king.go

package main

import (
	"github.com/hajimehoshi/ebiten/v2"
	"math"
)

type King struct {
	side   Side
	sprite *ebiten.Image
}

func NewKing(side Side) King {
	img := getSprite(side, "King")
	return King{
		side:   side,
		sprite: img,
	}
}

// Sprite implements Piece.
func (k *King) Sprite() *ebiten.Image {
	return k.sprite
}

// IsValidMove implements Piece.
func (k *King) IsValidMove(board *Board, x1 int, y1 int, x2 int, y2 int) bool {
	// Valid King move, if the piece moves from (X1, Y1) to (X2, Y2), the move is valid if and only if |X2-X1|<=1 and |Y2-Y1|<=1.
	other := board.PieceAt(x2, y2)
	return math.Abs(float64(x2-x1)) <= 1 && math.Abs(float64(y2-y1)) <= 1 && (other == nil || k.Side() != other.Side())
}

// Side implements Piece.
func (k *King) Side() Side {
	return k.side
}

var _ Piece = &King{}