void handleTopDownAdditionalPhysics(PhysicalProperties entityProps, IPhysicsObject entity, IPhysicsObject[] neighbours, GameTime gameTime)
{
// Gravity
if (entityProps.HasGravity)
{
if (entityProps.Velocity.X != 0)
{
var lerped = MathHelper.Lerp(entityProps.Velocity.X, 0, physSettings.Friction);
if (Math.Abs(lerped) < 2)
{
lerped = 0;
}
entityProps.Velocity.X = lerped;
}
if (entityProps.Velocity.Y != 0)
{
var lerped = MathHelper.Lerp(entityProps.Velocity.Y, 0, physSettings.Friction);
if (Math.Abs(lerped) < 2)
{
lerped = 0;
}
entityProps.Velocity.Y = lerped;
}
}
}
public void ApplyPhysics(PhysicalProperties entityProps, IPhysicsObject entity, GameTime gameTime)
{
var delta = (float)gameTime.ElapsedGameTime.TotalSeconds;
var lastPos = entityProps.Position;
var neighbours = new IPhysicsObject[0];
var overlappingObjs = new List <IPhysicsObject>();
// [ Y ]
entityProps.Position.Y += (entityProps.Velocity.Y * delta);
// get new neighbours since objects have probably moved
neighbours = chunkMap.GetNearbyCollidables(entity);
// overlaps
if (entity.IsOverlappingEnabled)
{
var overlaps = neighbours.Where(n => n.IsOverlappingEnabled && entity.OverlapBox.IntersectsWith(n.OverlapBox));
foreach (var overlap in overlaps)
{
overlap.OnOverlapping(entity);
entity.OnOverlapping(overlap);
if (!overlappingObjs.Contains(overlap))
{
overlappingObjs.Add(overlap);
}
}
}
// collision
if (entity.IsCollisionEnabled)
{
var collisions = neighbours.Where(n => n.IsCollisionEnabled && entity.CollisionBox.IntersectsWith(n.CollisionBox));
var hasCollided = false;
foreach (var collision in collisions)
{
if (hasCollided)
{
continue;
}
hasCollided = true;
var up = entityProps.Velocity.Y < 0;
entityProps.Velocity.Y = 0;
if (up)
{
entityProps.Position.Y = collision.CollisionBox.Bottom + 1;
}
else
{
entityProps.Position.Y = collision.CollisionBox.Top - entity.CollisionBox.Height;
}
collision.OnCollision(entity);
entity.OnCollision(collision);
}
}
// [ X ]
entityProps.Position.X = entityProps.Position.X + (entityProps.Velocity.X * delta);
// get new neighbours since objects have probably moved
neighbours = chunkMap.GetNearbyCollidables(entity);
if (entity.IsOverlappingEnabled)
{
// overlaps
var overlaps = neighbours.Where(n => n.IsOverlappingEnabled && entity.OverlapBox.IntersectsWith(n.OverlapBox));
foreach (var overlap in overlaps)
{
overlap.OnOverlapping(entity);
entity.OnOverlapping(overlap);
if (!overlappingObjs.Contains(overlap))
{
overlappingObjs.Add(overlap);
}
}
}
if (entity.IsCollisionEnabled)
{
// collision
var collisions = neighbours.Where(n => n.IsCollisionEnabled && entity.CollisionBox.IntersectsWith(n.CollisionBox));
var hasCollided = false;
foreach (var collision in collisions)
{
if (hasCollided)
{
continue;
}
hasCollided = true;
entityProps.Velocity.X = 0;
entityProps.Position.X = lastPos.X;
collision.OnCollision(entity);
entity.OnCollision(collision);
}
}
// track overlappers
entityProps.OverlappingObjects = overlappingObjs;
// get new neighbours since objects have probably moved
neighbours = chunkMap.GetNearbyCollidables(entity);
switch (physSettings.PhysicsType)
{
case PhysicsType.Platformer:
handlePlatformerAdditionalPhysics(entityProps, entity, neighbours, gameTime);
break;
case PhysicsType.Topdown:
handleTopDownAdditionalPhysics(entityProps, entity, neighbours, gameTime);
break;
}
// [ Chunk map update ]
chunkMap.UpdateEntity(entity);
}
void handlePlatformerAdditionalPhysics(PhysicalProperties entityProps, IPhysicsObject entity, IPhysicsObject[] neighbours, GameTime gameTime)
{
// [ Grounded flag ]
if (physSettings.HasGravity && entity.IsCollisionEnabled)
{
var groundedArea = new RectangleF(
entity.CollisionBox.X + (entity.CollisionBox.Width / 2),
entity.CollisionBox.Y + entity.CollisionBox.Height,
1, 1);
var groundingIntersections = neighbours.Where(n => groundedArea.IntersectsWith(n.CollisionBox));
var triggerOverlapEvents = false;
if (!entityProps.IsGrounded && groundingIntersections.Any())
{
entityProps.IsGrounded = true;
triggerOverlapEvents = true;
}
else if (entityProps.IsGrounded && !groundingIntersections.Any())
{
entityProps.IsGrounded = false;
triggerOverlapEvents = true;
}
if (triggerOverlapEvents)
{
foreach (var groundings in groundingIntersections)
{
groundings.OnOverlapping(entity);
entity.OnOverlapping(groundings);
}
}
}
// [ Gravity ]
if (physSettings.HasGravity && entityProps.HasGravity && !entityProps.IsGrounded)
{
// factors weight into equation
entityProps.Velocity.Y = MathHelper.Clamp(
entityProps.Velocity.Y + (physSettings.Gravity * entityProps.Weight),
-physSettings.TerminalVelocity,
physSettings.TerminalVelocity);
}
// [ Friction ]
if (physSettings.HasGravity &&
physSettings.HasFriction &&
entityProps.IsGrounded &&
entityProps.Velocity.X != 0)
{
var lerped = MathHelper.Lerp(entityProps.Velocity.X, 0, physSettings.Friction);
if (Math.Abs(lerped) < 2)
{
lerped = 0;
}
entityProps.Velocity.X = lerped;
}
}
