • Creating Entities from Tiles
      • Creating Entities from Object Layers
      • Accessing Tiled Properties
      • Working with Tiled Shapes
    • Tiled Files in Entities
    • TileEntityInstantiator
    • Using TiledObjects.Generated.xml
    • LayeredTileMap
      • Collisions
      • Destroy
      • FromTiledMapSave
      • Z
    • MapDrawableBatch
      • AddTile
      • CoordinateAdjustment
      • GetBottomLeftWorldCoordinateForOrderedTile
      • MergeOntoThis
      • NamedTileOrderedIndexes
      • PaintTile
      • PaintTileTextureCoordinates
      • ParallaxX
      • Paste
      • Properties
      • RemoveQuads
      • RenderingScale
      • SortAxis
    • TiledMapSave
    • TileShapeCollection
      • AddCollisionAtWorld
      • AddCollisionFrom
      • AddCollisionFromTilesWithProperty
      • AddMergedCollisionFromLayer
      • AddMergedCollisionFromTilesWithProperty
      • AdjustRepositionDirectionsOnAddAndRemove
      • CollideAgainst
      • CollideAgainstClosest
      • GetRectangleAtPosition
      • InsertCollidables
      • LastCollisionAxisAlignedRectangles
      • Rectangles
      • RemoveFromManagers
      • RemoveSurroundedCollision
  • 🟩Gum
    • Tutorials
      • Introduction and Setup
      • Screens in Gum
      • Gum Objects in Code
      • Events on Gum Objects
      • Events on Gum Objects Part 2
      • Exposed Variables
      • States
      • Adding Code to Gum Objects
    • Accessing Gum Screens in Code
    • Adding Components to Layers
    • Adding Gum Screens to FlatRedBall
    • Animations in Code
    • Components in FlatRedBall Entities
    • Converting Gum Coordinates
    • Creating Components in Code
    • GraphicalUiElement as IWindow
    • Gum Resolution
    • Gum Properties Tab
    • Gum Animations
      • How to Play Gum Screen Animations
      • Named Events
      • Setting Gum Animationchain Achx in Code
  • 🦴Spine
    • Setup
    • Atlas
    • Changing Spine Textures at Runtime
    • SpineDrawableBatch
      • Event
      • PlayAnimation
      • SetCollision
      • Skeleton
  • ⏸️Aseprite
    • AnimationChainList
  • 🏫API Documentation
    • FlatRedBall Engine
      • AI
        • LineOfSight
          • VisibilityGrid
        • Pathfinding
          • PositionedNode
          • Link
            • Cost
            • NodeLinkingTo
          • NodeNetwork
            • GetPath
            • UpdateShapes
            • Visible
          • TileNodeNetwork
            • AddAndLinkTiledNode
            • AddAndLinkTiledNodeWorld
            • OccupyTileWorld
            • SetCosts
      • Audio
        • AudioManager
          • AreSoundEffectsEnabled
          • CurrentlyPlayingSong
          • MasterSongVolume
          • MasterSoundVolume
          • Play
          • PlaySong
          • PlaySongs
          • StopSong
        • PositionedSound
        • Sound
      • Camera
        • AbsoluteRightXEdge
        • AbsoluteRightXEdgeAt
        • AddLayer
        • AddSpriteToBillboard
        • AspectRatio
        • AttachTo
        • BackgroundColor
        • CameraCullMode
        • ClearMinimumsAndMaximums
        • ClearsDepthBuffer
        • DestinationRectangle
        • DrawsShapes
        • DrawsToScreen
        • DrawsWorld
        • FarClipPlane
        • FieldOfView
        • FixAspectRatioYConstant
        • ForceUpdateDependencies
        • GetViewport
        • IsSpriteInView
        • KeepSpriteInScreen
        • Layer
        • Layers
        • Main
        • MaximumX
        • Orthogonal
        • OrthogonalHeight
        • OrthogonalWidth
        • PixelsPerUnitAt
        • Position
        • PositionRandomlyInView
        • RelativeXEdgeAt
        • RemoveLayer
        • RotationMatrix
        • SetBordersAtZ
        • SetLookAtRotationMatrix
        • SetSplitScreenViewport
        • UpdateViewProjectionMatrix
        • UpVector
        • UsePixelCoordinates
        • UsePixelCoordinates3D
        • View
      • Content
        • ContentLoadBatch
        • AnimationChain
          • AnimationChainListSave
        • ContentManager
          • AddUnloadMethod
          • FileAliases
          • IsAssetLoadedByName
          • Load
          • LoadFromGlobalIfExists
          • Multiple Content Managers
        • Math
          • Geometry
            • ShapeCollectionSave
        • Polygon
          • PolygonSave
        • Scene
          • CameraSave
          • SceneSave
        • SpriteEditorScene
          • Camera
      • Debugging
        • Debugger
          • CommandLineWrite
          • GetFullPerformanceInformation
