457 lines
12 KiB
Go
457 lines
12 KiB
Go
package engine
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import (
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"encoding/gob"
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"errors"
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"fmt"
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"image"
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"io/fs"
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"log"
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"reflect"
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"sync"
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"time"
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"drjosh.dev/gurgle/geom"
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"github.com/hajimehoshi/ebiten/v2"
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"github.com/hajimehoshi/ebiten/v2/ebitenutil"
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)
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var _ interface {
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Disabler
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Hider
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Identifier
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Updater
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Scanner
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} = &Game{}
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var (
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errNilComponent = errors.New("nil component")
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errNilParent = errors.New("nil parent")
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)
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func init() {
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gob.Register(&Game{})
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}
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// Game implements the ebiten methods using a collection of components. One
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// component must be the designated root component - usually a scene of some
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// kind.
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type Game struct {
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Disables
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Hides
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ScreenSize image.Point
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Root interface{} // typically a *Scene or SceneRef though
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Projection geom.IntProjection
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VoxelScale geom.Float3
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dbmu sync.RWMutex
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byID map[string]Identifier // Named components by ID
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byAB map[abKey]map[interface{}]struct{} // Ancestor/behaviour index
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drawList drawList // draw list :|
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par map[interface{}]interface{} // par[x] is parent of x
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}
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// Draw draws everything.
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func (g *Game) Draw(screen *ebiten.Image) {
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if g.Hidden() {
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return
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}
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// Hiding a parent component should hide the child objects, and the
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// transform applied to a child should be the cumulative transform of all
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// parents as well.
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// cache memoises the results for each component.
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type state struct {
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hidden bool
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opts ebiten.DrawImageOptions
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}
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cache := map[interface{}]state{
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g: {hidden: false},
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}
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// Draw everything in g.drawList, where not hidden (itself or any parent)
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for _, d := range g.drawList.list {
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// Is d hidden itself?
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if h, ok := d.(Hider); ok && h.Hidden() {
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cache[d] = state{hidden: true}
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continue // skip drawing
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}
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// Walk up g.par to find the nearest state in accum.
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var st state
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stack := []interface{}{d}
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for p := g.par[d]; ; p = g.par[p] {
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if s, found := cache[p]; found {
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st = s
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break
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}
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stack = append(stack, p)
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}
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// Unwind the stack, accumulating state along the way.
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for len(stack) > 0 {
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l1 := len(stack) - 1
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p := stack[l1]
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stack = stack[:l1]
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if h, ok := p.(Hider); ok {
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st.hidden = st.hidden || h.Hidden()
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}
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if st.hidden {
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cache[p] = state{hidden: true}
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continue
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}
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// p is not hidden, so compute its cumulative opts.
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if tf, ok := p.(Transformer); ok {
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st.opts = concatOpts(tf.Transform(), st.opts)
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}
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cache[p] = st
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}
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// Skip drawing if hidden.
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if st.hidden {
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continue
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}
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d.Draw(screen, &st.opts)
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}
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if true {
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// Infodump about draw list
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ebitenutil.DebugPrintAt(screen, fmt.Sprintf("len(drawList.list) = %d", len(g.drawList.list)), 0, 30)
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ebitenutil.DebugPrintAt(screen, fmt.Sprintf("len(drawList.rev) = %d", len(g.drawList.list)), 0, 45)
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}
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}
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// Layout returns the configured screen width/height.
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func (g *Game) Layout(outsideWidth, outsideHeight int) (w, h int) {
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return g.ScreenSize.X, g.ScreenSize.Y
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}
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// Update updates everything.
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func (g *Game) Update() error {
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if g.Disabled() {
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return nil
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}
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// Need to do a similar trick for Draw: disabling a parent object should
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// disable the child objects.
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// cache memoises the disabled state for each component.
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cache := map[interface{}]bool{
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g: false,
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}
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// Update everything that is not disabled.
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// TODO: do it in a fixed order? map essentially randomises iteration order
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for u := range g.Query(g.Ident(), UpdaterType) {
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// Skip g (note g satisfies Updater, so this would infinitely recurse)
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if u == g {
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continue
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}
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// Is u disabled itself?
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if d, ok := u.(Disabler); ok && d.Disabled() {
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cache[u] = true
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continue
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}
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// Walk up g.par to find the nearest state in accum.
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var st bool
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stack := []interface{}{u}
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for p := g.par[u]; ; p = g.par[p] {
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if s, found := cache[p]; found {
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st = s
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break
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}
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stack = append(stack, p)
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}
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// Unwind the stack, accumulating state along the way.
