111 lines
2.8 KiB
Go
111 lines
2.8 KiB
Go
package engine
|
|
|
|
import (
|
|
"encoding/gob"
|
|
"image"
|
|
|
|
"github.com/hajimehoshi/ebiten/v2"
|
|
)
|
|
|
|
// Ensure Camera satisfies interfaces.
|
|
var (
|
|
_ Identifier = &Camera{}
|
|
_ Drawer = &Camera{}
|
|
_ Prepper = &Camera{}
|
|
_ Scanner = &Camera{}
|
|
_ Updater = &Camera{}
|
|
)
|
|
|
|
func init() {
|
|
gob.Register(Camera{})
|
|
}
|
|
|
|
// Camera models a camera that is viewing a scene.
|
|
// Changes to the configuration take effect immediately.
|
|
// Camera ignores Scene.Draw and calls Scene's children's Draw.
|
|
type Camera struct {
|
|
ID
|
|
Scene *Scene
|
|
|
|
// Camera controls
|
|
Bounds image.Rectangle // world coordinates
|
|
Centre image.Point // world coordinates
|
|
Filter ebiten.Filter
|
|
Zoom float64 // unitless
|
|
|
|
game *Game
|
|
}
|
|
|
|
// Draw applies transformations to opts, then calls c.Scene.Draw with it.
|
|
func (c *Camera) Draw(screen *ebiten.Image, opts ebiten.DrawImageOptions) {
|
|
if c.Scene.Hidden {
|
|
return
|
|
}
|
|
|
|
// The lower bound on zoom is the larger of
|
|
// { (ScreenWidth / BoundsWidth), (ScreenHeight / BoundsHeight) }
|
|
zoom := c.Zoom
|
|
sz := c.Bounds.Size()
|
|
if z := float64(c.game.ScreenWidth) / float64(sz.X); zoom < z {
|
|
zoom = z
|
|
}
|
|
if z := float64(c.game.ScreenHeight) / float64(sz.Y); zoom < z {
|
|
zoom = z
|
|
}
|
|
|
|
// If the configured centre puts the camera out of bounds, move it.
|
|
centre := c.Centre
|
|
// Camera frame currently Rectangle{ centre ± (screen/(2*zoom)) }.
|
|
sw2, sh2 := float64(c.game.ScreenWidth/2), float64(c.game.ScreenHeight/2)
|
|
swz, shz := int(sw2/zoom), int(sh2/zoom)
|
|
if centre.X-swz < c.Bounds.Min.X {
|
|
centre.X = c.Bounds.Min.X + swz
|
|
}
|
|
if centre.Y-shz < c.Bounds.Min.Y {
|
|
centre.Y = c.Bounds.Min.Y + shz
|
|
}
|
|
if centre.X+swz > c.Bounds.Max.X {
|
|
centre.X = c.Bounds.Max.X - swz
|
|
}
|
|
if centre.Y+shz > c.Bounds.Max.Y {
|
|
centre.Y = c.Bounds.Max.Y - shz
|
|
}
|
|
|
|
// Apply other options
|
|
opts.Filter = c.Filter
|
|
|
|
// Compute common matrix (parts independent of parallax).
|
|
// Moving centre to the origin happens per component.
|
|
var comm ebiten.GeoM
|
|
// 2. Zoom (this is also where rotation would be)
|
|
comm.Scale(zoom, zoom)
|
|
// 3. Move the origin to the centre of screen space.
|
|
comm.Translate(sw2, sh2)
|
|
// 4. Apply transforms from the caller.
|
|
comm.Concat(opts.GeoM)
|
|
|
|
// Draw everything.
|
|
for _, i := range c.Scene.Components {
|
|
if d, ok := i.(Drawer); ok {
|
|
pf := 1.0
|
|
if s, ok := i.(ParallaxScaler); ok {
|
|
pf = s.ParallaxFactor()
|
|
}
|
|
var geom ebiten.GeoM
|
|
// 1. Move centre to the origin, subject to parallax factor
|
|
geom.Translate(-float64(centre.X)*pf, -float64(centre.Y)*pf)
|
|
geom.Concat(comm)
|
|
opts.GeoM = geom
|
|
d.Draw(screen, opts)
|
|
}
|
|
}
|
|
}
|
|
|
|
// Update passes the call to c.Scene.
|
|
func (c *Camera) Update() error { return c.Scene.Update() }
|
|
|
|
// Scan returns the only child (c.Scene).
|
|
func (c *Camera) Scan() []interface{} { return []interface{}{c.Scene} }
|
|
|
|
// Prepare grabs a copy of game.
|
|
func (c *Camera) Prepare(game *Game) { c.game = game }
|