simple lane changes with weird effects

game/game.go

@@ -73,6 +73,8 @@ func UpdateState(sOld State) State {
 		switch chooseCommand(t, sOld) {
 		case speedUp:
 			accelerate(t.Baton.Holder)
+		case left:
+			t.Baton.Holder.Lane++
 		}
 
 		moveBot(t.Baton.Holder, sOld)
@@ -89,6 +91,10 @@ func UpdateState(sOld State) State {
 }
 
 func chooseCommand(t Team, s State) command {
+	h := t.Baton.Holder
+	if collide(h.Pos+1, h.Lane, s) {
+		return left
+	}
 	return speedUp
 }
 
@@ -96,6 +102,7 @@ type command int
 
 const (
 	speedUp command = iota
+	left
 )
 
 func maybePassBaton(t *Team) {

game/physics.go

@@ -25,13 +25,13 @@ func accelerate(b *Bot) {
 
 func moveBot(b *Bot, s State) {
 	for i := 0; i < b.v; i++ {
-		if !collide(b.id, b.Pos+1, b.Lane, s) {
+		if !collide(b.Pos+1, b.Lane, s) {
 			b.Pos++
 		}
 	}
 }
 
-func collide(id, pos, lane int, s State) bool {
+func collide(pos, lane int, s State) bool {
 	for _, o := range s.Obstacles {
 		if o.Pos == pos && o.Lane == lane {
 			return true

gfx/gfx.go

@@ -29,7 +29,7 @@ func renderBots(s game.State, w *pixelgl.Window, d time.Duration, colors map[*ga
 				im.Color = colors[&s.Teams[i]]
 			}
 
-			pos := lanePos(bot.Pos, i, botWidth, b)
+			pos := lanePos(bot.Pos, bot.Lane, botWidth, b)
 
 			im.Push(pos)