collider now collides with boxes

engine/actor.go

@@ -24,7 +24,7 @@ type Actor struct {
 }
 
 func (a *Actor) CollidesAt(p Point3) bool {
-	bounds := Box{Min: p, Max: p.Add(a.Size)}.XY() // TODO: 3D collision
+	bounds := Box{Min: p, Max: p.Add(a.Size)}
 	for c := range a.game.Query(a.CollisionDomain, ColliderType) {
 		if c.(Collider).CollidesWith(bounds) {
 			return true

engine/box.go

@@ -0,0 +1,65 @@
+package engine
+
+import "image"
+
+// Box describes an axis-aligned rectangular prism.
+type Box struct {
+	Min, Max Point3
+}
+
+// String returns a string representation of b like "(3,4,5)-(6,5,8)".
+func (b Box) String() string {
+	return b.Min.String() + "-" + b.Max.String()
+}
+
+// Empty reports whether the box contains no points.
+func (b Box) Empty() bool {
+	return b.Min.X >= b.Max.X || b.Min.Y >= b.Max.Y || b.Min.Z >= b.Max.Z
+}
+
+// Eq reports whether b and c contain the same set of points. All empty boxes
+// are considered equal.
+func (b Box) Eq(c Box) bool {
+	return b == c || b.Empty() && c.Empty()
+}
+
+// Overlaps reports whether b and c have non-empty intersection.
+func (b Box) Overlaps(c Box) bool {
+	return !b.Empty() && !c.Empty() &&
+		b.Min.X < c.Max.X && c.Min.X < b.Max.X &&
+		b.Min.Y < c.Max.Y && c.Min.Y < b.Max.Y &&
+		b.Min.Z < c.Max.Z && c.Min.Z < b.Max.Z
+}
+
+// Size returns b's width, height, and depth.
+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(),
+	}
+}

engine/interface.go

@@ -49,7 +49,7 @@ type Bounder interface {
 
 // Collider components have tangible form.
 type Collider interface {
-	CollidesWith(image.Rectangle) bool
+	CollidesWith(Box) bool
 }
 
 // Disabler components can be disabled.

engine/iso.go

@@ -3,7 +3,6 @@ package engine
 import (
 	"encoding/gob"
 	"image"
-	"strconv"
 
 	"github.com/hajimehoshi/ebiten/v2"
 )
@@ -32,152 +31,6 @@ func init() {
 	gob.Register(&IsoVoxelSide{})
 }
 
