invert camera-scene relationship
This commit is contained in:
Josh Deprez
parent
2674234d62
commit
3452a32ddb
4 changed files with 84 additions and 94 deletions
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@ -10,22 +10,18 @@ import (
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// Ensure Camera satisfies interfaces.
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var _ interface {
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Identifier
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Drawer
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Prepper
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Scanner
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Updater
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} = &Camera{}
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func init() {
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gob.Register(&Camera{})
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}
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// Camera models a camera that is viewing a scene.
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// Changes to the configuration take effect immediately.
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// Camera ignores Scene.Draw and calls Scene's children's Draw.
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// Camera models a camera that is viewing a scene. (Camera is a child of the
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// scene it is viewing, for various reasons.) Changes to the fields take effect
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// immediately.
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type Camera struct {
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ID
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Scene Scener
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// Camera controls
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Centre image.Point // world coordinates
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@ -35,84 +31,6 @@ type Camera struct {
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game *Game
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}
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// Draw applies transformations to opts, then draws the contents of c.Scene.
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func (c *Camera) Draw(screen *ebiten.Image, opts ebiten.DrawImageOptions) {
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if c.Scene.IsHidden() {
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return
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}
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br := c.Scene.BoundingRect()
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// The lower bound on zoom is the larger of
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// { (ScreenWidth / BoundsWidth), (ScreenHeight / BoundsHeight) }
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zoom := c.Zoom
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sz := br.Size()
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if z := float64(c.game.ScreenWidth) / float64(sz.X); zoom < z {
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zoom = z
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}
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if z := float64(c.game.ScreenHeight) / float64(sz.Y); zoom < z {
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zoom = z
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}
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// If the configured centre puts the camera out of bounds, move it.
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centre := c.Centre
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// Camera frame currently Rectangle{ centre ± (screen/(2*zoom)) }.
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sw2, sh2 := float64(c.game.ScreenWidth/2), float64(c.game.ScreenHeight/2)
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swz, shz := int(sw2/zoom), int(sh2/zoom)
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if centre.X-swz < br.Min.X {
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centre.X = br.Min.X + swz
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}
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if centre.Y-shz < br.Min.Y {
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centre.Y = br.Min.Y + shz
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}
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if centre.X+swz > br.Max.X {
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centre.X = br.Max.X - swz
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}
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if centre.Y+shz > br.Max.Y {
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centre.Y = br.Max.Y - shz
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}
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// Apply other options
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opts.Filter = c.Filter
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// Compute common matrix (parts independent of parallax).
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// Moving centre to the origin happens per component.
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var comm ebiten.GeoM
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// 2. Zoom (this is also where rotation would be)
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comm.Scale(zoom, zoom)
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// 3. Move the origin to the centre of screen space.
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comm.Translate(sw2, sh2)
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// 4. Apply transforms from the caller.
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comm.Concat(opts.GeoM)
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// Draw everything.
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for _, i := range c.Scene.Scan() {
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d, ok := i.(Drawer)
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if !ok {
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continue
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}
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pf := 1.0
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if s, ok := i.(ParallaxScaler); ok {
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pf = s.ParallaxFactor()
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}
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var geom ebiten.GeoM
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// 1. Move centre to the origin, subject to parallax factor
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geom.Translate(-float64(centre.X)*pf, -float64(centre.Y)*pf)
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geom.Concat(comm)
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opts.GeoM = geom
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d.Draw(screen, opts)
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}
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}
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// DrawOrder passes the call to c.Scene.
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func (c *Camera) DrawOrder() float64 { return c.Scene.DrawOrder() }
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// Update passes the call to c.Scene.
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func (c *Camera) Update() error { return c.Scene.Update() }
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// Scan returns the only child (c.Scene).
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func (c *Camera) Scan() []interface{} { return []interface{}{c.Scene} }
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// Prepare grabs a copy of game (needed for screen dimensions)
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func (c *Camera) Prepare(game *Game) error {
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c.game = game
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@ -19,6 +19,7 @@ func init() {
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type Scene struct {
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ID
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Bounds // world coordinates
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Camera *Camera // optional; applies a bunch of transforms to draw calls
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Components []interface{}
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Disabled
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Hidden
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@ -30,12 +31,78 @@ func (s *Scene) Draw(screen *ebiten.Image, opts ebiten.DrawImageOptions) {
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if s.Hidden {
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return
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}
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// Draw everything.
