github.com/melonFunction/ebiten-camera

ebiten-camera

A simple camera implementation based on vrld's hump for LÖVE

Usage

📖 Docs
Look at the examples to see how to use the library.

Here is a stripped-down version of the example code, highlighting the most important functions.

It won't run, so please don't bother trying it 😄

var (
    cam *ebitenCamera.Camera
    // other vars excluded, such as tiles, PlayerX etc
)


func main() {
    w,h := 640, 480
    // excluding normal ebiten setup
    cam = camera.NewCamera(w, h, 0, 0, 0, 1)
}

func (g *Game) Update() error {
    // Follows the player
    cam.SetPosition(PlayerX+float64(PlayerSize)/2, PlayerY+float64(PlayerSize)/2)
    return nil
}

func (g *Game) Draw(screen *ebiten.Image) {
    // Clear camera surface
    cam.Surface.Clear()
    cam.Surface.Fill(color.RGBA{255, 128, 128, 255})
    // Draw tiles
    tileOps := &ebiten.DrawImageOptions{}
    cam.Surface.DrawImage(tiles, cam.GetTranslation(tileOps, 0, 0))
    // Draw the player
    playerOps := &ebiten.DrawImageOptions{}
    playerOps = cam.GetRotation(playerOps, PlayerRot, -float64(PlayerSize)/2, -float64(PlayerSize)/2)
    playerOps = cam.GetScale(playerOps, 0.5, 0.5)
    playerOps = cam.GetSkew(playerOps, 0, -0.5)
    playerOps = cam.GetTranslation(playerOps, PlayerX, PlayerY)
    cam.Surface.DrawImage(player, playerOps)
    
    // Draw to screen and zoom
    cam.Blit(screen)
}

Considerations

1. When setting the *ebiten.DrawImageOptions in the ebitenCamera.Surface.DrawImage function, the order of operation is important!
   Rotate, Scale, Skew and then Translate!

2. My example doesn't include a range for the camera's zoom to highlight what happens if you zoom too far in either direction. This is because I use a render texture to draw everything to, and I simply resize this when zooming in or out. This texture has a max size, causing the positioning logic to stop centering it. I'll probably change this at some point (unless you beat me to it with a PR, of course 😆)