MoveZ, etc

engine/actor.go

@@ -2,14 +2,10 @@ package engine
 
 import (
 	"encoding/gob"
-	"image"
 )
 
 // Ensure Actor satisfies interfaces.
-var _ interface {
-	Bounder
-	Prepper
-} = &Actor{}
+var _ Prepper = &Actor{}
 
 func init() {
 	gob.Register(&Actor{})
@@ -21,17 +17,14 @@ func init() {
 // Actor handles basic movement.
 type Actor struct {
 	CollisionDomain  string // id of component to look for colliders inside of
-	Pos             image.Point
-	Size            image.Point
+	Pos, Size        Point3
+	xRem, yRem, zRem float64
 
-	xRem, yRem float64
 	game *Game
 }
 
-func (a *Actor) BoundingRect() image.Rectangle { return image.Rectangle{a.Pos, a.Pos.Add(a.Size)} }
-
-func (a *Actor) CollidesAt(p image.Point) bool {
-	bounds := image.Rectangle{Min: p, Max: p.Add(a.Size)}
+func (a *Actor) CollidesAt(p Point3) bool {
+	bounds := Box{Min: p, Max: p.Add(a.Size)}.XY() // TODO: 3D collision
 	for c := range a.game.Query(a.CollisionDomain, ColliderType) {
 		if c.(Collider).CollidesWith(bounds) {
 			return true
@@ -49,7 +42,7 @@ func (a *Actor) MoveX(dx float64, onCollide func()) {
 	a.xRem -= float64(move)
 	sign := sign(move)
 	for move != 0 {
-		if a.CollidesAt(a.Pos.Add(image.Pt(sign, 0))) {
+		if a.CollidesAt(a.Pos.Add(Pt3(sign, 0, 0))) {
 			if onCollide != nil {
 				onCollide()
 			}
@@ -69,7 +62,7 @@ func (a *Actor) MoveY(dy float64, onCollide func()) {
 	a.yRem -= float64(move)
 	sign := sign(move)
 	for move != 0 {
-		if a.CollidesAt(a.Pos.Add(image.Pt(0, sign))) {
+		if a.CollidesAt(a.Pos.Add(Pt3(0, sign, 0))) {
 			if onCollide != nil {
 				onCollide()
 			}
@@ -80,6 +73,26 @@ func (a *Actor) MoveY(dy float64, onCollide func()) {
 	}
 }
 
+func (a *Actor) MoveZ(dz float64, onCollide func()) {
+	a.yRem += dz
+	move := int(a.zRem + 0.5)
+	if move == 0 {
+		return
+	}
+	a.zRem -= float64(move)
+	sign := sign(move)
+	for move != 0 {
+		if a.CollidesAt(a.Pos.Add(Pt3(0, 0, 0))) {
+			if onCollide != nil {
+				onCollide()
+			}
+			return
+		}
+		a.Pos.Z += sign
+		move -= sign
+	}
+}
+
 func (a *Actor) Prepare(g *Game) error {
 	a.game = g
 	return nil

engine/iso.go

@@ -150,6 +150,34 @@ func (b Box) Size() Point3 {
 	return b.Max.Sub(b.Min)
 }
 
+// Back returns an image.Rectangle representing the back of the box, using
+// the given projection π.
+func (b Box) Back(π image.Point) image.Rectangle {
+	b.Max.Z = b.Min.Z
+	return image.Rectangle{
+		Min: b.Min.IsoProject(π),
+		Max: b.Max.IsoProject(π),
+	}
+}
+
+// Front returns an image.Rectangle representing the front of the box, using
+// the given projection π.
+func (b Box) Front(π image.Point) image.Rectangle {
+	b.Min.Z = b.Max.Z
+	return image.Rectangle{
+		Min: b.Min.IsoProject(π),
+		Max: b.Max.IsoProject(π),
+	}
+}
+
+// XY returns the image.Rectangle representing the box if we forgot about Z.
+func (b Box) XY() image.Rectangle {
+	return image.Rectangle{
+		Min: b.Min.XY(),
+		Max: b.Max.XY(),
+	}
+}
+
 // IsoVoxmap implements a voxel map, painted using flat images in 2D.
 type IsoVoxmap struct {
 	ID

engine/sprite.go

@@ -25,7 +25,6 @@ type Sprite struct {
 	FrameOffset image.Point
 	Hidden
 	Sheet Sheet
-	ZOrder
 
 	anim *Anim
 }
@@ -35,6 +34,11 @@ func (s *Sprite) Draw(screen *ebiten.Image, opts *ebiten.DrawImageOptions) {
 	screen.DrawImage(s.Sheet.SubImage(s.anim.Cell()), opts)
 }
 
+// DrawOrder returns the Z position from Actor.Pos, and 0 bias.
+func (s *Sprite) DrawOrder() (int, int) {
+	return s.Actor.Pos.Z, 0
+}
+
 // Scan returns the Actor and the Sheet.
 func (s *Sprite) Scan() []interface{} {
 	return []interface{}{
@@ -54,7 +58,7 @@ func (s *Sprite) SetAnim(a *Anim) {
 
 // Transform returns a translation by the FrameOffset.
 func (s *Sprite) Transform() (opts ebiten.DrawImageOptions) {
-	opts.GeoM.Translate(cfloat(s.Actor.Pos.Add(s.FrameOffset)))
+	opts.GeoM.Translate(cfloat(s.Actor.Pos.XY().Add(s.FrameOffset)))
 	return opts
 }
 

game/aw.go

@@ -4,7 +4,6 @@ import (
 	"encoding/gob"
 	"errors"
 	"fmt"
-	"image"
 	"math"
 
 	"drjosh.dev/gurgle/engine"
@@ -71,7 +70,7 @@ func (aw *Awakeman) Update() error {
 	if ebiten.IsKeyPressed(ebiten.KeyShift) {
 		z = 2.0
 	}
-	aw.camera.PointAt(aw.Sprite.Actor.Pos.Add(aw.Sprite.Actor.Size.Div(2)), z)
+	aw.camera.PointAt(aw.Sprite.Actor.Pos.XY().Add(aw.Sprite.Actor.Size.XY().Div(2)), z)
 	return nil
 }
 
@@ -116,7 +115,7 @@ func (aw *Awakeman) realUpdate() error {
 	ux, uy := aw.vx, aw.vy
 
 	// Has traction?
-	if aw.Sprite.Actor.CollidesAt(aw.Sprite.Actor.Pos.Add(image.Pt(0, 1))) {
+	if aw.Sprite.Actor.CollidesAt(aw.Sprite.Actor.Pos.Add(engine.Pt3(0, 1, 0))) {
 		// Not falling.
 		// Instantly decelerate (AW absorbs all kinetic E in legs, or something)
 		if aw.jumpBuffer > 0 {

main.go

@@ -187,8 +187,8 @@ func writeLevel1() {
 				Sprite: engine.Sprite{
 					Actor: engine.Actor{
 						CollisionDomain: "level_1",
-						Pos:             image.Pt(100, 100),
-						Size:            image.Pt(8, 16),
+						Pos:             engine.Pt3(100, 100, 9),
+						Size:            engine.Pt3(8, 16, 8),
 					},
 					FrameOffset: image.Pt(-1, 0),
 					Sheet: engine.Sheet{
@@ -228,7 +228,6 @@ func writeLevel1() {
 						CellSize: image.Pt(10, 16),
 						Src:      engine.ImageRef{Path: "assets/aw.png"},
 					},
-					ZOrder: 9,
 				},
 			},
 		},