remove demo game

scene.transition.go

@@ -0,0 +1,61 @@
+package pncdsl
+
+import (
+	"image/color"
+
+	"github.com/hajimehoshi/ebiten/v2"
+	"github.com/hajimehoshi/ebiten/v2/vector"
+)
+
+// transition is a fade-to-black overlay used between scene swaps.
+type transition struct {
+	active   bool
+	t        float64
+	duration float64
+	out      bool // true: fading to black; false: fading from black
+	onMid    func()
+}
+
+func (t *transition) start(onMid func()) {
+	t.active = true
+	t.out = true
+	t.t = 0
+	t.duration = 0.25
+	t.onMid = onMid
+}
+
+func (t *transition) update(dt float64) {
+	if !t.active {
+		return
+	}
+	t.t += dt
+	if t.t >= t.duration {
+		if t.out {
+			if t.onMid != nil {
+				t.onMid()
+				t.onMid = nil
+			}
+			t.out = false
+			t.t = 0
+			return
+		}
+		t.active = false
+	}
+}
+
+func (t *transition) draw(dst *ebiten.Image, w, h int) {
+	if !t.active {
+		return
+	}
+	alpha := t.t / t.duration
+	if !t.out {
+		alpha = 1 - alpha
+	}
+	if alpha < 0 {
+		alpha = 0
+	} else if alpha > 1 {
+		alpha = 1
+	}
+	c := color.RGBA{0, 0, 0, uint8(alpha * 255)}
+	vector.DrawFilledRect(dst, 0, 0, float32(w), float32(h), c, false)
+}