Skip to content

Commit

Permalink
Allow previous game state to include eliminated snakes. Fixes #19.
Browse files Browse the repository at this point in the history
  • Loading branch information
@bvanvugt
bvanvugt committed Sep 10, 2020
1 parent 5fecc99 commit 92592c2
Show file tree
Hide file tree
Showing 2 changed files with 215 additions and 68 deletions.
174 changes: 117 additions & 57 deletions standard.go
View file
Original file line number Diff line number Diff line change
Expand Up @@ -201,6 +201,8 @@ func (r *StandardRuleset) CreateNextBoardState(prevState *BoardState, moves []Sn
nextState.Snakes[i].ID = prevState.Snakes[i].ID
nextState.Snakes[i].Health = prevState.Snakes[i].Health
nextState.Snakes[i].Body = append([]Point{}, prevState.Snakes[i].Body...)
nextState.Snakes[i].EliminatedCause = prevState.Snakes[i].EliminatedCause
nextState.Snakes[i].EliminatedBy = prevState.Snakes[i].EliminatedBy
}

// TODO: Gut check the BoardState?
Expand Down Expand Up @@ -244,67 +246,71 @@ func (r *StandardRuleset) CreateNextBoardState(prevState *BoardState, moves []Sn
}

func (r *StandardRuleset) moveSnakes(b *BoardState, moves []SnakeMove) error {
// Sanity check that all non-eliminated snakes have moves and bodies.
for i := 0; i < len(b.Snakes); i++ {
if len(b.Snakes[i].Body) == 0 {
return errors.New("found snake with zero size body")
snake := &b.Snakes[i]
if snake.EliminatedCause != NotEliminated {
continue
}
}
if len(moves) < len(b.Snakes) {
return errors.New("not enough snake moves")
}
if len(moves) > len(b.Snakes) {
return errors.New("too many snake moves")
}

for _, move := range moves {
var snake *Snake
for i := 0; i < len(b.Snakes); i++ {
if b.Snakes[i].ID == move.ID {
snake = &b.Snakes[i]
if len(snake.Body) == 0 {
return errors.New("found snake with zero size body")
}
moveFound := false
for _, move := range moves {
if snake.ID == move.ID {
moveFound = true
break
}
}
if snake == nil {
return errors.New("snake not found for move")
if !moveFound {
return errors.New("move not provided for snake")
}
}

// Do not move eliminated snakes
for i := 0; i < len(b.Snakes); i++ {
snake := &b.Snakes[i]
if snake.EliminatedCause != NotEliminated {
continue
}

var newHead = Point{}
switch move.Move {
case MoveDown:
newHead.X = snake.Body[0].X
newHead.Y = snake.Body[0].Y + 1
case MoveLeft:
newHead.X = snake.Body[0].X - 1
newHead.Y = snake.Body[0].Y
case MoveRight:
newHead.X = snake.Body[0].X + 1
newHead.Y = snake.Body[0].Y
case MoveUp:
newHead.X = snake.Body[0].X
newHead.Y = snake.Body[0].Y - 1
default:
// Default to UP
var dX int32 = 0
var dY int32 = -1
// If neck is available, use neck to determine last direction
if len(snake.Body) >= 2 {
dX = snake.Body[0].X - snake.Body[1].X
dY = snake.Body[0].Y - snake.Body[1].Y
if dX == 0 && dY == 0 {
dY = -1 // Move up if no last move was made
for _, move := range moves {
if move.ID == snake.ID {
var newHead = Point{}
switch move.Move {
case MoveDown:
newHead.X = snake.Body[0].X
newHead.Y = snake.Body[0].Y + 1
case MoveLeft:
newHead.X = snake.Body[0].X - 1
newHead.Y = snake.Body[0].Y
case MoveRight:
newHead.X = snake.Body[0].X + 1
newHead.Y = snake.Body[0].Y
case MoveUp:
newHead.X = snake.Body[0].X
newHead.Y = snake.Body[0].Y - 1
default:
// Default to UP
var dX int32 = 0
var dY int32 = -1
// If neck is available, use neck to determine last direction
if len(snake.Body) >= 2 {
dX = snake.Body[0].X - snake.Body[1].X
dY = snake.Body[0].Y - snake.Body[1].Y
if dX == 0 && dY == 0 {
dY = -1 // Move up if no last move was made
}
}
// Apply
newHead.X = snake.Body[0].X + dX
newHead.Y = snake.Body[0].Y + dY
}

