factor out renderProjection

game/env.go

@@ -50,7 +50,7 @@ func randomOpenPosition(ts []Team, os []Obstacle) Position {
 func randomObstacles(teams []Team) []Obstacle {
 	var os []Obstacle
 
-	const numObstacles = 5 * NumTeams
+	const numObstacles = 3 * NumTeams
 	for i := 0; i < numObstacles; i++ {
 		os = append(os, Obstacle{
 			Position: randomOpenPosition(teams, os),

game/game.go

@@ -213,5 +213,5 @@ const (
 	numRacers  = 3
 	NumTeams   = 8
 	NumLanes   = NumTeams
-	baseCharge = 18
+	baseCharge = 16
 )

gfx/gfx.go

@@ -147,37 +147,11 @@ func renderRacer(ctx context, batch *pixel.Batch, oldRacer, racer game.Racer, ac
 		Y: oldPos.Y + ctx.tween*(newPos.Y-oldPos.Y),
 	}
 
-	if active {
-		im := imdraw.New(nil)
-		projC := c
-		alpha := 0.25
-		projC.R *= alpha
-		projC.G *= alpha
-		projC.B *= alpha
-		projC.A = alpha
-		im.Color = projC
-		w := pic.Bounds().W() * 0.65
-
-		ll := pixel.Vec{
-			X: pos.X + w,
-			Y: pos.Y - w,
-		}
-		ur := pixel.Vec{
-			X: pos.X + w*float64(racer.Kinetics.V+1),
-			Y: pos.Y + w,
-		}
-		if ctx.tween < 1 {
-			ur.X = math.Min(ur.X, newPos.X+racerWidth)
-		}
-		ur.X = math.Max(ur.X, ll.X)
-
-		im.Push(ll)
-		im.Push(ur)
-		im.Rectangle(0)
-		im.Draw(batch)
-	}
-
 	bounds := pic.Bounds()
+	if active {
+		renderProjection(ctx, batch, c, bounds, racer.Kinetics, pos, newPos)
+	}
+
 	sprite := pixel.NewSprite(pic, bounds)
 	sprite.DrawColorMask(batch, pixel.IM.Moved(pos).ScaledXY(pos, pixel.Vec{1.7, 1.7}), c)
 
@@ -203,6 +177,36 @@ func renderRacer(ctx context, batch *pixel.Batch, oldRacer, racer game.Racer, ac
 	im2.Draw(batch)
 }
 
+func renderProjection(ctx context, b *pixel.Batch, c pixel.RGBA, bounds pixel.Rect, k game.Kinetics, pos, newPos pixel.Vec) {
+	im := imdraw.New(nil)
+	projC := c
+	alpha := 0.25
+	projC.R *= alpha
+	projC.G *= alpha
+	projC.B *= alpha
+	projC.A = alpha
+	im.Color = projC
+	w := bounds.W() * 0.65
+
+	ll := pixel.Vec{
+		X: pos.X + w,
+		Y: pos.Y - w,
+	}
+	ur := pixel.Vec{
+		X: pos.X + w*float64(k.V+1),
+		Y: pos.Y + w,
+	}
+	if ctx.tween < 1 {
+		ur.X = math.Min(ur.X, newPos.X+racerWidth)
+	}
+	ur.X = math.Max(ur.X, ll.X)
+
+	im.Push(ll)
+	im.Push(ur)
+	im.Rectangle(0)
+	im.Draw(b)
+}
+
 func renderBaton(pos pixel.Vec, b *pixel.Batch) {
 	im := imdraw.New(nil)
 	im.Color = colornames.Bisque