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for len(stack) > 0 {
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l1 := len(stack) - 1
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p := stack[l1]
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stack = stack[:l1]
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if d, ok := p.(Disabler); ok {
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st = st || d.Disabled()
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}
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cache[p] = st
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}
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// Skip updating if disabled.
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if st {
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continue
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}
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if err := u.(Updater).Update(); err != nil {
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return err
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}
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}
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// Sort the draw list (on every frame - this isn't as bad as it sounds)
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//sort.Stable(g.drawList)
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if err := g.drawList.topsort(); err != nil {
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return fmt.Errorf("drawList.topsort: %v", err)
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}
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// Truncate tombstones from the end.
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for i := g.drawList.Len() - 1; i >= 0; i-- {
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if g.drawList.list[i] != (tombstone{}) {
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break
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}
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g.drawList.list = g.drawList.list[:i]
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}
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return nil
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}
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// Ident returns "__GAME__".
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func (g *Game) Ident() string { return "__GAME__" }
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// Component returns the component with a given ID, or nil if there is none.
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// This only returns sensible values for registered components (e.g. after
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// LoadAndPrepare).
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func (g *Game) Component(id string) Identifier {
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g.dbmu.RLock()
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defer g.dbmu.RUnlock()
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return g.byID[id]
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}
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// Parent returns the parent of a given component, or nil if there is none.
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// This only returns sensible values for registered components (e.g. after
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// LoadAndPrepare).
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func (g *Game) Parent(c interface{}) interface{} {
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g.dbmu.RLock()
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defer g.dbmu.RUnlock()
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return g.par[c]
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}
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// Query looks for components having both a given ancestor and implementing
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// a given behaviour (see Behaviors in interface.go). This only returns sensible
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// values after LoadAndPrepare. Note that every component is its own ancestor.
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func (g *Game) Query(ancestorID string, behaviour reflect.Type) map[interface{}]struct{} {
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g.dbmu.RLock()
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defer g.dbmu.RUnlock()
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return g.byAB[abKey{ancestorID, behaviour}]
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}
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// Scan implements Scanner.
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func (g *Game) Scan() []interface{} { return []interface{}{g.Root} }
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// PreorderWalk calls visit with every component and its parent, reachable from
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// the given component via Scan, for as long as visit returns nil. The parent
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// value passed to visit when visiting component will be nil. The parent will be
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// visited before the children.
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func PreorderWalk(component interface{}, visit func(component, parent interface{}) error) error {
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return preorderWalk(component, nil, visit)
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}
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func preorderWalk(component, parent interface{}, visit func(component, parent interface{}) error) error {
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if err := visit(component, parent); err != nil {
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return err
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}
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sc, ok := component.(Scanner)
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if !ok {
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return nil
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}
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for _, c := range sc.Scan() {
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if err := preorderWalk(c, component, visit); err != nil {
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return err
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}
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}
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return nil
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}
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// PostorderWalk calls visit with every component and its parent, reachable from
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// the given component via Scan, for as long as visit returns nil. The parent
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// value passed to visit when visiting component will be nil. The children will
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// be visited before the parent.
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func PostorderWalk(component interface{}, visit func(component, parent interface{}) error) error {
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return preorderWalk(component, nil, visit)
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}
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func postorderWalk(component, parent interface{}, visit func(component, parent interface{}) error) error {
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if sc, ok := component.(Scanner); ok {
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for _, c := range sc.Scan() {
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if err := postorderWalk(c, component, visit); err != nil {
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return err
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}
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}
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}
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return visit(component, parent)
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}
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// LoadAndPrepare first calls Load on all Loaders. Once loading is complete, it
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// builds the component databases and then calls Prepare on every Preparer.
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// LoadAndPrepare must be called before any calls to Component or Query.
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func (g *Game) LoadAndPrepare(assets fs.FS) error {
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if g.VoxelScale == (geom.Float3{}) {
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g.VoxelScale = geom.Float3{X: 1, Y: 1, Z: 1}
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}
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// Load all the Loaders.
