lints, loading fix

engine/debug.go

@@ -52,6 +52,7 @@ type DebugToast struct {
 	Text  string
 }
 
+// Draw uses DebugPrintAt to draw d.Text at the position d.Pos.
 func (d *DebugToast) Draw(screen *ebiten.Image, _ *ebiten.DrawImageOptions) {
 	ebitenutil.DebugPrintAt(screen, d.Text, d.Pos.X, d.Pos.Y)
 }
@@ -60,12 +61,14 @@ func (d *DebugToast) String() string {
 	return fmt.Sprintf("DebugToast@%v", d.Pos)
 }
 
+// Toast sets the text to appear for 2 seconds.
 func (d *DebugToast) Toast(text string) {
 	d.Text = text
 	d.Timer = 120
 	d.Hides = false
 }
 
+// Update hides the toast text once the timer is exhausted.
 func (d *DebugToast) Update() error {
 	if d.Hides = d.Timer <= 0; !d.Hides {
 		d.Timer--
@@ -78,6 +81,7 @@ type PerfDisplay struct {
 	Hides
 }
 
+// Draw uses DebugPrint to print the TPS and FPS in the top-left.
 func (p PerfDisplay) Draw(screen *ebiten.Image, _ *ebiten.DrawImageOptions) {
 	ebitenutil.DebugPrint(screen, fmt.Sprintf("TPS: %0.2f  FPS: %0.2f", ebiten.CurrentTPS(), ebiten.CurrentFPS()))
 }

engine/drawdfs.go

@@ -43,6 +43,8 @@ type DrawDFS struct {
 	game *Game
 }
 
+// Draw draws all descendant components (that are not managed by some other
+// DrawManager) in a pre-order traversal.
 func (d *DrawDFS) Draw(screen *ebiten.Image, opts *ebiten.DrawImageOptions) {
 	stack := []ebiten.DrawImageOptions{*opts}
 	d.game.Query(d, DrawerType,
@@ -81,6 +83,7 @@ func (d *DrawDFS) Draw(screen *ebiten.Image, opts *ebiten.DrawImageOptions) {
 // DrawManager.
 func (DrawDFS) ManagesDrawingSubcomponents() {}
 
+// Prepare saves a reference to g.
 func (d *DrawDFS) Prepare(g *Game) error {
 	d.game = g
 	return nil

engine/fill.go

@@ -39,12 +39,13 @@ func init() {
 // Fill fills the screen with a colour.
 type Fill struct {
 	ID
-	Color color.Color
+	Colour color.Color
 	Hides
 }
 
+// Draw fills the screen with the colour.
 func (f *Fill) Draw(screen *ebiten.Image, opts *ebiten.DrawImageOptions) {
-	screen.Fill(opts.ColorM.Apply(f.Color))
+	screen.Fill(opts.ColorM.Apply(f.Colour))
 }
 
 func (f *Fill) String() string { return "Fill" }

engine/loading.go

@@ -22,19 +22,25 @@ import (
 	"time"
 )
 
+// LoadingSwitch switches between two subcomponents. While After is being
+// loaded asynchronously, During is shown. Once loading is complete, During
+// is hidden and After is shown.
 type LoadingSwitch struct {
-	During Hider
-	After  Hider
+	During, After interface {
+		Disabler
+		Hider
+	}
 
 	assets fs.FS
 }
 
-// Scan only scans s.During, thus, only s.During is loaded by Game directly.
+// Scan only scans s.During. Only s.During is loaded automatically - s.After is
+// loaded asynchronously from Prepare below.
 func (s *LoadingSwitch) Scan(visit VisitFunc) error {
 	return visit(s.During)
 }
 
-// Load stores a copy of assets to use later.
+// Load stores a copy of assets to pass to s.After.Load later.
 func (s *LoadingSwitch) Load(assets fs.FS) error {
 	s.assets = assets
 	return nil
@@ -43,7 +49,11 @@ func (s *LoadingSwitch) Load(assets fs.FS) error {
 // Prepare loads, registers, and prepares.After in a separate goroutine. Once
 // ready, LoadingSwitch hides s.During and shows s.After.
 func (s *LoadingSwitch) Prepare(game *Game) error {
-	go func() {
+	go s.loadAfter(game)
+	return nil
+}
+
+func (s *LoadingSwitch) loadAfter(game *Game) {
 	startLoad := time.Now()
 	if err := game.Load(s.After, s.assets); err != nil {
 		log.Printf("Couldn't load: %v", err)
@@ -51,6 +61,9 @@ func (s *LoadingSwitch) Prepare(game *Game) error {
 	}
 	log.Printf("LoadingSwitch: finished loading in %v", time.Since(startLoad))
 
