A shape added with HC:add*() would be reintroduced to the spatial hash
after HC:remove() when any of shape:move(), shape:rotate() or
shape:scale() was called after the removal.
Collecting collisions and then reporting leads to confusing behavior
when a previous collision callback resolved the collision, e.g.
platforms in jump in runs pushing the player upwards when standing on
two platforms at the same time.
Shape must have at least two functions:
- shape:bbox()
must return an axis aligned bounding box of the shape
- shape:collidesWith(other)
must return false, ... if the two shapes do not collide
must return true, sx, sy if the two shapes collide, where sx,sy is the
separation vector from from shape to other.
Convex shapes can use the supplied GJK algorithm. In that case the shape
must implement shape:support(dx,dy) which returns the point of the shape
that lies furthest in the direction of dx,dy.
Polygon triangulation bug:
In some cases Kongs triangulation algorithm produces triangles
with collinear points. The Polygon constructor removes one of
these and throws an error because there are not enough vertices.
Checking if the current points in a triangulation step are
collinear and discarding those triangles fixes the problem.
Class-commons lets you use any supporting class system as
backend for HC.
Add SpatialHash:draw() for debug purposes.