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startLoad := time.Now()
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if err := PreorderWalk(g, func(c, _ interface{}) error {
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l, ok := c.(Loader)
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if !ok {
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return nil
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}
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return l.Load(assets)
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}); err != nil {
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return err
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}
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log.Printf("finished loading in %v", time.Since(startLoad))
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// Build the component databases
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startBuild := time.Now()
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g.dbmu.Lock()
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g.byID = make(map[string]Identifier)
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g.byAB = make(map[abKey]map[interface{}]struct{})
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g.drawList.list = nil
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g.drawList.rev = make(map[Drawer]int)
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g.par = make(map[interface{}]interface{})
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if err := PreorderWalk(g, g.register); err != nil {
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return err
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}
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g.dbmu.Unlock()
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log.Printf("finished building db in %v", time.Since(startBuild))
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// Prepare all the Preppers
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startPrep := time.Now()
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for p := range g.Query(g.Ident(), PrepperType) {
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if err := p.(Prepper).Prepare(g); err != nil {
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return err
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}
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}
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log.Printf("finished preparing in %v", time.Since(startPrep))
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return nil
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}
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// Register registers a component into the component database (as the
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// child of a given parent). Passing a nil component or parent is an error.
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// Registering multiple components with the same ID is also an error.
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// Registering a component will recursively register all children found via
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// Scan.
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func (g *Game) Register(component, parent interface{}) error {
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if component == nil {
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return errNilComponent
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}
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if parent == nil && component != g {
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return errNilParent
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}
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g.dbmu.Lock()
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defer g.dbmu.Unlock()
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// walk goes in the right order for registering.
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return preorderWalk(component, parent, g.register)
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}
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func (g *Game) register(component, parent interface{}) error {
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// register in g.byID if needed
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if i, ok := component.(Identifier); ok {
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if id := i.Ident(); id != "" {
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if _, exists := g.byID[id]; exists {
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return fmt.Errorf("duplicate id %q", id)
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}
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g.byID[id] = i
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}
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}
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// register in g.par
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if parent != nil {
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g.par[component] = parent
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}
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// register in g.drawList
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if d, ok := component.(Drawer); ok {
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if _, exists := g.drawList.rev[d]; exists {
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// already registered
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return fmt.Errorf("double registration of %v", d)
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}
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g.drawList.rev[d] = len(g.drawList.list)
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g.drawList.list = append(g.drawList.list, d)
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}
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// register in g.byAB
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ct := reflect.TypeOf(component)
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for _, b := range Behaviours {
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if !ct.Implements(b) {
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continue
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}
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// TODO: better than O(len(path)^2) time and memory?
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for p := component; p != nil; p = g.par[p] {
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id, ok := p.(Identifier)
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if !ok || id.Ident() == "" {
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continue
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}
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k := abKey{id.Ident(), b}
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if g.byAB[k] == nil {
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g.byAB[k] = make(map[interface{}]struct{})
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}
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g.byAB[k][component] = struct{}{}
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}
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}
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return nil
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}
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// Unregister removes the component from the component database.
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// Passing a nil component has no effect. Unregistering a component will
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// recursively unregister child components found via Scan.
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func (g *Game) Unregister(component interface{}) {
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if component == nil {
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return
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}
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g.dbmu.Lock()
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postorderWalk(component, nil, func(c, _ interface{}) error {
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g.unregister(c)
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return nil
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})
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g.dbmu.Unlock()
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}
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func (g *Game) unregister(component interface{}) {
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// unregister from g.byAB, using g.par to trace the path
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ct := reflect.TypeOf(component)
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for _, b := range Behaviours {
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if !ct.Implements(b) {
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continue
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}
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for p := component; p != nil; p = g.par[p] {
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id, ok := p.(Identifier)
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if !ok || id.Ident() == "" {
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continue
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}
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k := abKey{id.Ident(), b}
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if g.byAB[k] == nil {
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continue
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}
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delete(g.byAB[k], component)
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}
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}
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// unregister from g.par
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delete(g.par, component)
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// unregister from g.drawList
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if d, ok := component.(Drawer); ok {
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if i, found := g.drawList.rev[d]; found {
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g.drawList.list[i] = tombstone{}
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delete(g.drawList.rev, d)
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}
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}
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// unregister from g.byID if needed
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if id, ok := component.(Identifier); ok && id.Ident() != "" {
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delete(g.byID, id.Ident())
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}
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}
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// --------- Helper stuff ---------
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type abKey struct {
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ancestor string
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behaviour reflect.Type
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}
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// concatOpts returns the combined options (as though a was applied and then b).
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func concatOpts(a, b ebiten.DrawImageOptions) ebiten.DrawImageOptions {
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a.ColorM.Concat(b.ColorM)
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a.GeoM.Concat(b.GeoM)
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if b.CompositeMode != 0 {
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a.CompositeMode = b.CompositeMode
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}
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if b.Filter != 0 {
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a.Filter = b.Filter
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}
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return a
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}
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