+	s.After.Disable()
+	s.After.Hide()
+
 	startBuild := time.Now()
 	if err := game.Register(s.After, s); err != nil {
 		log.Printf("Couldn't register: %v", err)
@@ -65,8 +78,8 @@ func (s *LoadingSwitch) Prepare(game *Game) error {
 	log.Printf("LoadingSwitch: finished preparing in %v", time.Since(startPrep))
 
 	// TODO: better scene transitions
+	s.During.Disable()
 	s.During.Hide()
+	s.After.Enable()
 	s.After.Show()
-	}()
-	return nil
 }

engine/solid.go

@@ -28,11 +28,13 @@ func init() {
 	gob.Register(&SolidRect{})
 }
 
+// SolidRect is a minimal implementation of a Collider defined by a single Box.
 type SolidRect struct {
 	ID
 	geom.Box
 }
 
+// CollidesWith reports if r overlaps with s.Box.
 func (s SolidRect) CollidesWith(r geom.Box) bool {
 	return s.Box.Overlaps(r)
 }

engine/tiles.go

@@ -159,6 +159,7 @@ type Tile interface {
 // StaticTile returns a fixed tile index.
 type StaticTile int
 
+// Cell returns s as an int.
 func (s StaticTile) Cell() int { return int(s) }
 
 // AnimatedTile uses an Anim to choose a tile index.
@@ -168,6 +169,7 @@ type AnimatedTile struct {
 	anim *Anim
 }
 
+// Cell returns the value of Cell provided by the animation.
 func (a *AnimatedTile) Cell() int { return a.anim.Cell() }
 
 // Scan visits a.anim.

engine/walls.go

@@ -126,6 +126,7 @@ func (u *WallUnit) Scan(visit VisitFunc) error {
 	return visit(u.Tile)
 }
 
+// Transform returns a translation by the position and offset.
 func (u *WallUnit) Transform() (opts ebiten.DrawImageOptions) {
 	opts.GeoM.Translate(geom.CFloat(
 		geom.CMul(u.pos, u.wall.UnitSize).Add(u.wall.UnitOffset),

example.go

@@ -81,21 +81,21 @@ func main() {
 		Projection: geom.SimpleProjection{},
 		VoxelScale: geom.Float3{
 			// Each voxel counts for this much (Euclidean) space.
-			X: 1,
-			Y: 1,
-			Z: math.Sqrt(3),
+			X: 1, Y: 1, Z: math.Sqrt(3),
 		},
 		Root: &engine.DrawDFS{
 			Child: engine.MakeContainer(
 				&engine.Fill{
 					ID:     "bg_fill",
-					Color: color.Gray{100},
+					Colour: color.Gray{100},
 				},
 				&engine.LoadingSwitch{
-					During: &engine.Billboard{
-						ID:  "loading_screen",
+					During: &engine.Scene{
+						ID: "loading_scene",
+						Child: &engine.Billboard{
 							Src: engine.ImageRef{Path: "assets/loading.png"},
 						},
+					},
 					After: &engine.Camera{
 						ID:    "game_camera",
 						Child: lev1,

example/assets.go

@@ -20,5 +20,6 @@ package example
 
 import "embed"
 
+// Assets is the embedded assets FS.
 //go:embed assets
 var Assets embed.FS

example/aw.go

@@ -65,6 +65,8 @@ type Awakeman struct {
 // Ident returns "awakeman". There should be only one!
 func (aw *Awakeman) Ident() string { return "awakeman" }
 
+// Update updates Awakeman, including capturing input, applying gravity and
+// movement, and repositioning the camera.
 func (aw *Awakeman) Update() error {
 	// TODO: better cheat for noclip
 	if inpututil.IsKeyJustPressed(ebiten.KeyN) {
@@ -257,6 +259,7 @@ func (aw *Awakeman) realUpdate() error {
 	return nil
 }
 
+// Prepare captures necessary references to other game components.
 func (aw *Awakeman) Prepare(game *engine.Game) error {
 	aw.game = game
 	cam, ok := game.Component(aw.CameraID).(*engine.Camera)
@@ -275,6 +278,7 @@ func (aw *Awakeman) Prepare(game *engine.Game) error {
 	return nil
 }
 
+// Scan visits &aw.Sprite.
 func (aw *Awakeman) Scan(visit engine.VisitFunc) error {
 	return visit(&aw.Sprite)
 }

example/bubble.go

@@ -31,6 +31,7 @@ var _ interface {
 	engine.Updater
 } = &Bubble{}
 
+// Bubble implements a single bubble within a simple particle system.
 type Bubble struct {
 	Life   int
 	Sprite engine.Sprite
@@ -38,6 +39,8 @@ type Bubble struct {
 	game *engine.Game
 }
 
