ebitencm

ebitencm (Ebitengine Chipmunk drawer) is an implementation of the cm.IDrawer Interface from setanarut/cm. This implementation utilizes hajimehoshi/ebiten/v2, making it possible to run across multiple platforms. Coordinate system is top-left by default, same as Ebitengine

Usage

Within your Draw() method, invoke the cm.DrawSpace() function, passing in both a *cm.Space and a *ebitencm.Drawer as parameters.

type Game struct {
	space  *cm.Space
	drawer *ebitencm.Drawer
}
func main() {
	game := &Game{}
	game.space = space
	game.drawer = ebitencm.NewDrawer()
}
func (g *Game) Draw(screen *ebiten.Image) {
	// Drawing with Ebitengine/v2
	cm.DrawSpace(g.space, g.drawer.WithScreen(screen))
}

Dragging

If you want to enable dragging, call the HandleMouseEvent() function within the Update method, passing the *cm.Space object. This will allow objects to be dragged using a mouse or touch device.

func (g *Game) Update() error {
	// Handling dragging
	g.drawer.HandleMouseEvent(g.space)
	g.space.Step(1 / 60.0)
	return nil
}

Camera transform

Use Drawer.GeoM{} for camera transform. The cursor position is calculated according to this matrix. Don't forget to reset GeoM with GeoM.Reset() in Update(). Here is an example with the setanarut/kamera package.

func (g *Game) Update() error {
	g.space.Step(1 / 60.0)

	// Apply camera transform to drawer
	g.drawer.GeoM.Reset()
	g.cam.ApplyCameraTransform(g.drawer.GeoM)

	// Enable cursor dragging
	g.drawer.HandleMouseEvent(g.space)

Camera demo

Run camera example on your local machine

go run github.com/setanarut/ebitencm/examples/camera@latest

• Camera Position = WASD
• Camera Rotation = Q / E
• Camera Zoom = Z / X
• Drag object = Cursor
• Reset camera = Backspace

Examples

Browse to the examples folder for all examples.