Add battery levels and indicator

game/game.go

@@ -147,6 +147,7 @@ type Racer struct {
 	Position Position
 	StartPos Position
 	Kinetics Kinetics
+	Battery  Battery
 }
 
 type Kinetics struct {
@@ -180,6 +181,10 @@ func NewState() State {
 					Lane: i,
 					Pos:  j * (Steps / numRacers),
 				},
+				Battery: Battery{
+					Capacity: baseCharge,
+					Charge:   baseCharge,
+				},
 			}
 			r.Position = r.StartPos
 			racers = append(racers, r)
@@ -199,8 +204,9 @@ func NewState() State {
 }
 
 const (
-	Steps     = 50
+	Steps      = 80
-	numRacers = 5
+	numRacers  = 3
 	NumTeams   = 8
 	NumLanes   = NumTeams
+	baseCharge = 4
 )

game/physics.go

@@ -8,6 +8,11 @@ func accelerate(r Racer) Racer {
 		r.Kinetics.A = MaxA
 	}
 
+	if r.Kinetics.A > r.Battery.Charge {
+		r.Kinetics.A = r.Battery.Charge
+	}
+	r.Battery.Charge -= r.Kinetics.A
+
 	r.Kinetics.V += r.Kinetics.A
 	if r.Kinetics.V > MaxV {
 		r.Kinetics.V = MaxV
@@ -51,6 +56,6 @@ func collide(pos, lane int, s State) interface{} {
 const (
 	baseAccel    = 1
 	MaxA         = 1
-	MaxV         = 3
+	MaxV         = 4
 	PassDistance = 2
 )

gfx/gfx.go

@@ -163,6 +163,23 @@ func renderRacer(ctx context, oldRacer, racer game.Racer, active bool, c pixel.R
 	bounds := pic.Bounds()
 	sprite := pixel.NewSprite(pic, bounds)
 	sprite.DrawColorMask(ctx.w, pixel.IM.Moved(pos).ScaledXY(pos, pixel.Vec{2, 2}), c)
+
+	im := imdraw.New(nil)
+	for i := 0; i < racer.Battery.Capacity; i++ {
+		pos := pos
+		pos.X -= racerWidth
+		pos.Y -= racerWidth
+		w := 4.0
+		pos.X += (w * 2) * float64(i)
+		im.Color = colornames.Yellow
+		im.Push(pos)
+		var lw float64
+		if i > racer.Battery.Charge {
+			lw = 1
+		}
+		im.Circle(w, lw)
+		im.Draw(ctx.w)
+	}
 }
 
 func renderBaton(pos pixel.Vec, w *pixelgl.Window) {