// Checks for collisions between the character and the level's tiles, and handles these collisions when needed.
void HandleTileCollisions(Vector2 previousPosition)
{
isGrounded = false;
standingOnIceTile = false;
standingOnHotTile = false;
// determine the range of tiles to check
Rectangle bbox = BoundingBoxForCollisions;
Point topLeftTile = level.GetTileCoordinates(new Vector2(bbox.Left, bbox.Top)) - new Point(1, 1);
Point bottomRightTile = level.GetTileCoordinates(new Vector2(bbox.Right, bbox.Bottom)) + new Point(1, 1);
for (int y = topLeftTile.Y; y <= bottomRightTile.Y; y++)
{
for (int x = topLeftTile.X; x <= bottomRightTile.X; x++)
{
Tile.Type tileType = level.GetTileType(x, y);
// ignore empty tiles
if (tileType == Tile.Type.Empty)
{
continue;
}
// ignore platform tiles if the player is standing below them
Vector2 tilePosition = level.GetCellPosition(x, y);
if (tileType == Tile.Type.Platform && localPosition.Y > tilePosition.Y && previousPosition.Y > tilePosition.Y)
{
continue;
}
// if there's no intersection with the tile, ignore this tile
Rectangle tileBounds = new Rectangle((int)tilePosition.X, (int)tilePosition.Y, Level.TileWidth, Level.TileHeight);
if (!tileBounds.Intersects(bbox))
{
continue;
}
// calculate how large the intersection is
Rectangle overlap = CollisionDetection.CalculateIntersection(bbox, tileBounds);
// if the x-component is smaller, treat this as a horizontal collision
if (overlap.Width < overlap.Height)
{
if ((velocity.X >= 0 && bbox.Center.X < tileBounds.Left) || // right wall
(velocity.X <= 0 && bbox.Center.X > tileBounds.Right)) // left wall
{
localPosition.X = previousPosition.X;
velocity.X = 0;
}
}
// otherwise, treat this as a vertical collision
else
{
if (velocity.Y >= 0 && bbox.Center.Y < tileBounds.Top && overlap.Width > 6) // floor
{
isGrounded = true;
velocity.Y = 0;
localPosition.Y = tileBounds.Top;
// check the surface type: are we standing on a hot tile or an ice tile?
Tile.SurfaceType surface = level.GetSurfaceType(x, y);
if (surface == Tile.SurfaceType.Hot)
{
standingOnHotTile = true;
}
else if (surface == Tile.SurfaceType.Ice)
{
standingOnIceTile = true;
}
}
else if (velocity.Y <= 0 && bbox.Center.Y > tileBounds.Bottom && overlap.Height > 2) // ceiling
{
localPosition.Y = previousPosition.Y;
velocity.Y = 0;
}
}
}
}
}
