1 /* 2 Package gohan provides an Entity Component System framework for Ebitengine. 3 4 An example game is available at /examples/twinstick, which may be built by 5 executing the following command (in /examples/twinstick): 6 7 go build -tags example . 8 9 Entity 10 11 A general-purpose object, which consists of a unique ID, starting with 1. 12 13 Component 14 15 The raw data for one aspect of an object, and how it interacts with the world. 16 Each component is assigned a unique ID, starting with 1. 17 18 type ExampleComponent struct { 19 X, Y float64 20 } 21 22 System 23 24 Each system runs continuously, performing actions on every entity that matches 25 each systems' set of required components. When no required components are 26 specified, the system will match all active entities. 27 28 type ExampleSystem struct { 29 Position *component.PositionComponent // Required component. 30 Velocity *component.VelocityComponent // Required component. 31 32 Sprite *component.SpriteComponent `gohan:"?"` // Optional component. 33 34 Enabled bool `gohan:"-"` // Not a component. 35 } 36 37 Component Design Guidelines 38 39 Components are located in a separate package, typically named component. They 40 should be public (start with an uppercase letter) and may be of any type. 41 Using only struct types (with zero or more public fields) and accessing the 42 structs via pointer is recommended. Components should not have any logic (i.e. game code) 43 within them, as all logic should be implemented within a system. 44 45 System Design Guidelines 46 47 Systems are located in a separate package, typically named system. They should 48 be public (start with an uppercase letter) and offer an instantiation function 49 named as follows: NewSystemNameHere(). Data should be stored within components 50 attached to one or more entities, rather than within the systems themselves. 51 References to components must not be maintained outside each Update and Draw 52 call, or else the application will encounter race conditions. 53 54 Environment Variables 55 56 Running an application with the environment variable GOHAN_DEBUG set to 1 57 will enable printing verbose system update and draw information. 58 */ 59 package gohan 60