public IEnumerable <ICell> GetVisibleCells(Vector2 pov, float radius)
{
var visible = GetCells();
var obstacles = GetCellsOfType(CellType.Tree)
.Where(x => Vector2.Distance(x.Bounds.Center.ToVector2(), pov) < radius);
visible = visible
.Where(x => Vector2.Distance(x.Bounds.Center.ToVector2(), pov) < radius);
var notVisible = new List <ICell>();
foreach (var obstacle in obstacles)
{
var ray = new Ray2(
pov,
Vector2.Subtract(obstacle.BoundingRectangle.Center, pov));
foreach (var cell in visible)
{
if (cell.Equals(obstacle))
{
continue;
}
if (ray.Intersects(cell.BoundingRectangle, out var rayNearDistance, out var rayFarDistance))
{
var distanceToCell = Vector2.Distance(pov, cell.BoundingRectangle.Center);
var distanceToObstacle = Vector2.Distance(pov, obstacle.BoundingRectangle.Center);
if (rayNearDistance >= 0 && rayFarDistance >= 0 &&
distanceToCell > distanceToObstacle)
{
notVisible.Add(cell);
}
}
}
visible = visible.Except(notVisible);
}
return(visible);
}
public static bool Crosses(this Ray2 ray, BoundingRectangle boundingRectangle, out float near, out float far)
{
if (ray.Direction.X < 0 && ray.Direction.Y < 0)
{
if (boundingRectangle.Center.X - boundingRectangle.HalfExtents.X > ray.Position.X ||
boundingRectangle.Center.Y - boundingRectangle.HalfExtents.Y > ray.Position.Y)
{
near = float.NaN;
far = float.NaN;
return(false);
}
BoundingRectangle dummyRect = new BoundingRectangle(
new Point2(2 * ray.Position.X - boundingRectangle.Center.X, 2 * ray.Position.Y - boundingRectangle.Center.Y),
boundingRectangle.HalfExtents);
Ray2 dummyRay = new Ray2(ray.Position, new Vector2(-ray.Direction.X, -ray.Direction.Y));
return(dummyRay.Intersects(dummyRect, out near, out far));
}
if (ray.Direction.X < 0)
{
if (boundingRectangle.Center.X - boundingRectangle.HalfExtents.X > ray.Position.X ||
boundingRectangle.Center.Y + boundingRectangle.HalfExtents.Y < ray.Position.Y)
{
near = float.NaN;
far = float.NaN;
return(false);
}
BoundingRectangle dummyRect = new BoundingRectangle(
new Point2(2 * ray.Position.X - boundingRectangle.Center.X, boundingRectangle.Center.Y),
boundingRectangle.HalfExtents);
Ray2 dummyRay = new Ray2(ray.Position, new Vector2(-ray.Direction.X, ray.Direction.Y));
return(dummyRay.Intersects(dummyRect, out near, out far));
}
if (ray.Direction.Y < 0)
{
if (boundingRectangle.Center.X + boundingRectangle.HalfExtents.X < ray.Position.X ||
boundingRectangle.Center.Y - boundingRectangle.HalfExtents.Y > ray.Position.Y)
{
near = float.NaN;
far = float.NaN;
return(false);
}
BoundingRectangle dummyRect = new BoundingRectangle(
new Point2(boundingRectangle.Center.X, 2 * ray.Position.Y - boundingRectangle.Center.Y),
boundingRectangle.HalfExtents);
Ray2 dummyRay = new Ray2(ray.Position, new Vector2(ray.Direction.X, -ray.Direction.Y));
return(dummyRay.Intersects(dummyRect, out near, out far));
}
if (boundingRectangle.Center.X + boundingRectangle.HalfExtents.X < ray.Position.X ||
boundingRectangle.Center.Y + boundingRectangle.HalfExtents.Y < ray.Position.Y)
{
near = float.NaN;
far = float.NaN;
return(false);
}
return(ray.Intersects(boundingRectangle, out near, out far));
}
public void intersects_point_test() {
var ray = new Ray2(new Point2(2, 1), new Vector2(2, 1));
Assert.False(ray.Intersects(new Point2(-2, -1)));
Assert.False(ray.Intersects(new Point2(0, 0)));
Assert.True(ray.Intersects(new Point2(6, 3)));
Assert.True(ray.Intersects(new Point2(2, 1)));
Assert.True(ray.Intersects(new Point2(4, 2)));
Assert.False(ray.Intersects(new Point2(1, 2)));
}