README
¶
spritengine
spritengine is a simple game engine written in Golang that provides the tools to easily build an 80s style 2D side-scrolling platformer.
A basic example game can be found in the example/ directory.
Sprites
Sprites are 16x16 pixels in size, represented by a group of 32 32-bit integers. They can contain up to 16 different RGBA colours as defined by a colour palette.
Sprites can be combined into groups to form larger sprites, and both individual sprites and groups can be easily drawn onto an image canvas.
A helper function is included to generate ready-to-use Golang sprite files from PNGs.
Game Objects
Game objects wrap sprites and add extra properties that the game can interact with, such as mass and velocity.
Levels
Levels represent a traditional game 'level' and contain all of the game objects required for that level. Under the hood the game delegates responsibility for repainting the canvas to the level.
Game
The game object contains all of the levels and is responsible for creating a window and capturing user input.
Documentation
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Index ¶
- Constants
- func GenerateFromPNGFile(inputFile string, outputFile string, packageName string, ...)
- type BeforePaint
- type Collision
- type CollisionHandler
- type DynamicData
- type EventHandler
- type FramePainter
- type Game
- type GameObject
- func (gameObject *GameObject) ClearDynamicData(key string)
- func (gameObject *GameObject) CurrentSprite() SpriteInterface
- func (gameObject *GameObject) GetCollisionEdge(collidingObject *GameObject) string
- func (gameObject *GameObject) GetDynamicData(key string, fallback interface{}) interface{}
- func (gameObject *GameObject) HasDynamicData(key string) bool
- func (gameObject *GameObject) Height() int
- func (gameObject *GameObject) IsResting() bool
- func (gameObject *GameObject) RecalculatePosition(gravity float64)
- func (gameObject *GameObject) SetDynamicData(key string, value interface{})
- func (gameObject *GameObject) Width() int
- type GameObjectStates
- type KeyListener
- type Level
- type Palette
- type Sprite
- type SpriteGroup
- type SpriteInterface
- type SpriteSeries
- type Vector
Constants ¶
const ( DirLeft = -1 DirRight = 1 DirStationary = 0 )
Direction constants
const ( EventFloorCollision = 0 EventDropOffLevel = 1 EventFreefall = 2 )
Event constants
const ( EdgeTop = "top" EdgeTopLeft = "top_left" EdgeTopRight = "top_right" EdgeBottom = "bottom" EdgeBottomLeft = "bottom_left" EdgeBottomRight = "bottom_right" EdgeLeft = "left" EdgeRight = "right" EdgeNone = "none" )
Collision edges
Variables ¶
This section is empty.
Functions ¶
Types ¶
type BeforePaint ¶
type BeforePaint func(level *Level)
BeforePaint is the signature for functions that are called on levels prior to them being repainted
type Collision ¶
type Collision struct {
GameObject *GameObject
Edge string
}
Collision is a struct that represents a collision with another game object
type CollisionHandler ¶
type CollisionHandler func(gameObject *GameObject, collision Collision)
CollisionHandler is the signature for functions that handle collision events
type DynamicData ¶
type DynamicData map[string]interface{}
DynamicData is a type that defines a repository of arbitrary game object data
type EventHandler ¶
type EventHandler func(eventCode int, gameObject *GameObject)
EventHandler is the signature for functions that handle game events
type FramePainter ¶
FramePainter is the signature for functions that handle frame painting
type Game ¶
type Game struct {
Title string
Width int
Height int
ScaleFactor int
TargetFrameRate int
FramePainter FramePainter
KeyListener KeyListener
Levels []*Level
CurrentLevelID int
CurrentFrame int
}
Game is a struct that defines a game and the window that contains it
func CreateGame ¶
func CreateGame(title string, width int, height int, scaleFactor int, targetFrameRate int, framePainter FramePainter, keyListener KeyListener, levels []*Level) *Game
CreateGame sets up a game and its window
func (*Game) BroadcastInput ¶
BroadcastInput sends the game input to the current level's objects if they are controllable
func (*Game) CurrentLevel ¶
CurrentLevel gets the current Level object
type GameObject ¶
type GameObject struct {
CurrentState string
States GameObjectStates
Position Vector
Mass float64
Velocity Vector
Direction int
IsFlipped bool
IsControllable bool
IsFloor bool
