public void Update(GameTime gameTime)
{
CurrentTime = gameTime;
var currentFrameBodies = Bodies.ToList();
//Update each body.
foreach (var body in currentFrameBodies)
{
//Check if the body moved. If it did, mark as dirty and update delta position.
//If not, just update its sensors.
Vector2 deltaPosition = body.Speed * gameTime.ElapsedGameTime.Milliseconds;
if (deltaPosition.X != 0 || deltaPosition.Y != 0)
{
MarkAsDirty(body, deltaPosition);
}
else
{
UpdateBodySensors(body);
}
//Apply gravity if not on ground.
body.Speed += Gravity * body.GravityScale *
gameTime.ElapsedGameTime.Milliseconds;
}
//Update dirty bodies.
foreach (var pair in dirtyBodies)
{
PhysicBody body = pair.Key;
Vector2 translation = pair.Value;
Vector2 penetration = Vector2.Zero;
//Body to tile collision.
bool collided = false;
if (body.IsTangible)
{
collided = HandleTileCollisionY(body, translation.Y, out penetration.Y);
}
body.Position.Y += translation.Y - penetration.Y;
if (body.IsTangible)
{
collided |= HandleTileCollisionX(body, translation.X, out penetration.X);
}
body.Position.X += translation.X - penetration.X;
//Tilemap collision response.
if (collided)
{
TileMapCollisionInfo info = new TileMapCollisionInfo();
info.GameTime = CurrentTime;
info.Penetration = penetration;
body.TileMapCollision(info);
}
//Body-to-body collision testing.
foreach (var other in currentFrameBodies)
{
collided = (body.MaskBits & other.CategoryBits) != 0 && (other.MaskBits & body.CategoryBits) != 0 &&
body != other && body.WorldBounds.Intersects(other.WorldBounds, out penetration);
if (collided)
{
if (Math.Abs(penetration.X) > Math.Abs(penetration.Y))
{
penetration.X = 0;
}
else
{
penetration.Y = 0;
}
if (body.IsTangible && other.Type == CollisionTypes.Solid)
{
body.Position -= penetration;
if (penetration.Y * body.Speed.Y > 0)
{
body.Speed.Y = 0;
}
else if (penetration.X * body.Speed.X > 0)
{
body.Speed.X = 0;
}
BodyCollisionInfo infoOther = new BodyCollisionInfo();
infoOther.GameTime = CurrentTime;
infoOther.Penetration = -penetration;
infoOther.CollidingBody = body;
other.BodyCollision(infoOther);
}
BodyCollisionInfo info = new BodyCollisionInfo();
info.GameTime = CurrentTime;
info.Penetration = penetration;
info.CollidingBody = other;
body.BodyCollision(info);
}
}
//Update sensors.
UpdateBodySensors(body);
}
dirtyBodies.Clear();
//Update global sensors.
foreach (var sensor in Sensors)
{
sensor.State = CheckSolid(sensor.Area, sensor.MaskBits, sensor.CategoryBits);
}
}
internal void TileMapCollision(TileMapCollisionInfo info)
{
TileMapCollisionEvent?.Invoke(info);
}