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if s.Camera == nil {
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// Draw everything, no camera transforms.
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for _, i := range s.Components {
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if d, ok := i.(Drawer); ok {
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d.Draw(screen, opts)
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}
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}
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return
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}
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// There is a camera; apply camera transforms.
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br := s.BoundingRect()
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// The lower bound on zoom is the larger of
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// { (ScreenWidth / BoundsWidth), (ScreenHeight / BoundsHeight) }
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zoom := s.Camera.Zoom
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sz := br.Size()
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if z := float64(s.Camera.game.ScreenWidth) / float64(sz.X); zoom < z {
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zoom = z
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}
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if z := float64(s.Camera.game.ScreenHeight) / float64(sz.Y); zoom < z {
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zoom = z
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}
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// If the configured centre puts the camera out of bounds, move it.
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centre := s.Camera.Centre
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// Camera frame currently Rectangle{ centre ± (screen/(2*zoom)) }.
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sw2, sh2 := float64(s.Camera.game.ScreenWidth/2), float64(s.Camera.game.ScreenHeight/2)
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swz, shz := int(sw2/zoom), int(sh2/zoom)
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if centre.X-swz < br.Min.X {
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centre.X = br.Min.X + swz
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}
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if centre.Y-shz < br.Min.Y {
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centre.Y = br.Min.Y + shz
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}
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if centre.X+swz > br.Max.X {
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centre.X = br.Max.X - swz
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}
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if centre.Y+shz > br.Max.Y {
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centre.Y = br.Max.Y - shz
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}
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// Apply other options
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opts.Filter = s.Camera.Filter
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// Compute common matrix (parts independent of parallax, which is step 1).
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// Moving centre to the origin happens per component.
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var comm ebiten.GeoM
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// 2. Zoom (this is also where rotation would be)
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comm.Scale(zoom, zoom)
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// 3. Move the origin to the centre of screen space.
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comm.Translate(sw2, sh2)
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// 4. Apply transforms from the caller.
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comm.Concat(opts.GeoM)
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// Draw everything.
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for _, i := range s.Components {
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d, ok := i.(Drawer)
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if !ok {
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continue
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}
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pf := 1.0
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if s, ok := i.(ParallaxScaler); ok {
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pf = s.ParallaxFactor()
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}
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var geom ebiten.GeoM
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// 1. Move centre to the origin, subject to parallax factor
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geom.Translate(-float64(centre.X)*pf, -float64(centre.Y)*pf)
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geom.Concat(comm)
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opts.GeoM = geom
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d.Draw(screen, opts)
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}
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}
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// Prepare does an initial Z-order sort.
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@ -58,8 +125,13 @@ func (s *Scene) sortByDrawOrder() {
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})
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}
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// Scan returns all immediate subcomponents.
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func (s *Scene) Scan() []interface{} { return s.Components }
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// Scan returns all immediate subcomponents (including the camera, if not nil).
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func (s *Scene) Scan() []interface{} {
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if s.Camera != nil {
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return append(s.Components, s.Camera)
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}
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return s.Components
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}
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// Scene returns itself.
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func (s *Scene) Scene() *Scene { return s }
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Binary file not shown.
8
main.go
8
main.go
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@ -33,10 +33,7 @@ func main() {
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Root: &engine.Scene{
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ID: "root",
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Components: []interface{}{
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&engine.Camera{
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ID: "game_camera",
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Scene: &engine.SceneRef{Path: "assets/level1.gobz"},
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},
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&engine.SceneRef{Path: "assets/level1.gobz"},
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&engine.DebugToast{ID: "toast", Pos: image.Pt(0, 15)},
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engine.PerfDisplay{},
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},
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@ -100,6 +97,9 @@ func writeLevel1() {
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level1 := &engine.Scene{
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ID: "level_1",
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Bounds: engine.Bounds(image.Rect(-32, -32, 320+32, 240+32)),
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Camera: &engine.Camera{
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ID: "game_camera",
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},
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Components: []interface{}{
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&engine.Fill{
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Color: color.Gray{100},
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