调用一个方法，需要一个派生类实例类型作为基类在VB.NET或C＃

我有两个对象 - 太空船和星球派生自基地Obj。我已经定义了几个类 - Circle，Triangle，Rectangle等，它们都继承自一个Shape类。

I have two objects - "Spaceship" and "Planet" derived from a base "Obj". I have defined several classes - Circle, Triangle, Rectangle, etc. which all inherit from a "Shape" Class.

为了碰撞检测的目的，我想给Obj a shape：

For collision detection purposes, I want to give Obj a "shape":

Dim MyShape as Shape

在宇宙飞船中，我可以：

So that in "Spaceship" I can:

MyShape = new Triangle(blah,blah)

，在Planet中可以：

and in "Planet" I can:

MyShape = new Circle(blah,blah)

我有一个方法（重载几次），它检查不同形状之间的冲突，例如：

I have a method (overloaded several times) which checks for collisions between different shapes, for example:

public shared overloads function intersects(byval circle1 as circle, byval circle2 as circle) as boolean

AND

public shared overloads function intersects(byval circle as circle, byval Tri as triangle) as boolean

当我使用派生类调用函数时，这样工作很好，例如：

This works fine when I call the function using the derived classes, for example:

dim A as new circle(blah, blah)
dim B as new triangle(blah, blah)
return intersects(A,B)

但是当我使用MyShape调用它时，我得到一个错误，因为该方法正在传递一个Shape（而不是派生类型）方法不会有重载。

But when I call it using MyShape, I get an error because the method is being passed a "Shape" (rather than the derived type) which the method does not have an overload for.

我可以通过执行以下操作来解决：

I could solve it by doing something like:

Public Function Translate(byval MyShape1 as Shape, byval MyShape2 as Shape )as boolean
if shape1.gettype = gettype(circle) and shape2.gettype=gettype(circle) then ''//do circle-circle detection
if shape1.gettype = gettype(triangle) and shape2.gettype=gettype(circle) then ''//do triangle-circle detection
End Function

但这看起来很乱。有更好的方法吗？

But that seems messy. Is there a better way?