          • TextBlue
          • WriteAutomaticallyUpdatedObjectInformation
      • Entities
        • CameraControllingEntity
        • IDamageable
        • IDamageArea
      • FlatRedBallServices
        • AddDisposable
        • AddManager
        • CornerGrabbingResize
        • Draw
        • ForceClientSizeUpdates
        • Game
        • GetManagerInformation
        • GlobalContentManager
        • GraphicsOptions
        • Initialize
        • IsLoaded
        • Load
        • Owner
        • Random
        • RenderAll
        • Unload
        • Update
        • WindowHandle
      • Graphics
        • Animation
          • AnimationChain
            • Clone
            • FrameToFrame
            • TotalLength
          • AnimationChainList
          • AnimationController
          • AnimationFrame
            • RelativeX
            • ShapeCollectionSave
            • Texture
          • IAnimationChainAnimatable
            • Animate
            • Animation and Timing
            • AnimationChains
            • AnimationSpeed
            • CurrentChainName
            • CurrentFrameIndex
            • JustChangedFrame
            • JustCycled
            • UseAnimationRelativePosition
        • BitmapFont
          • BMFC File
          • BitmapCharacterInfo
          • FNT File
          • Glyphs
          • LineHeightInPixels
          • RenderToTexture2D
        • BlendOperation
        • ColorOperation
          • Add
          • Color
          • ColorTextureAlpha
          • InterpolateColor
          • Modulate
          • Texture
        • GraphicsOptions
          • Filtering
          • IsFullScreen
          • ResolutionHeight
          • SetFullScreen
          • SetResolution
          • SizeOrOrientationChanged
          • TextureFilter
          • TextureLoadingColorKey
          • UseMultisampling
        • IColorable
          • Alpha
          • BlendOperation
          • Blue
          • ColorOperation
        • IDrawableBatch
          • Z
          • RenderState
        • IVisible
          • IgnoresParentVisibility
        • Layer
          • Layer Membership Details
          • LayerCameraSettings
          • Remove
          • RenderTarget
          • SortType
          • Sprites
          • UsePixelCoordinates
        • LayerCameraSettings
          • OrthogonalWidth
          • TopDestination
        • Particle
          • EmissionSettings
            • Drag
            • PixelSize
            • ScaleX
          • Emitter
        • PostProcessing
          • SwapChain
        • RenderBreak
        • Renderer
          • Draw
          • LastFrameRenderBreakList
          • RenderBreaksAllocatedThisFrame
        • Text
          • AdjustPositionForPixelPerfectDrawing
          • ColorOperation
          • DisplayText
          • GetWidth
          • Font
          • HorizontalAlignment
          • InsertNewLines
          • MaxWidth
          • MaxWidthBehavior
          • NewLineDistance
          • NumberOfLines
          • ScaleX
          • SetColor
          • SetPixelPerfectScale
          • VerticalAlignment
          • Width
        • TextManager
          • AddManuallyUpdated
          • AddText
          • AddToLayer
          • FilterTexts
          • RemoveText
        • Texture
          • RenderTargetSprite
          • ImageData
            • ApplyColorOperation
            • Fill
            • FromTexture2D
      • Gui
        • Cursor
          • Camera
          • ClickNoSlideThreshold
          • CustomUpdate
          • GetRay
          • IngnoreInputThisFrame
          • IsInWindow
          • IsOn
          • IsOn3d
          • PrimaryClick
          • PrimaryClickNoSlide
          • PrimaryPushTime
          • ScreenX
          • SecondaryClick
          • SetControllingGamepad
          • SetJoystickControl
          • TransformationMatrix
          • WindowOver
          • WidowPushed
          • WorldPosition
          • WorldX
          • WorldXAt
          • WorldYAt
          • XForUi
        • GuiManager
          • AddDominantWindow
          • BringsClickedWindowsToFront
          • BringToFront
          • GamepadsForUiControl
          • MakeRegularWindow
          • RemoveWindow
          • SortZAndLayerBased
          • Windows
        • IClickable
        • IInputReceiver
          • IWindow
            • CallClick
            • Enabled
          • ReceiveInput
      • Input
        • AnalogButton
        • AnalogStick
          • IsMaxPositionNormalized
        • DelegateBased1DInput
        • DelegateBased2DInput
