First run at basic structure

internal/ui/hud/hud.go

@@ -0,0 +1,52 @@
+package hud
+
+import (
+	"image/color"
+
+	"github.com/hajimehoshi/ebiten/v2"
+
+	"github.com/atridad/BigFeelings/internal/status"
+)
+
+// HUD overlay anchor.
+type Overlay struct {
+	X     int
+	Y     int
+	Color color.Color
+}
+
+// Paints the HUD overlay.
+func (o Overlay) Draw(screen *ebiten.Image, meters []status.Meter) {
+	if o.Color == nil {
+		o.Color = color.White
+	}
+
+	// Instruction text
+	instructions := Column{
+		Elements: []Element{
+			Label{Text: "Systems Prototype", Color: o.Color},
+			Label{Text: "Move with Arrow Keys / WASD", Color: o.Color},
+			Label{Text: "Track resource signals and plan ahead.", Color: o.Color},
+		},
+		Spacing: 7,
+	}
+	instructions.Draw(screen, 16, 16)
+
+	// Meter column
+	meterElements := make([]Element, 0, len(meters))
+	for _, meter := range meters {
+		meterElements = append(meterElements, Column{
+			Elements: []Element{
+				MeterLabel{Meter: meter, Color: o.Color},
+				Bar{Meter: meter, MaxWidth: 180, Height: 8, ShowBorder: false},
+			},
+			Spacing: 2,
+		})
+	}
+
+	meterPanel := Column{
+		Elements: meterElements,
+		Spacing:  16,
+	}
+	meterPanel.Draw(screen, o.X, o.Y)
+}