void Boids::MakeMoves( const GameState currentState, size_t teamIndex, std::vector<Move>& outMoves ) {
const Team& team = currentState.Teams[teamIndex];
const glm::vec2 teamAvaragePosition = CalculateAvaragePosition( currentState, teamIndex );
// Choose a new apple for the team as its goal if the previous goal-apple was taken.
if ( !currentState.IsTileWalkable( m_GoalTile ) || currentState.Board[m_GoalTile.y][m_GoalTile.x] != Tile::Apple ) {
m_GoalTile = currentState.FindClosestApple( teamAvaragePosition ); // TODO: Figure out another goal if there are no apples.
}
// Decide for each snake which direction it should move.
for ( size_t snakeIndex = 0; snakeIndex < team.Snakes.size(); ++snakeIndex ) {
const Snake& snake = team.Snakes[snakeIndex];
const glm::ivec2& snakeTile = snake.Segments[0];
const glm::vec2 snakePosition = glm::vec2( snakeTile );
// Calculate which moves the snake can make without dying this turn. // TODO: Take into account that tails move.
std::vector<Move> safeMoves;
if ( currentState.IsTileWalkable( snakeTile + glm::ivec2( 0, -1 ) ) ) {
safeMoves.push_back( Move::Up );
}
if ( currentState.IsTileWalkable( snakeTile + glm::ivec2( 0, 1 ) ) ) {
safeMoves.push_back( Move::Down );
}
if ( currentState.IsTileWalkable( snakeTile + glm::ivec2( -1, 0 ) ) ) {
safeMoves.push_back( Move::Left );
}
if ( currentState.IsTileWalkable( snakeTile + glm::ivec2( 1, 0 ) ) ) {
safeMoves.push_back( Move::Right );
}
// If there is only one safe move it is chosen, and we continue to the next snake instead.
if ( safeMoves.size() == 1 ) {
outMoves[snakeIndex] = safeMoves.front();
continue;
}
// Calculate and accumulate the effect of each rule that makes up boids (plus some extra ones specialized for the application snake/nibbles).
glm::vec2 newSnakeDirection = glm::vec2( 0.0f );
newSnakeDirection += RULE_FACTOR_GOAL * GoalDirection( currentState, teamIndex, snakeIndex );
newSnakeDirection += RULE_FACTOR_LOCAL_GOAL * LocalGoalDirection( currentState, teamIndex, snakeIndex );
newSnakeDirection += RULE_FACTOR_SEPERATION * SeperationDirection( currentState, teamIndex, snakeIndex );
if ( team.Snakes.size() > 1 ) { // Only apply team-rules if the snake is not alone in the team.
newSnakeDirection += RULE_FACTOR_COHESION * CohesionDirection( currentState, teamIndex, snakeIndex );
newSnakeDirection += RULE_FACTOR_ALIGNMENT * AlignmentDirection( currentState, teamIndex, snakeIndex );
newSnakeDirection += RULE_FACTOR_TEAM_SEPERATION * TeamSeperationDirection( currentState, teamIndex, snakeIndex );
}
outMoves[snakeIndex] = ChooseSafeMove( newSnakeDirection, outMoves[snakeIndex], safeMoves );
}
}
glm::vec2 Boids::LocalGoalDirection( const GameState& gameState, const size_t teamIndex, const size_t snakeIndex ) const {
const Team& team = gameState.Teams[teamIndex];
const Snake& snake = team.Snakes[snakeIndex];
const glm::vec2& snakePosition = snake.Segments[0];
// Find and calculate distance to closest apple.
const glm::ivec2 closestApple = gameState.FindClosestApple( snakePosition );
const glm::vec2 vectorToClosestApple = glm::vec2( closestApple ) - snakePosition;
const float distanceToClosestAppleSqrd = glm::dot( vectorToClosestApple, vectorToClosestApple );
// Return direction to closest apple if it is within detection distance.
if ( distanceToClosestAppleSqrd <= LOCAL_GOAL_DISTANCE * LOCAL_GOAL_DISTANCE ) {
if ( distanceToClosestAppleSqrd != 0.0f ) {
return vectorToClosestApple / distanceToClosestAppleSqrd; // Direction to the local goal (closest apple), diminishes with distance.
}
}
return glm::vec2( 0.0f ); // Apple not found (or on the same tile as the snake for some reason).
}