        • DelegateBasedPressableInput
        • I1DInput
        • I2DInput
        • IMouseOver
        • InputDeviceBase
        • InputManager
          • ClearAllInput
          • InputReceiver
        • IPressableInput
        • Keyboard
          • Clear
          • ControlPositionedObject
          • Get2DInput
          • GetKey
          • GetStringTyped
          • IgnoreKeyForOneFrame
          • KeyDown
          • KeyPushed
        • Mouse
          • GrabbedPositionedObject
          • IsOn3D
          • ModifyMouseState
          • Restricting Mouse to Screen Bounds
          • SetScreenPosition
        • TouchScreen
          • LastFrameGestures
          • ReadsGestures
        • Windows
          • WindowsInputEventManager
        • Xbox360GamePad
          • ButtonDown
          • ButtonMap
          • ButtonPosition vs Button
          • ButtonPushed
          • ControlPositionedObject
          • CreateDefaultButtonMap
          • Deadzone
          • DeadzoneType
          • FakeIsConnected
          • GamepadLayout
          • IgnoreButtonForOneFrame
      • Instructions
        • DelegateInstruction
        • IInstructable
          • Call
          • Cnstructions
          • Set
        • Instruction
        • InstructionList
          • ExecuteAndRemoveOrCyclePassedInstructions
        • InstructionManager
          • Add
          • AddSafe
          • Instructions
          • MoveThrough
          • MoveTo
          • MoveToAccurate
          • ObjectsIgnoringPausing
          • PauseEngine
          • Pulse
          • RotateToAccurate
        • Reflection
          • LateBinder
          • PropertyCollection
        • MethodInstruction
        • StaticMethodInstruction
      • IO
        • Csv
          • CsvHeader
          • CsvFilemanager
            • Cells with Multiple Lines
            • Color
            • CsvDeserializelist
            • Rows with Lists
          • RuntimeCsvRepresentation
            • FromList
            • GenerateCsvString
        • FileManager
          • BinarySerialize
          • CloneObject
          • FromFileText
          • GetAllFilesInDirectory
          • GetUserFolder
          • InitializeUserFolder
          • RelativeDirectory
          • SaveEmbeddedResource
          • SaveText
          • Standardize
          • UserApplicationDataForThisApplication
          • XmlDeserialize
          • XmlSerialize
      • Localization
        • LocalizationManager
      • Managers
        • IManager
      • Math
        • IAttachableRemovable
        • AttachableList
          • FindByName
          • MakeOneWay
        • Collision
          • CollisionManager
            • Relationships
            • Update
        • Geometry
          • AxisAlignedCube
            • CollideAgainstBounce
          • AxisAlignedRectangle
            • Axis Alignment And Rotation
            • CollideAgainstMoveSoft
            • Color
            • GetRandomPositionInThis
            • KeepThisInsideOf
            • LastMoveCollisionReposition
            • Left
            • RepositionDirections
          • Capsule2D
          • Circle
            • CollideAgainst
            • CollideAgainstBounce
            • CollideAgainstMove
            • IsPointInside
            • LastCollisionTangent
            • LastMoveCollisionReposition
            • ProjectParentVelocityOnLastMoveCollisionTangent
            • Visible
            • Z
          • Colliding a List of Shapes Against Itself
          • FloatRectangle
          • ICollidable
          • IScalable
            • Scale
          • Line
            • Color
            • LastCollisionPoint
            • RelativePoint1
            • SetFromAbsoluteEndpoints
          • Point
          • Polygon
            • AbsolutePointPosition
            • Clone
            • CollideAgainstBounce
            • CollideAgainstMove and Attachments
            • CollideAgainstMove
            • Color
            • CreateEquilateral
            • CreateRectangle
            • ForceUpdateDependencies
            • IsPointInside
            • LastMoveCollisionReposition
            • OptimizeRadius
            • Points
            • Position
            • ProjectParentVelocityOnLastMoveCollisionTangent
            • ScaleBy
            • Thin Polygon Problem
            • VectorFrom
            • Visible
            • Z
          • Segment
            • ClosestPointTo
          • Shape
          • ShapeCollection
            • AttachTo
            • AxisAlignedRectangles
            • CollideAgainst