IsInteractive bool
IsHidden bool
Level *Level
DynamicData DynamicData
FloorY float64
EventHandler EventHandler
CollisionHandler CollisionHandler
}
GameObject represents a sprite and its properties
func (*GameObject) ClearDynamicData ¶
func (gameObject *GameObject) ClearDynamicData(key string)
ClearDynamicData clears a piece of dynamic game object data
func (*GameObject) CurrentSprite ¶
func (gameObject *GameObject) CurrentSprite() SpriteInterface
CurrentSprite gets the current sprite for the object's state
func (*GameObject) GetCollisionEdge ¶
func (gameObject *GameObject) GetCollisionEdge(collidingObject *GameObject) string
GetCollisionEdge infers the edge on which an intersecting object collided with the game object
func (*GameObject) GetDynamicData ¶
func (gameObject *GameObject) GetDynamicData(key string, fallback interface{}) interface{}
GetDynamicData gets a piece of dynamic game object data, falling back to a defined value if the data does not exist
func (*GameObject) HasDynamicData ¶
func (gameObject *GameObject) HasDynamicData(key string) bool
HasDynamicData checks whether a piece of dynamic game object data exists
func (*GameObject) Height ¶
func (gameObject *GameObject) Height() int
Height gets the height of the game object
func (*GameObject) IsResting ¶
func (gameObject *GameObject) IsResting() bool
IsResting determined whether the game object is currently atop another game object
func (*GameObject) RecalculatePosition ¶
func (gameObject *GameObject) RecalculatePosition(gravity float64)
RecalculatePosition recalculates the latest X and Y position of the game object from its properties
func (*GameObject) SetDynamicData ¶
func (gameObject *GameObject) SetDynamicData(key string, value interface{})
SetDynamicData sets a piece of dynamic game object data
func (*GameObject) Width ¶
func (gameObject *GameObject) Width() int
Width gets the width of the game object
type GameObjectStates ¶
type GameObjectStates map[string]SpriteSeries
GameObjectStates is a type that defines the various states (and accompanying sprites) of game objects
type KeyListener ¶
type KeyListener func(event key.Event, gameObject *GameObject)
KeyListener is the signature for functions that handle key events for controllable game objects
type Level ¶
type Level struct {
BackgroundColour color.RGBA
Gravity float64
GameObjects []*GameObject
Game *Game
PaintOffset Vector
BeforePaint BeforePaint
}
Level is a struct that defines a single level of a game
func (*Level) AssignFloors ¶
func (level *Level) AssignFloors()
AssignFloors iterates through all objects in the level and defines which object beneath them (if any) should be considered their 'floor' object, setting its top edge as the lowest point that the object can fall
func (*Level) CalculateCollisions ¶
func (level *Level) CalculateCollisions()
CalculateCollisions iterates through all objects in the level and defines which objects (if any) intersect them
type Sprite ¶
Sprite is a struct that represents sprite objects
func CreateSprite ¶
CreateSprite creates a sprite object based on a set of hex-encoded scanlines
func (*Sprite) AddToCanvas ¶
AddToCanvas draws the sprite on an existing image canvas
type SpriteGroup ¶
SpriteGroup is a struct that represents a group of sprites that form a larger individual sprite
func CreateSpriteGroup ¶
func CreateSpriteGroup(width int, height int, sprites *[]*Sprite) (*SpriteGroup, error)
CreateSpriteGroup creates a sprite group based on a grid size and collection of sprites
func (*SpriteGroup) AddToCanvas ¶
func (spriteGroup *SpriteGroup) AddToCanvas(canvas *image.RGBA, targetX int, targetY int, mirrorImage bool)
AddToCanvas draws the sprite group on an existing image canvas
func (*SpriteGroup) Height ¶
func (spriteGroup *SpriteGroup) Height() int
Height gets the pixel height of the sprite group
func (*SpriteGroup) Width ¶
func (spriteGroup *SpriteGroup) Width() int
Width gets the pixel width of the sprite group
type SpriteInterface ¶
type SpriteInterface interface {
AddToCanvas(canvas *image.RGBA, targetX int, targetY int, mirrorImage bool)
Width() int
Height() int
}
SpriteInterface is an interface that defines objects that can be treated a single sprites
type SpriteSeries ¶
type SpriteSeries struct {
Sprites []SpriteInterface
CyclesPerSecond int
}
SpriteSeries is a type that defines a series of sprites that form an animation for a game object state
Source Files
Directories