private bool CheckPolygonGrid(IShape A, Vector2 APos, IShape B, Vector2 BPos, out Contact[] contacts)
{
PolygonShape polygonShapeA = A as PolygonShape;
GridShape gridB = B as GridShape;
Rectangle polygonBoundingBox = polygonShapeA.BoundingBox + APos,
gridBoundingBox = gridB.BoundingBox + BPos;
// test grid bounds
if (!gridBoundingBox.Intersects(polygonBoundingBox))
{
contacts = null;
return(false);
}
Polygon polygonA = new Polygon(polygonShapeA.Shape);
polygonA.Translate(APos);
List <Contact> gridContacts = TestGrid(gridB, BPos, polygonBoundingBox,
(Polygon tilePolygon) => {
SAT.Test(polygonA, tilePolygon, out Contact? tileContact);
return(tileContact);
}
);
if (gridContacts.Count > 0)
{
contacts = gridContacts.ToArray();
return(true);
}
contacts = null;
return(false);
}
private List <Contact> TestGrid(GridShape grid, Vector2 gridPos, Rectangle otherBoundingBox, System.Func <Polygon, Contact?> SAT)
{
List <Contact> contacts = new List <Contact>();
Polygon boxTilePolygon = new Polygon(grid.BoxTilePolygon);
boxTilePolygon.Translate(gridPos);
(int column, int row)start = grid.ConvertPosition(gridPos, otherBoundingBox.TopLeft - Vector2.One),
end = grid.ConvertPosition(gridPos, otherBoundingBox.BottomRight + Vector2.One);
List <Polygon> tilePolygons = new List <Polygon>();
foreach ((int Column, int Row, GridShape.TileShape Shape)tile in grid.Tiles(start, end))
{
tilePolygons.Clear();
if (tile.Shape != null)
{
if (tile.Shape is GridShape.BoxTileShape boxShape)
{
tilePolygons.Add(boxShape.CreateCollisionPolygon(grid, gridPos, tile.Column, tile.Row));
}
else if (tile.Shape is GridShape.PolygonTileShape polygonShape)
{
tilePolygons.AddRange(polygonShape.CreateCollisionPolygons(grid, gridPos, tile.Column, tile.Row));
}
else
{
throw new System.InvalidOperationException($"Unable to find shape '{tile.Shape.GetType().Name}'.");
}
}
Location cell = new Location(tile.Column, tile.Row);
foreach (Polygon tilePolygon in tilePolygons)
{
Contact?contact = SAT(tilePolygon);
if (contact == null)
{
continue;
}
contacts.Add(new Contact(contact.Value.Position, contact.Value.Normal, contact.Value.PenetrationDepth, cell));
}
}
return(contacts);
}
private bool CheckCircleGrid(IShape A, Vector2 APos, IShape B, Vector2 BPos, out Contact[] contacts)
{
CircleShape circleA = A as CircleShape;
GridShape gridB = B as GridShape;
// test grid bounds
Vector2 closestPoint = new Rectangle(BPos, gridB.Size).ClosestPoint(APos);
Vector2 diff = closestPoint - APos;
if (Vector2.Dot(diff, diff) > circleA.Radius * circleA.Radius)
{
contacts = null;
return(false);
}
List <Contact> gridContacts = TestGrid(gridB, BPos, new Rectangle(APos - circleA.Radius, APos + circleA.Radius),
(Polygon tilePolygon) => {
SAT.Test(circleA, APos, tilePolygon, out Contact? tileContact);
if (tileContact == null)
{
return(null);
}
return(new Contact(closestPoint, tileContact.Value.Normal, tileContact.Value.PenetrationDepth, null));
}
);
if (gridContacts.Count > 0)
{
contacts = gridContacts.ToArray();
return(true);
}
contacts = null;
return(false);
}