            • CollideAgainstBounceWithoutSnag
            • CollideAgainstMove
            • CollideAgainstMoveWithoutSnag
            • LastCollisionAxisAlignedRectangles
            • SortAscending
            • Visible
          • ShapeManager
            • AddToLayer
            • Remove
            • ShapeDrawingOrder
          • ShapeMerger
          • Shapes and 2D Collision
          • Sphere
        • IAttachable
          • Attachment Updates in the Engine
          • Detach
          • ParentRotationChangesPosition
          • ParentRotationChangesRotation
          • TopParent
        • IRotatable
          • RotationMatrix
        • MathFunctions
          • AbsoluteToWindow
          • AngleToAngle
          • AngleToVector
          • GetPointInCircle
          • GetPositionAfterTime
          • RegulatAngle
          • RotatePointAroundPoint
          • RoundFloat
          • RoundToInt
          • WidowToAbsolute
        • Paths
          • Path
        • PositionedObjectList
          • Add
          • AttachTo
          • Clear
          • GetFirstAfter
          • GetFirstAfterPosition
          • SortXInsertionAscending
        • Splines
          • Spline
            • GetPositionAtLengthAlongSpline
      • Performance
        • Measurement
          • Section
            • GetAndStartContextAndTime
            • Save
            • ToStringVerbose
      • PositionedObject
        • Acceleration
        • AttachTo
        • Children
        • Clone
        • Drag
        • ForceUpdatedependencies
        • ForceUpdatedependenciesDeep
        • Initialize
        • KeepTrackOfReal
        • LastPosition
        • Mirrored properties
        • ParentRotationChangesPosition
        • ParentRotationChangesRotation
        • Position
        • RelativePosition
        • RelativeRotationZ
        • RelativeVelocity
        • RemoveSelfFromListsBelongingTo
        • RotationZ
        • SetRelativeFromAbsolute
        • TimedActivity
        • TopParent
        • UpdateDependencies
        • Velocity
        • Z
      • Screens
        • Screen
          • ContentManagerName
          • CustomDestroy
          • IsActivityFinished
          • MoveToScreen
          • PauseThisScreen
        • ScreenManager
          • Activity
          • CurrentScreen
          • Start
      • Sprite
        • Alpha
        • AnimateSelf
        • AnimationChains
        • AnimationSpeed
        • Bottom
        • BottomTextureCoordinate
        • Changing a Sprite's Origin
        • ColorOperation
        • CurrentChainName
        • CurrentFrameIndex
        • IgnoreAnimationChainTextureFlip
        • Inheriting from the Sprite Class
        • JustCycled
        • LeftTextureCoordinate
        • PixelSize
        • Position
        • RightTextureCoordinate
        • SetAnimationChain
        • SetScaleXRatioToY
        • Sorting and Overlapping
        • Sprite vs Texture2d
        • Texture Coordinates
        • Texture
        • TextureAddressMode
        • TextureCoordinate
        • TextureFilter
        • TextureScale
        • TimeIntoAnimation
        • TopTextureCoordinate
        • UseAnimationRelativePosition
        • Vertices
        • VerticesForDrawing
        • Visible
      • SpriteList
      • SpriteManager
        • AddDrawableBatch
        • AddManagedInvisibleSprite
        • AddManualSprite
        • AddParticleSprite
        • AddPositionedObject
        • AddSprite
        • AddToLayer
        • AddZBufferedDrawableBatch
        • AddZBufferedSprite
        • AutomaticallyUpdatedSprites
        • Camera
        • ConvertToAutomaticallyUpdated
        • ConvertToManagedInvisible
        • ConvertToManuallyUpdated
        • ConvertToZBufferedSprite
        • DrawableBatches
        • ManagedPositionedObjects
        • ManualUpdate
        • MaxParticleCount
        • MoveToBack
        • OrderedSortType
          • Z
        • OrderedSprites
        • RemoveDrawableBatch
        • RemoveLayer
        • RemovePositionedObject
        • RemoveSprite
        • RemoveSpriteOneWay
        • SortTexturesSecondary
        • SortYSpritesSecondary
        • UnderAllDrawnLayer
      • TimeManager
        • Accumulating Time
        • CurrentScreenSecondsSince
        • CurrentTime
        • Profiling
        • SecondDifference
        • SecondsSince
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  • Introduction
  • FlatRedBall collision terminology
  • Shapes and Visible Objects
  • Shapes can be Visible
  • CollideAgainst
  • CollideAgainstMove
  • CollideAgainstBounce
  • Want to learn more?

