first "mvp"

- Crop empty space around sprite
- Add github action to build
- Correct dragging algorithm

.github/workflows/main.yml

@@ -0,0 +1,39 @@
+name: Go package
+
+on: [push]
+
+jobs:
+  build:
+
+    runs-on: ['ubuntu-latest', 'windows-latest', 'macos-latest']
+    steps:
+      - uses: actions/checkout@v3
+
+      - name: Set up Go
+        uses: actions/setup-go@v3
+        with:
+          go-version: 1.18
+
+      - name: Build
+        run: go build -v ./...
+
+      - name: Upload linux
+        if: runner.os == 'Linux'
+        uses: actions/upload-artifact@v3
+        with:
+          name: shark-linux
+          path: shark
+
+      - name: Upload macOS
+        if: runner.os == 'macOS'
+        uses: actions/upload-artifact@v3
+        with:
+          name: shark-osx
+          path: shark
+
+      - name: Upload Windows
+        if: runner.os == 'Windows'
+        uses: actions/upload-artifact@v3
+        with:
+          name: shark-win.exe
+          path: shark.exe

.gitignore

@@ -1 +1,2 @@
 /shark
+/shark.exe

main.go

@@ -12,6 +12,9 @@ import (
 	"github.com/hajimehoshi/ebiten/v2/inpututil"
 )
 
+const SPRITE_X = 100
+const SPRITE_Y = 123
+
 //go:embed sprites/idle/*
 var IdleSprites embed.FS
 
@@ -33,14 +36,28 @@ type Game struct {
 	Ticks             int
 	ShouldResetToIdle bool
 	IsDragging        bool
-	StartMouseX       int
-	StartMouseY       int
+	PreviousMousePos  Vector
+	WinStartPos       Vector
+	MouseStartPos     Vector
 }
 
-func GlobalCursorPosition() (x, y int) {
+type Vector struct{ x, y int }
+
+func CreateVector(x, y int) Vector {
+	return Vector{x, y}
+}
+
+func (this Vector) Add(that Vector) Vector {
+	return Vector{this.x + that.x, this.y + that.y}
+}
+func (this Vector) Subtract(that Vector) Vector {
+	return Vector{this.x - that.x, this.y - that.y}
+}
+
+func GlobalCursorPosition() Vector {
 	cx, cy := ebiten.CursorPosition()
 	wx, wy := ebiten.WindowPosition()
-	return cx + wx, cy + wy
+	return Vector{cx + wx, cy + wy}
 }
 
 func (g *Game) Update() error {
@@ -57,27 +74,23 @@ func (g *Game) Update() error {
 		g.CurrentAnim = Drag
 		g.Ticks = 0
 		g.CurrentFrame = 0
-		g.StartMouseX, g.StartMouseY = GlobalCursorPosition()
-		return nil
+		g.PreviousMousePos = GlobalCursorPosition()
+		g.WinStartPos = CreateVector(ebiten.WindowPosition())
+		g.MouseStartPos = GlobalCursorPosition()
 	}
 	if inpututil.IsMouseButtonJustReleased(ebiten.MouseButtonLeft) {
 		g.IsDragging = false
 		g.CurrentAnim = Idle
 		g.Ticks = 0
 		g.CurrentFrame = 0
-		return nil
 	}
 
-	if g.IsDragging {
-		currentX, currentY := GlobalCursorPosition()
-		diffX := currentX - g.StartMouseX
-		diffY := currentY - g.StartMouseY
-
-		wx, wy := ebiten.WindowPosition()
-		ebiten.SetWindowPosition(wx+diffX, wy+diffY)
-
-		g.StartMouseX, g.StartMouseY = GlobalCursorPosition()
+	mousePos := GlobalCursorPosition()
+	if g.IsDragging && mousePos != g.PreviousMousePos {
+		newWinPos := g.WinStartPos.Add(mousePos.Subtract(g.MouseStartPos))
+		ebiten.SetWindowPosition(newWinPos.x, newWinPos.y)
 	}
+	g.PreviousMousePos = mousePos
 
 	g.Ticks++
 	if g.Ticks < 10 {
@@ -107,19 +120,21 @@ func (g *Game) Draw(screen *ebiten.Image) {
 				),
 			)
 	*/
-	debugStr := ""
-	if ebiten.IsMouseButtonPressed(ebiten.MouseButtonLeft) {
-		debugStr += "Dragging\n"
-	}
-	if ebiten.IsMouseButtonPressed(ebiten.MouseButtonRight) {
-		debugStr += "Right click\n"
-	}
-	ebitenutil.DebugPrint(screen, debugStr)
 	screen.DrawImage(g.CurrentAnim.Frames[g.CurrentFrame], nil)
+	/*
+		debugStr := ""
+		if ebiten.IsMouseButtonPressed(ebiten.MouseButtonLeft) {
+			debugStr += "Dragging\n"
+		}
+		if ebiten.IsMouseButtonPressed(ebiten.MouseButtonRight) {
+			debugStr += "Right click\n"
+		}
+		ebitenutil.DebugPrint(screen, debugStr)
+	*/
 }
 
 func (g *Game) Layout(outsideWidth, outsideHeight int) (w, h int) {
-	return outsideWidth / 3, outsideHeight / 3
+	return SPRITE_X, SPRITE_Y
 }
 
 func NewAnim(sprites embed.FS, subdir string) *Anim {
@@ -149,7 +164,7 @@ func main() {
 	var game Game
 	game.CurrentAnim = Idle
 
-	ebiten.SetWindowSize(500, 540)
+	ebiten.SetWindowSize(SPRITE_X*3, SPRITE_Y*3)
 	ebiten.SetWindowTitle("Shark!")
 	ebiten.SetWindowDecorated(false)
 	ebiten.SetScreenTransparent(true)