Atlas

_examples/atlas/atlas.go

@@ -0,0 +1,64 @@
+package main
+
+import "github.com/firefly-zero/firefly-go/firefly"
+
+func init() {
+	firefly.Boot = boot
+	firefly.Render = render
+}
+
+var (
+	atlas = firefly.NewAtlas(16, 16)
+
+	knight = atlas.Sprite(0, 0)
+	wall   = atlas.Sprite(2, 0)
+	cat    = atlas.Sprite(3, 0)
+	key    = atlas.Sprite(4, 0)
+	door   = atlas.Sprite(0, 1)
+)
+
+var frame = 0
+
+func boot() {
+	atlas.Load("atlas")
+}
+
+func render() {
+	firefly.ClearScreen(firefly.ColorBlack)
+
+	w := 16
+	h := 16
+
+	// top wall
+	wall.Draw(firefly.P(2*w, 2*h))
+	wall.Draw(firefly.P(3*w, 2*h))
+	wall.Draw(firefly.P(4*w, 2*h))
+	wall.Draw(firefly.P(5*w, 2*h))
+	wall.Draw(firefly.P(6*w, 2*h))
+
+	// bottom wall
+	wall.Draw(firefly.P(2*w, 6*h))
+	wall.Draw(firefly.P(3*w, 6*h))
+	door.Draw(firefly.P(4*w, 6*h))
+	wall.Draw(firefly.P(5*w, 6*h))
+	wall.Draw(firefly.P(6*w, 6*h))
+
+	// left wall
+	wall.Draw(firefly.P(2*w, 2*h))
+	wall.Draw(firefly.P(2*w, 3*h))
+	wall.Draw(firefly.P(2*w, 4*h))
+	wall.Draw(firefly.P(2*w, 5*h))
+	wall.Draw(firefly.P(2*w, 6*h))
+
+	// right wall
+	wall.Draw(firefly.P(6*w, 2*h))
+	wall.Draw(firefly.P(6*w, 3*h))
+	wall.Draw(firefly.P(6*w, 4*h))
+	wall.Draw(firefly.P(6*w, 5*h))
+	wall.Draw(firefly.P(6*w, 6*h))
+
+	// characters and items
+	knight.Draw(firefly.P(3*w, 4*h))
+	cat.Draw(firefly.P(5*w, 4*h))
+	key.Draw(firefly.P(4*w, 5*h))
+}

_examples/atlas/firefly.toml

@@ -0,0 +1,7 @@
+author_id = "demo"
+app_id = "go-atlas"
+author_name = "Demo"
+app_name = "Atlas Demo (Go)"
+
+[files]
+atlas = { path = "atlas.png" }

_examples/atlas/go.mod

@@ -0,0 +1,9 @@
+module atlas
+
+go 1.24.0
+
+replace github.com/firefly-zero/firefly-go => ../../
+
+require github.com/firefly-zero/firefly-go v0.10.0
+
+require github.com/orsinium-labs/tinymath v1.1.0 // indirect

_examples/atlas/go.sum

@@ -0,0 +1,4 @@
+github.com/orsinium-labs/tinymath v1.0.0 h1:Uzp3GmjWIBxMObx4MQi9ACDu4Q8WKjSRakB1OMo9Bu0=
+github.com/orsinium-labs/tinymath v1.0.0/go.mod h1:WPXX6ei3KSXG7JfA03a+ekCYaY9SWN4I+JRl2p6ck+A=
+github.com/orsinium-labs/tinymath v1.1.0 h1:KomdsyLHB7vE3f1nRAJF2dyf1m/gnM2HxfTeV1vS5UA=
+github.com/orsinium-labs/tinymath v1.1.0/go.mod h1:WPXX6ei3KSXG7JfA03a+ekCYaY9SWN4I+JRl2p6ck+A=

firefly/callbacks.go

@@ -27,37 +27,45 @@ var (
 )
 
 //go:export boot
-func boot() { //nolint
+func boot() {
 	if Boot != nil {
 		Boot()
 	}
 }
 
 //go:export update
-func update() { //nolint
+func update() {
 	if Update != nil {
 		Update()
 	}
 }
 
 //go:export render
-func render() { //nolint
+func render() {
 	if Render != nil {
 		Render()
 	}
 }
 
 //go:export before_exit
-func beforeExit() { //nolint
+func beforeExit() {
 	if BeforeExit != nil {
 		BeforeExit()
 	}
 }
 
 //go:export cheat
-func cheat(c, v int32) int32 { //nolint
+func cheat(c, v int32) int32 {
 	if Cheat != nil {
 		return int32(Cheat(int(c), int(v)))
 	}
 	return 0
 }
+
+var (
+	_ = boot
+	_ = update
+	_ = render
+	_ = beforeExit
+	_ = cheat
+)

firefly/graphics.go

@@ -566,6 +566,46 @@ func (c Canvas) Image() Image {
 	return Image(c)
 }
 
+// Helper for working with spritesheets.
+//
+// Constructed by [NewAtlas].
+type Atlas struct {
+	img        Image
+	spriteSize Size
+}
+
+// Create a new [Atlas] with the given sprite dimensions.
+func NewAtlas(spriteW, spriteH int) Atlas {
+	return Atlas{spriteSize: S(spriteW, spriteH)}
+}
+
+// Set the underlying spritesheet image for the atlas.
+//
+// Should be called before any [Sprite.Draw].
+// The best is to call it once from [Boot].
+func (a *Atlas) Load(path string) {
+	a.img = LoadImage(path, nil)
+}
+
+// Create a reference to a sprite within the atlas.
+func (a *Atlas) Sprite(row, col int) Sprite {
+	pos := P(row*a.spriteSize.W, col*a.spriteSize.H)
+	return Sprite{atlas: a, pos: pos}
+}
+
+type Sprite struct {
+	atlas *Atlas
+	pos   Point
+}
+
+// Render the sprite at the given position.
+//
+// Make sure to call [Atlas.Load] first.
+func (s Sprite) Draw(p Point) {
+	sub := s.atlas.img.Sub(s.pos, s.atlas.spriteSize)
+	sub.Draw(p)
+}
+
 // Fill the whole frame with the given color.
 func ClearScreen(c Color) {
 	clearScreen(int32(c))