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  1. Tutorials
  2. Math Tutorials

Introduction to Collision

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Introduction

The term "collision" in game development refers to both detecting whether objects are touching as well as changing the state of these objects when this touching occurs.

Almost all games requires some type of collision. For example, Pong used ball vs. paddle collision and Super Mario Bros. performs collision between Mario and the ground to test whether he should fall or not. Even games which might not seem to use collision likely do. For example, mouse-driven adventure games like used collision to detect whether the cursor is overlapping certain areas when clicking.

The only games free from collision are pure text-based games, but it's likely that if you're working on one of those you probably won't need to use FlatRedBall.

FlatRedBall collision terminology

Before we get into how FlatRedBall handles collision, let's cover some basic terminology.

Collision

We've already discussed what a collision is, so let's give some examples. The following image shows three situations and labels whether a collision is occurring:

Notice that collision doesn't just occur if the edges of two objects are touching. When FlatRedBall performs collision, it considers objects to be filled in. Therefore, if one object is inside of another, a collision is still occurring.

"Move" collision

A move collision is a collision where one or both of the involved shapes are repositioned during the collision to prevent overlap. The term "move" was selected because this type of collision can result in the shapes moving to new positions. The amount that each shape is moved depends on their masses relative to each other. It is very common to make one object static by giving it a non-zero mass and giving the other object a mass of zero. The following image shows the result of a move collision assuming that the rectangle is static and the circle is not.

To use FlatRedBall terms, move collisions will adjust the position of the involved shape(s) if a collision does occur.

"Bounce" collision

A "bounce" collision is a collision which can be used to simulate physics. As the name implies, bounce collisions cause objects to bounce against each other. Just like move collisions, bounce collisions use the masses of two objects to calculate how the forces from the bounce should be applied. Just like with move collisions, it is common to have one object in a bounce collision have a non-zero mass while the other has a mass of zero. This causes one of the shapes (the one with the non-zero mass) to not be affected by the collision.

Shape

You may also be expecting there to be a Shape interface or class that all shapes implement. Actually, there isn't such an interface or class. The reason for this is performance. Initial performance measurement tests in FlatRedBall showed that the majority of time spent in collision loops is the actual method calls. In other words, we compared the amount of time required to call collision methods to the amount of time calling "empty" methods and over half of the time was spent in the method call.

Shapes and Visible Objects

Shapes can be Visible

CollideAgainst

using FlatRedBall.Math.Geometry;

Add the following at class scope:

Circle firstCircle;
Circle secondCircle;

Add the following to Initialize after initializing FlatRedBall:

firstCircle = ShapeManager.AddCircle();
firstCircle.X = -10;
secondCircle = ShapeManager.AddCircle();

Add the following to Update:

firstCircle.X = InputManager.Mouse.WorldXAt(0);
firstCircle.Y = InputManager.Mouse.WorldYAt(0);

if (firstCircle.CollideAgainst(secondCircle))
{
    firstCircle.Color =
        Color.Orange;
}
else
{
    firstCircle.Color =
        Color.Blue;
}

CollideAgainstMove

We'll use Velocity for the following example: Use the same using statements, class-level declarations, and Initialize code as above, then replace the custom Update logic with the following:

InputManager.Keyboard.ControlPositionedObject(firstCircle);

// We use equal masses here so that each is moved the same
// amount.  You can change these values to achieve different
// relative masses.
firstCircle.CollideAgainstMove(secondCircle, 1, 1);

base.Update(gameTime);

The first "1" argument is the mass of the first object. The second "1" is the mass of the second object. Try changing the first argument to 0. This will make secondCircle immovable. Then try changing the first argument back to 1, then the second to 0. This will make the moving circle unaffected by secondCircle.

