Dungeon-Delvers/Pathfind.cs at master · CaptainDrewBoy/Dungeon-Delvers · GitHub

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using System;
using Dungeon_Delvers.Managers;
using Dungeon_Delvers.Creatures;
using Microsoft.Xna.Framework;
namespace Dungeon_Delvers;

static class PathFind
{
    public static Directions? BresenhamLine(int x0, int y0, int x1, int y1, int range, Tile[,] tiles)
    {
        if (Math.Sqrt(Math.Pow(x0  - x1, 2) + Math.Pow(y0 - y1, 2)) > range)
        {
            return null;
        }

        bool swap = Math.Abs(y1-y0) > Math.Abs(x1-x0);
        bool oneZeroSwap = false;
        if (swap)
        {
            (x0, y0) = (y0, x0);
            (x1, y1) = (y1, x1);
        }

        if (x0 > x1)
        {
            oneZeroSwap = true;
            (x0, x1) = (x1, x0);
            (y0, y1) = (y1, y0);
        }

        int dx = x1 - x0;
        int dy = Math.Abs(y1 - y0);
        int D = dx / 2;
        int y = y0;
        int ySign;
        if (y0 < y1) ySign = 1;
        else ySign = -1;

        // The first point to move to in order to move towards player
        for (int x = x0; x <= x1; x++)
        {
            if (swap)
            {
                if (tiles[y, x].IsWall) return null;
            }
            else
            {
                if (tiles[x, y].IsWall) return null;
            }

            D -= dy;
            if (D < 0)
            {
                y += ySign;
                D += dx;
            }
        }

        if (swap) // swapping back
        {
            (x0, y0) = (y0, x0);
            (x1, y1) = (y1, x1);
        }

        if (oneZeroSwap)
        {
            (x0, x1) = (x1, x0);
            (y0, y1) = (y1, y0);
        }

        // You might be tempted to claim that the naming of these variables is at best unhelpful.
        // I would be inclined to agree
        Directions direction;
        bool XLessThan = y1 < y0;
        bool XMoreThan = y1 > y0;
        bool YLessThan = x1 < x0;
        bool YMoreThan = x1 > x0;

        if (XLessThan && YLessThan) direction = Directions.UpLeft;
        else if (XMoreThan && YLessThan) direction = Directions.UpRight;
        else if (XLessThan && YMoreThan) direction = Directions.DownLeft;
        else if (XMoreThan && YMoreThan) direction = Directions.DownRight;
        else if (XMoreThan) direction = Directions.Right;
        else if (XLessThan) direction = Directions.Left;
        else if (YMoreThan) direction = Directions.Down;
        else direction = Directions.Up; // YLessThan
        return direction;
    }

    public static Creature? CreatureInDir(Directions direction, Point position, Tile[,] tiles)
    {
        Point movement;
        Tile tile;
        switch (direction)
        {
            case (Directions.UpLeft):
                movement = new Point(-1, -1);
                break;
            case (Directions.UpRight):
                movement = new Point(1, -1);
                break;
            case (Directions.DownLeft):
                movement = new Point(-1, 1);
                break;
            case (Directions.DownRight):
                movement = new Point(1, 1);
                break;
            case (Directions.Up):
                movement = new Point(0, -1);
                break;
            case (Directions.Down):
                movement = new Point(0, 1);
                break;
            case (Directions.Left):
                movement = new Point(-1, 0);
                break;
            default: // Directions.Right
                movement = new Point(1, 0);
                break;
        }

        do
        {
            position += movement;
            tile = tiles[position.Y, position.X];
        } while (!tile.IsWall && tile.Creature == null &&
                position.X < tiles.GetLength(0)-1 && position.X > 0 &&
                position.Y < tiles.GetLength(0)-1 && position.Y > 0);

        return tile.Creature;
    }
}