-// Point3 is a an element of int^3.
-type Point3 struct {
-	X, Y, Z int
-}
-
-// Pt3(x, y, z) is shorthand for Point3{x, y, z}.
-func Pt3(x, y, z int) Point3 {
-	return Point3{x, y, z}
-}
-
-// String returns a string representation of p like "(3,4,5)".
-func (p Point3) String() string {
-	return "(" + strconv.Itoa(p.X) + "," + strconv.Itoa(p.Y) + "," + strconv.Itoa(p.Z) + ")"
-}
-
-// XY applies the Z-forgetting projection. (It returns just X and Y.)
-func (p Point3) XY() image.Point {
-	return image.Point{p.X, p.Y}
-}
-
-// Add performs vector addition.
-func (p Point3) Add(q Point3) Point3 {
-	return Point3{p.X + q.X, p.Y + q.Y, p.Z + q.Z}
-}
-
-// Sub performs vector subtraction.
-func (p Point3) Sub(q Point3) Point3 {
-	return p.Add(q.Neg())
-}
-
-// CMul performs componentwise multiplication.
-func (p Point3) CMul(q Point3) Point3 {
-	return Point3{p.X * q.X, p.Y * q.Y, p.Z * q.Z}
-}
-
-// Mul performs scalar multiplication.
-func (p Point3) Mul(k int) Point3 {
-	return Point3{p.X * k, p.Y * k, p.Z * k}
-}
-
-// CDiv performs componentwise division.
-func (p Point3) CDiv(q Point3) Point3 {
-	return Point3{p.X / q.X, p.Y / q.Y, p.Z / q.Z}
-}
-
-// Div performs scalar division by k.
-func (p Point3) Div(k int) Point3 {
-	return Point3{p.X / k, p.Y / k, p.Z / k}
-}
-
-// Neg returns the vector pointing in the opposite direction.
-func (p Point3) Neg() Point3 {
-	return Point3{-p.X, -p.Y, -p.Z}
-}
-
-// Coord returns the components of the vector.
-func (p Point3) Coord() (x, y, z int) {
-	return p.X, p.Y, p.Z
-}
-
-// IsoProject performs isometric projection of a 3D coordinate into 2D.
-//
-// If π.X = 0, the x returned is p.X; similarly for π.Y and y.
-// Otherwise, x projects to x + z/π.X and y projects to y + z/π.Y.
-func (p Point3) IsoProject(π image.Point) image.Point {
-	/*
-		I'm using the π character because I'm a maths wanker.
-
-		Dividing is used because there's little reason for an isometric
-		projection in a game to exaggerate the Z position.
-
-		Integers are used to preserve that "pixel perfect" calculation in case
-		you are making the next Celeste.
-	*/
-	q := image.Point{p.X, p.Y}
-	if π.X != 0 {
-		q.X += p.Z / π.X
-	}
-	if π.Y != 0 {
-		q.Y += p.Z / π.Y
-	}
-	return q
-}
-
-// Box describes an axis-aligned rectangular prism.
-type Box struct {
-	Min, Max Point3
-}
-
-// String returns a string representation of b like "(3,4,5)-(6,5,8)".
-func (b Box) String() string {
-	return b.Min.String() + "-" + b.Max.String()
-}
-
-// Empty reports whether the box contains no points.
-func (b Box) Empty() bool {
-	return b.Min.X >= b.Max.X || b.Min.Y >= b.Max.Y || b.Min.Z >= b.Max.Z
-}
-
-// Eq reports whether b and c contain the same set of points. All empty boxes
-// are considered equal.
-func (b Box) Eq(c Box) bool {
-	return b == c || b.Empty() && c.Empty()
-}
-
-// Overlaps reports whether b and c have non-empty intersection.
-func (b Box) Overlaps(c Box) bool {
-	return !b.Empty() && !c.Empty() &&
-		b.Min.X < c.Max.X && c.Min.X < b.Max.X &&
-		b.Min.Y < c.Max.Y && c.Min.Y < b.Max.Y &&
-		b.Min.Z < c.Max.Z && c.Min.Z < b.Max.Z
-}
-
-// Size returns b's width, height, and depth.
-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
@@ -267,7 +120,8 @@ func (v *IsoVoxelSide) DrawOrder() (int, int) {
 	if v.front {
 		z += v.vox.ivm.VoxSize.Z - 1
 	}
-	return z, dot(v.vox.pos.XY(), v.vox.ivm.DrawOrderBias)
+	bias := dot(v.vox.pos.XY(), v.vox.ivm.DrawOrderBias)
+	return z, bias
 }
 
 // Transform offsets the image by either OffsetBack or OffsetFront.

engine/point.go

@@ -0,0 +1,90 @@
+package engine
+
+import (
+	"image"
+	"strconv"
+)
+
+// Point3 is a an element of int^3.
+type Point3 struct {
+	X, Y, Z int
+}
+
+// Pt3(x, y, z) is shorthand for Point3{x, y, z}.
+func Pt3(x, y, z int) Point3 {
+	return Point3{x, y, z}
+}
+
+// String returns a string representation of p like "(3,4,5)".
+func (p Point3) String() string {
+	return "(" + strconv.Itoa(p.X) + "," + strconv.Itoa(p.Y) + "," + strconv.Itoa(p.Z) + ")"
+}
+
+// XY applies the Z-forgetting projection. (It returns just X and Y.)
+func (p Point3) XY() image.Point {
+	return image.Point{p.X, p.Y}
+}
+
+// Add performs vector addition.
+func (p Point3) Add(q Point3) Point3 {
+	return Point3{p.X + q.X, p.Y + q.Y, p.Z + q.Z}
+}
+
+// Sub performs vector subtraction.
+func (p Point3) Sub(q Point3) Point3 {
+	return p.Add(q.Neg())
+}
+
+// CMul performs componentwise multiplication.
+func (p Point3) CMul(q Point3) Point3 {
+	return Point3{p.X * q.X, p.Y * q.Y, p.Z * q.Z}
+}
+
+// Mul performs scalar multiplication.
+func (p Point3) Mul(k int) Point3 {
+	return Point3{p.X * k, p.Y * k, p.Z * k}
+}
+
+// CDiv performs componentwise division.
+func (p Point3) CDiv(q Point3) Point3 {
+	return Point3{p.X / q.X, p.Y / q.Y, p.Z / q.Z}
+}
+
+// Div performs scalar division by k.
+func (p Point3) Div(k int) Point3 {
+	return Point3{p.X / k, p.Y / k, p.Z / k}
+}
+
+// Neg returns the vector pointing in the opposite direction.
+func (p Point3) Neg() Point3 {
+	return Point3{-p.X, -p.Y, -p.Z}
+}
+
+// Coord returns the components of the vector.
+func (p Point3) Coord() (x, y, z int) {
+	return p.X, p.Y, p.Z
+}
+
+// IsoProject performs isometric projection of a 3D coordinate into 2D.
+//
+// If π.X = 0, the x returned is p.X; similarly for π.Y and y.
+// Otherwise, x projects to x + z/π.X and y projects to y + z/π.Y.
+func (p Point3) IsoProject(π image.Point) image.Point {
+	/*
+		I'm using the π character because I'm a maths wanker.
+
+		Dividing is used because there's little reason for an isometric
+		projection in a game to exaggerate the Z position.
+
+		Integers are used to preserve that "pixel perfect" calculation in case
+		you are making the next Celeste.
+	*/
+	q := image.Point{p.X, p.Y}
+	if π.X != 0 {
+		q.X += p.Z / π.X
+	}
+	if π.Y != 0 {
+		q.Y += p.Z / π.Y
+	}
+	return q
+}