+// NewBubble creates a bubble. Before it can be used, the return value needs to
+// be loaded, registered, and prepared.
 func NewBubble(pos geom.Int3) *Bubble {
 	return &Bubble{
 		Life: 60,
@@ -72,6 +75,7 @@ func NewBubble(pos geom.Int3) *Bubble {
 	}
 }
 
+// Scan visits &b.sprite.
 func (b *Bubble) Scan(visit engine.VisitFunc) error {
 	return visit(&b.Sprite)
 }
@@ -80,11 +84,14 @@ func (b *Bubble) String() string {
 	return fmt.Sprintf("Bubble@%v", b.Sprite.Actor.Pos)
 }
 
+// Prepare saves a reference to g.
 func (b *Bubble) Prepare(g *engine.Game) error {
 	b.game = g
 	return nil
 }
 
+// Update moves the bubble randomly, and handles unregistering the bubble when
+// it has "popped".
 func (b *Bubble) Update() error {
 	b.Life--
 	if b.Life <= 0 {

geom/int3.go

@@ -26,7 +26,7 @@ type Int3 struct {
 	X, Y, Z int
 }
 
-// Pt3(x, y, z) is shorthand for Int3{x, y, z}.
+// Pt3 returns Int3{x, y, z}.
 func Pt3(x, y, z int) Int3 {
 	return Int3{x, y, z}
 }

geom/matrix.go

@@ -98,7 +98,7 @@ func (a IntMatrix2x3) Apply(v Int3) image.Point {
 // RatMatrix3 implements a 3x3 matrix with rational number entries.
 type RatMatrix3 [3][3]Rat
 
-// IdentityRatMatrix3x4 is the identity matrix for RatMatrix3x4.
+// IdentityRatMatrix3 is the identity matrix for RatMatrix3.
 var IdentityRatMatrix3 = RatMatrix3{
 	0: [3]Rat{0: {1, 1}},
 	1: [3]Rat{1: {1, 1}},

geom/misc.go

@@ -40,6 +40,11 @@ func Dot(p, q image.Point) int {
 	return p.X*q.X + p.Y*q.Y
 }
 
+// CSign applies Sign componentwise to the Point.
+func CSign(p image.Point) image.Point {
+	return image.Point{X: Sign(p.X), Y: Sign(p.Y)}
+}
+
 // ---------- Some other helpers ----------
 
 // FSign returns the sign of the float64 (-1, 0, or 1).

geom/polygon.go

@@ -21,6 +21,7 @@ import (
 	"math"
 )
 
+// Cardinal directions, as used in the return from PolygonExtrema.
 const (
 	East = iota
 	North

geom/projection.go

@@ -54,6 +54,7 @@ func (SimpleProjection) Project(z int) image.Point { return image.Pt(0, z) }
 // Projection uses two floats to define a custom projection.
 type Projection struct{ X, Y float64 }
 
+// Sign returns the componentwise sign of π.
 func (π Projection) Sign() image.Point {
 	return image.Pt(int(FSign(π.X)), int(FSign(π.Y)))
 }
@@ -71,7 +72,8 @@ func (π Projection) Project(z int) image.Point {
 // be used in e.g. a diametric projection (IntProjection{X:0, Y:2}).
 type IntProjection image.Point
 
-func (π IntProjection) Sign() image.Point { return image.Point(π) }
+// Sign returns CSign(π).
+func (π IntProjection) Sign() image.Point { return CSign(image.Point(π)) }
 
 // Project returns (z/π.X, z/π.Y), unless π.X or π.Y are 0, in which case that
 // component is zero

geom/spline.go

@@ -51,7 +51,7 @@ func (s *LinearSpline) Prepare() error {
 	return nil
 }
 
-// Interpolate, given x, returns y where (x,y) is a point on the spline.
+// Interpolate returns y where (x,y) is a point on the spline.
 // If x is outside the spline, it extrapolates from either the first or
 // last segments of the spline.
 func (s *LinearSpline) Interpolate(x float64) float64 {
@@ -236,9 +236,9 @@ func (s *CubicSpline) Prepare() error {
 	return nil
 }
 
-// Interpolate, given x, returns y where (x,y) is a point on the spline.
-// If x is outside the spline, it extrapolates from either the first or
-// last segments of the spline.
+// Interpolate returns y where (x,y) is a point on the spline.
+// If x is outside the spline, it extrapolates from the first or last point
+// together with s.Preslope or s.Postslope.
 func (s *CubicSpline) Interpolate(x float64) float64 {
 	N := len(s.Points)
 	if x < s.Points[0].X {