InputManager.Keyboard.ControlPositionedObjectAcceleration(firstCircle, 10);

// We use equal masses here so that each is moved the same
// amount.  You can change these values to achieve different
// relative masses.
firstCircle.CollideAgainstBounce(
    secondCircle,
    1,// firstCircle mass
    1,// secondCircle mass
    1); // elasticity

Now the two Circles will collide against each other and bounce. Of course, you will probably notice that this setup results in secondCircle being moved off of the screen very quickly. You may want to change the firstCircle's mass to 0 to keep the secondCircle on screen so you can test multiple collisions.

Want to learn more?

You're probably pretty familiar with the word "shape". In FlatRedBall, shape defines a shape like a square, triangle, or circle. To be a little more precise, a shape is an object which is a , has collision methods, and is managed by the class.

Of course this ratio can fluctuate depending on the complexity of the collision method and the frequency of collision occurrence. However, making a method virtual makes the method call itself take longer than otherwise, and we decided to give up the convenience of a base class for better performance. FlatRedBall provides a number of shape classes, and this list may continue to grow as more sophisticated collision needs are satisfied. If you'd like to find out which shape classes are available, check out the page.

Most games use to detect whether collision is occurring; however, not all games keep collision visible. Therefore, it is likely that your game will use for collision and another type of object for drawing (such as ). In this situation, the that you use will approximate the collidable area of your visible object. In some cases simple such as and will be sufficient. In cases where more complex collision shapes are needed, the object is a good alternative. In more complex situations multiple Shapes can be used.

As you'll see in the next sections where we begin writing some sample code, Shapes have a Visible property which can be used to control whether the FlatRedBall Engine draws them. In the following examples the that are created through the will automatically be set to be Visible. When using Shapes only for collision and attaching them to other objects, it is not necessary to create them through or add them to the . Keep this in mind as you read other documentation about .

Collision can be detected between shapes simply by calling CollideAgainst. The following code example creates two . One is positioned at the point of the mouse. If a collision occurs, the moving Circle becomes orange. Otherwise, it is blue. Add the following using statements:

WARNING: The code above may not compile because the Color struct is not qualified (the code doesn't know which namespace it is in). Which "using" statement you add to your code depends on which version of FlatRedBall you are using. For more information, see the page.

The CollideAgainst method is a method that only returns whether collision has occurred - it does not modify the calling or the argument . The following sections describe methods which do.

The CollideAgainstMove method returns a true or false depending on whether the calling and the argument are touching. This method also modifies the Position of one or both .

Keep in mind that since this method modifies the Position, we should not directly modify the Positions in custom code every frame. Doing so would result in the CollideAgainstMove and our own code both attempting to control the Position of the involved . While this won't cause a crash, it may result in unexpected or undesirable behavior. In most cases where CollideAgainstMove is used, the involved (or their Parent ) are controlled either by Velocity or Acceleration.

The third method that we'll look at is . The us all of the same functionality as CollideAgainstMove( true/false return value as well as repositioning), but it also modifies the involved Velocity values. For bouncing to behave properly, we have to make sure that we're not controlling the involved position or velocity. Therefore, this leaves us with controlling acceleration. To use , simply replace your custom Update code with the following:

This article covers a lot of information about collisions; however, this topic has a lot of depth. To find out more, start at the page and follow the links to the information you're interested in.

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PositionedObject
ShapeManager
ShapeManager
Shapes
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Sprites
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AxisAlignedRectangles
Polygon
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ShapeManager
ShapeManager
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Circle
Color
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CollideAgainstBounce
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King's Quest VI
CollidingCircles.png