public WorldObject(Intersection intersection)
{
X = intersection.X;
Y = intersection.Y;
IntersectsWith = intersection.IntersectsWith;
Distance = intersection.Distance;
}
/// <summary>
/// Checks if certain coordinates are outside of the level boundaries
/// </summary>
/// <param name="coordinates">coordinates on grid (not array indexes)</param>
/// <param name="grid">the grid to search in</param>
/// <returns></returns>
private bool IsOutOfBounds(Intersection coordinates, int[][] grid)
{
Point gridCell = CoordsToGrid(coordinates);
return gridCell.Y < 0 || gridCell.Y >= grid.Length
|| gridCell.X < 0 || gridCell.X >= grid[0].Length;
}
/// <summary>
/// Use raycasting to find the nearest intersection with an object on the grid at a specified angle
/// </summary>
/// <param name="angle"></param>
/// <param name="grid"></param>
/// <returns></returns>
private Intersection FindIntersection(Angle angle, int[][] grid)
{
bool foundX = false;
bool foundY = false;
// Distance from current point to next intersection for X-axis and Y-axis
double angleTan = Math.Tan(angle.ToRadians());
double deltaX = wallSize / angleTan;
double deltaY = wallSize * angleTan;
// Correct the deltaX/deltaY values
if (angle.FacingSouth())
{
deltaX = -deltaX;
}
if (angle.FacingEast())
{
deltaY = -deltaY;
}
// Location of horizontal (X) and vertical (Y) intersections
Intersection intersectionX = null;
Intersection intersectionY = null;
// Distance to next horizontal intersection
if (angle.FacingNorth() || angle.FacingSouth())
{
while (intersectionX == null || (!foundX && !IsOutOfBounds(intersectionX, grid)))
{
if (intersectionX == null)
{
intersectionX = new Intersection();
intersectionX.IntersectsWith = IntersectionAxe.Xaxe;
intersectionX.Y = Math.Floor(player.Position.Y / wallSize) * wallSize;
intersectionX.Y += angle.FacingNorth() ? -0.001 : wallSize;
intersectionX.X = player.Position.X + (player.Position.Y - intersectionX.Y) / angleTan;
}
else
{
// Target the next horizontal intersection
intersectionX.X = intersectionX.X + deltaX;
intersectionX.Y += angle.FacingNorth() ? -wallSize : wallSize;
}
foundX = ContainsItem(intersectionX, grid);
}
}
// Distance to next vertical intersection
if (angle.FacingWest() || angle.FacingEast())
{
while (intersectionY == null || (!foundY && !IsOutOfBounds(intersectionY, grid)))
{
if (intersectionY == null)
{
intersectionY = new Intersection();
intersectionY.IntersectsWith = IntersectionAxe.Yaxe;
intersectionY.X = Math.Floor(player.Position.X / wallSize) * wallSize;
intersectionY.X += angle.FacingWest() ? -0.001 : wallSize;
intersectionY.Y = player.Position.Y + (player.Position.X - intersectionY.X) * angleTan;
}
else
{
// Target the next vertical intersection
intersectionY.X += angle.FacingWest() ? -wallSize : wallSize;
intersectionY.Y = intersectionY.Y + deltaY;
}
foundY = ContainsItem(intersectionY, grid);
}
}
// Determine which wall is nearest to our starting point
if (!(IsOutOfBounds(intersectionX, grid) && IsOutOfBounds(intersectionY, grid)))
{
Intersection intersection = ChooseNearest(angle, intersectionX, intersectionY);
// Calculate distance from player to the intersection
intersection.SetDistance(player.Position, angle);
return intersection;
}
return null;
}
/// <summary>
/// Converts world coordinates to grid coordinates (eg. 10,10 = 0,0)
/// </summary>
/// <param name="coordinates">world coordinates</param>
/// <returns>grid coordinates</returns>
private Point CoordsToGrid(Intersection coordinates)
{
return new Point((int)(coordinates.X / wallSize), (int)(coordinates.Y / wallSize));
}
/// <summary>
/// Checks if certain coordinates on the specified grid contain an item
/// </summary>
/// <param name="coordinates">coordinates on map (not array indexes)</param>
/// <param name="grid">the grid to search in</param>
/// <returns></returns>
private bool ContainsItem(Intersection coordinates, int[][] grid)
{
Point gridCell = CoordsToGrid(coordinates);
return (gridCell.Y >= 0 && gridCell.Y < grid.Length)
&& (gridCell.X >= 0 && gridCell.X < grid[0].Length)
&& grid[gridCell.Y][gridCell.X] != 0;
}
/// <summary>
/// Returns the intersection that is nearest to the player
/// </summary>
/// <param name="angle"></param>
/// <param name="intersectionX">Horizontal intersection point</param>
/// <param name="intersectionY">Vertical intersection point</param>
/// <returns></returns>
private Intersection ChooseNearest(Angle angle, Intersection intersectionX, Intersection intersectionY)
{
// If either horizontal or vertical intersection was left empty we can simply return the other one
if (intersectionX == null)
{
return intersectionY;
}
else if (intersectionY == null)
{
return intersectionX;
}
else
{
// Determine which intersection is nearest
double distanceX = Math.Abs(Math.Abs(player.Position.X - intersectionX.X) / Math.Cos(angle.ToRadians()));
double distanceY = Math.Abs(Math.Abs(player.Position.X - intersectionY.X) / Math.Cos(angle.ToRadians()));
if (distanceX < distanceY)
{
return intersectionX;
}
else
{
return intersectionY;
}
}
}