engine/solid.go

@@ -2,7 +2,6 @@ package engine
 
 import (
 	"encoding/gob"
-	"image"
 )
 
 var _ Collider = SolidRect{}
@@ -13,9 +12,9 @@ func init() {
 
 type SolidRect struct {
 	ID
-	Bounds
+	Box
 }
 
-func (s SolidRect) CollidesWith(r image.Rectangle) bool {
+func (s SolidRect) CollidesWith(r Box) bool {
-	return s.BoundingRect().Overlaps(r)
+	return s.Box.Overlaps(r)
 }

engine/tiles.go

@@ -47,13 +47,13 @@ type Tilemap struct {
 }
 
 // CollidesWith implements Collider.
-func (t *Tilemap) CollidesWith(r image.Rectangle) bool {
+func (t *Tilemap) CollidesWith(b Box) bool {
 	if t.Ersatz {
 		return false
 	}
 
 	// Probe the map at all tilespace coordinates overlapping the rect.
-	r = r.Sub(t.Offset)
+	r := b.XY().Sub(t.Offset) // TODO: pretend tilemap is a plane in 3D?
 	min := cdiv(r.Min, t.Sheet.CellSize)
 	max := cdiv(r.Max.Sub(image.Pt(1, 1)), t.Sheet.CellSize) // NB: fencepost
 

engine/walls.go

@@ -39,13 +39,13 @@ type Wall struct {
 }
 
 // CollidesWith implements a tilerange collosion check, similar to Tilemap.
-func (w *Wall) CollidesWith(r image.Rectangle) bool {
+func (w *Wall) CollidesWith(b Box) bool {
 	if w.Ersatz {
 		return false
 	}
 
 	// Probe the map at all tilespace coordinates overlapping the rect.
-	r = r.Sub(w.Offset)
+	r := b.XY().Sub(w.Offset)
 	min := cdiv(r.Min, w.UnitSize)
 	max := cdiv(r.Max.Sub(image.Pt(1, 1)), w.UnitSize) // NB: fencepost
 

main.go

@@ -171,15 +171,15 @@ func writeLevel1() {
 			},
 			&engine.SolidRect{
 				ID:  "ceiling",
-				Bounds: engine.Bounds(image.Rect(0, -1, 320, 0)),
+				Box: engine.Box{Min: engine.Pt3(0, -1, 0), Max: engine.Pt3(320, 0, 100)},
 			},
 			&engine.SolidRect{
 				ID:  "left_wall",
-				Bounds: engine.Bounds(image.Rect(-1, 0, 0, 240)),
+				Box: engine.Box{Min: engine.Pt3(-1, 0, 0), Max: engine.Pt3(0, 240, 100)},
 			},
 			&engine.SolidRect{
 				ID:  "right_wall",
-				Bounds: engine.Bounds(image.Rect(320, 0, 321, 240)),
+				Box: engine.Box{Min: engine.Pt3(320, 0, 0), Max: engine.Pt3(321, 240, 100)},
 			},
 			&game.Awakeman{
 				CameraID: "game_camera",