// Append new head, pop old tail
snake.Body = append([]Point{newHead}, snake.Body[:len(snake.Body)-1]...)
}
// Apply
newHead.X = snake.Body[0].X + dX
newHead.Y = snake.Body[0].Y + dY
}

// Append new head, pop old tail
snake.Body = append([]Point{newHead}, snake.Body[:len(snake.Body)-1]...)
}
return nil
}
Expand All @@ -331,9 +337,13 @@ func (r *StandardRuleset) maybeEliminateSnakes(b *BoardState) error {
return lenI > lenJ
})

// Iterate through snakes checking for eliminations.
// First, iterate over all non-eliminated snakes and eliminate the ones
// that are out of health or have moved out of bounds.
for i := 0; i < len(b.Snakes); i++ {
snake := &b.Snakes[i]
if snake.EliminatedCause != NotEliminated {
continue
}
if len(snake.Body) <= 0 {
return errors.New("snake is length zero")
}
Expand All @@ -347,40 +357,90 @@ func (r *StandardRuleset) maybeEliminateSnakes(b *BoardState) error {
snake.EliminatedCause = EliminatedByOutOfBounds
continue
}
}

// Next, look for any collisions. Note we apply collision eliminations
// after this check so that snakes can collide with each other and be properly eliminated.
type CollisionElimination struct {
ID string
Cause string
By string
}
collisionEliminations := []CollisionElimination{}
for i := 0; i < len(b.Snakes); i++ {
snake := &b.Snakes[i]
if snake.EliminatedCause != NotEliminated {
continue
}
if len(snake.Body) <= 0 {
return errors.New("snake is length zero")
}

// Check for self-collisions first
if r.snakeHasBodyCollided(snake, snake) {
snake.EliminatedCause = EliminatedBySelfCollision
snake.EliminatedBy = snake.ID
collisionEliminations = append(collisionEliminations, CollisionElimination{
ID: snake.ID,
Cause: EliminatedBySelfCollision,
By: snake.ID,
})
continue
}

// Check for body collisions with other snakes second
hasBodyCollided := false
for _, otherIndex := range snakeIndicesByLength {
other := &b.Snakes[otherIndex]
if snake.ID == other.ID {
if other.EliminatedCause != NotEliminated {
continue
}
if r.snakeHasBodyCollided(snake, other) {
snake.EliminatedCause = EliminatedByCollision
snake.EliminatedBy = other.ID
if snake.ID != other.ID && r.snakeHasBodyCollided(snake, other) {
collisionEliminations = append(collisionEliminations, CollisionElimination{
ID: snake.ID,
Cause: EliminatedByCollision,
By: other.ID,
})
hasBodyCollided = true
break
}
}
if snake.EliminatedCause != NotEliminated {
if hasBodyCollided {
continue
}

// Check for head-to-heads last
hasHeadCollided := false
for _, otherIndex := range snakeIndicesByLength {
other := &b.Snakes[otherIndex]
if other.EliminatedCause != NotEliminated {
continue
}
if snake.ID != other.ID && r.snakeHasLostHeadToHead(snake, other) {
snake.EliminatedCause = EliminatedByHeadToHeadCollision
snake.EliminatedBy = other.ID
collisionEliminations = append(collisionEliminations, CollisionElimination{
ID: snake.ID,
Cause: EliminatedByHeadToHeadCollision,
By: other.ID,
})
hasHeadCollided = true
break
}
}
if hasHeadCollided {
continue
}
}

// Apply collision eliminations
for _, elimination := range collisionEliminations {
for i := 0; i < len(b.Snakes); i++ {
snake := &b.Snakes[i]
if snake.ID == elimination.ID {
snake.EliminatedCause = elimination.Cause
snake.EliminatedBy = elimination.By
break
}
}
}

return nil
}

Expand Down
Loading

0 comments on commit 92592c2

Please sign in to comment.